Advanced Techniques for Replacing Chromium: An Information Exchange November 7-8,1995
Sponsored by:
National Defense Center NDCEE for Environmental Excellence operated by:
Concurrent Technologies Corporation
Co-sponsored by: BIRL OSHA A GENDA P RESENTATIONS Paul Chalmer National Center for Manufacturing Sciences (NCMS) 3025 Boardwalk Ann Arbor, MI 48108-3266 Phone: (3 13) 995-4911 Fax: (313) 995-1150
Final Report of NCMS Alternatives to Chromium Project
The final report of the NCMS Alternatives to Chromium Project is now available to the general public. The Report summarizes performance of 29 chromium free alternatives for conversion coating of aluminum on 5 aluminum alloys. The coatings were tested for salt spray corrosion resistance, paint adhesion, and contact electrical resistivity. An environmental impact study of the alternatives is also included. Mr. Bruce D. Sartwell Surface Chemistry Branch Naval Research Laboratory Washington, DC 20375 Phone: (202) 767-0722 Fax: (202) 767-3321
Overview of ESTCP Project on Replacement of Chromium Electroplating Using Advanced Physical Deposition Technologies
The Environmental Security Technology Certification Program (ESTCP) is managed by the office of the Deputy Under Secretary of Defense for Environmental Security, with the purpose of demonstrating and validating promising innovative technologies that target DOD’S most urgent environmental needs and are projected to pay back the investment within five years through cost savings and improved efficiencies. Projects are awarded on a competitive basis and the project to be described in this presentation was proposed to the ESTCP review board in August with the result that it was highly rated and is expected to be approved for a FY96 start. It has two objectives: (1) To demonstrate and validate HVOF thermal spray and PVD coatings as cost-effective and technologically superior alternatives to hard chromium in maintenance operations at Army, Navy, and Air Force depots, and (2) To demonstrate and validate HVOF and PVD coatings as alternatives to chromium coatings applied by OEM’s on military aircraft components and on piston rings for DOD ground vehicles. The project follows on to the highly successful ARPA project managed by BIRL and includes many of the same participants. Key issues in the project will be obtaining program manager or system command approval for the coatings insertion and transferring the expertise related to deposition of coatings with optimum properties to depot personnel. The presentation will provide more information on project plans, milestones, participants, and funding. John H. Beatty, PhD Corrosion Science Team Leader US Army Research Laboratory, Materials Directorate 102 Maryland Hall Johns Hopkins University Baltimore, MD 21218 Phone: (4 10) 516-4748 Fax: (4 10) 516-5293
Program Name PVD Coatings and Ion Beam Processing as Alternatives to Electroplating Nature of Program Applied Research Funding Agency SERDP/DoD Team Involved Army Research Laboratory, Naval Research Laboratory Other Important Corpus Christi Army Depot, Cherry Point Naval Depot, Basic Agencies/Partners Industrial Research Laboratory, Jet Process Corp., ATCOM, NAWC, and NDCEE
Joint Army/Navy Research to Replace Electroplated Chromium
The Army Research Laboratory and the Naval Research Laboratory are investigating PVD coatings and ion beam techniques to replace electroplated chromium. Two variations on ion-assisted PVD are (1) ion-beam-assisted deposition (IBAD) and (2) magnetron sputtering. The types of coatings to be investigated include TiN, (Ti, Al)N, CrN, Ta, W, and diamond-like carbon, all of which have been previously investigated for corrosion and wear applications. For re-work operations the proposed solution is to rebuild the component using an alternative electroplating technique such as electroless nickel, machine it to final tolerance, and then apply one of the above PVD coatings to provide significant wear and corrosion resistance. Performance testing will include 1) sliding wear tests with realistic loads, speeds, and/or salt spray methods, and 4) low- cycle/high-cycle fatigue, or rolling-contact fatigue, and 5) hot-hardness tests. Glen H. Graham, CEF Oklahoma City Air Logistics Center Propulsion Division, Process Engineering Section OC-ALc/LPPEE 3001 Staff Drive Post 2B 91 Tinker AFB. OK 73145-3034 Phone: (405) 736-5121 Fax: (405) 736-2501
Search for Chromium Plating Substitutes at OC-ALC
The Oklahoma City Air Logistics Center has been trying to find a suitable substitute for Chromium Plating since the mid 1980’s. Early substitutions with a high phosphorus electroless nickel and limitations of that coating will be discussed. The results of brush plating coatings, nickel alloys, and High Velocity plasma spray tests will be given. The current status of Chromiumplating will also be given. Douglas Smith Concurrent Technologies Corporation 1450 Scalp Avenue Johnstown. PA 15904 Phone: (814) 269-2545 Fax: (8 13) 269-2798
Toxic Effects of Hexavalant Chromium
Chromium metal was first isolated in 1798. The chief uses of chromium and chromium compounds are in stainless and alloy steels, refractory products, tanning agents, for leather, pigments, electroplating, catalysts, and in corrosion-resistant products. A wide range of chromium alloys and inorganic chromium alloys are encountered in the workplace. The chromium compounds vary in their toxic and carcinogenic effects. For this reason, it is necessary to divide chromium and its inorganic compounds into a number of groupings, each with recommendations based on available toxicological and epidemiological evidence. Water-soluble hexavalent chromium compounds have a TLV-TWA of 0.05 mg/m3. This is considered adequate to reduce potential for irritation of the respiratory tract and possible kidney and liver damage. Certain water-insoluble hexavalent chromium compounds have a TLV-TWA of 0.05 mg/m3 and have the designation as a Al confirmed human carcinogen. Chromium Toxicology
Douglas Smith, Ph.D. Task Leader, CTC
NDCEE
l Sources of Occupational Exposure l Pharmacokinetics l Epidemiology l Cancer Etiology l Recommended Limits l Biological Exposure Indices
1 Sources of Occupational Exposure
l Abundant Element in Earth Crust - Low Daily Human Intake
l Metals & Alloys: Stainless Steel
l Cr II: Chromous Chloride/Sulfate
l Cr Ill: Chromic Oxide/Sulfate/Chloride/Potassium Sulfate
l Cr VI: - Water - Soluble: Chromic Acid, Chromates (Na, P, NH4, Li, Ce, Ru) - Water - Insoluble: Chromates (Zn, Ca, Pb, Ba, Sr) NDCEE
Pharmacokinetics
l Absorption: Lung, G.I. Tract, and Skin (Essential Dietary Element) l Distribution. Rapid - Storage in Red Blood Cell l Excretion: Rapid - Mainly in Urine l Site of Action: - Kidney - Non-Carcinogenic Response - Lung - Carcinogenic Response - Skin - Ulcerations, Hypersensitivity, and Allergy
2 Epidemiology (Human
l Chromium Metal and Divalent/Trivalent Compounds - Low Toxicity, Dermatitis - Dust Accumulation in Lungs
l Hexavalent Chromium (% of Workers in 1930) - Skin Ulcerations (Chrome Holes) - 80% - Ulcerated Nasal Septa - 52% - Dermatitis - 43% - Lung Cancer - 15 Fold Increase in Exposed Workers
Cancer Etiology (Proposed)
l Hexavalent Form Readily Crosses Cell Membranes l Hexavalent Chromium Reduced to Trivalent Form l Trivalent Chromium Metabolically Active -Binds Nucleic Acids in Cells -Altered DNA/RNA
3 Recommended Limits
l Chromium (Cr) CAS: 7440-47-3
l TLV-TWA - 0.5 mg/m3 - Metal & Cr II/Ill - 0.05 mg/m3 - Cr VI/Chromite Ore
l Insoluble Cr VI/Chromite Ore Listed - Al- Confirmed Human Carcinogen
NDCEE
Biological Exposure Indices
l Half life in Urine Ranges 15 to 41 Hours
l Normal Urinary Chromium < 5 ug/g Creatinine
l Limit <30 ug/g (TLV-TWA 0.05 mg/m3)
l Blood Measurements not Valid
NDCEE
4 Melissa Weis-Klingenberg Associate Process Engineer Concurrent Technologies Corporation 1450 Scalp Avenue Johnstown, PA 15904 Phone: (814) 269-6415 Fax: (8 14) 269-2798
Program Name Ion Beam Processing for Environmental Acceptable Coatings Nature of Program Ion Beam Processing for Replacing or Reducing the Use of Hexavalent Chromium Funding Agency DOD and ARDEC
Ion Beam Processing for Environmentally Acceptable Coatings
“Ion Beam Processing for Environmentally Acceptable Coatings*’ is a task being conducted by CTC, through the National Defense Center for Environmental Excellence (NDCEE) contract. The use of ion beam processes as a means for replacing or enhancing hexavalent chromium electrodeposits is being investigated under this program.
Components suitable for ion beam processing have been selected, and the test protocols for qualifying the alternative coating or surface modification have been defined. Replacement coatings and the most appropriate coating strategies were selected based on part application and current depot refurbishment procedure. The system to be used at CTC is currently being fabricated and will be available for demonstration and validation of the selected coatings in April, 1996. Detailed information on this and other work being conducted or planned will be covered during the presentation. Ion Beam Processing for Environmentally Acceptable Coatings
Government POC: J. Hirvonen, ARL B. Sartwell, NRL Technical Advisor: M. Otoonl, ARDEC NDCEE POC: Melissa Weis NDCEE Thrust Manager: Brian Manty Project # N. 001
CTC
Task Objective
Examine, demonstrate, and qualify Ion Beam Processing methods as alternatives to chromium and/or cadmium electrodeposits
CTC
Page 1 Approach
Page 2 Fork Assembly
Manufacturer: Sikorsky
Chromium Thickness: 2 mil minimum
CTC
Page 3 Main Landing Gear
Manufacturer: Boeing Chromium Thickness: 5 - 10 mils
Rear Compressor Drive Shaft Manufacturer: Pratt & Whitney
Chromium Thickness: 2 - 8 mils
-- CTC
Page 4 Bomb Hook
Manufacturer: Various Chromium Thickness: 0.3 mils
Ion Beam Processing Equipment Specification l Equipment Capabilities -High energy (120 keV) gas ion implantation -Ion beam assisted deposition with two low energy ion sources >> End Hall Source (50-120 eV) >> RF Bucket Source (500-1500 eV) -Electron beam evaporation (15 kW ) )) One source with one 156 cc crucible )) One source with four 25 cc crucibles
Page 5 Ion Beam Processing Equipment Specificatlon
l Equipment: - Chamber (overall length 207.5”) >> Main chamber 72” length by 72” diameter >> One extension 42.25” length by 36” diameter >> Load lock system 48.25” length by 36” diameter - Closed-loop cooling water system - Variable speed and angle substrate table >> Load-bearing capacity of 1000 Ibs. >> 24” diameter - Variable speed manipulator >> Load-bearing capacity of 2000 Ibs. >> Accommodate various size components CTC
4 5 6
Page 6 Coatings Selected for Investigation
l Performed literature search on candidate coatings l Ranked coatings based on wear, adhesion, corrosion, and producibility data l Selected coatings l Identified vendors offering coating services
l identified base material specifications and reviewed requirements for sample coupons
Coatings Selected for Investigation
l IBAD coatings -Titanium nitride - Chromium nitride - Chromium - nickel - Diamond-like carbon
l Electroplated coating - Nickel sulfamate
l IBAD base coatings - Zinc - Iron
Page 7 Project Plans l Finalize Test Protocols for selected components l Obtain IBAD coated/implanted samples for testing l Design fixtures for a selected component to be treated at vendor site l Document component treatment and submit report l Install Ion Beam equipment in 4/96
Page 8 Paul W. Fecsik Senior Process Engineer Hughes Aircraft Company Bldg. 826 P.O. Box 11337 Tucson, AZ 85750 Phone: (520) 794-4105 Fax: (520) 794-9463
Program Name Chromium Elimination & Mil SPEC Elimination Initiatives Nature of Program Finding and implementing alternatives to the use of Chrome in processes supporting the finishing of aluminum & steel alloys at the Missile Systems Division of Hughes Aircraft Company in Tucson, AZ Funding Agency Hughes Aircraft Company Team Involved Hughes aircraft Company via its participation with the Joint Group Acquisition Pollution Prevention (JG-APP), Hughes Aircraft Company’s Acquisition Reform and the Reinvention Laboratory Objectives
Chromium Elimination & MIL SPEC Elimination Initiatives
This presentation is an overview of efforts undertaken at Hughes Aircraft Company to eliminate chromium in plating and surface finishing processes and associated rinse waters to date. Processes considered are Chemical Conversion Coat per MIL-C- 5541, Passivation per QQ-P-35, MIL STD 186 & ASTM A380 and Phosphatizing per DOD-P- 16232.
The plating & Surface finishing Department at Hughes Missile Systems Company in Tucson (Air Force Plant #44) has made preparations on an existing computer controlled and automated production Aluminum Finishing Line to incorporate any selected non chromate chemical conversion coat process selected by the JG-APP in concert with the NDCEE. This plating line currently is utilized for a variety of missile programs representing all services. The non chrome process would run in parallel (or simultaneously) to the existing MIL-C-5541 Chromate Conversion Coat process during a final qualification phase prior to production use. The long range intent would be to operate to an internal procedure which would be available to the general public while allowing Hughes to simultaneously eliminate the use of chrome and Mil Specs on a major process.
Similar efforts are underway in the Passivation and Phosphatizing processes. Interim steps to eliminate chrome from rinse waters via ion exchange will also be discussed. John W. Bibber, Ph.D. Research Director SANCHEM, Inc. 1600 S. Canal Street Chicago, IL 60616 Phone: (3 12) 733-6100 Fax : (3 12) 733-7432
Nature of Program: Alternatives to Chromates used in conversion coatings Funding Agency: Self Team involved: SANCHEM Inc., ELECTROSTEAM Inc.
A Chrome Free Conversion Coating for Aluminum with the Corrosion Resistance of Chrome
The cleaning, deoxidization and conversion coating of automotive aluminum alloys with a commercial non-toxic and chrome-free pretreatment system is described in detail. The results of paint adhesion and filiform testing with powder coatings, solvent and water borned epoxies and various urethane coatings is presented along with comparison data for chrome and other non-chromate systems. Neutral salt-spray data is presented. In addition, scanning electron micrographs of treated surfaces are shown along with data on the physical and chemical composition of the surfaces. Marty Borruso Utility Metal Research Corporation 14 Van Street Stanton Island, NY 10310 Phone: (7 18) 720-6646 Fax: (7 18) 720-5946
Application of Poylorganometalicsiloxanes for Aerospace Components Garson P. Shulman President Alumitec Products Corporation 3820 Del Amo Blvd. #207 Torrence, CA 90503 Phone: (3 10) 793-9861 Fax : (3 10) 373-2389
Program Name Corrossion Protection with Organic Sealants Nature of Program Research & Development Funding Agency Private Investors Team Involved Alumitec Products Corp. (G. P. Shulman and A. J. Bauman), Douglas Aircraft Co. (Thomas D. Brown)
Organic Sealants for Anodized Aluminum-Chromate Free Corrosion Protection.
Further development of organic sealants, long chain carboxylic acids, as corrosion protecting sealants for anodized aluminum will be described. Specifically, use of solution in N-methylpyrrolidine (NMP) to enhance paintability, and use of NMP/water mixtures to remove excess sealant have been successful. By coating during immersion through the oily layer into water. A water emulsion has been used for application to oil based inks and dyes to minimize smearing. Protection of steel by coating with aluminum, followed by anodizing and sealing, has been achieved, with salt spray lifetimes in excess of 900 hours. ORGANIC SEALANTS FOR ANODIZED ALUMINUM- CHROMATE FREE CORROSION PROTECTION Garson P. Shulman and A.J. Bauman Alumitec Products Corporation, Torrance CA 90503 Long chain carboxylic acids can be used to seal anodized aluminum (1). Previous patents (2,3) and papers (4) based on our work have described the excellent corrosion resistance attainable (Table I), as measured by ASTM B-117 Salt Spray, Electrical Impedance Spectroscopy (EIS). or Galvanic Current between Dissimilar Metals. Tests based on exposure to strong acids (ASTM B-136 Dye Stain and B-680 Acid Dissolution) generally fail. The strong acids used destroy the hydrophobic coating by converting aluminum soap back to the free acid, allowing attack on the highly porous oxide layer. Conventional hot water sealing swells the oxide initially formed, closing the pores. TABLE I. SALT SPRAY TESTING OF 2024 SOFT ANODIZED ALUMINUM TREATED WITH CHELATING AGENTS DISSOLVED IN ISOSTEARIC ACID CHELATING AGENT AMOUNT TIME TO FAILURE (%) (5 Pits) (hours) BZA* saturated 816 BZT+ 0 2050 BZT 0.1 1650 BZT 0.5 1400 BZT 1.0 1200 BZT 3.0 1056 BZA PRETREATMENT 0 1556 BZT** 0.1 1650 * = BENZOTRIAZOLE-5-CARBOXYLIC ACID + = BENZOTRIAZOLE ** = SANODAL DYED BEFORE SEALING Our line of products, Alumitec AC, D, E, FC, and I, is based on use of isostearic acid. This commercial material is a mixture of many isomers of stearic acid, which lowers the melting point to 10°C (50°F). It is relatively non-toxic (LD50=25 g/kg), non-flammable (Flash Point 1820C), and not corrosive. Boiling point is well in excess of 300°C at atmospheric pressure. The several varieties of Alumitec products are tailored to specific application: Alumitec AC-Aircraft grade with rigid QC specifications and certifications, specifically formulated for long bath life. Alumitec D--The Standard Grade, Isostearic acid 99.9%, Benzotriazole 0.1% Alumitec. E--Water emulsion for application over oil-based inks and dyes without smudging Alumitec FC-Acceptable for incidental food contact. Contains Citric acid as chelating agent. Alumitec I --No additives, when bath life is not a factor To date, the sealants have been applied to 380 diecast and 2024, high copper corrosion prone alloys, 1100, relatively pure aluminum, 5000 series alloys as window screen and coating on steel, 6061 and 7075 alloys. Corrosion resistance has ranged from 480 hours with emulsion to over 4000 hours with corrosion resistant 5000 and 6000 series alloys. Dipping in full strength isostearic acid leaves an oily residue on the metal surface. In the laboratory this can be removed by wiping with cotton cloths or paper towels. On production scale, excess can be removed by tumbling with absorbents or by immersion in N- methylpyrrolidone (NMP) Water mixtures. Following up on the use of NMP for removal of excess, a series of experiments was conducted to provide a paintable surface. As shown in Table II, application of Alumitec D as a 15 to 25% solution in NMP gives a surface which accepts epoxy primer, paint (and presumably adhesives), without dropping salt spray life below 336 hours. Recovery of isostearic acid and NMP is accomplished by adding excess water, skimming the acid from the surface for re-use, then evaporating water to leave either NMP/water mixture or pure NMP (Figure 1). TABLE II. TESTING OF PANELS SEALED WITH ISOSTEARIC ACID SOLUTIONS IN N-METHYLPYRROLIDONE
ISOSTEARIC ACID TIME TO FAILURE PAINTABILITY (%) (B-117 SALT SPRAY) (WET TAPE TEST) (hours) (EPOXY PRIMER) 10 300 pass 15 500 pass 25 1400 pass 50 ---- fail 100 2050 fail To reduce the cost of initially filling a tank with our sealants, experiments were conducted to take advantage of the fact that these sealants (except the emulsion) are oily liquids which float on water. Parts were coated by immersing through the oily layer into water. Salt spray panels (3x10 in. 2024) were sealed after anodizing using a tank containing 2.5 gallons of water and 1 quart of Alumitec D. Salt spray testing was discontinued at 1938 hours with no pitting observed. Corrosion protection of steel (and any other metal that can be coated with aluminum) can be accomplished by subjecting the aluminum coated part to anodizing and Alumitec sealing. Ion Vapor Deposition and Flame Spray can not be used because porosity of the coatings allow current flow to the steel. For example, a 3x10 inch panel of IVD aluminum on steel showed an initial current of 350 amp, compared to the usual 20 to 30 amp, since no high resistance oxide coating forms on exposed steel. Panels cut from a dip-coated sheet (0.8 mil thickness ^ 5000 series aluminum on steel) were masked with organic polymer coating at the edges. Anodizing was successful, isostearic acid sealant was applied, and a panel sent for salt spray testing. After 900 hours the test was discontinued. The center of the panel was intact, but corrosion (white rust) was spreading from the masked edges. Small panels, 2.5x2.5 inch were electroplated using the SIGAL process at Alumiplate, to a thickness of 1 mil (24 microns). Anodizing produced an 0.3 mil oxide layer which was sealed with Alumitec D. The salt spray test is in progress, with no corrosion after 960 hours. We believe that aluminum applied by thermal decomposition coating from iodides or alkyls could also be anodized and used for corrosion protection. ACKNOWLEDGEMENT We wish to thank Thomas D. Brown of Douglas Aircraft Co. for the Paintability Studies, Sandy Donaldson of Alumiplatz for Electroplating Steel, Joe Hillock of Hillock Anodizing for Anodizing Aluminum coated Steel, and Martin Kendig of Rockwell Science Center and Kathy Lewis of Courtalds Aerospace for the electrical measurements. REFERENCES 1. I.R. Kramer and C.F. Burrows, U.S. Patent 3,510,411 (1970) 2. G.P. Shulman and A.J. Bauman, U.S. Patent 5,169,455 (1992) 3. A.J. Bauman, U.S. Patent 5,362,569 (1994) 4. G.P. Shulman and A.J. Bauman, Metal Finishinq 93, No.7, 16 (1995)
ISOSTEARIC ACID& NMP Recycling Lawrence “Larry” Carlson Parker Amchem 32100 Stephenson Highway Madison Heights, MI 48071 Phone: (810) 583-4123 Fax: (8 10) 583-2976
Chrome-Free Light Metals Treatment for Aerospace and Other Industries
A technology status and update will be given pertinent to the elimination of chromium compounds in non-electrolytic chemistries which are aqueous-based and run both reactively and non-reactively on candidate substrates. Peter Chesney Manager, Spray Forming Babcock & Wilcox Nuclear Equipment Division 91 Stirling Avenue PO Box 291 Barberton, OH 44203 Phone: (2 16) 860- 1306 Fax: (2 16) 860-6274
Program Name Spray Forming Nature of Program Rapid Solidification of Metal Coatings from Fluid Funding Agency Navy NSWC - MANIECH Team Involved Babcock & Wilcox
Development of Clad Bar for Hydraulic Piston Rods
Spray Forming is a low cost rapid solidification technology which has been developed for manufacture of large diameter pipe for defense applications. Equipment for spray forming five ton ladles of molten metal into pipe up to lm diameter x 8m long is currently being installed at Babcock & Wilcox. An engineering study is under way to convert the equipment for manufacture of clad billet for rolling into bi-metallic bar. The plant is described together with preliminary results from small scale rolling trials for hydraulic piston rods which could be a low cost alternative to chrome plate. Stephen P. Gaydos Principal Technical Specialist McDonnell Douglas Aerospace St. Louis MO Phone: (3 14) 233-3451 Fax : (3 14) 234-6934
Improved Low Chrome Seal for Anodize
Low chrome seals, containing 10 to 50 ppm of hexavalent chromium are being used as a replacement for solutions containing 5% sodium or potassium dichromate (20,000 ppm hexavalent chromium ) for sealing aluminum anodize coatings. The low chrome seals have been used successfully for sealing anodize coatings, but these dilute seal baths are very susceptible to contamination problems and need to be purified or dumped more frequently than the currently used dichromate seals. Contamination from improper rinsing or poor water quality can raise or lower the pH of the seal and poison the seal bath with undesirable salts, and these conditions produce an inferior seal of the anodize coating which gives poor corrosion resistance and low paint adhesion. McDonnell Douglas has improved the tank life of low chrome seal baths by adding a buffer to the seal that stabilizes the pH and minimizes the effect of seal bath poisons. This presentation compares a buffered low chrome seal with a low chrome seal and a 5% dichromate seal that have been contaminated with sulfate (from improper rinsing of sulfuric acid anodize solution on anodized parts) and silicate (from poor water quality). The effects of the contaminants on corrosion resistance and paint adhesion for the different seals will be given. Results will show that a buffered low chrome seal can give the same robustness as a 5% dichromate seal. Robert Guillemette Senior Materials Engineer Sikorsky Aircraft 6900 Main Street S312A2 Stratford, CT 06497-9129 Phone: (203) 386-7559 Fax: (203) 386-7523
Program Name Chromium Plate Replacement Nature of Program Replacement of Chromium Plate with Thermal Spray Coatings Funding Agency Army Team Involved Sikorsky
Thermal Spray Coatings for Helicopter Components to Replace Chromium
Many helicopter components depend on chromium plate’s wear resistance for performance. Major applications are in hydraulics and counter-faces for Teflon impregnated surfaces.
Thermal spray coatings have begun replacing chrome plate in several applications. Examples are provided to show a design methodology following to implement coating change.
Helicopter components are subjected to constant vibrations, hence the effect of coatings on fatigue strength is a primary concern. Fatigue data from coated coupons is presented to reveal that fatigue strength is very dependent on R-ratio, coating thickness and adhesion and strain limit of the coating.
Pin on disc, Taber, and Falex standardized tests provide valuable wear information during candidate screening. However, they have been poor predictor of full scale performance. Full scale wear testing is required in hydraulic applications to ascertain elastomeric seal compatibility. Examples are provided to show the large wear improvement of thermal spray coatings over chromium plate. Surface finish is shown to be a critical parameter is seal wear life.
Corrosion performance is important due to severity of environment. Low altitude flying (Nap of the Earth, NOE) and operation from unprepared landing areas subject components to extreme corrosion/erosion conditions. Salt fog corrosion testing is used to screen coatings but does not, even remotely, reflect in service conditions. Field testing remains the only method for correct evaluation. Corrosion results are provided for several coatings including crevice corrosion conditions. Michael Moskowitz Marketing Director SIFCO Selective Plating 5708 Schaaf Road Cleveland, OH 44131 Phone: (2 16) 524-0099 Fax: (2 16) 523-6331
Selective Brush Plating Technology
Selective (Brush) Plating Technology as a viable alternative to tank plating in general and to chromium plating in particular. Currently existing, proven methods of selectively plating nickel and various Ni or Co-based alloys with a hardness range from 2-- to 600 HV, without the need for plating tanks, without extensive masking, and with very low solution volumes. I
Doug Hutchinson Vice President Liquid Development Company 3748 East 91st Street Cleveland, OH 44105 Phone: (800) 321-9194 Fax : (216) 641-6416
Program Name Brush Plating Hard Trivalent Chrome Nature of Program To develop a trivalent chrome solution for brush plating Funding Agency Self funded Team Involved LDC and Dr. Zoltan Mathe
Brush Plating Hard Trivalent Chromium
The brush plating industry has successfully supplied manufacturing and repair companies worldwide for over 30 years. Brush plating has extended machinery life and efficiently repaired worn equipment and parts. But applications have been limited by the fact that never before has the brush plating industry had a viable hard chrome solution, hexavalent or trivalent formulation. Now one is available.
In developing this new product the fact that OSHA and the EPA were tightening the noose around hexavalent bath chrome users, played a significant role.
It was believed that the development of a trivalent hard chrome would open doors for brush platers as well as offer bath platers a new alternative to the hexavalent chrome headache.
This new solution is both operator and environmentally friendly. The deposit is comparable in hardness and wear characteristics as tank chrome.
Finally, the solution is available in a decorative version, also. Su-Jen Ting Research Scientist Chemat Technology, Inc. 19365 Business Center Dr. #9 Northridge, CA 91324 Phone: (8 18) 727-9786 Fax: (8 18) 727-9477
Nature of Program: SBIR Research Funding Agency: Air Force Team involved: Su-Jen Ting, Haixing Zheng, C.J. Chu, Ang-Van Do
Sol-gel Coating as a Surface Pretreatment Process for Adhesively Bonding Aluminum Alloys
Currently the most advanced surface pretreatment technique for aluminum alloys adhesive bonding is the anodization process. One of the most widely used anodization processes is the Phosphoric Acid Anodizing (PAA). However these anodization processes use large amounts of water and power, furthermore toxic chromates have to be added in the precleaning and priming steps to enhance the environmental durability and corrosion resistance of the bonding surface. Thus a sol-gel derived inorganic-organic coating is an environmentally benign and simple alternative for aluminum alloys surface pretreatments by incorporating thermally active organics into the porous alumina coating. A systematic study was conducted on a series of water-based coating solutions. The coating was deposited on the aluminum surface by dip-coating or spray-coating. The resultant bonding strength and environmental durability were investigated after the pretreated aluminum alloys were bonded with commercially available adhesives. The lap shear and wedge crack test results are very comparable to the test results of the PAA samples. Both chromate and nonchromate bonding using our sol-gel pretreatment show high bonding strength and good environmental durability. The possibility of eliminating priming step was also investigated using this sol-gel pretreatment process. Wim J. van Ooij Professor University of Cincinnati Department of Materials Science & Engineering Cincinnati, OH 45221 Phone: (5 13) 556-3194 Fax: (4 13) 556-2569
Program Name: Physical /Chemical Technologies for Pollution Prevention & Waste Treatment Nature of Program: Chromate Replacement in Metal Finishing Funding Agency: EPA Team involved: University of Cincinnati (W.J. Van Ooij), & Brent America, Inc
Novel Silane -based Pretreatments of Metals to Replace Chromate and Phosphate Treatment
In this Program we are developing simple, one-step rinses with aqueous solutions of silanes for the metals cold-rolled steel, galvanized steel and aluminum. These treatments will be optimized so as to replace currently used chromate, phosphate and combined treatments in a wide range of metal-processing industries. The silane solutions consist of an organofunctional silane, a non-functional silane which acts as a croslinker, and an organic silicate. The organofunctional silane is different for each metal used. We are also studying the stability of the silanes in the solution, as our ultimate goal is to develop concentrated mixtures of the three components which can be diluted on site to result in an active aqueous solution. The treatments are cost effective , do not involve toxic chemicals and produce only small amounts of waste. Ronald J. Glovan Spray Casting Project Manager MSE-Technology Applications Inc. P.O. Box 4078 Butte, MT 59702
Program Name Demonstration and Validation of Spray Casting Nature of Program Chromium Replacement Funding Agency USAF Team Involved MSE-TA, CTC, ARDEC, and USAF
Wear and Corrosion Characteristics of PCAP Sprayed Versalloy 50 Coatings
In order to evaluate the wear and corrosion characteristics of Pressure Controlled Atomization Process (PCAP) coatings applied to AISI 4130 substrates, a four phase experimental design was setup. Phase 1 consisted of spray tests at five different standoff distances to evaluate spray deposit profiles for a determination of a deposit standard deviation. The standard deviation was used in phase 2, where a total of eight spray tests were conducted. Coatings were sprayed at 0.5, 1, 2, and 3 distance between successive spray deposits. The samples sprayed during this test included a Taber Abraser abrasive wear coupon, an ASTM B 117 corrosion coupon, and a metallurgical evaluation coupon. The results of phase 2 were used to determine the test conditions for phase 3, where a total of 22 spray tests were conducted. Corrosion, wear, and metallurgy were again evaluated. Phase 3 consisted of two verification tests at selected parameters. test results will be shown and conclusions presented. Mr. David Schario Senior Process Engineer Concurrent Technologies Corporation 1450 Scalp Avenue Johnstown, PA 15904 Phone: (8 14) 269-6465 Fax: (8 14) 269-2798
Program Same National Defense Center for Environmental Excellence (NDCEE) Nature of Program Inorganic Thrust Area Funding Agency DOD
Inorganic Finishing Activities at Concurrent Technologies Corporation
This presentation describes the capabilities and activities associated with the Inorganic Finishing Thrust Area of the National Defense Center for Environmental Excellence (NDCEE) which is operated by Concurrent Technologies Corporation (CTC) in Johnstown, PA. CTC, a not-for-profit corporation, is a national resource assisting the U.S. industrial base to achieve manufacturing agility and competitiveness. Through ongoing relationships with government, industry, and academia. CTC performs research, development, demonstration, deployment, training, and educational activities solving manufacturing problems for a broad range of clients. CTC's expert staff has the experience and knowledge to assure rapid and effective transition of leading-edge technologies. Mr. Schario will detail the equipment and processes available for demonstration at NDCEE, describe the on-going activities and tasks, and explain how and who to contact to use the demonstration factory. CTC's Inorganic Finisking Thrust Area
Process alternatives that reduce heavy metal and other hazardous discharges from inorganic coating operations
Government POC: Andy Goetz - ARDEC NDCEE POC: Brian Manty - Thrust Manager Presented by: David Schario Date: November & 1995
Mlsslon of the lnorganic Finishing Thrust Area
Transition environmentally-conscious surface finishing techniques
Reduce or eliminate the use and discharge of: Heavy Metals (Cadmium and Chromium) Cyanides Other Hazardous Materials CTC
Page 1 Closed Loop Line Lab - Scale
Solutions: Electroless Ni, Electroless NiB, NiWB, NiWSiC, non-cyanide Cu, ZnNi (alk. & acid) No Cr, Cad. Cn
Page 2
A. J. Armini President Implant Sciences Corporation 107 Audobon Road, #5 Wakefield, MA 01880 Phone: (6 17) 236-0700 Fax : (617) 246-1167
Program Name Cathodic Arc Deposition of Chromium Nature of Program Pollution Reduction Funding Agency EPA Team Involved ISC, CCAD
Replacement of Chromium Electroplating Using a Cathodic Arc Process
Cathodic arc deposition is an environmentally benign, high-rate chromium replacement process which uses no hexavalent Cr. and is amendable to large-scale industrial production. The process is energy efficient, with process economics competitive with electroplating. It employs an ionized beam of metal ions, which produces thick(up to 100mil) coatings with excellent quality, adherence and surface coverage.
Cathodic arc coatings 4.4 microns thick on 52100 bearing steel were produced at a rate of 1.5 microns per minute. The coatings were mirror smooth and scratch adhesion tests up to 30 Newtons showed no delamination. Measurements of the sliding wear factor vs. an alumina pin was 3.7 x 100mm3/N-meter vs. 3.9 x 10-5 mm3/N-meter for electroplated chrome. A turbulent salt water test showed no corrosion in a 10 hour test where the uncoated steel was totally covered with thick rust.
A detailed economic analysis will be presented of a 1500 Amp cathodic-arc coating plant vs. an 1800 Amp electroplate tank facility. When both factories are used at full capacity in a three-shift operation, a small hydraulic shaft would cost $6.84 for a cathodic-arc coating vs. $5.64 each for the electroplate coating. Jay T. Scheuer Technical Staff Member Los Alamos National Laboratory Mail Stop E526 Los Almos, NM 87544 Phone: (505) 665-6525 Fax: (505) 665-3552
Program Name: Plasma Source Ion Implantation Nature of Program: Cooperative Research and Development Agreement Funding Agency: U.S. Department of Energy Team involved: LANL (K.C. Walter, M.A. Nastasi, I. Henins, C.P. Munson, W.A. Reass), Empire Hard Chrome (Rej of W.G. Home)
Plasma Source Ion Implantation to Extend Chrome Plating Lifetime
Nitrogen ion implantation has demonstrated the ability to dramatically increase the surface hardness and decreasethe wear rate of electroplated chromium, resulting in waste stream reduction. Advantages of ion implantation over other surface modification techniques include its ability to provide implanted atomic concentrations above limits imposed by chemical solubility at low temperature without causing dimensional changes. Plasma source Ion Implantation (PSII), is a non-line of sight technique which eliminates the need for beam rastering. beam masking and target manipulation required by conventional beamline implantation for complicated geometries. In certain applications PSII may replace hard chrome plating by producing a low-friction, high-strength, corrosion resistant surface on the uncoated base material.
Laboratory testing has shown that a retained nitrogen dose of 2 x 1017 atoms/cm’ is sufficient to increase the surface hardness of electroplated Cr by 24% and decrease the pinon-disk wear rate by a factor of four. Data from numerous industrial applications of ion implantation show more dramatic lifetime improvements.
The site of the worlds largest PSII facility, Los Almos National Laboratory (LANL) has pursued PSII scale-up through collaborations with over 20 US companies. LANL has recently entered into a cooperative research and development agreement to assist Empire Hard Chrome (Chicago, IL) in establishing the worlds first commercial PS facility. LANL will assist Empire to develop process recipes, optimize operating conditions, and choose successful applications of PSII to chrome plated components. Jogender Singh Associate Professor Applied Research Laboratory, Penn State P.O. Box 30 State College, PA 16804 Phone: (814) 863-9898 Fax: (814)-863-1183
Nature of Program: Replacement of Chromium Electroplating Processing Team involved: Applied Research Laboratory, Penn State
Heavy Metal Plating Replacement by High Energy Beams
A number of U.S. Government agencies and private industries have major efforts to develop new processes and/or materials that would replace the existing chromium (Cr) electroplating process which is considered as hazardous manufacturing process. The electroplated chromium (Cr) coatings is normally used in areas where wear, corrosion, and/or oxidation are a factor in equipment performance. An overview of the alternative coating processes will be presented. Various coatings are being developed at ARL Penn State by high energy beam processes such as laser cladding and electron beam physical vapor deposition (EB-PVD). Some of these coatings developed to date have demonstrated high performance levels that may be sufficient for the replacement of Cr electroplating.. Catherine E. Taylor Research Assistant University of Cincinnati Department of Materials Science and Eng. Cincinnati, OH 45221-0012 Phone: 513-556-4117 Fax 513-556-2569
Program Name: Plasma processes for Pretreatment of Aluminum Nature of Program: Replacement of Cr conversion coatings by plasma polymerized films Funding Agency: EPA Team involved: University of Cincinnati, Ford Motor Company
Plasma Processing as an Effective Pretreatment for Metals
Plasma processing is becoming increasingly popular as a method of pretreating a variety of surfaces.Plasma etching will remove carboneous contamination from metal surfaces and createa stable surface. Plasma polymerization can be used to deposit thin continuous, pinhole-free primer films. Within a plasma, ionized atoms and molecules, free radicals, and energetic electrons interact with the substrate or a film on the substrate surface to either etch the surface or deposit a highly crosslinked coating. This interaction with the surface leads to a good adhesion between the plasma polymerized film and the substrate. These factors, coupled with environmental concerns of conventional metal treatments, fostered our interest in plasma processing. Since the vacuum requirements (about 1 Torr) are easily met, the treatment can be carried out as a batch or continuous process. The use of vacuum also ensures the cleanliness of the process because pretreatment and deposition can be carried out in the same vacuum system. A variety of monomers can be polymerized to produce coatings with a wide range of structures. Hexamethyldisiloxanc was plasma polymerized with oxygen to produce silicon oxide primer coatings. Lap joints prepared from aluminum primed with plasma polymerized films performs well in cyclic corrosion tests in which joints were placed under load and subjected to warm humid conditions and salt water bath. Electrogalvanized steel panels primed with plasma polymers were coated with E-coat, scribed and the growth of the crack from the scribe was measured and compared favorably to that of zinc phosphated electrogalvanized steel. In this presentation we demonstrate the potential of this technology by showing that plasma polymerized coatings deposited on aluminum and electrogalvanized steel perform exceptionally well as primers in corrosion tests. James H. Arps Research Scientist Materials and Structures Division Southwest Research Institute P.O. Drawer 28510 San Antonio, TX 78228-0510 Phone: (2 10) 522-6588 Fax : (2 10) 522-6965
Large Area Ion Beam Techniques for the Improvement and Replacement of Hard Chrome Coatings
Ion Beam methods of surface modification and coating are inherently environmentally clean technologies. Widely applied in the semiconductor industry for more than two decades, ion implantation is now gaining acceptance as a method for improving wear resistance and service life in industrial applications such as machine tools. Under contract with the U.S. Army Tank Automotive Command (TACOM), SwRI has examined the use of ion beam treatments to increase the reliability and durability of combustion engine components. A key area of this research has been the study of ion implanted hard chrome plated piston rings. Dual implants of metal and gaseous ions may offer much improved hardness and wear resistance over conventional nitrogen ion implantation. The reaction of the metal ions such as yttrium with nitrogen produces a fine dispersion of precipitates and intersitials which strengthen the material and prevent the movement of dislocations. In reciprocating wear tests, treated ring segments showed a factor of three reduction in wear rate. Further, an abrupt decrease in the friction coefficient of more than 50% was observed after initial run-in. This improvement in tribology is likely due to amorphization of the near surface layer produced by the implantations. Treated rings are currently being evaluated in full scale engine tests.
SwRI has also developed a promising coating techniques which addresses the issue of chrome replacement. The patented IBADEN process is a combination of electroless nickel with an overcoat of diamond-like carbon laid down b ion beam assisted deposition. While offering corrosion protection and hardness comparable to chrome, nickel has a high coefficient of friction which makes it an unacceptable replacement in many applications. However, a coating of diamond-like carbon (DLC) on nickel provides a hard, adherent, sliding surface with a lower friction coefficient than chrome. Brief description of the DLC deposition process, SwRIs capabilities in this area, and recent work in evaluating the IBADEN coating as a non-chrome replacement will be presented. J. M. Williams Oak Ridge National Laboratory Building 3137 M/S 6057 PO Box 2008 Oak Ridge, TN 37831-6057 Phone: (423) 574-6265 Fax: (423) 576-8 135
Nitrogen Ion Implantation of Alloys and Comparison of Properties with Other Materials
The nanoindentation hardness techniques and the atomic force microscopy technique have been combined in a study of surface and near-surface properties of nitrogen-ion implanted alloys versus ion fluence. The two alloys studied were Ti-6Al-4V and a CoCrMo alloy. Properties results have been compared with those of non-ion implanted reference materials, such as electroplated hard chrome, r-utile, and amorphous . TiO2 Large areas of both alloys were polished to finish levels of approximately 1 nm, but for the CoCrMo, the finish level, by profilometer, over long traces is limited to about 30nm. This results from the very different hardness of the carbide and matrix phases of the alloy. In either case, nanoindentations of only 50nm in depth still penetrate to about 50 times the local roughness values. The alloys were ion implanted to the same respective treatment depths (150nm) by use of an energy grade suitable for each alloy. By 6 x 1017/cm2, the hardness of the Ti-alloy had increased from a value of 4 GPa to 12 Gpa. A rutile crystal was amorphized by ion bombardment, so that a hardness value for amorphous TiO2 could be obtained. The results indicate that after only a small dose, the Ti alloy is harder than its own passive oxide. Ion implantation first softens and then rehardens the carbide phase of the CoCrMo. The matrix of that alloy is not quite as hardenable as the Ti-6Al-4V alloy. These results are relevant to orthopedics applications, tribological mechanisms, ion implantation process design, and substitute coatings for electroplated hard chrome.
Research is sponsored by the Division of Materials Sciences, U.S,. Department of Energy, under contract DE-,AC05-840R21400 with Lockheed Martin Energy Systems, Inc.
*The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. DE-AC95-S40r21495. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published from of this contribution, or allow others to do so, for U.S. Government purpose. Summary
Hexavalent Cr is Primary Occupational Concern Toxic to Kidney and Skin, Known Human Carcinogen Workplace Exposures via Lung and Damaged Skin TLV-TWA 0.5 mg/m3 for Cr II/III and 0.05 mg/m3 Cr VI BEI - 30 ug/g in Urine NDCEE
5 Christine A. Branson Environment Group Manager Industrial Technology Institute 2901 Hubbard Road P.O. Box 1485 Ann Arbor, MI 48106-1485 Phone: (3 13) 769-4021 Fax: (3 13) 769-4064
Program Name Common Sense Initiative for the Metal Finishing Sector Nature of Program Pollution Prevention for Hard Chrome Electroplaters Funding Agency Technology Reinvestment Project (EPA, NIST, DOE) Team Involved Industrial Technology Institute (C. A. Branson, J. e. Hensley, and K. J. Saulter), Cleveland Advanced Manufacturing Program (L. D’ Agostino and L.C. Boyd)
Common Sense For Hard Chrome Platers
Metal Finishing has been a focus of the Energy, Environment, and Manufacturing (EEM) Technology Access Project funded under the Technology Reinvestment Project. The EEM project includes a series of Technology Demonstration Projects, one of which, Pollution Prevention for Hard Chrome Electroplaters, is also part of the research agenda for the Common Sense Initiative (CSI) Workshop 2 on Research and Technology, under joint direction by both EPA and NIST. EPA’s CSI brings together multiple stakeholders in an attempt to create new environmental protection strategies that are cleaner, cheaper, and smarter than the ones in use today. The Hard Chrome Technology Demonstration Project is focused on four industrial sites in Michigan and Ohio, and includes measurements of air emissions, fugitive emissions, and a comparison of air quality test methods. The presentation will give (1) an overview of the CSI Metal Finishing Subcommittee and Workshop Activities, and (2) an update on Workshop 2 - Research and Technology, focusing on the Hard Chrome Technology Demonstration Project. Michael W. Poe Mid-Atlantic Associates, Ltd 11805 Antietam Road Lake Ridge, VA 22192 Phone: (703) 49l-3992 Fax: (703) 49l-0444
Life Extension by Design... the Economic Impact
In light of increasing global competition, our aging industrial equipment base, and limited resources, many industries are finding it difficult to maintain their equipment with essentially the same methods used for the last 20 years. For many organizations, the “necessary evil” of maintenance and repair has yet to be converted to a profit center through the programmed efficiencies that accrue from an integrated refurbishment program which optimizes life cycle performance.
OEM replacement components are necessarily generalized and designed for “average” service conditions. ‘Lowest price” competition in the multi-billion-dollar replacement spares business makes it impossible to design for all conditions. This, combined with variations in operating environments, conspires to limit the life cycle potential for a broad range of critical industrial components. Any purchasing agent can detail the costs of replacement spare parts; however, the scrap value of a worn part is only a small fraction of what its new counterpart costs. For this reason, rejuvenating “prematurely scrapped” parts for continued useful service makes economic sense.
Unscheduled downtime, with it attendant process losses and rescheduling requirements due to early component failure, is perhaps the single largest profit drain in industrial operations. Optimized component life cycles provide a direct and positive contribution to downtime related requirements that unnecessarily siphon off critical resources which could - and should - be put to better productive.
Spare parts inventories and their associated carrying costs account for additional hidden costs of operation. since spare parts inventories are a direct function of operational life cycles (evidenced by downtime), extending the life cycles of critical components effectively reduces inventory spares requirements. The capital investment required to maintain replenishment spares inventories (i.e., shipping, receiving, storage, insurance, accounting, and administrative costs) typically adds 30-40% per annum to the acquisition cost. In much the same way that “Just-In-Time” (JIT) production inventory programs have shown their value by freeing unproductive capital, controlled JIT inventory spare parts reserves provide similar benefits. These benefits are compounded when “standard” new parts are treated prior to first use, thus providing extended life cycle benefits from the beginning of their productive lives. Keith 0. Legg Business Development Manager BIRL, Northwestern University 1801 Maple Avenue Evanston, IL 60201 Phone: (708) 467- 1572 Fax: (708) 467-1022
Program Name Hard Chrome Coatings - Advanced Technology for Waste Elimination Nature of Program Demonstration/Evaluation Funding Agency ARPA Grant #MDA 972-93-l-0006 Team Involved BIRL, Cummins Piston Ring Div. (Freidoon Rastagar), GE Aircraft Engines (Jerry Schell), CCAD (Al Gonzalez), NRL (Bruce Sartwell), Dover Industrial Chrome (Ariel Schrodt)
ARPA Program: Hard Chrome Coatings - Advanced Technology for Waste Elimination. I - Chrome Replacement Technologies
This talk will report or finding on chrome alternatives for the ARPA-funded program to evaluate methods for cleaning up and replacing the electrolytic hard chrome (EHC) process. We shall report our general findings in the first phase of the program, concentrating on new insights gained over the past year.
We have evaluated physical vapor deposited (PVD) vacuum coatings, high velocity fuel (HVOF) thermal sprays, and laser coatings. Our findings are summarized as follows.:
1. The laser coatings are excellent technically but can too easily damage the substrate to make them acceptable in the maintenance depot environmental.
2. HVOF coatings are excellent both for initial hard coating at the original equipment manufacturer (OEM) and for rebuilding worn components as the depot level.
3. PVD coatings, especially combined with plasma nitriding of the substrate, are some of the most effective chrome replacements for OEM use and are now being demonstrated both for aerospace use and on piston rings.
4. Cost analysis shows that HVOF and PVD coatings are cost-effective EHC replacements for certain common geometries, and that materials use is a critical factor in their costs. Life-cycle costing, combined with analysis of their performance, shows these advanced coatings to be even more cost-effective. ARPA Program: Hard Chrome Coatings - Advanced Technology for Waste Elimination II - Chrome Clean-Up Technologies
This talk will report our findings on electrolytic hard chrome (EHC) plating waste minimization methods developed and demonstrated in the ARPA-funded program to evaluate methods for cleaning up and replacing the EHC process. Several methods of reducing hexavalent chrome waste in the standard EHC process have been evaluated, falling into the following areas:
1. Mist emission reduction through the use of fluorosurfactants - air emissions can be reduced by 99% (well below the new Clean Air Act regulation limits). This not only reduces emissions but also reduces maintenance costs and rinse water use while maintaining or improving product quality.
2. Bath chemistry analysis - new chemistry analysis equipment has been developed based on optical absorption methods. This approach is cheaper, simpler, and as accurate as more complex standard methods. analysis systems for plating baths and discharge water are currently under test.
3. Chrome stripping and recycling - anodic stripping into chromic acid allows chrome to be stripped from many alloys and recycled to the plating bath, but it is limited to alloys that are not high in chromium.
4. Alternative anode materials - platinized titanium anodes avoid the generation of lead chromate waste but do not promote oxidation of trivalent chrome to hexavalent chrome. Alternative materials under development are likely to be cheaper and are under evaluation. James H. Lindsay Staff Research Engineer Physical Chemistry Development 30500 Mound Rd. Bldg. 1-6 GM Research & Development Center Warren, MI 48090-9055 Phone: (810) 986-0696 or (818) 226-0696 Fax: (8 10) 986-8697 or (8 18) 226-8697
Chromium Alternatives in the Automotive Industry
This presentation is a general discussion of chromium alternatives from the perspective of the automotive industry. Hexavalent chromium has been used in a variety of areas. Besides coatings, etches for plated plastics, and fastener finishes. The discussion hem stresses the product needs which must be maintained with any alternative process. Neil Sylvestre Project Leader The MITRE Corporation 7535 Colshire Drive Mclean, VA 22102 Phone: (703) 883-5708 Fax: (703) 883-1951
Team Involved: MITRE, McCLellan Air Force Base
Functional Testing and Practical Limitations of Alternatives to the Use of Chrome Plating for Aircraft Refurbishment at McClellan Airforce Base, California
Chromium is the coating of choice in many metal finishing applications throughout the Air Force, particularly at depot maintenance facilities. Depending on the application, chromium can be used to impact many desirable physical and chemical properties, including wear resistance, hardness, resistance to galling and corrosion resistance. In addition, its ability to be applied to complex geometries and internal diameters makes chromium electroplating of steel for engineering purposes is major use chromium in aircraft refurbishment activities.
The Sacramento Air Logistics Center (SM-ALC) at McClellan Air Force Base (APB) refurbishes a variety of airframes and components on aircraft including the A-10, F- 16, F-15, F-111, KC-135, etc. Due to wear, age, or damage, the aircraft hydraulic components must be stripped of coatings, inspected for base metal integrity, and recoated to restore the parts to original specifications.
When chromium is applied to hydraulics, landing gear, rotating shafts, gears, and surfaces that are subjected to sliding or roiling wear, the coating must be abrasion- resistant, low-friction, and resistant to galling. The majority of hard chrome plating applied at SM-ALC is for refurbishment of hydraulic component assemblies, which must meet the piston rod and seal wear tests conducted per MIL-C-5503. Furthermore chrome-plated components must meet or exceed the basic hardness, porosity, and corrosion resistance requirements of Federal Specification QQ-C-320. The plating is applied generally to 10-30 mils thickness to allow for dimensional restoration and grinding tolerance limits.
It is widely known that hexavalent chromium has significant health, safety, and environmental problems. Therefore, SM-ALC has adopted a proactive approach in substituting non-chromium based processes as the most cost-effective means for achieving regulatory compliance.
Working closely with SM-ALC, The MITRE Corporation concluded that the use of High Velocity Oxy-Fuel (HVOF) applied tungsten carbide-cobalt(WC-Co) can potentially replace eighty percent of the McClellan AFB chromium usage, while a composite nickle-tungsten-silicon carbide(Takada process) composite electroplate would be used for the remaining twenty percent.
These technologies require continued development before they can be fully implemented into the refurbishment activity. These metal finishing technologies are more environmentally friendly than the coating methods that are currently used which contain chromium, however, some questions remain concerning their functional performance in aircraft hydraulic applications and manufacture-ability. Since coupon and ASTM testing does not directly verify the suitability of the coatings in their intended applications, continued development is being conducted at SM-ALC. This entails the testing of these alternative coatings for functional suitability in simulated flight motion conditions, fatigue debit effects, corrosion protection, and wear resistance, as well as the prototyping of manufacturing processes. Test specimen preparation and functional performance tests are being performed by SM-ALC shops to obtain data on manufacture-ability and gain customer acceptance through familiarity.
Functional testing, which is the subject of this paper, consists of quantitative data, in the form of leakage and wear (for hydraulic assemblies), on two seal designs representative of primary seal types used at McClellan AFB, as a function of candidate rod coating type, and surface finish(optional). The applied hydraulic condition of service is representative of an aircraft hydraulic actuator.
This paper focuses on the results and recommendations of the original analysis, a description of the part specific limitations of various chrome replacement alternatives, and a description of the ongoing functional testing of the alternatives. D. Kent Dickie Marketing Director McGean-Rohco, Inc. 2910 Harvard Avenue Cleveland, OH 44105-3010 Phone: (216) 441-4900 x5529 Fax: (216) 441-1377
Very Hard Electroless Nickel Deposits
A discussion of new technology which produces electroless nickel deposits with as-plated hardnesses which range from 825-925 HV100.
Areas to be discussed include x-ray diffraction studies, physical properties and performance characteristics and operating parameters. Ed McComas Senior Engineer National Chemical Corporation
Replacement of Hard Chromium with Nickel Boron
Replacement of Cr and NiB
. General Motors Tooling . Sensormatic Extended Life of Al . Newspaper Equipment . Textile Equipment . Air-frame Applications . Howmet Cavity Moles I
Ahmet N. Palazoglu Associate Professor University of California, Davis Department of Chemical Eng & Mat Science Davis, CA 95616 Phone: (9 16) 752-8774 Fax: (916) 752-1031
Nature of Program: Research Funding Agency: U.S. EPA, California EPA Team involved: Amorphovs Technologies International (Dr. G. Graef & Prof. J. Groza)
Study of Ni-W-B as Alternative to Chromium Plating
A ternary alloy of Ni-W-B has been suggested as an altenative to hexavalent chromium in electroplating applications. It has been reported that the alloy deposit , referred to as AMPLATE®, exhibits very attractive performance characteristics such as hardness, corrosion resistance and a shiny finish. In this study, we will focus on the environmental impact of the plating process and compare it with typical hexavalent chromium plating processes. Primarily we will discuss the plating bath properties as they relate to rinsing and drag-out performance. Recovery and recycle of tungsten will also be addressed to provide potential methods for bath regeneration. As a part of the materials properties, hardness tests will be presented. These indicate improved values of Vickers microhardness when the deposit is annealed around 4000 C. We will also discuss the potential benefits of a computer simulation model in determining optimal operating conditions for the plating process. The AspenPlus software to develop the related operational units such as the plating baths, rinsing tanks and the recovery units. Paul Hancharik Manager, Product Support Atotech USA, Inc. 1000 Harvard Avenue Cleveland, OH 44109 Phone: (216) 749-8168 Fax : (216) 749-8156
Use of Trivalent Chrome as a Replacement for Hexavalent Chrome in Both Decorative and Functional Plating
This presentation will cover an update on the use of trivalent chrome as a replacement for hexavalent chrome in both decorative and functional plating. It will review the current application and market acceptance of trivalent chrome in both applications.