DOCSLIB.ORG

Improved Ablation Resistance of Carbon∓Phenolic Composites by Introducing Zirconium Diboride Particles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Improved Ablation Resistance of Carbon∓Phenolic Composites by Introducing Zirconium Diboride Particles Composites: Part B 47 (2013) 320–325 Contents lists available at SciVerse ScienceDirect Composites: Part B journal homepage: www.elsevier.com/locate/compositesb Improved ablation resistance of carbon–phenolic composites by introducing zirconium diboride particles ⇑ Yaxi Chen a, , Ping Chen a, Changqing Hong b, Baoxi Zhang b, David Hui c a School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning 116024, PR China b Key Laboratory of Science and Technology for Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin, Heilongjiang 150001, PR China c Dept. of Mechanical Engineering, University of New Orleans, New Orleans, LA 70124, United States article info abstract Article history: Carbon–phenolic (C–Ph) composites are well fabricated to meet the requirements of thermal protection Received 13 September 2012 system by introducing ZrB2 particles. TG analysis demonstrates that the existence of ZrB2 particles could Received in revised form 19 October 2012 obviously aggrandize the char yield of phenolic, although it does not enhance the thermal stability of Accepted 1 November 2012 phenolic. What is more, the employed method of introducing ZrB could notably improve ablation resis- Available online 29 November 2012 2 tance and insulation performance of C–Ph composites, which is mainly owing to the formation of ZrO2 and B2O3. As depicted in the microstructure, the ablation rate of matrix is evidently higher than carbon Keywords: fibers in the C–Ph composites. However, the ablation rate of carbon fibers is identical to matrix in Z C–Ph A. Polymer–matrix composites (PMCs) composites. B. Thermal properties D. Thermal analysis Ó 2012 Elsevier Ltd. All rights reserved. E. Thermosetting resin Ablation resistance 1. Introduction vapor grown carbon fibers, exhibit extremely good erosion resis- tance and display less weight loss compared with the composites A spacecraft, entering or traveling through an atmosphere at (composed of woven ex-rayon carbon fibers, carbon black fillers very high speed when typically subjected to a high heat flux, re- and phenolic) [8]. Furthermore, it appears to be a far better insula- quires a thermal protection system (TPS) to maintain a relatively tor. The C–Ph composites, treated with polyhedral oligomeric ‘‘cold’’ temperature, so lots of thermal protection materials have silsequioxanes, emerge a better ablative performance [9].H3PO4À been extensively investigated to protect space vehicle against the coated carbon fiber–phenolic composites can undergo stronger aerodynamic heating encountered in hypersonic flight [1]. The thermomechanical influence during ablation, and give a lower ero- ablation materials represent one of the traditional approaches to sion rate to retard the ablation process [10]. The composites, mak- thermal protection systems which have been vastly explored and ing of three-dimension reticulated SiC ceramic, carbon fibers and investigated [2,3]. The mechanism of ablation materials is that a boron-modified phenolic, have less linear ablation rate compared quantity of energy is excellently absorbed by removed material. with pure boron modified phenolic or carbon fiber/boron-modified The carbon–phenolic composites (C–Ph) are considered exten- phenolic composites [11]. Nanosilica powder modified sively to be efficient ablative thermal protection materials [4,5], rayon-based carbon–fabric/phenolic composites reveal improved owing to their excellent ablative resistant properties. Ablative ablation resistance, reduced thermal conductivity and higher in- resistance of C–Ph composites plays a very important role in aero- ter-laminar shear strength at a controlled quantity [12]. In general, space application when subject to high temperatures. Many efforts these methods are frequently utilized to improve the ablative have been made to evidently improve this performance of C–Ph performance of C–Ph composites by modification carbon fibers or composites in recent years. Boron modified phenolic is synthesized phenolic, interface treatment and addition of other compounds. from boric acid, phenol, and formaldehyde, and it is widely used as Zirconium diboride (ZrB2) has high melting point (P3000 °C), matrix of C–Ph ablation composites, because of its good heat resis- which oxidizes to ZrO2 and B2O3 [13]. Some previous works have tance, mechanical properties, electric properties and absorbance of been well reported that the formation of protective ZrO2 coating neutron radiation [6,7]. C–Ph composites, containing 30–45 wt% could markedly improve ablation resistance of carbon composites [14]. In addition, ZrB2 and B4C particles are applied as oxidation inhibitors to improve significantly ablation performance of bulk ⇑ Corresponding author. Tel./fax: +86 451 86403016. C–C composites [15]. However, the effects of ZrB2 on the ablation E-mail address: [email protected] (Y. Chen). performance of C–Ph composites are still unclear. 1359-8368/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.compositesb.2012.11.007 Y. Chen et al. / Composites: Part B 47 (2013) 320–325 321 In this article, we extensive review the current state of this 3. Results and discussion exciting field, and emphasize that the effects of introducing ZrB2 particles on the ablation and insulation performance of C–Ph com- 3.1. Thermogravimetry (TG) and X-ray diffraction analysis posites. It is well fabricated by impregnating method that phenolic resin and ZrB2 particles fill the pores of the carbon fiber fabric. The The thermal stabilities of cured phenolic and the cured mixture, ablation performance of introducing ZrB2 particles modified car- containing phenolic and ZrB2 (mass ration 1:0.2), are explored by bon–phenolic (Z C–Ph) composites is reasonable tested by oxy- thermal gravimetric analysis. Thermal gravimetric curves are pre- gen–acetylene, and the temperatures of the ablated surface and sented in Fig. 2. the back surface are real-time monitored. The influence of ZrB2 As well known, the phenolic has pyrolysis phenomenon when on thermal stability of phenolic is investigated extensively. In addi- the temperature exceeds 300 °C, and the weight loss below tion, the mechanisms of improving ablation resistance are deeply 300 °C is not mainly owing to the pyrolysis of phenolic but the discussed. post-cured process [16].InFig. 2, we could find that the mixture and phenolic all have the thermal degradation phenomenon when 2. Experimental the temperature goes up to 300 °C. More and more thermal degra- dation byproducts are found when the temperature continues to For the purpose of proper demonstration, the proposed three- creep from 480 °C to 650 °C. It is clear that ZrB2 particle does not dimensional carbon fibers fabric was impregnated in mixture. change the temperature distribution of phenolic pyrolysis, and The three-dimensional carbon fibers matrix was defined as the thermal stability of phenolic does not increase significantly. 40  40  40 mm (with the density q = 0.185 g/cm3). The mixture The char yield of phenolic and phenolic containing ZrB2 at 1000 °C are 67.3% and 73.4%, respectively. If calculated weight loss contained ethanol, phenolic and ZrB2 powders at the mass ration of 1:1:0.2. It was the optimum to manufacture Z C–Ph composites was owing to the pyrolysis of phenolic, and ZrB2 weight was con- which has implied in our previous work. The three-dimensional sidered to be constant, the char yield of the mixture at 1000 °C carbon fibers fabric was put into the mixture for 20 min. Then should be 72.7%. This value is lower than the measured value of we left the fabric over 24 h to evaporate the solvent. The heating phenolic contains ZrB2. Therefore, the weight gain reactions should cure was done in 30 min, 90 min and 180 min in an oven at be occurred in this condition. 80 °C, 110 °C and 150 °C, respectively. In addition, the heating rate Fig. 3 reveals that the XRD patterns of the products after TG was approximately 1 °C/min, and sample cooling was completed at analysis. The XRD spectrum for the mixture demonstrates the for- the room temperature. The cured fabric (0.515 g/cm3) was divided mation of ZrO2, which results from the reactions between ZrB2 and into smaller sample with the size of £25  20 mm for oxygen– the pyrolysis products of phenolic in N2 atmosphere. It is well acetylene testing, and the C–Ph composites (0.491 g/cm3) was also known that the main pyrolysis products of phenolic include hydro- decollate to sub-sample of £25  20 mm. This mixture contains gen, methane, slight amount of ethane, water, small amount of car- ethanol and phenolic at the mass ration of 1:1. bon dioxide, carbon monoxide and porous amorphous carbon (the Thermogravimetry (TG) analysis was carried out by TGA/ char from phenolic) [16]. Two reactions of forming ZrO2 are given SDTA851e (Switzerland). The samples were placed in alumina cru- by: cibles, and heated from normal temperature (21 °C) to 1000 °C ZrB2ðsÞþ5COðgÞ¼ZrO2ðsÞþB2O3ðgÞþ5CðsÞð1Þ with increased heating rate of 5 °C/min in N2 atmosphere. The phase composition was analyzed by an X-ray diffraction device 2ZrB2ðsÞþ5CO2ðgÞ¼2ZrO2ðsÞþ2B2O3ðgÞþ5CðsÞð2Þ (Cu Ka radiation, D/max-RB, Japan). Ablation performance was The byproduct of B2O3 is not detected by XRD due to its evapo- tested by oxygen–acetylene. Scheme of the ablation experiments ration under N2 atmosphere [17–19]. Therefore, the increased char medium is shown in Fig. 1. The flow rates of oxygen and acetylene yield of the mixture contributes to the formation of ZrO2(s) and were 500 l/h and 400 l/h, respectively. The oxygen–acetylene gun C(s). As shown in Fig. 3, broad peaks (a and b) are observed at 2h with 2 mm dimension was perpendicular to the surface of the angles of about 24°and 44°, respectively. They are characteristics specimen, and the distance from gun to the surface of the specimen of amorphous carbon from phenolic [20]. However, these broad was 50 mm.
Load more

Recommended publications
  • Processing, Microstructure, and Mechanical Properties of Zirconium Diboride-Molybdenum Disilicide Ceramics and Dual Composite Architectures
    Scholars' Mine Doctoral Dissertations Student Theses and Dissertations Spring 2017 Processing, microstructure, and mechanical properties of zirconium diboride-molybdenum disilicide ceramics and dual composite architectures Ryan Joseph Grohsmeyer Follow this and additional works at: https://scholarsmine.mst.edu/doctoral_dissertations Part of the Energy Systems Commons, and the Materials Science and Engineering Commons Department: Materials Science and Engineering Recommended Citation Grohsmeyer, Ryan Joseph, "Processing, microstructure, and mechanical properties of zirconium diboride- molybdenum disilicide ceramics and dual composite architectures" (2017). Doctoral Dissertations. 2561. https://scholarsmine.mst.edu/doctoral_dissertations/2561 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. PROCESSING, MICROSTRUCTURE, AND MECHANICAL PROPERTIES OF ZIRCONIUM DIBORIDE-MOLYBDENUM DISILICIDE CERAMICS AND DUAL COMPOSITE ARCHITECTURES by RYAN JOSEPH GROHSMEYER A DISSERTATION Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY in MATERIALS SCIENCE AND ENGINEERING 2017 Submitted to: Gregory Hilmas, Advisor William Fahrenholtz Jeffrey Smith David Van Aken Lokeswarappa Dharani iii PUBLICATION DISSERTATION OPTION This dissertation consists of the following five articles that will be submitted for publication as follows and have been formatted in the style of the journal Ceramics International. The manuscripts entitled, “ZrB2-MoSi2 Ceramics with Varying MoSi2 Content: Part 1. Processing and Microstructure with Varying ZrB2 Particle Size:” (Paper I, Pages 50–80), and the manuscript entitled “ZrB2-MoSi2 Ceramics with Varying MoSi2 Content: Part 2.
    [Show full text]
  • Interface Engineering of Graphene Nanosheet Reinforced Zrb2
    Interface engineering of graphene nanosheet reinforced ZrB2 composites by tuning surface contacts Yanhui Zhang∗„y and Stefano Sanvito∗„y E-mail: [email protected]; [email protected] Abstract The mechanical properties of heterophase interfaces are critically important for the behaviour of graphene-reinforced composites. In this work, the structure, adhe- sion, cleavage and sliding of heterophase interfaces, formed between a ZrB2 matrix and graphene nanosheets, are systematically investigated by density functional theory, and compared to available experimental data. We demonstrate that the surface chemistry of the ZrB2 matrix material largely shapes the interface structures (of either Zr-C-Zr or B-C-B type) and the nature of the interfacial interaction. The Zr-C-Zr interfaces present strong chemical bonding and their response to mechanical stress is significantly influenced by graphene corrugation. In contrast B-C-B interfaces, interacting through the relatively weak π-π stacking, show attributes similar to 2D materials heterostruc- tures. Our theoretical results provide insights into the interface bonding mechanisms in arXiv:1904.09008v1 [cond-mat.mtrl-sci] 18 Apr 2019 graphene/ceramic composites, and emphasize the prospect for their design via interface engineering enabled by surface contacts. 1 Keywords ZrB2, graphene, interface, mechanical properties, ultra-high temperature ceramics, density functional theory, ceramic matrix composites 1 Introduction Within the last ten years, the use of graphene as nanofiller in ceramic matrix composites (CMCs),
    [Show full text]
  • Impact Testing of Zirconium Diboride Mark David Flores University of Texas at El Paso, [email protected]
    University of Texas at El Paso DigitalCommons@UTEP Open Access Theses & Dissertations 2012-01-01 Impact Testing of Zirconium Diboride Mark David Flores University of Texas at El Paso, [email protected] Follow this and additional works at: https://digitalcommons.utep.edu/open_etd Part of the Mechanical Engineering Commons Recommended Citation Flores, Mark David, "Impact Testing of Zirconium Diboride" (2012). Open Access Theses & Dissertations. 2283. https://digitalcommons.utep.edu/open_etd/2283 This is brought to you for free and open access by DigitalCommons@UTEP. It has been accepted for inclusion in Open Access Theses & Dissertations by an authorized administrator of DigitalCommons@UTEP. For more information, please contact [email protected]. IMPACT TESTING OF ZIRCONIUM DIBORIDE MARK D. FLORES Department of Mechanical Engineering APPROVED: Jack F. Chessa Ph.D., Chair Chintalapalle V. Ramana, Ph.D. Cesar Carrasco, Ph.D. Benjamin C. Flores, Ph.D. Interim Dean of the Graduate School Copyright © by Mark D. Flores 2012 IMPACT TESTING OF ZIRCONIUM DIBORIDE by MARK D. FLORES THESIS Presented to the Faculty of the Graduate School of The University of Texas at El Paso in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Mechanical Engineering THE UNIVERSITY OF TEXAS AT EL PASO May 2012 Abstract Materials research is one of the driving forces that stimulate new ideas and concepts in a wide range of engineering applications. Material research allows engineers and scientists the ability to find new ways to use high performance materials to advance technology in the aerospace industry. In this study, Zirconium Diboride (ZrB2) will be the subject of impact testing at various speeds.
    [Show full text]
  • Improved Performances of Sibcn Powders Modified Phenolic Resins-Carbon Fiber Composites
    processes Article Improved Performances of SiBCN Powders Modified Phenolic Resins-Carbon Fiber Composites Wenjie Yuan 1,2, Yang Wang 1,2, Zhenhua Luo 1,2, Fenghua Chen 1,2,*, Hao Li 1,2,* and Tong Zhao 1,2,* 1 Key Laboratory of Science and Technology on High-tech Polymer Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; [email protected] (W.Y.); [email protected] (Y.W.); [email protected] (Z.L.) 2 School of Chemical Science, University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected] (F.C.); [email protected] (H.L.); [email protected] (T.Z.) Abstract: The effect of SiBCN powder on properties of phenolic resins and composites was analyzed. Compared with phenolic resins, the thermal stability of SiBCN powder modified phenolic resins (the SiBCN phenolic resins) by characterization of thermogravimetric analysis (TGA) improved clearly. It was found by X-ray photoelectron spectroscopy (XPS) that reactions between SiBCN powder and the pyrolysis product of phenolic resins were the main factor of the increased residual weight. TGA and static ablation of a muffle furnace were used to illustrate the roles of SiBCN powder on increasing oxidation resistance of SiBCN powder-modified phenolic resin–carbon fiber composites (SiBCN–phenolic/C composites), and the oxidative product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). For SiBCN–phenolic/C composites, the occurrence of oxidation reaction and the formation of protective crust contributed to improving oxidative resistance. The result of the oxygen-acetylene test showed that the linear ablation rate (LAR) and mass ablation rate (MAR) of phenolic resin–carbon fiber Citation: Yuan, W.; Wang, Y.; Luo, Z.; composites reduced from 0.052 ± 0.005 mm/s to 0.038 ± 0.004 mm/s and from 0.050 ± 0.004 g/s to Chen, F.; Li, H.; Zhao, T.
    [Show full text]
  • Combined Dilatometry and Mass Spectrometry of Sintering And
    COMBINED DILATOMETRY AND MASS SPECTROMETRY OF SINTERING AND EVOLVED GASES OF BARIUM TITANATE AND ZIRCONIUM DIBORIDE WITH SINTERING ADDITIVES _______________________________________ A Thesis presented to the Faculty of the Graduate School University of Missouri _______________________________________ In Partial Fulfillment Of the Requirements for the Degree Master of Science _______________________________________ by MURRAY MOSS Dr. Stephen J. Lombardo, Thesis Supervisor DECEMBER 2012 The undersigned, Appointed by the Dean of the Graduate School, have examined the thesis entitled COMBINED DILATOMETRY AND MASS SPECTROMETRY OF SINTERING AND EVOLVED GASES OF BARIUM TITANATE AND ZIRCONIUM DIBORIDE WITH SINTERING ADDITIVES Presented by Murray Moss A candidate for the degree of Master of Science And hereby certify that in their opinion it is worth of acceptance. Dr. Stephen J. Lombardo _____________________________________________ Dr. David Retzloff _____________________________________________ Dr. Alan Whittington _____________________________________________ ACKNOWLEDGEMENTS I would like to first thank Dr. Stephen J. Lombardo for giving me the opportunity to work in his lab and for all the time he has spent with me on this project. Dr. Lombardo has been all that a teacher and mentor should be: an invaluable source of knowledge, one which motivates and challenges you to grow, all the while showing enormous patience. I really appreciate all you have done for me and wish you success in the future. Secondly, I would like to thank the GAANN (Graduate Assistantship in Areas of National Need) Fellowship for financial support for both myself and the lab, and for the opportunity to meet other professionals by attending conferences. I would also like to thank my Thesis Committee members Dr. Retzloff and Dr.
    [Show full text]
  • University of Birmingham Synthesis of Ultra-Refractory Transition Metal
    University of Birmingham Synthesis of ultra-refractory transition metal diboride compounds Fahrenholtz, William G.; Binner, Jon; Zou, Ji DOI: 10.1557/jmr.2016.210 Document Version Peer reviewed version Citation for published version (Harvard): Fahrenholtz, WG, Binner, J & Zou, J 2016, 'Synthesis of ultra-refractory transition metal diboride compounds', Journal of Materials Research, vol. 31, no. 18, pp. 2757-2772. https://doi.org/10.1557/jmr.2016.210 Link to publication on Research at Birmingham portal Publisher Rights Statement: Checked for eligibility: 04/10/2016. COPYRIGHT: © Materials Research Society 2016 Fahrenholtz, W.G., Binner, J. and Zou, J. (2016) ‘Synthesis of ultra-refractory transition metal diboride compounds’, Journal of Materials Research, 31(18), pp. 2757–2772. doi: 10.1557/jmr.2016.210. https://www.cambridge.org/core/journals/journal-of-materials-research/article/synthesis-of-ultra-refractory-transition-metal-diboride- compounds/439AC30524D1F1E2970F306B038DD857 General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. •Users may freely distribute the URL that is used to identify this publication. •Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. •User may use extracts from the document in line with the concept of ‘fair dealing’ under the Copyright, Designs and Patents Act 1988 (?) •Users may not further distribute the material nor use it for the purposes of commercial gain.
    [Show full text]
  • Sintering of Zirconium Diboride-Silicon Carbide (Zrb2-SIC
    UNIVERSITÉ DE LIMOGES UNIVERSITI MALAYSIA SARAWAK ÉCOLE DOCTORALE DOCTORAL PROGRAM Science et Ingénierie en Matériaux, Advanced Material Mécanique, Energétique et Aéronautique FACULTY OF ENGINEERING FACULTÉ DES SCIENCES ET TECHNIQUES Department of Mechanical and Laboratoire Sciences des Procédés Céramiques et Manufacturing Engineering Traitements de Surfaces (UMR CNRS – 7315) THÈSE DOCTEUR DE L’UNIVERSITÉ DE LIMOGES Spécialité: Matériaux Céramiques et Traitements de Surface et DOCTOR OF PHILOSOPHY UNIVERSITI MALAYSIA SARAWAK Speciality: Advanced Material Présentée et soutenue par Dayang Salyani Binti ABANG MAHMOD Octobre, 2017 Sintering of Zirconium Diboride-Silicon Carbide (ZrB2-SiC) and Titanium Diboride-Silicon Carbide (TiB2-SiC) Ceramic Composites and Laser Surface Treatment: Potential Application in Low Temperature Protonic Ceramic Fuel Cells (LTPCFCs) JURY: Président Andrew Ragai Henry Rigit Professor Ir. Dr., Universiti Malaysia Sarawak Kota Samarahan, Sarawak, Malaysia. Rapporteurs Laurence Latu-Romain Associate Professor, Université de Grenoble Alpes, France. Ramesh Singh A/L Kuldip Singh Professor Ir. Dr., University of Malaya, Kuala Lumpur, Malaysia. Pang Suh Cem Professor Dr., Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia. Examinateurs Jean-Claude LABBE Professor Emeritus, Université de Limoges, France. Nicolas GLANDUT Associate Professor, Université de Limoges, France. Amir Azam KHAN Professor Dr., Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia. ii | P a g e To the Parents Who Nurtured Me To Brothers and Sister Who Never Doubt on Me To the Teachers Who Inspired, Engaged, Passionate and Amazing Human Beings To All Who Continue to Fight And To the Readers iii | P a g e “Never give up on anybody, Miracles do happen” “It’s supposed to be hard. If it wasn’t hard, everyone would do it.
    [Show full text]
  • Federal Register/Vol. 82, No. 129/Friday, July 7, 2017/Rules And
    31442 Federal Register / Vol. 82, No. 129 / Friday, July 7, 2017 / Rules and Regulations Paragraph 6002 Class E Airspace DEPARTMENT OF COMMERCE a contribution to delivery systems (other Designated as Surface Areas. than manned aircraft) for such weapons. * * * * * Bureau of Industry and Security In 1993, the MTCR’s original focus on missiles for nuclear weapons delivery AWP CA E2 Arcata, CA [Modified] 15 CFR Parts 742, 744, 772, and 774 was expanded to include the Arcata Airport, CA proliferation of missiles for the delivery ° ′ ″ ° ′ ″ (Lat. 40 58 40 N., long. 124 06 31 W.) [Docket No. 170202139–7139–01] of all types of weapons of mass That airspace within a 4.1-mile radius of RIN 0694–AH33 destruction (WMD), i.e., nuclear, Arcata Airport. chemical and biological weapons. Such Paragraph 6004 Class E Airspace Revisions to the Export Administration proliferation has been identified as a Designated as an Extension to a Class D or Regulations Based on the 2016 Missile threat to international peace and Class E Surface Area. Technology Control Regime Plenary security. One way to address this threat * * * * * Agreements is to maintain vigilance over the transfer of missile equipment, material, and AGENCY: AWP CA E4 Arcata, CA [New] Bureau of Industry and related technologies usable for systems Arcata Airport, CA Security, Commerce. capable of delivering WMD. MTCR (Lat. 40°58′40″ N., long. 124°06′31″ W.) ACTION: Final rule. members voluntarily pledge to adopt the That airspace extending upward from the Regime’s export Guidelines and to SUMMARY: surface within 2.9 miles each side of the 153° The Bureau of Industry and restrict the export of items contained in bearing from Arcata Airport extending from Security (BIS) is amending the Export the Regime’s Annex.
    [Show full text]
  • Assessment of the State of the Art of Ultra High Temperature Ceramics
    Assessment of the State of the Art of Ultra High Temperature Ceramics Sylvia Johnson, Matt Gasch, NASA Ames Research Center, Moffett Field CA 94035 Mairead Stackpoole, ELORET Corp, Moffett Field CA 94035 1.0 Introduction Ultra High Temperature Ceramics (UHTCs) are a family of materials that includes the borides, carbides and nitrides of hafnium-, zirconium- and titanium-based systems. UHTCs are famous for possessing some of the highest melting points of known materials. In addition, they are very hard, have good wear resistance, mechanical strength, and relatively high thermal conductivities (compared to other ceramic materials). Because of these attributes, UHTCs are ideal for thermal protection systems, especially those that require chemical and structural stability at extremely high operating temperatures. UHTCs have the potential to revolutionize the aerospace industry by enabling the development of sharp hypersonic vehicles or atmospheric entry probes capable of the most extreme entry conditions. 2.0 Background UHTCs originated in the early 1960s. Some of the earliest and most thorough work to date was performed then by the company ManLabs, under a research program funded by the Air Force Materials Laboratory (AFML) 1-2. Work on UHTCs was initiated to meet the need for high temperature materials that would allow the development of maneuverable hypersonic flight vehicles. Since then, intermittent research has made some progress, but several significant challenges remain in the use of UHTCs, and these materials have yet to be widely implemented. Strong covalent bonding is responsible for the high melting points, moduli, and hardness of the UHTC family of materials3-4. High negative free energies of formation also give UHTCs excellent chemical and thermal stability under many conditions.
    [Show full text]
  • Bureau of Industry and Security, Commerce § 772.1
    Bureau of Industry and Security, Commerce § 772.1 of Columbia, Puerto Rico, and all terri- NOTE: If an ECCN specifies one or more of tories, dependencies, and possessions of the six elements of ‘‘use’’ in the heading or the United States, including foreign control text, only those elements specified trade zones established pursuant to 19 are classified under that ECCN. U.S.C. 81A–81U, and also including the User-accessible programmability. (Cat 4, outer continental shelf, as defined in 5, and 6)—The facility allowing a user section 2(a) of the Outer Continental to insert, modify, or replace ‘‘pro- Shelf Lands Act (43 U.S.C. 1331(a)). grams’’ by means other than: United States airline. Any citizen of (a) A physical change in wiring or the United States who is authorized by interconnections; or the U.S. Government to engage in busi- (b) The setting of function controls ness as an airline. For purposes of this including entry of parameters. definition, a U.S. citizen is: Utilization facility. (a) As defined by 10 (a) An individual who is a citizen of CFR 110.2 of the Nuclear Regulatory the United States or one of its posses- Commission Regulations, utilization sions; or facility means a nuclear reactor, other (b) A partnership of which each mem- than one that is a production facility, ber is such an individual; or any of the following major components (c) A corporation or association cre- of a nuclear reactor: Pressure vessels ated or organized under the laws of the designed to contain the core of a nu- United States, or of any State, Terri- clear reactor, other than one that is a tory, or possession of the United production facility, and the following States, of which the president and two- major components of a nuclear reactor: thirds of the board of directors and (1) Primary coolant pumps; other managing officers thereof are (2) Fuel charging or discharging ma- such individuals and in which at least chines; and 75 percent of the voting interest is (3) Control rods.
    [Show full text]
  • Ultra High Temperature Ceramics: E-Mail: [email protected] Densification, Properties and Thermal Stability
    High Temperature Materials J.F. Justin, A. Jankowiak (Onera) Ultra High Temperature Ceramics: E-mail: [email protected] Densification, Properties and Thermal Stability ypersonic flights, re-entry vehicles, and propulsion applications all require Hnew materials that can perform in oxidizing or corrosive atmospheres at temperatures in excess of 2000°C and sometimes over the course of a long working life. Ultra High Temperature Ceramics (UHTCs) are good candidates to fulfill these requirements. Within this family, the ZrB2 and HfB2 based composites are the most attractive. The oxidation resistance of diboride-based compounds is better than that of SiC-based ceramics thanks to the formation of multi-oxide scales composed of a refractory oxide (skeleton) and a glass component. Onera is actively involved in several programs to develop such materials for both hypersonic civilian flights and for propulsion systems. In this paper, we present the ZrB2-SiC, ZrB2-SiC-TaSi2 and HfB2-SiC-TaSi2 composites developed in the Onera laboratories for leading edges or air intakes of future hypersonic civilian aircrafts flying up to Mach 6 (T~1100°C-1500°C) with comparisons with the state of the art. Then we discuss new perspectives for higher temperature applications (T>2000°C). Introduction cycling lifetimes are modest. The development of structural materials for use in oxidizing and rapid heating environments at temperatures Ultra High Temperature Ceramics (UHTCs) are good choices for several above 1600°C is therefore of great importance for engineering. extreme applications: thermal protection materials on hypersonic aerospace vehicles or re-usable atmospheric re-entry vehicles, Density Melting Material Crystal structure specific components for propulsion, furnace elements, refractory (g/cm3) température (°C) crucibles, etc.
    [Show full text]
  • Thermal Properties of Zirconium Diboride - Transition Metal Boride Solid Solutions
    Scholars' Mine Masters Theses Student Theses and Dissertations Spring 2014 Thermal properties of zirconium diboride - transition metal boride solid solutions Devon Lee McClane Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Materials Science and Engineering Commons Department: Recommended Citation McClane, Devon Lee, "Thermal properties of zirconium diboride - transition metal boride solid solutions" (2014). Masters Theses. 7265. https://scholarsmine.mst.edu/masters_theses/7265 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. 0 1 THERMAL PROPERTIES OF ZIRCONIUM DIBORIDE – TRANSITION METAL BORIDE SOLID SOLUTIONS by DEVON LEE MCCLANE A THESIS Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE IN MATERIALS SCIENCE AND ENGINERING 2014 Approved by William G. Fahrenholtz, Advisor Greg E. Hilmas, Co-Advisor Wayne Huebner 2 iii PUBLICATION THESIS OPTION The thesis has been prepared in the style utilized by the Journal of the American Ceramic Society. Pages 1-28 contain an Introduction and Literature Review for background purposes. Pages 29-59 entitled “Thermal Properties of (Zr,TM)B2 Solid Solutions with TM = Hf, Nb, W, Ti, and Y” was accepted for publication in the Journal of the American Ceramic Society in February of 2014. Pages 60-92 entitled “Thermal Properties of (Zr,TM)B2 Solid Solutions with TM = Ta, Mo, Re, V, and Cr” was submitted to the Journal of the American Ceramic Society in March of 2014.
    [Show full text]