Design Engineering

Steve Koelzer Vice President, Research & Development K & K Products & Consulting 709 W. Remington Drive Sunnyvale, CA 94087 e-mail: [email protected]

Two-bit Engineering

re automobiles dead? They still vehicles, or else have hideous smog. ingredient is the film-former. Metal A don’t go anywhere by them- Microprocessor control port fuel never touches metal, as evidenced by selves. AMD gets more press out of injection, air/fuel ratio by oxygen diamond anvil cell testing. This shows trifles than General Motors’ tomb- sensing, infrared degree wheel timing that oil “crystallized” at millions of stone orders. Swords into plowshares exactness (same HP from 87 or 92 psi’s, letting metal pieces rip off ... bumpers into computer discs. Cars octane!), etc. GM’s Generation III without contact. In certain can be very sophisticated, with the small block accomplishes four-valve unlubricated conditions, materials can help of microprocessors. Just think: performance with the generously possess zero friction.2 With networking, you may never need managed two. A forthcoming advance Although brass on ice is as slick as to leave your home ... or your car! is electric-hydraulic valve actuation. Teflon®, so may be something else. If it weren’t for computers 20 years I’ll leave to your imagination the Unlubricated diamond-like carbon ago, the internal combustion engine multiplicity of valve timing programs (DLC) was ion-beam-deposited would have died by now, and we to conduct the performance (i.e., (0.0002 in.) onto CVD diamond would have electric and hydrogen economical power) of your dream (0.000002 in.) on a silicon engine, integrating fuel delivery disc substrate and tested for friction programs. Twist a knob and push the and wear using a CVD diamond- pedal! Drag racing still has not tipped hemispheric stylus. Wear was allowed any microprocessor-con- 2x10-7 mm3/nm, and coefficient of trolled acceleration devices—only for friction was 0.005 in monitoring. Yet, ingenuity has pushed atmosphere. In humid air and , 1 -7 -5 the massive machines down to the /4- 2.5x10 and 0.02, 3x10 and 0.04, mile limit in 4.5 sec and at 333 mph! respectively. Though DLC use is There’s no sense in all this progress limited to 480 °F, this could without addressing the old thermody- be applied to surfaces of bearings, namic culprits: Heat loss and friction. valves, cams, gears and computer Plating can dramatically affect discs, etc.3 Note that the mating efficiency, with the aid of some surfaces are DLC and CVD diamond. engineering design.1 Now this gives rise to the old Let’s start with friction, because it correlation between surface hardness rubs everybody the wrong way. We and friction. It’s actually the shear begin here because nobody does modulus that predicts hardness rather anything without heat loss, and that than bulk modulus. As such, the causes friction. Don’t feel picked on. calculated hardness of beta-carbon Rules are rules. Here is thermo- is 60 percent of that of dynamics simplified: (1) You can diamond (cubic-born nitride is 50 never get ahead; (2) You cannot break percent). [Crystalline] beta-carbon even; (3) You can’t even get out of nitride still has not been synthesized. the game. Films of beta-carbon nitride (amor- Friction comes in two flavors: phous carbon nitride) are better at Lubricated and unlubricated. Typi- protecting disc drives than [DLC] cally, if surfaces are relatively amorphous hydrogenated carbon, and smooth, they tend to slide, not weld were adopted last year. Several together, if they have dissimilar hundred 1–2 nm-thick alternating crystal lattices. They also have less layers of nitride and carbon friction when they are oiled. Have you nitride tested to slightly greater ever heard an engine that is racing hardness than cubic-, the without oil? They key treatment second best to diamond. “In the end, Free Details: Circle 118 on reader service card.

60 PLATING & SURFACE FINISHING what matters is the performance of a differential control of heat adsorption, about existing engines’ metal absorp- material in a given application.”4 will become inevitable conclusions. tion, with reflectivities from 20 Lubrication involves EHD filming Now we can discuss thermo. percent (oxided) to 70 percent and rheological fluidity, ZN/P. Engineering texts mention that the (polished aluminum). However, a Surface microstructure is involved majority (>89%) of heat is transferred two-percent increase in reflectivity with the latter,5 and crankshaft friction by radiation at furnace temperature (from 97% to 99%) could dictate the is extremely low anyway, riding the (>100 °C). Infrared reflection deci- need for lower octane, retarded fluid film. The majority of friction in mates heat adsorption, if complete ignition, longer strokes, shorter rods, ICE’s comes from the rings. The EHD reflectivity could be achieved. IR delayed exhaust valve timing and film thickness between piston rings wavelengths are from 1–1,000 µm. turbo-supercharging, etc., for inesti- and cylinder wall can be measured in Water and carbon dioxide (the mable efficiency increases. running engines.6 Chrysler-Benz is products of combustion) emit—and contemplating how to eliminate rings. absorb—strongly in this region. References This may be borne of successful Experiments with tantalum oxide- 1. Plating and Surface Finishing, Feb. 1998, pulsed electrophoretic codeposition of coated gold plating (97% reflectivity p. 16. cubic-boron nitride/molybdenum @ 10 µm) on piston/chamber/wall 2. Plating and Surface Finishing, “Design disulfide on piston skirts,7 which immediately showed >20 percent Engineering,” July 1998. reduce wear, friction, etc. Engineering power and efficiency at 2,000 rpm, 3. NASA Tech Briefs, July 1998, p. 62 design can look at various develop- with nearly complete combustion and (www.nasatech.com—TSP, Materials category). ments from the patent literature dramatically reduced block tempera- 8 4. Science News, 154, July 11, 1998, p. 28. concerning various ringless piston ture, as well as a demonstrated need 5. Plating and Surface Finishing, “Design designs. Engineering designers may for better combustion sealing. Engineering,” August 1998. be able to adapt the EHD film Consider near-speed-of-light IR 6. 1998 SAE Internat’l. Congress & Expo- thickness-measuring technique to velocity (1 in./nanosec) in the sition, “Engine Component Technology” assess piston-wall differential combustion charge and absorbing one sessions, ISBN-0-7680-0137-4. expansion. Further, matching CTE of of 100 collisions (a 99% IR reflector), 7. Personal communication, Jack Lofstrum, wall with piston (to maintain suffi- and you’ll soon see it doesn’t take ClearClad Coatings, Inc. cient gap for a fluid film), as well as long to absorb radiant heat. Think 8. Personal experiments, 1994-95.

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