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1346 |
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Monday, June 02, 2008, Room 04 5:00 PM Printing and Paper - Hard Chrome Replacement Modern coating systems for long lasting printing performance, latest coating developments for rolls in paper machines; Optimized coatings for replacing galvanic hard chrome coatings |
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A life cycle comparison of hard chrome and thermal sprayed coatings: A case example of aircraft landing gears |
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Nikhil Krishnan* / Columbia University, USA Armelle Vardelle / SPCTS, University of Limoges, France Jean Legoux/ Industrial Materials Institute, CNRC, Canada |
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Electroplated hard chromium is widely coated onto parts to provide resistance to corrosion, wear and impact. The electroplating process, however, has significant health and environmental impacts. Air emissions during the electroplating process contain hexavalent chromium (Cr+6) - a known carcinogen, furthermore the process is energy intensive and generates hazardous waste. Because of health and environmental issues related to hard chromium plating, there have been several efforts to find alternatives. One of the more efficient technologies among the substitutes is High Velocity Oxy-Fuel (HVOF) thermal spraying. This technology is commercially available today, and has comparable or superior performance characteristics. Comparing the environmental footprints of the hard chrome and HVOF processes, however, requires examining environmental impacts throughout the life cycle of both processes. A major use of hard chromium plating is in aerospace applications. In particular, the substitution of chrome coatings on aircraft landing gear with HVOF coatings of cermets (WC-Co) represents a significant commercial opportunity. In this paper, we therefore compare the life cycle environmental footprints of hard chromium and HVOF coatings for aircraft landing gear. In previous work, we performed a preliminary and a generic life cycle comparison of hard chrome and thermal sprayed coatings [1]. Our results indicated that hard chrome platings have generally larger environmental footprints across human health, ecosystem and resource consumption measures, primarily owing to the presence of airborne Cr+6 emissions and electricity consumption. We realized that a more definitive comparison of environmental impacts would depend on understanding: (i) specific process parameters (including choice of thermal sprayed materials, part geometries and overspray) and (ii) The effect of upstream life cycle emission factors (e.g. regional energy mixes, feedstock manufacturing, etc.) In this paper we examine both these factors by narrowing the scope of our analysis to specific process parameters and part geometries and by specifically examining the impacts of variability in upstream life cycle emission factors. References 1. Costil S., Liao H., Montavon G., Vardelle A., Krishnan N., ?Life Cycle Assessment (LCA) of Thermal-Sprayed and Chromium Electroplated Coatings,? International Thermal Spray Conference, Seattle, May 16 2006. |