Wear and wear mechanism simulation of heavy-duty engine intake valve and seat inserts |
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Authors: | Y S Wang S Narasimhan J M Larson S K Schaefer |
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Affiliation: | (1) Engine Components Operations, Eaton Corporation, 19218 B Drive South, 49068 Marshall, MI, USA |
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Abstract: | A silicon-chromium alloy frequently used for heavy-duty diesel engine intake valves was tested against eight different insert
materials with a valve seat wear simulator. Wear resistance of these combinations was ranked. For each test, the valve seat
temperature was controlled at approximately 510 °C, the number of cycles was 864,000 (or 24 h), and the test load was 17,640
N. The combination of the silicon-chromium valve against a cast iron insert produced the least valve seat wear, whereas a
cobalt-base alloy insert produced the highest valve seat wear. In the overall valve seat recession ranking, however, the combination
of the silicon-chromium valve and an iron-base chromium-nickel alloy insert had the least total seat recession, whereas the
silicon-chromium valve against cobalt-base alloy, cast iron, and nickel-base alloy inserts had significant seat recession.
Hardness and microstructure compatibility of valve and insert materials are believed to be significant factors in reducing
valve and insert wear.
The test results indicate that the mechanisms of valve seat and insert wear are a complex combination of adhesion and plastic
deformation. Adhesion was confirmed by material transfer, while plastic deformation was verified by shear strain (or radial
flow) and abrasion. The oxide films formed during testing also played a significant role. They prevented direct metal-to-metal
contact and reduced the coefficient of friction on seat surfaces, thereby reducing adhesive and deformation-controlled wear. |
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Keywords: | engine valve seat wear heavy-duty engine valve seat wear simulation wear mechanism |
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