The correct use of lubricant is the key of warm compaction powder metallurgy. Different lubricants produce different lubrication effects and their optimal application temperature will be different. Three different lubricants were used to study the effects of friction coefficient on warm compaction process. Friction coefficients of these lubricants were measured at temperatures ranging from ambient temperature to 200 ℃. Iron-base samples were prepared using different processing temperatures and their green compact densities were studied.
A novel powder metallurgy (P/M) material with high wear resistance is developed in orderto decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests ofthis material are conducted. It indicates that the wear resistance of the newly developed P/M materialhas been improved and much better than that of the formerly used alloy steel. Moreover, three differentsealing structures are designed and theoretically analyzed with respect to the characteristic of hydro-dynamic sealing. Through comparative experiments of component leakage and engine run-in for dif-ferent valve guide structures, it proves that the structure with a machined sealing groove but not in-stalled with a seal-ring cannot only reduce the specific lubricant consumption (SLC) of cylinder head,but also decrease the wear of valve stem and valve guide.
