Manufacturing of a NbC Particulate Reinforced P/M Iron-Base Valve-Guide Cup

The introduction of ceramic particulate into metallic powder will unavoidably lower the compressibility and formability of the mixed powder. In order to overcome these problems, in this study, warm compaction was introduced in the forming of an NbC particulate reinforced iron-base valve-guide cup, which is used in a combustion engine. Warm compaction was used not only because it can provide compacts with high green density but also it can increase the formability of the mixed powder. The part composed of an iron-base material which possesses 10wt%NbC with a relative density of 97.7%, a tensile strength of 815MPa, an elongation of 1.5%, a hardness of HRC33 and an impact toughness of 11J/cm2. Its working surface composed of an iron-base material which possesses 15wt% NbC with a high relative density of 98.2%, a tensile strength of 515MPa, a hardness of HRC 58 and a remarkable tribological behavior. The sintered part successfully passed a 500 hours bench test. No serious wear on the working surface can be observed after the test. Results indicated that the sintered part has excellent wear resistivity and the NbC particulate reinforced iron-base composite is a suitable material for parts that work under severe wear condition.