Fabrication of NbCp-Reinforced Iron Matrix Composites by PM Techniques and Its Warm Compaction

NbC was used as reinforced particles in the fabrication of iron-base composite. Die wall lubricated warm compaction (DWLWC) was introduced in the forming of iron-base composites and also a valve-guide cup, that used in a combustion engine. The influences of fabrication parameters such as ball milling time, annealing temperature and time, warm compaction temperature, different NbC contents, sintering properties and wear resistance were studied. Results indicated that the fine NbC particles embedded in the iron particles and evenly distributed in the mixed powder after ball milling. DWLWC was used not only to increase the green density but also to improve the formability of the mixed powder and to improve compact's green strength to facilitate handling. With sintering temperature of 1280°C and sintering time of 80 minutes, high density and high performance NbC particulate reinforced iron-base composites and a valve guide cup with layered materials can be obtained. The cup composed of two kinds of composites. The composite containing 10wt% NbC was used as base material while the composite that process 15wt% NbC was used to form the working surface. No serious wear on the working surface can be observed after the test.