Papers by Author: Li Pin Wen

Abstract: Warm compacting and sintering behaviors of pre-mixed Fe-2Ni-2Cu-1Mo-1C powders were studied. Results showed that green density increased with compacting temperature and then fell slightly; the maximum green density was obtained at about 120°C. Green compact density and spring back effect of the pre-mixed powder increased gradually as the compacting pressure increased. Sintered density first increased and then fell as the temperatures went up under different sintering temperatures for 50 minutes, but the trends of sintering dilatation were first reduced and then increased. Sintered density first reduced and then increased with the prolonged sintering time at 1300°C, but the trends of dimension change after sintering were the very reverse. Tensile strength, elongation and hardness of the warm compacted Fe-2Ni-2Cu-1Mo-1C materials generally increased as sintering temperature and sintering time went up.

Abstract: A 15 wt.% NbC particulate reinforced iron-based composite was prepared by using warm compaction PM technique. It possesses a high relative density of 98%, a tensile strength of 515 MPa, a hardness of HRC 58 and a remarkable tribological behavior. Warm compaction was used because it can provide compacts with high green density and also increase the formability of the mixed powder. Furthermore, it can provide green strength that is strong enough to handle compacts before sintering. Block on ring tribotester was employed to study the compact’s friction and wear behavior using GCr15 steel as counterpart. A load of 980 N was used. The friction coefficient was 0.085 when the number 20 engine oil as lubricant was used. The results showed that the sintered composite has excellent wear resistivity. This material was then applied in the valve-guide cup of a combustion engine and subject to 500 hour bench test. The cup showed good performance for this test and did not shown any severe wear on the working surface after the test was completed. Therefore, it is a suitable material for parts that are exposed to severe wear condition.