The Influence of Processing Parameters on Mechanical Properties of Spark Plasma Sintered Chromium Carbide Based Cermets

Present paper discusses the influence of spark plasma sintering (SPS) on the microstructure and perfomances of chromium carbide based cermets. The effect of SPS parameters (temperature, pressure) is discussed. It is shown that SPS enables to produce more fine grained chromium carbide based cermets compared to conventional liquid phase sintering. Hardness and fracture toughness are exhibited.

Oxide Reduction Processes, Microstructure and Properties of Sintered Chromium Pre-Alloyed Steel

The reduction processes during the sintering of Fe-3Cr-0.5Mo+0.5C pre-alloyed powder using continuous monitoring of exhaust gas composition (CO, CO2, H2O) have been identified and interpreted in relation to the density (6.5-7.4 g/cm3), sintering temperature (1120 and 1200°C), heating and cooling rates (10 and 50°C/min) and type of sintering atmosphere (10%H2-N2, N2), respectively. The progress in reduction processes was evaluated by the change in C and O contents, and fracture strength values as well. The results were compared with metallographic study of microstructure and fractographic observations of fracture surfaces. Higher sintering temperature (1200°C) and low density (<7.0 g/cm3) resulted in a relative decrease in oxygen content by more than 80%. Higher cooling rate (50°C/min) eliminates re-oxidation during cooling. High density of 7.4 g/cm3,achievedby double pressing, indicated to have a negative effect on reduction processes due to restricted replenishment of the “microclimate” atmosphere with the processing gas. Higher O2 content causes weakening of interfaces with residual oxides.