Optimization of Quenching Process for ZTAP/ High Chromium Cast Iron Composites

In order to solve the problem of cracking of ZTAP(Zirconia toughened alumina ceramic particles)reinforced HCCI(high chromium cast iron)matrix composites,the quenching process was optimized.ZTAP reinforced HCCI matrix composites were prepared by infiltration method with gravity sand casting.The thermal expansion curves of HCCI and the composites were measured at different cooling rates by Glebble-3500.The microstructure of the HCCI matrix and the composites were characterized by X-ray diffraction,light microscopy,SEM,ESD,and EPMA.The tested mechanical properties include Rockwell hardness and impact toughness.The deformation differences of HCCI and the composite at different cooling rates were obtained according to the test results of thermal expansion coefficient curve and changes in microstructure and mechanical properties,and air cooling was the most favorable for the composites to have good hardness and not easy to crack.The cooling rate during air cooling is approximately equal to 21℃/s in this work.When the quenching process was air cooling,the impact toughness and hardness of the composites are 3.7 J/cm^(2) and 61.8 HRC,respectively,and the deformation difference between the composites and HCCI was 20μm at 300℃.