Microstructure And Wear Resistance Of High Chromium Cast Iron Modified By Nano Materials

In this paper,the high chromium cast iron samples with Ti C,VC and CeO₂nano-powders were prepared through spraying nano solvent on the surface of the mold.Microstructure of the high chromium cast iron was investigated by means of optical microscope?OM?,scanning electron microscope?SEM?and EDS.Hardness,impact toughness and wear resistance of the samples were tested by Rockwell apparatus,impact testing machine,pin-on-disk wear tester and step device.The microstructure and mechanical properties of the high chromium cast iron with different content of nanoparticles were studied,and the wear mechanism was investigated as well.Without nanoparticles,the microstructure of the centre area was coarser than that of the surface.The discontinuous rods morphology of the eutectic carbides and unevenly distributed carbides were observed in the high chromium cast iron.Serious fatigue wear with large spalling appeared on the worn surface and accompanied by cracks.The fracture mechanism was transgranular cleavage fracture.The refined austenite and carbide were obtained with Ti C nano-powders addition.The carbide was evenly distributed around the matrix and its morphology was changed from coarse acicular to small short rod.The impact toughness of the sample increased by47.62% with the addition of 0.015% nano Ti C,and the characteristics of ductile fracture appeared as the dimple was observed from the fracture morphology.The wear rate decreased by 47.73%.The smallest friction coefficient and wear rate with smooth wear scar were obtained.Refined solidification microstructure and improved mechanical properties were obtained by adding VC nano-powders.The morphology of carbide changed from coarse strip to small rod or block mass with addition of 0.015% VC nanoparticles.The impact toughness increased 40.29% and the wear rate decreased by 38.18%.and the wear resistance was improved with increasing content of nano-VC particles.With the nano-CeO₂ content increased,refined and well distributed carbide appeared.Seldom changes of the wear resistance and the toughness were obtained by adding 0.015%nano CeO₂ particles.And still rod like carbide appeared on the sample.But the wear ratedecreased by 26.13% and the impact toughness increased by 13.55% with addition of0.024% nano CeO₂,and the round and regular carbide was obtained.