ZTA Particle Reinforced High Alloy Wear Resistant Cast Iron Composites

High chromium cast iron material has excellent wear resistance and low production cost,and is widely used in important industrial fields such as coal mine,national defense,metallurgy and construction,but its wear resistance is still insufficient under large impact conditions.In recent years,many scholars at home and abroad have added W,Mo,V and other alloy elements to the research of high manganese and high chromium cast iron materials and developed a variety of high alloy wear-resistant materials.Among the alloy elements,Cr,W,Mo,V and other elements are carbide forming elements,which react with C element to form high hardness carbide during solidification process,which can effectively improve the macro hardness of the material surface,but these carbide will split the matrix at the same time,resulting in the decrease of the toughness of the material.Mn has the function of stabilizing austenite,which is beneficial to obtain a certain volume fraction of austenite structure and improve the toughness of the material.Therefore,a new wear-resistant material with high hardness and toughness can be obtained by reasonably adding carbide forming elements such as W,Mo,Cr and Mn elements.In this paper,the influence of W addition on the structure and properties of high alloy cast iron under the premise of high manganese content was studied in detail.On this basis,heat treatment and ZTA particle addition were carried out to further optimize the wear resistance of the material.The main conclusions are as follows:Adding 0%,4%,6%and 10%W elements to high Mn and high Cr cast iron for liquid phase sintering,it is found that the main phase of the solidified material matrix is austenite,and many types of high hardness carbide such as M2C type carbide,M6C type carbide and M7C3 type carbide are precipitated.With the increase of W element mass fraction,the amount of carbide in the sample gradually increases.When the W element mass fraction is 10%,a large number of reticular carbide structures are generated,which has adverse effects on the material properties.The results show that the hardness and wear resistance of high alloy cast iron are 36.78%and 19.53%higher than that of common high chromium cast iron with the same Cr content when the W content is 6%,which is the best in four groups of high alloy cast iron with different W content.Therefore,the formula with 6%W content is selected for subsequent heat treatment and reinforcement particles are added to prepare composite materials.High alloy cast iron was quenched at 1050? and tempered at 500?,550? and 600?respectively.The results show that the martensite content in the matrix of high alloy cast iron samples increases after heat treatment,and the types of carbide are similar to those of as-cast samples,but the morphology is different.The reticular carbide in the sample was basically eliminated,and the cementite changed from short rod to fine particle.The structural changes improve the surface macrohardness,impact toughness and wear resistance of the heat-treated samples compared with the as-cast samples.Among them,the surface macrohardness and impact toughness of the samples obtained after 1050? air-cooled quenching and 600?furnace cold tempering are increased by 9.84%and 54.71%respectively compared with the as-cast samples.The mass wear amount is reduced by 27.71%compared with the as-cast sample,and the comprehensive properties of the material are obviously improved.ZTA particles reinforced high alloy cast iron composites were prepared by liquid phase sintering method with simple process and low cost by adding 10%,20%,30%and 40%volume fractions of ZTA particles to high alloy cast iron matrix.The wettability between ZTA particles and cast iron is poor,but the Ti element contained in the matrix can react with Al2O3 at the interface.Mn element reacts with Al2O3 to form a layer of glass phase on the surface of ZTA particles,which binds the particles and the matrix,and the composite effect is obviously improved.The bonding effect is good,and the liquid phase sintering method is feasible.When scanning the sample,it was found that a small amount of cracking occurred in the matrix after the volume fraction of ZTA particles reached 30%,which had adverse effects on the comprehensive properties of the material.The wear resistance of the composite was tested by friction and wear.It was found that the average friction coefficient of the wear surface of the material decreased rapidly with the increase of ZTA particle volume fraction,and stabilized after the ZTA particle volume fraction reached 20%.Based on the structure and properties of the composite,it is considered that the most suitable volume fraction of reinforcing particles in ZTA particle reinforced high alloy cast iron composite prepared in this paper is 20%.