Research On Microstructure And Performance Of Fe-Cu-Ni-Sn-based Matrix Of Grinding Wheel

With the rapid development of ceramic tile industry in china,the manufacturers put forward higher requirements for the performance of diamond grinding wheels used to abrase porcelain tile edge.The metal matrix used for fixing diamond grits plays a key role in the performance of the grinding wheel.The Fe-based matrix has been widely used because of its low price and convenient preparation.However,the performance gaps of the matrixes produced by variant manufacturers are very large,which leads to significantly different of the sharpness and life of the grinding wheels.In this paper,the effect of sintering temperatures on the elemental mechanical mixed powders and the pre-alloyed powder sintered bodies were studied by means of OM,SEM,EDS,XRD and other methods,such as relative density,hardness,bending strength and abrasion resistance test,and the sintering process of Fe-Cu-Ni-Sn-based matrix of grinding wheel was investigated.The effects of elemental Zn powder and CuZnSn pre-alloyed powder content on the microstructure and properties of Fe-based matrix were further analyzed,respectively,so as to get a better comprehensive performance of Fe-based matix.This paper aims at providing a reference for determining the sintering process and the content of binders added to the matrix of diamond grinding wheel.The results showed that the main phases of the mixed powder sintered body were composed of(Cu,Sn),(Cu,Zn)solid solution and intermetallic compounds Cu41Sn11 and Cu5Zn8.The microstructure of the pre-alloyed powder sintered body is finer and the amount of needle-like phases is more than that of the mixed powder sintered body,and the new phase Cu6Sn5 appeared with the increase of the sintering temperature.The relative densities of the two kinds of sintered bodies were not much different,and the hardness of the pre-alloyed powder sintered body was higher than that of the former,but the bending strength was lower than the former with the same process conditions.With the sintering temperature rising,the amounts of gray phase composed of(Cu,Sn)solid solution in the microstructures of the Fe-based matrix were increased,the black phases were made up of the iron-rich phase,(?-Fe,Ni)and Fe4Cu3 compounds,some black phases were dispersed by the gray phase,and the amount of bright gray structure dominated by Ni4 Sn and Cu41Sn11 was slightly reduced.The effects of the holding time and the sintering pressure on the Fe-based matrix were the same as that of the sintering temperature.The relative density and bending strength of Fe-based matrix increased first and then decreased with the raise of sintering temperature and prolonging the holding time.For the hardness,there was a tendency to rise as a whole.The sintering pressure had less influence on the density and hardness.The bending strength also enlarged first and then declined.Moreover,the trend of abrasion resistance was similar to the hardness value.The sintering process parameters of the Fe-based matrix was optimized as follows: sintering temperature 750?,holding time 3min and sintering pressure 20 kN.In the optimized sintering process condition,the relative density of the matrix was 99.7%,and the hardness was 103.5HRB,and the bending strength was 869.1MPa,and the amount of wear was 272.6mg.Compared with the original Fe-based matrix,the main phase composition of the matrix added elemental Zn powder was almost unchanged,but a small amount of Cu0.61Zn0.39 appeared.With the increase of Zn content,the amounts of bright gray phase and gray phase decreased and increased,respectively,while variation of dark gray phase was not obvious.After adding the pre-alloyed powder in the Fe-based matrix,Cu0.61Zn0.39 and CuZn2 phases appeared,but other phases were same as the original Fe-based matrix.With the increase of the content of pre-alloyed powder,the microstructure characteristics were similar to that of Fe-based matrix adding Zn.With the growing of the content of Zn or pre-alloyed powder,the density and hardness of Fe-based matrix were decreased,however,the bending strength increased first and then reduced.When the amount of Zn was 2.8wt% or pre-alloy powder was 8wt.%,the bending strength reached the maximum of 987.5MPa and 984.2MPa,respectively.Adding the same amount of diamond to the original Fe-based matrix and to the Fe-based matrix with 2.8wt.% Zn or 8wt.% pre-alloyed powder,the gripping force coefficient of the three knots were 71.6%,78.9% and 81.0%,respectively.The third coefficient is slightly larger than the others.The result implied that the interface between the Fe-based matrix and diamond can be further improved by adding appropriate content of Zn or pre-alloyed powder into the matrix.