Research On The New Technology Of Microwave Sintering Of Metal-based Diamond Circular Saw Blade

Metal-bonded diamond saw blade has been widely used in the processing of building,stone,ceramics,semiconductor and other brittle materials.With the development of science and technology,the requirements for the preparation and performance of diamond saw blades are higher.The strength loss of the diamond is easily caused by the conventional hot pressing at high temperature and high pressure,and the cold pressing sintering strength can not meet the requirements of the complex working conditions.In this paper,we combine the microwave heating technology superiority and technical characteristics of preparing diamond saw blade.The application of microwave sintering technology for preparation of Cu based and Fe based diamond saw blade,research on microwave sintering of diamond saw blade mechanism,sintering process and material properties etc.,we get the following conclusions:（1）Microwave can heat the metal powder through dielectric loss.With the increase of heating temperature,the absorbing ability,absorbing and transforming ability and penetrating ability of metal powder are enhanced.The metal powder compact can achieve rapid heating and sintering in the microwave.The Fe based powder compacts has the best warming characteristics.The temperature rise performance of the Co powder compact is the worst.The average heating rate of all the materials in the sintering process is above 25°C/min.At the same time,the penetration volume of metal powder is related to the particle size and sintering temperature of metal powder.The smaller the particle size can get a higher penetration volume at high temperature.The microwave penetration volume fraction of metal Fe and Co powder in this paper is close to 100%at 900°C,which means that microwave can completely penetrate the metal powder to achieve whole heating.（2）According to the characteristics of the preparation of metal materials by the microwave cold pressing and sintering,the implementation scheme of the microwave sintering process is formulated.The microwave cold pressing sintering Cu based diamond saw blade parameters were studied.The optimum sintering process by microwave cold pressing sintering as follow:the sintering temperature is 860-900°C,cold pressure is 300-450 MPa,holding time is 30-45 min.With the increase of sintering temperature,the pore size of Cu matrix microstructure decreases,and the pore size becomes larger after reaching 900°C,and the microstructure is first uniform and then the grain growth trend.The bonding interface of Cu and Fe is enriched in liquid phase,and the reinforcing effect of liquid phase improves the strength of metal matrix.At the same time,it is found that Ti is enriched in the interface between diamond and metal,enhancing the wettability of the metal matrix to diamond,and improving the holding capacity of the matrix to the diamond.（3）Microwave hot pressing sintering method of Fe based diamond saw blade optimal ratio is as follows:Fe_0.62Sn_0.05Ni_0.08Cu_0.25.Under the optimal formulation conditions,the best sintering process for microwave hot pressing sintering is as follows:sintering temperature is 770-820°C,sintering pressure is 17-22 MPa,holding time is3-6 min.With the increase of sintering temperature,the microstructure distribution of Fe matrix is more and more uniform,and the size of the hole decreases first and then increases.The wettability between the metal matrix and diamond is enhanced,and the gap between the contact surfaces is obviously narrowed.When the sintering temperature of the Fe matrix is under 820°C,there is no graphitization transition.In the microwave field,sufficient alloying and solid solution strengthening effect between components make the metal matrix have good mechanical properties.（4）Compared with the conventional sintered diamond saw blade,the relative density,hardness and holding force coefficient of the microwave cold pressed sintered samples increased by 1.35%,2.73%and 6.79%,respectively.Meanwhile,the fractured pores of the materials after microwave cold pressing sintering were few,and diamond and matrix combination were better.Compared with conventional hot pressing sintering,the relative density,hardness,transverse fracture strength and impact toughness of microwave hot pressed sintered materials increased by 1.5%,1.21%,6.40%and11.43%,respectively.At the same time,the fracture of the material after the microwave hot pressing has more dimple and the composition is evenly distributed,and the fracture mechanism is characterized by ductile fracture.The local liquid phase formation of microwave sintering process,the sintering cutter wear resistance and cutting of more excellent microwave.