Effect Of Boronizing Treatment On Microstructure, Thermal Shock Resistance And Cutting Performance Of Cermets

Nano TiN modified Ti（C,N）-Based Cermets were made by powdermetallurgical method, and then solid powder Boronizing Treatment was conductedon cermets. Effect of Boronizing Treatment on microstructure, mechanical propertyof Ti（C,N）-Based Cermets were studied, and Effect of Boronizing Treatment onThermal Shock Resistance, Cutting Profermance of Ti（C,N）-Based Cermets werealso studied.This thesis is composed of six chapters. In the first chapter,the developprocess, preparing process,microsructure,mechanical property,thermal shockresistance and cutting property of Ti（C,N）-based cermets were introduced. Thedevelop process of tool materials and boronizing method were also introduced. Theapplication and development of boronizing method and tool materials were mainlyintroduced.In chapter two, The preparing process and Boronizing Treatmen of Nanomodified Ti（C,N）-Based Cermets were introduced in detail. Meawhile, the testmethod of cermets’mechanical property and the representation of microstructurewere summarized too.In the third chapter, we discussed the effect of Boronizing Treatment onmicrostructure and properties of nano modified Ti（C,N）-based cermets. Resultsshow that:（1） On the sample surface,the thickness of boronized layer was about30μm, which consisted of borides such as TiB₂, MoB₂, CoB, Ni₃B and so on;（2） Theboronized layer was not like comb type, which different from steel andsteel-bonded hard alloy;（3） The microhardness of the surface increased by43%, butthe bending strength decreased.In the fourth chapter, we studied the effect of Boronizing Treatment onThermal Shock Resistance of nano modified Ti（C,N）-based cermets. The ThermalShock Resistance of nano modified Ti（C,N）-based cermets include boronizedsamples and non-boronized samples were investigated by quenching-strength test,indentation-quench test and notches pre-made in the end of samples. All the results obtained by these three methods conformably show that the Thermal ShockResistance of non-boronized samples better than boronized samples. By the notchespre-made in the end of samples method, the boronized samples longer thannon-boronized samples in the incubation period of notch crack. But the crack onceformed, the crack growth rate of boronized samples was faster than non-boronizedsamples.In the fifth chapter, the effect of Boronizing Treatment on CuttingPerformance of nano modified Ti（C,N）-based cermets tool were studied. We mainlyinvestigated working durability and wear mechanism of boronized andnon-boronized tools in the same cutting parameters condition. Results show that:The working durabiliry of boronized tools longer than non-boronized tools whenVc=200m/min.But when Vc=300m/min or400m/min, the ture is opposite. The wearmechanism of these two type tools all include abrasive wear, adhesion wear,oxidative wear, and diffusion wear. Along with the increase of the cutting speed,the wear mechanism of these two type tools all mainly turn abrasive wear toadhesion wear.Chapter six summarized the whole thesis and gave same advice on futureworks.