Effect Of Binder Phase On Microstructure And The Cutting Properties Of Ti(C, N)-based Cermets

This thesis is composed of five chapters.In the first chapter,the microstructure and properties of Ti(C,N)-based cermets as well as its development history were introduced.At the same time,the study on the phase interface between hard phase and binder,the effectiveness of addition agents on the microstructure and mechanical properties and the sintering methords were briefed.In chapter two,we focused on the preparation process,testing method of mechanical properties and characterization methods of microstructure of Ti(C, N)-based cermets.Effects of Co partly and completely replace Ni on the microstructure and properties of the superfine Ti(C,N)-based cermets were discussed in chapter three. The research shows:1) The white core and gray shell structure is easily found in the cermets(sample A,B) with more Ni as binder.A few Co replaces Ni as binder can refine the grain,but the grain will coarsen with the increasing of Co contents.2) The intermetallic compound is both found in the cermets with 5%Ni10%Co and 15%Co due to the agglomeration of Co,which hinder the appearance of white inner shell and white core structure and reduce the bending strength and toughness.3) The cermet with the binder phase of Ni and Co can obviously improve the cermet's bending strength,hardness and fracture toughness,however,Ni and Co need to be selected with the appropriate ratio.The cutting performance of experimental cutting inserts between the metallographic phase contents of 15%Co and 15%Ni against AISI 1045 carbon steel was researched in chapter four,in which we mainly investigated the influence of cutting speed on the tool's cutting performance and the wear mechanism.The results show that Co diffused easier than Ni during the cutting process,the cermet of 15%Ni as binder will easier emergence the crescent moon hollow attrition than the cermet of 15%Co as binder because of its poor plastic deformation capacity. However,the cermet of Co containing is liable to tipping under high speed because of the existence of intermetallic compound.Chapter five summarized the whole thesis and gave some advice on future works.