Study On Properties Of Tib₂-TiN Ceramic Tool Toughened By Carbon Fiber

The purpose of the study was to improve the Ti B2-Ti N ceramic material mechanical properties,especially the fracture toughness.The influence of content of carbon fibers,metal binder additives,sintering temperature and holding time on the microstructure and mechanical properties of Ti B2-Ti N ceramic cutting tool materials has been studied.The toughening mechanism of Csf reinforcing Ti B2-Ti N ceramic materials has been revealed;The friction and wear properties of typical refractory materials were studied,and the wear mechanism was revealed.In addition,the specific research contents and results were as follows.First of all,according to the design principles of ceramic cutting tool materials and the goal of this topic,the enhancements of Ti B2 based ceramic cutting tool materials were determined to use Ti N and Csf,metallic phase was Ni.In this paper,physical and chemical compatibility and wettability between raw materials were analysized,sintering process and the experimental scheme were made,and the test methods were expounds.Experimental research the influence of of Csf content,Ni content and sintering process parameters on microstructure and mechanical properties of the Ti B2-Ti N-Csf ceramic cutting tool materials.And the results showed that,with the content of Csf increased,Ti B2-Ti N ceramic material hardness decreased gradually.However,the flexural strength and the fracture toughness increased first and then decreased;With the sintering temperature rose,the hardness,flexural strength and fracture toughness of Ti B2-Ti N ceramic tool material decreased;And with the holding time extended,the hardness,flexural strength and fracture toughness of Ti B2-Ti N ceramic tool materials were increased first and then decreased.When Csf content was 1.5wt.%,Ni content was 10%,the sintering temperature was 1600℃,sintering pressure was 20 MPa and the holding time was 40 min,Ti B2-Ti N-Csf ceramic cutting tool materials obtained optimal mechanical properties,which were 19.92 GPa of vickers hardness,933.12 MPa of flexural strength and 10.81MPa·m1/2 of fracture toughness.The toughening and reinforcing mechanisms of Ti B2-Ti N ceramic tool materials were crack bridging,fiber toughening,crack deflection and grain removal.Experiment studied the dry friction and wear properties of Ti B2-Ti N ceramic cutting tool materials and typical difficult-to-machine materials 316 L austenitic stainless steel,YG6 carbide and TC4 titanium alloy,the results showed that:(1)During the dry friction process,the main wear mechanisms between Ti B2-Ti N ceramic cutting tool materials and 316 L austenitic steel ball was oxidation wear,accompanied by a certain amount of adhesive wear and abrasive wear.Under the fixed load,the friction coefficient and wear rate decreased with the increase of slip velocity.The friction coefficient and wear rate of the material increased with the increase of load.(2)During the friction and wear process of Ti B2-Ti N ceramic material and YG6 cemented carbide ball,the wear mechanisms were mainly abrasive particles wear and adhesive wear,accompanied by a certain degree of fatigue wear.Under the fixed load,the friction coefficient and wear rate decreased with the increase of slip velocity.At the fixed slip velocity,the friction coefficient of the material decreased with the increase of load,and the wear rate of the material increased with the increase of load.(3)During the friction and wear process of Ti B2-Ti N ceramic materials and TC4 titanium alloy ball,the wear mechanism of the material were oxidation wear and a certain degree of abrasive wear and adhesion wear.Under the fixed load,the friction coefficient of the material decreased with the increase of slip velocity,while the wear rate of the material increased with the increase of slip velocity.At the fixed slip velocity,the friction coefficient of the material decreased with the increase of load,and the wear rate of the material increased with the increase of load.