Study On Tribological Behavior Of CBN-WC-10Co Composites

The cBN-WC-lOCo composites fabricated by SPS method has high strength,high hardness and better fracture toughness than cBN.Therefore,the cBN-WC-lOCo can be widely used in many applications.In the machining process,the wear of tool directly affects the machining precision,surface integrity,surface quality and especially the cost of the machined part.Therefore,it is fairly important to explore the wear resistance of cBN-WC-10Co composites.In this thesis,the wear behaviors of three different cBN-WC-10Co composites were studied and the wear resistance and wear mechanism of cBN-WC-10Co composites were explored.The effects of experimental parameters on friction coefficient,wear rate and surface SEM morphologies were revealed.The main research contents are as follows:(1)The mechanical properties of CBN-WC-lOCo materials were studied.The Vickers hardness tester and densitometer were used to measure the hardness and density of the material.The effects of different particle size CBN particles on the hardness and density of the material were revealed.The surface morphology of the material was observed by environmental scanning electron microscopy and the WC particle size after sintering was measured.The results show that the CBN particles greatly improve the hardness of the material,while the CBN particle size has no obvious effect on the hardness of the material.In addition,the large cBN particles has better sintering performance than the small one.(2)The wear experiments of CBN-WC-lOCo materials were carried out,and the influence of normal load and sliding speed on the wear resistance of the materials was investigated.The wear resistance of the material was tested by wear tester.The wear volume of the material was measured by surface profilometer.The surface morphology was observed by scanning electron microscope.The results show that the friction coefficient decreases with the increase of the normal load,and the wear rate increases with the increase of the normal load.In addition,the CBN particle reduces the wear rate of the material,which effectively improves the wear resistance of the material;the main friction and wear mechanism is abrasive wear,accompanied by a small amount of oxidative wear.(3)Relationship between wear resistance of CBN-WC-lOCo material and particle size of CBN particles was revealed.The results show that the CBN-WC-10Co material with small particle CBN exhibits good friction performance when the normal load is small.When the normal load is increased to 70 N,the material sintered with large particles of CBN behaves more wear-resistant;The CBN particles are embedded in the WC-10Co cemented carbide substrate to remove the SiC material as micro-cutting edges.