Study On Alumina Based Self-lubricating Ceramic Cutting Tools Added With Nickel Boron Coated Calcium Fluoride Composite Powder

In order to make a further research on the self-lubricating ceramic cutting tool,In this paper,the effect of solid lubricant on the mechanical properties of ceramic tool material is cut in point.Aiming at the disadvantage of low mechanical property of solid lubricant and the wear resistance and the wear resistance of the self lubricating ceramic cutting tool can not be properly considered.The application of surface coating technology to the preparation of self lubricating ceramic cutting tool is presented.The alloy Ni-B was coated on the surface of CaF₂ particles by ultrasonic chemical plating method.The outer layer is formed with a metal property and the inner layer has a lubricating property of the composite powder and then add it into the ceramic matrix.Preparation of ceramic cutting tool materials by vacuum hot pressing sintering process is Al₂O₃/TiB₂/CaF₂@Ni-B.While ensuring the mechanical properties of self lubricating ceramic tool material,the self lubrication function of material is realized.The Ni-B coated CaF₂ powder was prepared by ultrasonic chemical plating.The concentration,temperature,stirring rate and the effect of pH on the plating rate and weight gain rate were analyzed.And the optimal coating conditions: optimization of nickel sulfate,boron sodium hydride,ethylenediamine and stabilizer concentration respectively 18g/L,1.3g/L,60ml/L and 1mg/L,pH is 14,stirring rate is 45r/min,temperature 65-75℃ is obtained.The appearance of CaF₂ coated composite powder is compact,there is no sharp corners,and it does not contain other impurities.The experiments were conducted to study the contrast between CaF₂@Ni-B with 10 vol % and CaF₂ with 10 vol.%and it is found that the mechanical properties of the material are improved,the hardness of the material is increased by 2%,the fracture toughness is increased by 27%,and the bending strength is increased by 7%.The effect of CaF₂@Ni-B content on the mechanical properties of self lubricating ceramic cutting tools was studied by experiments.Its hardness,fracture toughness and bending strength were 16.2GPa,8.2MPa·m1/2 and 495 MPa.The effect of sintering process on the mechanical properties of the self-lubricating ceramic tool material was studied.It shows that 5vol.% and 10%vol.CaF₂@Ni-B materials with good mechanical properties were selected as self lubricating ceramic cutting tools and cut 45 steel with different cutting parameters in the form of dry cutting.At the same time,the experiment will be compared with the direct addition of CaF₂ tool.The influence of cutting parameters on the effective cutting distance of the cutting tool and the surface roughness of the workpiece is studied.The wear mechanism of two kinds of tool flank is studied.The experimental results show that with the increase of cutting speed,tool flank wear speed is accelerated,the effective cutting distance of the two kinds of cutting tools is reduced continuously.The cutting distance of AB ceramic cutting tool is better than that of ABF@5.At the same time,with the increase of the cutting speed,the surface quality of the cutting tool is also improved.the surface quality of ABF@5 ceramic cutting tool is better than that of AB ceramic tool.The results show that the cutting effect of the self lubricating ceramic cutting tool with CaF₂@Ni-B is superior to the AB ceramic tool in machining the surface quality of the workpiece.The cutting performance of ABF10 and ABF@10 two kinds of self lubricating ceramic tool materials in cutting 45 steel was analyzed and compared.the ABF@10 effective cutting distance to cutting distance is superior to the ABF10.It is showed that the wear resistance of the self-lubricating ceramic tool material with CaF₂@Ni-B is better than that of the self-lubricating ceramic tool material with CaF₂.The experimental results show that with the increasing of the cutting speed,the surface quality of the machined parts of the two kinds of tool materials is improved,and the results show that the surface quality of the workpiece is good.The relationship between cutting force and friction coefficient of 4 kinds of ceramic cutting tools is studied experimentally,and with the addition of solid lubricant,the cutting force of ceramic cutting tool is reduced,and the main cutting force and radial force decrease obviously.When the content of CaF₂@Ni-B is 10%,the friction coefficient of ceramic tool is the least.But the cutting force and the friction coefficient of the coated and uncoated two kinds of cutting tools have little difference.