Preparation Of AlMgB₁₄-TiB₂ Coating Tool And Study On Cutting Behavior Of Titanium Alloy

Although titanium alloy is widely used in a number of fields,the machining process is difficult because its low thermal conductivity、low modulus and high chemical reactivity characteristics will lead to sharp tool wear,affect the processing efficiency,increase the cost of processing,and have an adverse effect on the quality of the workpiece processing.In this case,coating on the cutting tool is one of the effective methods to improve the cutting performance.However,due to the high chemical reactivity of titanium alloy,the traditional coating tool is easy to form adhesive wear in the cutting process,which leads to the deterioration of the coating tool performance.Therefore,according to the characteristics of titanium alloy cutting process,coating tools with good hardness and low chemical reactivity with titanium should be prepared to improve the cutting performance of the tool.Boride coatings with low reaction tendency to titanium and good mechanical properties have attracted wide attention,researchers have conducted relevant experiments on cutting titanium alloys with boride coating tools and verified the feasibility of this kind of coatings in cutting titanium alloys.However,the boride coating often has the problems of too thin deposition thickness,limiting the full play of coating performance,coating and substrate binding is not strong,the allowed cutting speed is not high.In order to solve the problem of boride coating tool and give full play to the performance of boride coating tool in the cutting process,the effects of different pretreatment conditions and sputtering parameters on the structure and performance of AlMgB₁₄-TiB₂ coating during DC magnetron sputtering were systematically studied in this paper.Ti6A14V,the most widely used titanium alloy,was selected as the workpiece,and the cutting experiments were designed to verify the performance of the coating tool under dry cutting conditions.The static diffusion experiment was designed to simulate the element diffusion process in titanium alloy cutting.The experimental results were characterized by scanning electron microscopy（SEM）,nanomechanics test system,energy dispersion spectrometer（EDS）,X-ray photoelectron spectroscopy（XPS）and transmission electron microscopy（TEM）.The conclusions are as follows:（1）Through the regulation of each process of magnetron sputtering and the characterization of the prepared coating samples,it is found that pretreatment、bias、temperature and substrate rotation can improve the adhesion of the coating on the tool through different action mechanisms;The reduction of the distance between target and substrate,the increase of sputtering power can simultaneously improve the deposition rate of the coating;The stability of the deposited coating components is good,indicating that the different performance is related to the coating structure,but not related to the composition.（2）Through the comparison experiment of Ti6A14V cutting processing using coated cutting tools and uncoated cutting tools under dry cutting conditions with different cutting parameters,the different flank wear indicates that AlMgB₁₄-TiB₂ coating can slow down tool wear and prolong tool service life.The improvement effect of the coating on tool cutting performance is shown in different cutting parameters,which shows that the coating has a wide range of application.（3）The tool wear morphology shows that the main wear mechanisms of tool cutting titanium alloy are abrasive wear,adhesive wear and diffusion wear,where the coating alleviates the three wear mechanisms.Static diffusion experiments show that the coating inhibits the diffusion of tool elements to titanium,which verifies the effect of coating on diffusion wear.