| With the rapid development of the mechanical manufacturing industry in the direction of semi-automation and full automation,especially various lathes and CNC machine tools and grinding machines and milling machines etc.are widely used in which production and life and the core components of these machining are the tools.Therefore,the service life of the tool plays a leading role in the normal operation and operation of the machine.This requires that it should have a good friction and wear properties as well as excellent cutting performance to meet industrial needs and save production costs.How to effectively extend the service life of the tool and enhance the cutting performance has become a hot research topic in modern manufacturing.In this paper,H13 steel was selected as the experimental research object,and Al2O3 thin films were deposited on the surface of the substrate by RF magnetron sputtering.Firstly,the influence of background vacuum,target power,working pressure and O2 flow rate on the deposition rate and performance of Al2O3 coating were explored by single factor analysis method,and the process range of each factor were narrowed.Secondly,in order to obtain the optimal process parameters of the Al2O3 film preparation path,the effects of three factors and three levels on the film properties were studied by orthogonal test.Then,using the range method,the order of influence on the deposition rate and the degree of influence of each level of each factor on the test index were discussed.After the optimal optimization path was obtained by the comprehensive balance method,the surface morphology of the coating was observed by scanning electron microscopy and the energy spectrum analysis was carried out to verify the rationality of the optimal process parameters.Finally,the Al2O3 film obtained under normal conditions was subjected to high temperature annealing treatment to explore the effects of different thickness of Al2O3film on the phase structure and comprehensive properties of the Al2O3 film after annealing.The crystal structure of Al2O3 coatings with the same film thickness was normalized,annealed at 800?and annealed at 1000?,and the coatings were analyzed by SEM.The results of the study are as follows.?1?When the background vacuum is 9.0×10-52.0×10-5Pa,the deposition rate increases from 3.924nm/min to 5.067nm/min.A background vacuum of 5.0×10-5Pa was selected for all tests.?2?As the target power increases from 80W to 120W,the deposition rate of Al2O3 coating increases from 1.95nm/min to 5.30nm/min;however,the surface roughness also increases,increasing from 0.09?m to 0.045?m.?3?When the O2 flow rate is increased from 0.6sccm to 0.8sccm,the roughness of the coating is reduced from 0.073?m to 0.040?m,and the deposition rate also decreases.As the O2 flow continues to increase,the surface roughness of the coating will be stable.?4?With the increase of working pressure,the deposition rate of the coating first changed and then decreased slowly,and the deposition rate also decreased from4.72nm/min to 2.07nm/min.When the working pressure is from 0.5 to 1.5 Pa,the surface roughness of the coating is slowly increased from 0.037?m to 0.040?m.Continue to increase the working pressure,the surface roughness will remain within a fixed range.?5?It is concluded that the order of influence of various factors on the deposition of Al2O3 thin films is that the working pressure has the greatest influence on the deposition of Al2O3 thin films,followed by the flow rate of O2,and the target power has the least influence on the deposition of Al2O3 thin films.According to the orthogonal test method,the optimum process combination in a certain process range is 120W+0.5Pa+0.8sccm.At this time,the deposition rate is the fastest,reaching6.18nm/min.The composite hardness and surface roughness of Al2O3 coatings deposited with optimized process parameters are 554.7HV and 0.037 micron respectively.The preparation time of the coating was 97.087 min.Al2O3 thin films were prepared by the optimum process parameters,and the surface morphology and energy spectrum were analyzed.The rationality of the optimum process parameters was obtained.?6?Finally,it is concluded that different film thicknesses have no effect on the crystalline structure of the films annealed at normal,800 and 1000.They are still amorphous,but the intrinsic hardness increases with the increase of the film thickness in the threshold range.The crystalline structure and structure of Al2O3 coatings can be changed at different annealing temperatures with the same film thickness.After annealing at 800C,the phase structure of?-Al2O3 appears.After annealing at 1000C,the main phase of the coating is crystalline?-Al2O3.The coatings were observed by SEM,and the films with good density and uniform grain size were obtained. |
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