Study On Study On The Chemical And Mechanical Polishing Process Of Titanium Alloy

Titanium alloy has high mechanical strength,fatigue resistance,oxidation resistance,corrosion resistance and other excellent properties,more and more widely used in integrated circuits,MEMS,optical mold and other high-precision devices.At present,there are few researches on CMP process of titanium alloy at home and abroad,so it is of great significance to explore chemical-mechanical polishing process for machining efficiency and surface quality of titanium alloy.In this paper,the interaction effect of process parameters on machining properties in chemical-mechanical polishing of titanium alloy was investigated,the removal mechanism of chemical-mechanical polishing of titanium alloy was analyzed,and a particle swarm optimization BP network model was established.The main research contents are as follows:1.Analysis of the influence of chemical mechanical polishing fluid on processing qualityThe effect of PH value,oxidant concentration and abrasive concentration on the mechanical polishing properties of titanium alloy and the optimal parameter combination were investigated by orthogonal test.The results show that the factors affecting the material removal rate are as follows:A（PH value）>C（abrasive concentration）>B（oxidant concentration）.The factors affecting the surface roughness are as follows:A（PH value）>B（oxidant concentration）>C（abrasive concentration）.According to the range analysis:the best process parameter combination A₂B₃C₄（PH 4,oxidant concentration 3%,abrasive concentration 40%）for material removal rate,and the best process parameter combination A₁B₃C₃（p H 2,oxidant concentration 3%,abrasive concentration 30%）for surface roughness.2.Optimization of chemical mechanical polishing parameters of titanium alloyThe interaction among pressure,rotation speed and flow velocity was investigated by response surface experiment,and a regression prediction model for machining properties of chemical-mechanical polished titanium alloy was established.The test results show that the order of influence of polishing parameters on surface roughness is pressure>flow rate>speed.The order of influence on material removal rate is velocity>pressure>speed.The process parameters corresponding to the minimum surface roughness and maximum material removal rate were:pressure 3k Pa,flow rate 20m1/min,rotation speed 80r/min;The minimum surface roughness is 13.58nm,and the maximum material removal rate is 115.35nm/min.The error of surface roughness and material removal rate after polishing is less than 5%.The prediction and comparison of particle swarm optimization BP neural network results shows that PSO-BP neural network is more accurate than BP neural network.3.Removal mechanism analysis of titanium alloy by chemical-mechanical polishingThe surface mechanical properties of titanium alloy before and after soaking were tested by different loads.It was found that the surface mechanical properties of titanium alloy before and after soaking had obvious changes when the load was 5m N,which was more suitable for measuring the difference of surface mechanical properties of titanium alloy before and after soaking.The hardness and elastic modulus of titanium alloy surface decrease first and then increase with the increase of p H and H₂O₂concentration in polishing liquid,while the maximum pressing depth of titanium alloy surface increases first and then decreases with the increase of p H and H₂O₂concentration in polishing liquid.When the concentration of H₂O₂is 3%and p H is 4,the hardness and elastic modulus of the surface are the minimum,and the maximum pressing depth is the maximum.The removal mechanism of titanium alloy CMP was investigated.