Research On Chemical Mechanical Polishing Slurry And Polishing Mechanism Of 304 Stainless Steel

With the rapid development of display technology,flexible display technology is widely used in various industries because of its excellent performance.Stainless steel foil has good flexibility,corrosion resistance and other excellent properties,and can be used as a flexible display substrate.However,because the flexible display substrate requires extremely high surface quality,it requires super-finishing of the stainless steel material.Chemical mechanical polishing is currently the best global flattening technology for superfinishing of stainless steel materials.Among them,polishing solution is the key technology in chemical mechanical polishing technology,however,most of the reported stainless steel polishing solutions have used strong acid,strong alkali or other strong corrosive reagents,which are potentially harmful to operators and the environment,contrary to the concept of green processing and manufacturing,and still have the problem of difficult to balance polishing quality and efficiency.Therefore,it is of great practical importance to study new polishing solutions for stainless steel.The main research direction of this thesis is new 304 stainless steel polishing solution,firstly,using single-factor experiment,the composition and content of 304stainless steel polishing solution was optimized,mainly including abrasive grain type,pH value,oxidant concentration,surfactant concentration and complexing agent concentration,and finally determined the main components of new polishing solution for 304 stainless steel are:3 wt.%grain size 50 nm Al₂O₃ abrasive grain,0.3 wt.%H₂O₂,L-malic acid to adjust the pH value to 3,0.3 wt.%OP-10,1.5 wt.%glycine and deionized water.The additives used in this new polishing solution,such as H₂O₂ and L-malic acid,are inexpensive and environmentally friendly reagents,which are not potentially harmful to the operator and the environment.On this basis,the effects of the three main polishing process parameters polishing pressure,polishing pad speed and polishing time on the chemical mechanical polishing effect of 304 stainless steel at different levels were investigated through orthogonal tests.The experimental results were analyzed based on the polar difference method,and the optimal combination of polishing process parameters was obtained:polishing pressure of 16.3 kPa,polishing pad speed of 100 rpm,and polishing time of 35 min.Finally,polishing experiments on304 stainless steel using the developed new polishing solution and optimized process parameters can reduce the surface roughness Ra value to 0.539 nm in a measurement area of 70×50μm²,and the material removal rate MRR reaches 255.2 nm/min,realizing green,high quality and efficient ultra-precision processing of 304 stainless steel.To investigate the interaction of the factors in the chemical mechanical polishing system,the reactions between the components in the polishing solution and the surface of 304 stainless steel occurring during the polishing process were investigated.In this thesis,electrochemical experiments,X-ray photoelectron spectroscopy experiments and infrared spectroscopy experiments are used to investigate the mechanism of chemical mechanical polishing process of 304 stainless steel.During a material removal cycle,the surface of 304 stainless steel is first oxidized by H₂O₂,producing an oxide film that covers the surface of the workpiece.And then,this oxide film reacts with H⁺in an acidic environment and corrodes and dissolves,producing metal ions.Afterwards,the metal ions generated by corrosion are complexed by L-malic acid and glycine,forming complexes and remaining adsorbed on the surface of the oxide layer.Finally,the oxide adsorbed layer is removed by mechanical grinding of Al₂O₃ abrasive grains to reveal a fresh surface.At this point,a material removal cycle is completed.In this cycle,the stainless steel surface damage layer is gradually removed,the final formation of ultra-fine surface.