Study On Chemical Mechanism And Polishing Solution Preparation Of Chemical Mechanical Polishing Of Tungsten Cobalt Cemented Carbide

Tungsten-cobalt cemented carbide is a widely used tool material.The surface processing quality of tungsten-cobalt cemented carbide tool has an important influence on the development of manufacturing industry.Chemical mechanical polishing?CMP:Chemical Mechanism and Polishing?is currently recognized as a super-precision planarization technology.The CMP method is used to polish the surface of tungsten-cobalt cemented carbide material,which can effectively improve its surface quality.CMP is a synergy between machinery and chemistry.Its chemical mechanism is one of the hot issues in current research.In this paper,a more in-depth study on the chemical action mechanism of tungsten-cobalt cemented carbide under different chemical reagents was carried out,and on this basis,the corresponding CMP polishing solution was prepared.The main research contents are as follows:?1?The chemical corrosion behavior of tungsten-cobalt cemented carbide in six different corrosive media solutions of H₂O₂,H₃PO₄,Na₂SO₄,Na Cl,KOH,KMn O₄ was studied.Immersing the alloy in the above six corrosion medium solutions,it was found that in acidic solutions?H₂O₂,H₃PO₄,KMn O₄?and neutral solutions?Na Cl,Na₂SO₄?,the hard phase WC was protected as the cathode of the entire battery.At the phase boundary between the hard phase and the bonding phase,the Co layer corrodes first as the most anode feature.When the corrosion of the Co layer at the phase boundary reaches a critical point,the interlayer bonding phase?begins to corrode as a secondary anode feature.Among them,the corrosion rate is fast in acidic solutions H₂O₂ and H₃PO₄;in KMn O₄ solution,a thick oxide film is formed on the surface to suppress galvanic corrosion,and the above corrosion process stops quickly;in neutral solutions Na Cl and Na₂SO₄,The corrosion rate is slow.In the alkaline solution KOH,Co is passivated,causing the potential of the binding phase?electrode to be lower than WC,making WC the anode and the?phase the cathode.?2?The chemical mechanism of tungsten-cobalt cemented carbide in the above six different chemical reagents was studied.when polishing in H₂O₂ and H₃PO₄,while the Co precipitation on the alloy surface reaches the critical point,the stress applied by the abrasive particles is mainly concentrated on the surface of the WC particles,losing The strength of the WC particles supported by the bonding phase decreases.Under the scratching and compressive stress of the abrasive particles,the smaller WC particles are directly pulled out,the surface layer of the larger WC particles is broken into WC grains,and then the surface layer is mechanically Remove.When polishing in KMn O₄ solution,it mainly shows the alternating process of oxidation film formation and mechanical film removal.When it is polished in neutral?Na₂SO₄,Na Cl?and alkaline KOH solutions,its chemical action is extremely small,which can be regarded as only mechanical action,mainly manifested as the extrusion of the binder Co,followed by the partial drop and breakage of WC particles,But the process is very slow.?2?The composition of tungsten-cobalt cemented carbide CMP polishing solution was studied.Through experiment and theoretical analysis,Al₂O₃ particles with a size of 1?m were selected as polishing abrasive particles,the p H value of the polishing liquid was determined to be around 7,and triethanolamine oleate was selected C₂₄H₄₇NO₄ is used as corrosion inhibitor of polishing liquid,and potassium stearate C₁₇H₃₅COOK is used as surfactant of polishing liquid.?3?Through orthogonal test,the optimized ratio of the content of abrasive,oxidizer,corrosion inhibitor and surfactant in the polishing liquid of tungsten-cobalt cemented carbide was obtained.The optimized composition ratio of polishing solution is:abrasive particle concentration 17.5wt%,oxidant concentration 15wt%,corrosion inhibitor concentration0.25wt%,surfactant concentration 0.3wt%.The stability and reliability of the polishing solution under this ratio were verified through experiments.