Study On Chemical Mechanical Polishing Process Of GCr15 Bearing Based On Environment-friendly Slurry

GCr15 bearing steel is one of the most commonly used high chromium-bearing steels.It has wear resistance and corrosion resistance.It is widely used to bear inner,outer rings,cutting tools,measuring tools,molds,and other mechanical parts.Among them,the bearing is one of the critical applications of bearing steel.The bearing's structural design and manufacturing accuracy are essential to the life and quality of the approach.At the same time,the material used in the direction is also the key to the bearing steel.The bearing steel plays an extremely important role in the quality,service life and reliability of the bearing product.The performance of the bearing steel affects the bearing.One of the key factors of performance.Therefore,low surface roughness,especially ultra-smooth surface,is of great significance for bearings.Chemical mechanical polishing is an ultra-precision machining technology that can achieve smooth and non-damaged surfaces.However,in the chemical mechanical polishing process,in order to achieve good surface quality and high material removal rate,strong acids,strong alkalis or hazardous chemicals are often used in the polishing liquid to enhance the chemical corrosion effect in the chemical mechanical polishing process or Corrosion inhibition effect.These hazardous chemicals have potential hazards to operators and equipment and even affect the sustainable development of the ecological environment,seriously deviating from the concept of"green manufacturing".Therefore,it has become the trend of chemical mechanical polishing to develop environmentally friendly green polishing fluids and achieve ultra-precision surface processing under these conditions.Therefore,this article mainly explores the influence of green polishing liquid on the polishing performance of bearing steel and the mechanism of action.Using chemical mechanical polishing technology,combined with electrochemical experiments,XPS detection technology and other experimental methods.Firstly,the influence of green complexing agent on the polishing performance of bearing steel is studied;Secondly,the impact of green corrosion inhibitor on the polishing performance of bearing steel is studied first.At last,a two-step method is used to prepare the super smooth surface of GCr15 bearing steel.After polishing for 10 minutes in the first polishing step,the surface morphology changes from rough and uneven to smooth.In the second polishing step,continue on the basis of the first step.After 8 minutes of polishing,the surface of the nano-level precision GCr15 bearing steel with a surface roughness R_a of 1.0 nm in the scanning area of 97.9×97.9?m²was realized.The main research content and results of this article are as follows:(1)The effect of green complexing agent on the polishing performance of GCr15bearing steel was exploredWhen the composition of the polishing liquid is mainly composed of 50 mM Ethylenediamine disuccinate and 0.1 wt%H₂O₂ at p H 5.0,the material removal rate of GCr15bearing steel is 366 nm/min,and the surface roughness R_a is 3.6 nm.Among them,H₂O₂mainly provides oxidation,and ethylenediamine succinic acid mainly provides complexation together to form an incomplete and low mechanical strength reaction film on the surface of GCr15 bearing steel.The abrasive particles mainly provide the mechanical force to remove the reaction film.Under the condition of adding ethylenediamine succinic acid to the polishing solution,with H₂O₂ and the increase of the concentration,the material removal rate reaches the peak and then decreases.This is mainly because when the H₂O₂ concentration is 0.1 wt%,the GCr15 bearing steel.The composite film formed on the surface is composed of iron oxides and iron complexes,which are porous and have low mechanical strength and are easily removed.When the concentration of H₂O₂ further increases,the material removal rate gradually decreases,mainly because the surface of GCr15 bearing steel is mainly composed of an oxide layer,and the oxide layer is dense and has high mechanical strength.(2)The effect of green corrosion inhibitor on the polishing performance of GCr15bearing steel was exploredThe effects of green corrosion inhibitors phytic acid,sodium carboxymethyl cellulose,3-amino-1,2,4-triazole,1,2,4-triazole on the chemical mechanical polishing of GCr15 bearing steel were explored.The results show that 1,2,4-triazole has the best surface quality compared to the other three corrosion inhibitors.Under the condition of adding 1,2,4-triazole to the polishing solution,1,2,4-triazole can be chemically adsorbed and physically adsorbed on the surface of GCr15 bearing steel and has a protective effect through chemical adsorption.1,2,4-Triazole forms a film on the surface of the steel,which inhibits corrosion through adsorption,creating an obstacle between the surface of GCr15 bearing steel and the surrounding environment.1,2,4-Triazole can react with Fe²⁺or Fe³⁺to form complexes.The corrosion inhibition film formed by 1,2,4-triazole can effectively prevent the anodic reaction of the active part from occurring,thereby increasing the overall average activation energy barrier and reducing corrosion and wear caused by corrosion.(3)Optimization of green process for CMP of GCr15 bearing SteelA two-step method is used to prepare the super smooth surface of GCr15 bearing steel.In the first step of polishing,the components of the polishing solution are deionized water,2wt%colloidal silica,50 mM ethylenediamine disuccinic acid,0.1 wt%H₂O₂,10 mM 1,2,4-triazole,When the p H is 3.0,down force is 5.0 kg.the damage layer caused by mechanical processing has been completely removed after polishing for 10 minutes.The surface roughness of GCr15 bearing steel decreases linearly,and the surface morphology changes from the initial roughness to smooth and flat surface.In the second step of polishing,when the composition of the polishing solution is deionized water,2 wt%colloidal silica,50 mM ethylenediamine disuccinic acid,0.1 wt%H₂O₂,10 mM 1,2,4-triazole,p H is 9.0 and down force is 7.0 kg,because a dense passivation film is formed on the surface,after polishing for 8 minutes on the basis of the first step,a 97.9×97.9?m² scanning area of the inner surface is achieved.The surface of nano-level precision GCr15 bearing steel with a roughness R_a of 1.0 nm.