Study On The Preparation And Performance Of Precision Lapping Liquid

In the field of precision machining, Oil-based slurry possesses not only the effect of grinding removal, but also the properties of cleaning, lubricating and anti-rust. SiC has the feature of low density, high hardness and anti-oxidation, which become a ideal choice of abrasive in abrasive products. Nowadays, preparation of oil-based slurry and silicon carbide abrasive have been widely studied, while the research on preparation of silicon carbide oil-based grinding fluid was rarely reported. In this paper, micron ?-SiC was selected to be free abrasives to prepare high-performance precision lapping slurries. Meanwhile, in order to solve the problem of powders agglomerate, and enhanced the hydrophobicity of the powder, coupling agent KH550,KH570 and modifying agent Span 60 were used to modification after the pretreatment.Moreover, the effects of the dispersion process, the kind and concentration of dispersants were also discussed in this article.The hydrophobicity of the powder before and after the modification were investigated via capillary method and viscometry. The compose and surface structure of SiC powders were tested by XRD and FT-IR, the change of the covering amount was analyzed by TG-DSC, and the agglomerate of the powders and the surface topography of the workpiece after grinding were observed by SEM. What's more, the optimum ratio of the based oil was determined by anti-oxidation tests, the best dispersion process and the most suitable dispersing agent were confirmed by orthogonal test and sedimentation test.The experiment results show that when kerosene and castor oil mixed at a mass ratio of 2: 3, the sample has the oxidation stability, and it has viscosity stability at a high shear rate. The SiC powders by alkaline cleaning possessed good suspension stability and weak adhesive resistance, due to the obviously removal of the organic matter and impurities on the surface. In the treatment schemes of coupling agent, the SiC powders modified by KH570 had the better hydrophobicity compared with KH550, and the modified powders were uniformly dispersed, which had no obvious agglomeration. The Span 60 with low HLB was selected to modify SiC powders. The modified SiC powders were coated with modified groups successfully, and the powders had uniform distribution and no agglomeration as well. In addition, for double coated modification, KH570 and Span 60 was successfully grafted on SiC surface, and the powders appeared the best hydrophobicity than any single coatedmodification.The conditions of orthogonal experiment which was used to confirm that the best dispersing technology of the SiC powders in based oil included: milling time 4 h,rotating speed 600 r/min, ball-to-powder weight ratio 1:5; The hyperdispersant Tech-5080 with longer solvation molecular chain possessed the best dispersing performance when a single dispersant was added. The compound addition with hyperdispersant Tech-5080 and nonionic surfactant OP-7 could improve the stability of the slurry. The orthogonal test between dispersing agent and nonionic surfactant showed that 8% Tech-5080 and 5% OP-7 with 90 min pre-mixed time was the optimal dispersion solution. And the prepared slurry had good oxidation resistance and good grinding performance.