The Basic Research On Preparation Of SiC Grinding Wheel By Sol-Gel In-situ Method

The traditional vitrified grinding wheel using for precision grinding were obtained after mixing,pressing and sintering a few microns to dozens of micrometers of power binder and ultrafine abrasive.The power agglomeration and coarse binder particles made the grinding wheel microstructure coarse and poor uniformity,which made the grinding wheel grinding performance not ideal.This paper used the whole liquid material as the vitrified bond and SiC as abrasive to prepare the vitrified bond SiC grinding wheels by the sol-gel in-situ method.The properties of the R2O-ZnO-Al2O3-SiO2 multi-component sol bond were studied.And discussed the modification of SiC.The properties of the mixed slurry and the vitrified bond SiC sintered bodies were discussed by using dispersants,defoamer and different process conditions.The main contents and results as follows:(1)Vitrified bond was prepared by sol-gel in-situ method,when the sintered temperature was 850?.The Li2ZnSiO4 and LiAlSi2O6 were in the bond,and the expansion coefficient of the bond was 6.6×10-6/?.(2)KH550 silane coupling was used as surfactant to modify the surface of SiC powders.Results showed that the surface of SiC powders was successfully coated by KH550 layers through grafting reaction,which did not change their phase and structure.When the amount of KH550 was 5wt%,their average size D50 also were reduced from 4.11?m to 1.70?m,Zeta potential of SiC increased,the suspensibility and dispersibility of powders in sol were improved.(3)With the increase of the temperature of the system,the viscosity of the mixed slurry gradually increased and the initial gel time was shortened.The experiment was carried out at a temperature of 50? and a gel temperature of 80?.With the increase of solid content,the viscosity of the system gradually increased,the initial gel time decreased.When the solid content was 60vol%,the micro-structure of the sintered body was more uniform,the porosity was 26.1%,the maximum density was 1.92g/cm3,and the bending strength reached 54.06MPa.(4)The order of dispersion is:FDN>Na3PO4·12H20>(NaP03)6>CH3(CH2)11OS03Na.When the addition amount of FDN was 0.4wt%,the dispersion and mobility of the system were best.The order of defoamer is:DD>DP-304>DP-307,when the content of DD defoamer was 0.2wt%,the structure of the composite sintered body was uniform,density and flexural strength reached the maximum,respectively 2.12g/cm3 and 65.1MPa.(5)Compared with the no additives sintered body,the addition of 0.4wt%FDN and 0.2wt%DD defoamer body's structure was compact and uniform,the density and flexural strength were max.The surface quality of cemented carbide polished by the new designed wheel was good.No deep scratches were observed,and the surface roughness Ra was 0.04?m,which was lower 0.05?m than that no additives sintered body.