Study On The Preparation And Property Of ZnO Coated Miro Diamond Powder

Vitrified bond diamond tool is a high-performance abrasive for its high speed, highefficiency, high precision, low grinding cost and low environmental pollution. It isfabricated mainly by hot/cold press sintering method, during which process diamond iseasy to be oxidized, leading to its degradation and serious influence on its applications. Inthis work, we prepared protective ZnO coating on the surface of diamond in order toinhibit the oxidation of diamond.First, we prepared ZnO coated diamond powders using urea precipitation method.Studied have shown that: Zn5(CO3)2(OH)6coated diamond powders were obtained underthe condition of the following, n[Zn(NO3)2]: n[(NH2)2CO]=1:20, using SDS as thesurfactant with the concentration of0.5mM,5g/300mL diamond powders with an averageparticle size of10m, in a water bath of80°C for2h. Zn5(CO3)2(OH)6was composed ofmassive nano plates and it decomposed into ZnO when heated to300°C for2h. XRD、FESEM and DSC-TG were used to analyze the samples. Results showed that the crystalstructure of ZnO was wurtzite, the thickness of ZnO coating was about4.25m and theon set oxidation temperature of diamond was delayed by about70°C because of ZnOcoating.Secondary, crystal growth theory was utilized to discuses the effects ofsupersaturation on the coating quality, and the relationship between the level of urea usedand the effect of coating process.Finally, vitrified bond diamond composites were prepared with ZnO coated diamondpowders and SiO2-B2O3-Al2O3glass powders by hot press method. The volume fraction ofdiamond was25%. The sintering press, sintering temperature and sintering time were28MPa,700°C and5min, respectively. The bending strength of the composite wasincreased by24%and the volume density was increased from90.6%to97.4%.