The Influences Of Cemented Carbide Surface Pretreatment On Diamond Coating Properties

Diamond film coated cemented carbide cutting tools have broad prospects for their excellent properties.The binder phase of cemented carbide Co is the main factor limits its industrialization.In that condition,the traditional two-step process was developed to be the main practice method to eliminate Co for the advantages of high efficiency and low economic.Based on the traditional two-step pretreatment,we have studied the basic law of the pretreatment on cemented carbide systematic and comprehensive.And then the mechanism of the influence on film/substrate adhesion by Co has been studied.Furthermore,the new pretreatment method based on traditional two-step has been developed,it was not only fill the gaps in this filed,but also has important guiding significance to practical production.The main research contents and results of this paper are as follows:1.The basic law of traditional two-step pretreatment has been study.The results show that alkali treatment has a saturation point about 20-30min;it can increase the roughness of cemented carbide surface for about 30 times.Acid treatment can quickly reduce the surface roughness of cemented carbide to about 100nm while removing the surface Co,the etching depth no more changes after 15s.The higher the treat temperature,the deeper the etching depth.Ultrasonic cleaning of deionized water is an indispensable step in the two-step process.Eliminating this step will lead to the introduction of impurities like CoSO₄ on the cemented carbide surface.2.The influence mechanism of etching depth and Co on film/substrate adhesion was studied.The results show that the etching depth should be moderate,and in this study,combined with CVD diamond deposition conditions,it is appropriate to 6?m.During the deposition of CVD diamond,the interaction between Co and C in the nucleation stage is mainly reflected in the non-crystalline C of the Co surface coating 1-2nm.3.The effect of the new pretreatment method on the performance of cemented carbide diamond coating was studied.Results show that without alcohol ultrasonic dispersion,the seeding process would introduce“tumor growth”during the deposition of CVD diamond on cemented carbide surface.Compared with the traditional two-step method,the new pretreatment method improves the performance of the complex shape tool effectively.