Influence of Pretreatment before CVD Diamond Coating Process on the Strength of Cemented Carbide Substrate AITranslate

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Chinese Library Classification Number:TG135.5[一般工业技术—材料科学与工程]

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CVD diamond-coated cemented carbide tool is ideal for the machining of composite materials,including non-ferrous metals,alloys,graphite,ceramic,and carbon fiber reinforced plastic(CFRP).However,the pretreatment process of WC-Co cemented carbide substrate before diamond coating reduces the strength of the substrate while eliminating Co on the surface to improve the adhesion of the coating.The influence mechanism of pretreatment on the substrate strength of WC-6Co cemented carbides with two WC grain sizes was studied through orthogonal experiments.The surface morphology and Co content of the sample were analyzed by SEM and EDS,and the phase composition of the sample surface was analyzed by XRD.The results show that both acid and alkali pretreatment significantly decrease the strength of the substrate,while heat treatment can eliminate the unfavorable influence of acid and alkali treatment on the strength.The influence of pretreatment on the strength of cemented carbide substrate with different WC grain sizes is obviously different.In general,the decrease in transverse rupture strength(TRS)after pretreatment is greater for coarse-grained cemented carbides,and the Weibull modulus of TRS also decreases more significantly.Comparatively speaking,the TRS of coarse-grained cemented carbide is more sensitive to acid corrosion time,t_C,while that of fine-grained cemented carbide is more affected by alkali corrosion time,t_M.Therefore,an appropriate pretreatment system should be matched to the composition and microstructure of different cemented carbide substrates before diamond coating.