Effect of Wet Grinding Process on Microstructure and Properties of Ultra-Coarse-Grained Cemented Carbides Prepared by Gentle Ball Milling Method AITranslate

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Chinese Library Classification Number:TG135.5[一般工业技术]

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In view of the fact that it is difficult to prepare ultra-coarse grain cemented carbides with WC average grain size(d_WC)greater than 8μm by traditional ball milling method,this paper adopted two specifications(ϕ5.5 mm andϕ10.5 mm,aspect ratio 1.5∶1)of rod-shaped grinding media combined with different wet grinding time,so that the wet grinding strength can maintain at the degree of only mixing without excessive crushing,and the ultra-coarse-grained cemented carbides with d_WC greater than 8μm were successfully prepared.Their microstructure and physical and mechanical properties were then analyzed.The results show that the crushing and mixing effect of the large rod grinding media on the material is inferior to that of the small rod.With the increase of the small rod grinding media mass and the wet grinding time,the porosity and Co phase uniformity of the alloy are obviously improved,but the d_WC decreases gradually.With the decrease of d_WC,the hardness and strength of the alloy increase,while the thermal conductivity and the fracture toughness decrease.The ultra-coarse-grained cemented carbide with porosity of A02B00 level and d_WC of≥8μm can be prepared under the conditions of small rod and wet grinding time of 12 h or large rod and wet grinding time of 20 h.The hardness value is maintained at about 900 HV₅₀,the bending strength value exceeds 1800 MPa,the thermal conductivity exceeds 140 W/(m·K),and the maximum fracture toughness value is 21.6 MPa·m^1/2.Compared with super-coarse-grained cemented carbide,ultracoarse-grained cemented carbide shows better inhibition and hindrance to the generation and propagation of cracks,along with superior fracture toughness.