Powder extrusion molding of nanocrystalline WC-l0Co composite cemented carbide

Abstract

The rods that were shaped from nanocrystalline WC-10.21 Co-0.42 VCI Cr₃ C₂(wt%) composite powders by using powder extrusion molding (PEM) were investigated. The nanocrystalline WC-10.21 Co-0.42 VC/Cr₃ C₂ (wt%) composite powders were prepared by the spray thermal decomposition-continuous reduction and carburization technology. In order to improve the properties of rods shaped by using powder extrusion molding, the cold isostatic pressing (CIP) technology was used before or after debinding. Specimens were sintered by vacuum sintering and hot isostatic pressing (HIP). The density, Rockwell A hardness, magnetic coercivity, and magnetic saturation induction of sintered specimen were measured. The microstructure of the green bodies and the sintered specimens was studied by scanning electron microscopy (SEM). Results show that the rod formed by using powder extrusion molding after debinding and followed by cold isostatic pressing can be sintered to 99.5% density of composite cemented carbide rods with an average grain size of about 200–300 nm, magnetic coercivity of 30.4 KA/m, Rockwell A hardness of 92.6 and magnetic saturation induction of 85%. Superfine WC-10Co cemented carbide rods with excellent properties were obtained.

Keywords

powder extrusion molding / cold isostatic pressing / nanocrystalline / WC-10.21 Co-0. 42 VC/Cr₃ C₂(wt%) / composite powders

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