Effect of adding method of Cr on microstructure and properties of WC–9Ni–2Cr cemented carbides

• Published in: International journal of refractory metals & hard materials 2013-05, Vol.38, p.1-6
• Main Authors: Shi, Kai-hua, Zhou, Ke-chao, Li, Zhi-you, Zan, Xiu-qi, Xu, Shang-zhi, Min, Zhao-yu
• Format: Article
• Language: English
• Subjects: Cemented carbides; Chromium; Microstructure; Properties
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2012.11.010

The WC–9Ni–2Cr cemented carbides were prepared by ball milling method and low pressure sintering. The microstructure and properties of the cemented carbides were then investigated using scanning electron microscopy, mechanical property tester and immersion corrosion tests. The results showed that the adding method of Cr significantly influenced the microstructure and properties of the WC–9Ni–2Cr cemented carbides. Cemented carbides with Cr added in the form of chromium carbide (Cr3C2) were characterized by carburizing and showed a relative lower density, while the addition of metallic chromium and nichrome (Ni–18Cr) resulted in the formation of (W,Cr)C phase and a decrease in the bending strength. However, no defects were found in the microstructure of the cemented carbides in which Cr was added via Cr–Cr3C2 composite powder. Furthermore, cemented carbides prepared with nichrome powder and metallic Cr powder exhibited a higher immersion corrosion resistance in neutral tap water after soaking six times according to BS:6920:2000. The adding method of Cr significantly influenced the microstructure and properties of the WC-9Ni-2Cr cemented carbides. Cemented carbides prepared with nichrome powder and metallic Cr powder exhibited a higher immersion corrosion resistance in neutral tap water. Because the weight of Ni dissolving from all the specimens is lower than 10μg/L after soaking for six times according to BS:6920:2000, the cemented carbide products can be used in potable water system. [Display omitted] ► (W,Cr)C was observed in WC–9Ni–2Cr by adding metallic Cr and nichrome powder. ► The hardness values of the four groups of cemented carbides are similar. ► WC–9Ni–2Cr with nichrome powder addition has the lowest bending strength value. ► WC–9Ni–2Cr with nichrome powder addition has the best corrosion resistance.