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| Study on Microstructure and Properties for Co-rich Layers Cemented Carbides by Surface Nitriding Treatment |
| GONG Manfeng1, SUI Guangzhou1, LIAN Haishan1, LI Mingsheng1,
MO Deyun1, CHEN Jian2, WU Shanghua2
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1 Institute of Mechatronic Engineering, Lingnan Normal University, Zhanjiang 524048;
2 College of Mechatronic Engineering, Guangdong University of Technology, Guangzhou 510220 |
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Abstract The Co-rich layers and Ti-rich hard phase-layers on cemented carbides were prepared by a two-step sintering technology, respectively. The microstructure, sintering phases and mechanical properties of cemented carbides before and after nitriding treatment were studied. The ~20 μm-thick Co-rich layers were obtained on the surface of specimen under vacuum sintering condition, and no cubic carbide phase was contained in the Co-rich layers. The surfaces of specimen appear a kind of hill topography and own bright silver metal luster which were confirmed by microstructure morphology analysis. It can be used to repair the micro-defects, e.g. micro-cracks or micro-holes, on the surface of specimens, improve the toughness of cemented carbides surface, and enhance the interfacial bonding strength between the coating and the substrate. The fine grain ~1 μm-thick Ti-rich hard phase layers could be prepared in situ on the specimen surface by nitridation. The Ti-rich hard phase layers appear gold or brown color and a relatively smooth surface by microstructure analysis. Through comparison and analysis, it could be concluded that though the densities of specimens are decreased as a result of nitridation treatment, but simultaneously some properties can be significantly improved, such as fine grain size distribution and favorable surface micro-strain in the Ti-rich hard phase, which can promote surface hardness with remote toughness loss, and also effectively improve wear resistance and lifetime of cemented carbide tools.
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Published: 02 May 2018
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2017, Vol. 31 
