不同含量WC颗粒增强激光熔覆截齿涂层性能研究

刘东刚; 梁国星; 郝新辉; 贾文婷; 杨世清; 黄永贵; 赵建; 吕明

LIU Dong-gang,LIANG Guo-xing,HAO Xin-hui,JIA Wen-ting,YANG Shi-qing,HUANG Yong-gui,ZHAO Jian,LYU Ming.Properties of Laser Cladded Coating on Pick with Different Content of WC Particles[J],52(9):408-419

Properties of Laser Cladded Coating on Pick with Different Content of WC Particles

Received:August 14, 2022 Revised:November 10, 2022

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DOI：10.16490/j.cnki.issn.1001-3660.2023.09.037

KeyWord:pick laser cladded Co-based/WC composite coating WC particles friction and wear corrosion resistance

Author	Institution
LIU Dong-gang	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
LIANG Guo-xing	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
HAO Xin-hui	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
JIA Wen-ting	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
YANG Shi-qing	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
HUANG Yong-gui	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
ZHAO Jian	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China
LYU Ming	Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan , China

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Abstract:

The work aims to solve the wear failure of the pick, and study the mechanism of how different amount of WC particles effect on the surface morphology, crack rate, microhardness, wear and corrosion resistance of laser cladded Co-base/WC composite coatings on picks made out of 42CrMo. A Co-based/WC composite coating was prepared on 42CrMo substrate. The characteristics of the cladding layer effected by different amount of WC particles were studied by means of X-ray diffraction (XRD), a scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), a microhardness tester, a friction and wear tester and an electrochemical workstation. The surface of the laser cladded Co-based/WC composite coating was relatively even. Staggered cracks appeared on the surface of the cladding layer with WC particles content exceeding 30%. With the additive of WC particles content increased, the crack rate increased significantly, and could increase to 35% as the content of WC particles being up to 80%. Three types of cracks were mainly produced in the cladding layer, internal cracks in the cladding layer, cracks in the bonding zone between the cladding layer and the substrate, and cracks in the overlapping zones between multiple layers. When the content of WC particles was low, cracks were mainly appeared as internal cracks and cracks in the bonding zone, and formed independently. Three types of cracks appeared at the same time when high content of WC particles were presented, and the formation of cracks in the bonding zone caused the formation of the other two types of cracks; The microhardness of Co-based/WC composite coating was higher than that of the 42CrMo substrate (378 HV0.2), and the average microhardness of the cladding layer increased from 448HV0.2 to 890HV0.2 with the increase of WC particles content; The average coefficient of friction (Ecof) of Co-based/WC composite coating was less than that of the 42CrMo substrate (0.567). When the content of WC particles was up to 10%, the average coefficient of friction of the cladding layer was 0.411, which was about 10% lower than that of the substrate. As the content of WC particles was increased to 80%, the average friction coefficient of the cladding layer was 0.270, which was half of that of the substrate. The wear loss of the layer was obviously less than that of 42CrMo substrate (18.6 mg). The wear loss of the pure Co-based layer was 9.8 mg, which was about 50% lower than that of the substrate. With the increase of WC particles content, the wear loss of the cladding layer gradually decreased. Then the WC content was 80%, the wear loss was only 1.0 mg, which was about 95% lower than that of the 42CrMo substrate. The wear mechanism of cladding layer was adhesive wear and abrasive wear, and with the increase of WC particles content, both kinds of wear were being suppressed. The corrosion resistance of the cladding layer increased first and then decreased with the increase of WC content. The corrosion resistance of the cladding layer increased in the first place and then decreased with the increase of WC content. The optimal corrosion resistance and the minimum current density (1.465×10–7 A/cm2) of the cladding layer was achieved when the WC particle content was 30%, compared with current density (8.031×10–6 A/cm2) of the substrate, it was reduced by 98%. The addition of WC particles could refine grains to a certain extent to make the cladding layer more dense. WC particles with highly stable chemical properties and newly formed hard phases were dispersed in the cladding layer, and could act as a physical barrier, reduce or block the corrosion of grain boundaries and bonding phases, and improve the corrosion resistance of the cladding layer. If the content of WC particles was too much, cracks and other defects would appear in the cladding layer, increase the corrosion channel and reduce the corrosion resistance. Thus, the content of WC particles has a significant effect on the crack sensitivity of Co-based/WC composite cladding layer, microhardness and wear/corrosion resistance of the cladding layer, which can be improved significantly by the addition of WC particles via the fine grain, dispersion and solution strengthening.