| LU Hai-jun,SHUI Jian-hong,WANG Kai,SHANG Yong,JIANG Hai-feng,WEI Jin.Effects of Dissolving and Precipitating of WC Particles on Performance of Ni60 Coating[J],52(3):189-196 |
| Effects of Dissolving and Precipitating of WC Particles on Performance of Ni60 Coating |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.03.016 |
| KeyWord:WC Ni60 shear strength abrasive wear cladding current |
| Author | Institution |
| LU Hai-jun |
China Railway Engineering Equipment Group Tunnel Equipment Manufacturing Co., Ltd., Henan Xinxiang , China |
| SHUI Jian-hong |
Sinohydro Bureau 11 Co., Ltd., Henan Sanmenxia , China |
| WANG Kai |
China Railway Engineering Equipment Group Tunnel Equipment Manufacturing Co., Ltd., Henan Xinxiang , China |
| SHANG Yong |
China Railway Engineering Equipment Group Tunnel Equipment Manufacturing Co., Ltd., Henan Xinxiang , China |
| JIANG Hai-feng |
China Railway Engineering Equipment Group Tunnel Equipment Manufacturing Co., Ltd., Henan Xinxiang , China |
| WEI Jin |
China Railway Engineering Equipment Group Tunnel Equipment Manufacturing Co., Ltd., Henan Xinxiang , China |
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| Abstract: |
| The Ni60 coatings containing WC particles have been widely used because of its excellent performance. The effects of preparation technology, size and content of WC particles on performance of Ni60 coatings are in-depth studied, but the effects of different eutectic carbides generated during cladding are not so clear. The work aims to study the effects of different eutectic carbides on the shear strength and wear resistance of Ni60 coatings containing WC particles to improve the performance of Ni60 coatings. Long squares made by 42CrMo steel with dimensions of 100 mm×40 mm×20 mm were used as matrix and ground by a grinder before cladding. Different Ni60 coatings containing 10% WC particles(50-150 μm) were prepared with different cladding currents (110, 140 170, 200 A) by plasma arc. The samples for wear test were single-side coating, and the samples for shear test were double-side coating. The microhardness of different coatings was measured by microhardness (HV-1000Z). The dry abrasive wear tests were performed on grain-abrasion testing machine (MLGS-225C) and the weight losses were calculated. The shear tests were carried out by universal testing machine (UTM535X-30T) with a selfmade shear tooling which had a square hole in the middle, the areas of the coating and the maximal forces during shear test were measured, and the shear strengths were calculated. The wear morphology, microstructure and phase composition were studied by scanning electron microscope (EM-30AX+) and X-ray diffraction (XRD-6100X). The results showed that the coatings by different cladding currents were mainly composed of γ-(Fe,Ni), M23C6, M7C3, WC, W2C, FeNi3 and FeW2B2. When the current increased from 110 A to 200 A, the microhardness of the coatings decreased from 846.7HV to 665.6HV, and the shear strength increased from 174.7 MPa to 373.2 MPa. The weight loss decreased initially, followed by an increase when the cladding current was larger than 140 A, the minimum weight loss was 0.434 g when the cladding current was 140 A. Massive eutectic carbides were generated by alloying elements such as W, Cr and C in the coating. When the cladding current was not above 140 A, the massive eutectic carbide can stop hard abrasive particles from scratching the coating matrix because of its high hardness and large size, which can enhance the abrasive resistance of the coating; When the cladding current was larger than 140 A, eutectic herringbone carbides containing W, Cr and C were generated, which were hard and crisp. And eutectic herringbone carbides would break into fragments first and then turned to pellets under the continuous impact of hard abrasive particles, then the protective effect of eutectic herringbone carbides on coating matrix was reduced. The pellets can be easily stripped from the coating when the coating matrix around them were worn off, which resulted in a further decrease of the abrasive resistance of the coating. The change of cladding current can affect the composition, morphology and quantity of eutectic carbides of Ni60 coatings containing WC particles. Small cladding current is conducive to the formation of massive eutectic carbides, which can improve the wear resistance of the coating. The Ni60+WC(10%) coating has the best comprehensive performance when the cladding current is 140 A. |
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