电子束熔覆WC-CoCr涂层的表面结构以及耐磨性

Surface microstructure and anti-wear of WC-CoCr coatings cladded by electro beam

摘要:

镍基合金在含氯介质中有着优异的耐蚀性能，但其耐磨性不足。本文首先利用HVOF在Inconel617基体上沉积WC--CoCr涂层，研究了经过电子束重熔获得新的改性层表面形貌以及相成分。电子束处理后，一些喷涂层的结构缺陷得到了改善，涂层空隙减少，晶粒得到了细化，由于生成了高硬度的新相（尤其是Co6W6C相），熔覆层的显微硬度为1100HV0.3，为基体显微硬度（550HV0.3）的两倍。通过摩擦磨损实验分析，试样相比于基体的滑动磨损行为，其磨损率有着显著的降低，而EDS分析表明，熔覆层内出现了新的元素，基体与涂层达到了良好的冶金结合。此外，熔覆层在盐水中的抗腐蚀能力有所提高。

Abstract:

Nickel based alloy has good corrosion resistance in chloride medium, but its wears resistance is insufficient.In this paper, WC-CoCr coatings were prepared on Inconel617 alloy surface by HVOF (high velocity oxygen fuel). Electron beam remelting process is explored to modify the morphology and the phase composition of the coated layer. Some structural defects of as-sprayed coating have been improved after electron beam treatment. Tribological tests concerning the sliding wear behaviour of the tested materials revealed a significant decrease of the wear rate for the alloyed surface in comparison with the base material. After high energy electron beam treatment, the micro-hardness of the surface is 1100 HV0.3 which is about 2 times as much as the matrix (550HV0.3) due to the formation of new phase (especially the Co₆W₆C phase) with high hardness, the amount of porosity of the coatings are reduced, and the grain is finer. EDS spectrum analysis found that the process of electron beam cladding elements occurred in the proliferation of cladding layer and the substrate to achieve a good metallurgical bonding. Moreover, the corrosion resistance of the cladding layer in salt water is higher than that of the matrix.