Microstructure, wear, and oxidation resistance of nanostructured carbide-strengthened cobalt-based composite coatings on Invar alloys by laser cladding
Microstructure, wear, and oxidation resistance of nanostructured carbide-strengthened cobalt-based composite coatings on Invar alloys by laser cladding
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DOI：
10.1016/j.surfcoat.2019.125188
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发表时间：
2020-01
影响因子：
5.4
通讯作者：
Y. Zou;Binghui Ma;H. Cui;F. Lu;P. Xu
中科院分区：
文献类型：
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作者：
Y. Zou;Binghui Ma;H. Cui;F. Lu;P. Xu
为了强化因瓦合金，采用激光熔覆技术在因瓦合金表面制备了纳米碳化物强化钴基熔覆层。熔覆层由立方γ-(Fe，Ni)或Co基固溶体和晶界处的W2C、Cr3C2/V8C7、CoCx、Nb碳化物等硬质合金组成。熔覆层在不改变因瓦合金热膨胀系数的情况下，提高了合金的耐磨性和抗氧化性。结果表明，复合涂层的摩擦系数比因瓦基材降低了28.6%。在1073K时，有包覆层的样品的氧化层厚度为18.4xμm，比因瓦衬底的氧化层厚度(88.38xμm)要薄。Cr3C2的抗氧化性高于Vc和Cr3C2与Vc的混合物，但Vc掺杂的熔覆层的耐磨性优于Cr3C2或Vc+Cr3C2的熔覆层。认为元素扩散、碳化物强化以及通过位错和塑性变形性强化界面是因瓦合金的表面强化机制。
To strengthen Invar alloy, nanostructured carbide-strengthened cobalt-based cladding layers were fabricated on an Invar alloy by laser cladding. The cladding layers contained cubic γ-(Fe, Ni) or Co-based solid solution and hard carbides such as W2C, Cr3C2/V8C7, CoCx, and niobium carbide at the grain boundaries. The cladding layers improved the wear and oxidation resistance of the Invar alloy without changing its coefficient of thermal expansion. The results indicated that the friction coefficient of composite coatings decreased by 28.6% compared with that of Invar substrate. The oxide layers of samples with cladding layers were 18.4 μm thick at 1073 K, which was thinner than that of Invar substrate (88.38 μm). Cr3C2displayed higher oxidation resistance than that of VC and a mixture of Cr3C2and VC; however, VC-doped cladding layers exhibited better wear resistance than that of cladding layers with Cr3C2or VC and Cr3C2. Elemental diffusion, carbide strengthening, and interface strengthening through the dislocations and plastic deformability at the carbide/matrix interface were believed to be the surface strengthening mechanism of Invar alloys.