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<p>In order to obtain a reasonable multi-pass overlap rate when preparing CNTs to regulate WC/Ni composite coatings on the surface of H13 steel, cladding layers at different lap rate of 20%, 30%, 40% and 50% were prepared. The effect of the lap rate on the macroscopic morphology of the cladding layer was observed using by metallographic microscope. The effect of the lap rate on the microstructure and element segregation of the cladding layer was analyzed by SEM. The microhardness of the coating at different laps rates was analyzed by Vickers hardness tester. The wear resistance of the coating was tested by ring–block friction and wear testing machine. The research results indicate that when the lap rate is 40%, the surface flatness of the cladding layer is the best. With the increase in the overlap rate, the planar crystals and cellular crystals in the early microstructure gradually become dominated by dendrites and columnar crystals, and the particles show a continuous trend of shrinking. The grain size is gradually coarsened due to the accumulation of heat input, but the grain coarsening will be inhibited due to the heterogeneous nucleation effect of CNTs. All these demonstrate that CNTs can resist decomposition. Their one-dimensional nano-structure helps to inhibit grain growth and maintain the fine-grained structure of the coating. The main phase of the coating is still a hard phase composed of Ni–Cr–Fe solid solution and various carbides (such as WC, W<sub>2</sub>C, Cr<sub>3</sub>C<sub>2</sub>, Cr<sub>7</sub>C<sub>3</sub> and Cr<sub>23</sub>C<sub>6</sub>). The increase in the lap rate also affects the reduction in the coating hardness. However, when the average microhardness is the highest, the presence of WC large particles causes the hardness value to fluctuate more, which is not conducive to the consistency of coating performance. When the lap rate is 40%, the hardness of the coating reaches 769HV, and the differences at each point are relatively small. Meanwhile, the wear amount on the coating surface after 90 minutes was only 6.9mg, which was the least among the four lap rates. The hard phase on the worn surface is finely and evenly distributed and relatively flat, with no obvious scratches or peeling, and only slight adhesive wear.</p>

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Effect of Lap Rate on Microstructure and Properties of CNTs-Modulated WC/Ni-Based Coatings

  • 期刊论文

  • 发表日期：

    2026年1月12日

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  • Xuyao Huo,
  • Shuai Huang,
  • Qingqiao Wang,
  • Yafang Zhang

摘要

In order to obtain a reasonable multi-pass overlap rate when preparing CNTs to regulate WC/Ni composite coatings on the surface of H13 steel, cladding layers at different lap rate of 20%, 30%, 40% and 50% were prepared. The effect of the lap rate on the macroscopic morphology of the cladding layer was observed using by metallographic microscope. The effect of the lap rate on the microstructure and element segregation of the cladding layer was analyzed by SEM. The microhardness of the coating at different laps rates was analyzed by Vickers hardness tester. The wear resistance of the coating was tested by ring–block friction and wear testing machine. The research results indicate that when the lap rate is 40%, the surface flatness of the cladding layer is the best. With the increase in the overlap rate, the planar crystals and cellular crystals in the early microstructure gradually become dominated by dendrites and columnar crystals, and the particles show a continuous trend of shrinking. The grain size is gradually coarsened due to the accumulation of heat input, but the grain coarsening will be inhibited due to the heterogeneous nucleation effect of CNTs. All these demonstrate that CNTs can resist decomposition. Their one-dimensional nano-structure helps to inhibit grain growth and maintain the fine-grained structure of the coating. The main phase of the coating is still a hard phase composed of Ni–Cr–Fe solid solution and various carbides (such as WC, W2C, Cr3C2, Cr7C3 and Cr23C6). The increase in the lap rate also affects the reduction in the coating hardness. However, when the average microhardness is the highest, the presence of WC large particles causes the hardness value to fluctuate more, which is not conducive to the consistency of coating performance. When the lap rate is 40%, the hardness of the coating reaches 769HV, and the differences at each point are relatively small. Meanwhile, the wear amount on the coating surface after 90 minutes was only 6.9mg, which was the least among the four lap rates. The hard phase on the worn surface is finely and evenly distributed and relatively flat, with no obvious scratches or peeling, and only slight adhesive wear.