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<p>To extend hot work roll life, this study laser-clad Al/Ni-doped cobalt-based alloy coatings, systematically investigating Al/Ni doping effects on their microstructure, phase composition, microhardness, hot hardness, and 800&#xa0;°C high-temperature tribological behavior.The results showed that the Al/Ni-doped Co-based coatings formed a metallurgical bond with the substrate, presenting a dense and homogeneous microstructure without porosity or cracks, and were mainly composed of <i>γ</i>-Co, M<sub>23</sub>C<sub>6</sub>, and M<sub>7</sub>C<sub>3</sub> phases. Al/Ni addition promoted the precipitation of Al-enriched strengthening phases and refined the microstructure. Benefiting from the combined effects of solid solution, dispersion, and grain refinement strengthening, the Co21-AlNi coating’s microhardness significantly increased from 356.9 to 385 HV<sub>0.2</sub>, retaining 214 HV<sub>0.2</sub> at 800&#xa0;°C (superior to 162 HV<sub>0.2</sub> of Co21 coating and 34 HV<sub>0.2</sub> of the substrate). Additionally, the formation of a dense, adherent composite oxide film (enriched with Cr<sub>2</sub>O<sub>3</sub>, Co<sub>3</sub>O<sub>4</sub>, CoCr<sub>2</sub>O<sub>4</sub>, and CoAl<sub>2</sub>O<sub>4</sub>) and dispersed hard phases significantly improved the Co21-AlNi coating’s wear resistance and friction reduction at 800&#xa0;°C, with a friction coefficient of ~ 0.39 and a wear volume only 8.1% of the substrate. The dominant wear mechanism was oxidative wear accompanied by slight abrasive and adhesive wear. This study provides a theoretical basis for developing high-performance, durable coatings for hot-rolled components.</p>

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Effect of Al and Ni Doping on the Microstructure and High-Temperature Properties of Laser Cladding Cobalt-Based Alloy Coatings

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • Ji Zhou,
  • Ruohui Shuai,
  • Jikai Yang,
  • Liyan Lou,
  • Yi Liu,
  • Junhao Lu,
  • Zhihai Cai,
  • Jing Li,
  • Zhiguo Xing,
  • Haidou Wang,
  • Chengxin Li

摘要

To extend hot work roll life, this study laser-clad Al/Ni-doped cobalt-based alloy coatings, systematically investigating Al/Ni doping effects on their microstructure, phase composition, microhardness, hot hardness, and 800 °C high-temperature tribological behavior.The results showed that the Al/Ni-doped Co-based coatings formed a metallurgical bond with the substrate, presenting a dense and homogeneous microstructure without porosity or cracks, and were mainly composed of γ-Co, M23C6, and M7C3 phases. Al/Ni addition promoted the precipitation of Al-enriched strengthening phases and refined the microstructure. Benefiting from the combined effects of solid solution, dispersion, and grain refinement strengthening, the Co21-AlNi coating’s microhardness significantly increased from 356.9 to 385 HV0.2, retaining 214 HV0.2 at 800 °C (superior to 162 HV0.2 of Co21 coating and 34 HV0.2 of the substrate). Additionally, the formation of a dense, adherent composite oxide film (enriched with Cr2O3, Co3O4, CoCr2O4, and CoAl2O4) and dispersed hard phases significantly improved the Co21-AlNi coating’s wear resistance and friction reduction at 800 °C, with a friction coefficient of ~ 0.39 and a wear volume only 8.1% of the substrate. The dominant wear mechanism was oxidative wear accompanied by slight abrasive and adhesive wear. This study provides a theoretical basis for developing high-performance, durable coatings for hot-rolled components.