Scholarlink

<p>Effective utilization of ammonia fuel in gas turbines poses several challenges. Ammonia corrosion is one of the critical issues for the materials of the turbine components. Therefore, prevention of ammonia-based degradation of bulk materials and thermally sprayed coatings is indispensable. The potential of an oxide layer formed on high velocity oxy-fuel flame (HVOF)-sprayed CoNiCrAlY coating by heat treatment in air in preventing ammonia corrosion was studied. A comparative corrosion assessment of Hastelloy X substrate, as-sprayed and pre-oxidized CoNiCrAlY coating was conducted under NH<sub>3</sub> environment from 500&#xa0;°C to 800&#xa0;°C. The degradation behaviors of the substrate and the coatings were elucidated. Hastelloy X was found to undergo near-surface nitridation, whereas significant internal nitridation of the as-sprayed coating was observed due to the inter-connected porosities and imperfect inter-splat boundaries. X-ray diffraction analysis showed CrN, Ni<sub>3</sub>N and Fe<sub>2-3</sub>N phases in Hastelloy X, while the nitrided layer in CoNiCrAlY coating consisted of CrN, AlN, Ni<sub>3</sub>N and Co<sub>2</sub>N phases. On the other hand, no nitridation of the pre-oxidized coating was identified. The continuous and dense Al<sub>2</sub>O<sub>3</sub> layer formed on the surface of the coating effectively impeded nitrogen diffusion and consequent internal nitridation. Hence, pre-oxidized coatings may be useful for ammonia-fueled gas turbines.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Pre-oxidized HVOF-sprayed CoNiCrAlY Coating for the Mitigation of Ammonia Corrosion for Pure Ammonia Combustion Gas Turbines

  • 期刊论文

  • 发表日期：

    2025年12月4日

查看全文
  • Tina Ghara,
  • Seiji Kuroda,
  • Takashi Yanagisawa,
  • Mohammed Shahien,
  • Masato Suzuki,
  • Takahiro Inoue,
  • Kentaro Shinoda

摘要

Effective utilization of ammonia fuel in gas turbines poses several challenges. Ammonia corrosion is one of the critical issues for the materials of the turbine components. Therefore, prevention of ammonia-based degradation of bulk materials and thermally sprayed coatings is indispensable. The potential of an oxide layer formed on high velocity oxy-fuel flame (HVOF)-sprayed CoNiCrAlY coating by heat treatment in air in preventing ammonia corrosion was studied. A comparative corrosion assessment of Hastelloy X substrate, as-sprayed and pre-oxidized CoNiCrAlY coating was conducted under NH3 environment from 500 °C to 800 °C. The degradation behaviors of the substrate and the coatings were elucidated. Hastelloy X was found to undergo near-surface nitridation, whereas significant internal nitridation of the as-sprayed coating was observed due to the inter-connected porosities and imperfect inter-splat boundaries. X-ray diffraction analysis showed CrN, Ni3N and Fe2-3N phases in Hastelloy X, while the nitrided layer in CoNiCrAlY coating consisted of CrN, AlN, Ni3N and Co2N phases. On the other hand, no nitridation of the pre-oxidized coating was identified. The continuous and dense Al2O3 layer formed on the surface of the coating effectively impeded nitrogen diffusion and consequent internal nitridation. Hence, pre-oxidized coatings may be useful for ammonia-fueled gas turbines.