Scholarlink

<p>In order to enhance the hot corrosion resistance of 316H stainless steel exposure to Na<sub>2</sub>CO<sub>3</sub> molten salt, CrN coating was fabricated on its surface using the double glow plasma surface alloying technology. The CrN coating surface showed some pits caused by ion bombardment, with a roughness of 94&#xa0;nm (Ra). The CrN coating consisted of an outer layer (16.5&#xa0;μm) and a diffusion layer (14.8&#xa0;μm). Within the range of 0-5&#xa0;μm from the coating surface, the N content decreased gradually along the thickness direction, while the Cr content increased. Cr and N content remained relatively stable within the range of 5-16.5&#xa0;μm. Elemental interdiffusion led to the formation of a diffusion layer between the substrate and the coating. CrN coating composed of CrN hard phase, [Fe,Cr] phase, and solid solution N, which allowed the coating to exhibit high hardness (25.6 GPa), elastic modulus (320.8 GPa), load bearing capacity and resistance to plastic deformation. During the initial stage of hot corrosion (0-1&#xa0;h), the Na<sub>2</sub>CO<sub>3</sub> molten salt did not participate in the oxidation reaction and the surface of 316H stainless steel was covered by Fe<sub>2</sub>O<sub>3</sub>/Cr<sub>2</sub>O<sub>3</sub>/FeCr<sub>2</sub>O<sub>4</sub>/NiFe<sub>2</sub>O<sub>4</sub> mixed oxide film. As the hot corrosion time increased (&gt;1&#xa0;h), Na<sub>2</sub>CO<sub>3</sub> participated in the oxidation reaction, reacting with Fe<sub>2</sub>O<sub>3</sub> to form NaFeO<sub>2</sub>. The different properties between the oxides and the involvement of Na<sub>2</sub>CO<sub>3</sub> accelerated the spalling of the oxide film, resulting in severe corrosion of the 316H stainless steel. During the hot corrosion process, the transformation of CrN to Cr<sub>2</sub>N caused cracks in the coating, leading to the outward diffusion of Fe from the substrate and the formation of FeCr<sub>2</sub>O<sub>4</sub>. The corrosion products on the CrN coating surface were Cr<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>N, FeCr<sub>2</sub>O<sub>4,</sub> and NaCrO<sub>2</sub>, and they did not change with the increase of corrosion time. CrN coating showed better hot corrosion resistance than 316H stainless steel.</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

Corrosion Mechanism of 316H Stainless Steel and Gradient CrN Coating Exposure to Na2CO3 Molten Salt in Air Environment

  • 期刊论文

  • 发表日期：

    2025年11月17日

查看全文
  • Fengkun Li,
  • Hongyan Wu,
  • Fanyeqi Yang,
  • Yingbin Ma,
  • Pingze Zhang,
  • Feng Ding

摘要

In order to enhance the hot corrosion resistance of 316H stainless steel exposure to Na2CO3 molten salt, CrN coating was fabricated on its surface using the double glow plasma surface alloying technology. The CrN coating surface showed some pits caused by ion bombardment, with a roughness of 94 nm (Ra). The CrN coating consisted of an outer layer (16.5 μm) and a diffusion layer (14.8 μm). Within the range of 0-5 μm from the coating surface, the N content decreased gradually along the thickness direction, while the Cr content increased. Cr and N content remained relatively stable within the range of 5-16.5 μm. Elemental interdiffusion led to the formation of a diffusion layer between the substrate and the coating. CrN coating composed of CrN hard phase, [Fe,Cr] phase, and solid solution N, which allowed the coating to exhibit high hardness (25.6 GPa), elastic modulus (320.8 GPa), load bearing capacity and resistance to plastic deformation. During the initial stage of hot corrosion (0-1 h), the Na2CO3 molten salt did not participate in the oxidation reaction and the surface of 316H stainless steel was covered by Fe2O3/Cr2O3/FeCr2O4/NiFe2O4 mixed oxide film. As the hot corrosion time increased (>1 h), Na2CO3 participated in the oxidation reaction, reacting with Fe2O3 to form NaFeO2. The different properties between the oxides and the involvement of Na2CO3 accelerated the spalling of the oxide film, resulting in severe corrosion of the 316H stainless steel. During the hot corrosion process, the transformation of CrN to Cr2N caused cracks in the coating, leading to the outward diffusion of Fe from the substrate and the formation of FeCr2O4. The corrosion products on the CrN coating surface were Cr2O3, Cr2N, FeCr2O4, and NaCrO2, and they did not change with the increase of corrosion time. CrN coating showed better hot corrosion resistance than 316H stainless steel.