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High-Temperature Oxidation Behavior of NiCoCrAlY Coatings Deposited by Laser Cladding on 304 Stainless Steel
Metals and Materials International ( IF 3.5 ) Pub Date : 2021-01-19 , DOI: 10.1007/s12540-020-00927-y
Yuxin Li , Jinhao Nie , Yixin Yang , Peikang Bai , Hongjian Zhang , Zhanyong Zhao , Shouzheng Wei , Jie Cai , Qingfeng Guan

Abstract

To improve the high-temperature resistance of the key hot-end parts of the steam turbine, NiCoCrAlY coatings were deposited on a 304 stainless steel substrate by laser cladding. The microstructure and high-temperature oxidation behavior of the NiCoCrAlY coatings were analyzed. The results showed that the NiCoCrAlY coatings contained γ/γ′ and β phases, and the microstructure was mainly composed of elongated columnar crystals. In addition, after 100 h of oxidation at three different oxidation temperatures (750, 850 and 950 °C), the coatings showed a relatively low oxidation rate, which was approximately a quarter of the oxidation rate of the substrate. At the same time, the protective Cr2O3 scales were formed on the coating surface. When the oxidation temperature was 850 °C, the FeCr2O4 spinel formed and internal oxidation zone appeared, when the oxidation temperature reached 950 °C, the FeCr2O4 spinel gathered in the local area on the surface of the Cr2O3 scale and the internal oxidation was aggravated. In other words, as the oxidation temperature increased, the Fe element in the matrix formed the FeCr2O4 spinel, which accelerated the consumption of Cr element in the coatings and reduced the overall oxidation resistance of the NiCoCrAlY coatings.

Graphic Abstract



中文翻译:

在304不锈钢上激光熔覆NiCoCrAlY涂层的高温氧化行为。

摘要

为了提高汽轮机关键热端部件的耐高温性,通过激光熔覆将NiCoCrAlY涂层沉积在304不锈钢基底上。分析了NiCoCrAlY涂层的组织和高温氧化行为。结果表明,NiCoCrAlY涂层含有γ/γ'和β相,其显微组织主要由细长的柱状晶体组成。此外,在三种不同的氧化温度(750、850和950°C)下氧化100小时后,涂层的氧化速率相对较低,约为基材氧化速率的四分之一。同时,在涂层表面形成保护性的Cr 2 O 3氧化皮。当氧化温度为850°C时,FeCr形成2 O 4尖晶石并出现内部氧化区,当氧化温度达到950°C时,FeCr 2 O 4尖晶石聚集在Cr 2 O 3鳞片表面的局部区域,内部氧化加剧。换句话说,随着氧化温度的升高,基体中的Fe元素形成了FeCr 2 O 4尖晶石,这加速了涂层中Cr元素的消耗,并降低了NiCoCrAlY涂层的整体抗氧化性。

图形摘要

更新日期:2021-01-19
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