4.7 Article

Properties of alumina coatings prepared on silica-based ceramic substrate by plasma spraying and sol-gel dipping methods

期刊

CERAMICS INTERNATIONAL
卷 47, 期 19, 页码 27453-27461

出版社

ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2021.06.168

关键词

Silica-based core; Alumina coating; Plasma spraying; Sol-gel dipping method

资金

  1. Shenzhen Development and Reform Commission Project [SZDRC 20181000]

向作者/读者索取更多资源

Silica-based ceramic cores are used in manufacturing turbine blades, but reactions with active metals in superalloys can reduce their quality. Alumina coatings prepared using plasma spraying and sol-gel dipping methods were compared, with the former showing peeling at high temperatures and the latter demonstrating improved performance. The alumina coating effectively prevented interfacial reactions between the superalloy and the silica-based substrate during casting.
Silica-based ceramic cores are widely used in the manufacturing of hollow, nickel-based, superalloy turbine blades. However, elemental Hf, Ti, Al, and other active metals in the superalloy can react with silica-based ceramic cores during casting, resulting in a reduction in the quality of the turbine blades. In this study, both plasma spraying and sol-gel dipping methods were used to prepare alumina coatings on silica-based ceramic substrates to prevent the interfacial reaction. The performance of the alumina coatings prepared by both methods was evaluated by comparative analysis of the surface roughness, bonding interface morphologies, and the adhesive characteristics of the coating. The plasma-sprayed alumina coating has a roughness greater than 5 mu m and peeled away from the substrate due to the difference in thermal expansion between SiO2 and Al2O3 at temperatures above 1500 degrees C, rendering the silica-based substrate with the plasma-sprayed alumina coating unfit for the application requirements of the casting process. The alumina coating prepared by the sol-gel dipping method improved the roughness of the substrate from Ra 2.39 mu m to Ra 1.83 mu m, and no peeling was observed when heated to 1550 degrees C for 30 min due to the pinning characteristics of the coating on the substrate. Furthermore, the interfacial reaction between the DZ125 superalloy melt and the silica-based substrate coated with alumina by solgel dipping method were investigated. The alumina coating effectively inhibited the interfacial reaction and no reaction products were detected during the directional solidification with pouring temperature of 1550 degrees C and withdraw rate of 5 mm/min. While a uniform, 4-5 mu m thick HfO2 reaction layer formed between the uncoated substrate and the DZ125 alloy melt. Two dipping-drying cycles were required to ensure the alumina sol completely covered the surface of the substrate.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.7
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据