Chao Sun

Hot Corrosion Behavior of a Cr-Modified Aluminide Coating on a Ni-Based Superalloy

A Cr-modified aluminide coating is prepared on a Ni-based superalloy using arc ion plating and subsequent pack cementation aluminizing. Hot corrosion behavior of the Cr-modified aluminide coating exposed to molten Na2SO4/K2SO4 (3:1) or Na2SO4/NaCl (3:1) salts at 900xa0°C in static air are evaluated as well as the aluminide coating. The results indicate that compared with the aluminide coating, the anti-corrosion properties of the Cr-modified aluminide coating in the both salts are improved, which should be attributed to the beneficial effect of the Cr in the coating. The corrosion mechanism of the Cr-modified aluminide coating, especially the role of Cr in the mixture salt corrosion, is discussed.

CYCLIC OXIDATION AND HOT CORROSION BEHAVIORS OF A GRADIENT NiCoCrAlYSi COATING

MCrAlY (M=Ni and/or Co) coatings are widely used as overlays or bond coats for thermal barrier coatings due to their good performance against high temperature oxidation and hot corrosion. Usually, high Al content in the MCrAlY coatings can benefit the performance and lifetimes of the coatings. However, MCrAlY coatings usually contain only restricted Al content because high Al content might lead to brittleness and potential crack. Design of gradient coating can be used to solve the problem, since it can provide a balance between high Al content and high stress bearing ability. Therefore, much attention has been paid to coatings with gradient structures, and these coatings show good oxidation and corrosion resistance. In this work, a gradient and a conventional NiCoCrAlYSi coating were prepared by arc ion plating technique and subsequent annealing treatment. Cyclic oxidation tests of the two coatings were carried out between room temperature and 1000 °C . The hot corrosion tests of the coatings were performed in two different mixed salts of 75%Na2SO4+25%K2SO4 and 75%Na2SO4+25%NaCl (mass fraction) at 900 °C. The results indicated that the gradient coating possessed a graded distribution of Al-rich outer *国家自然科学基金资助项目51001106 收到初稿日期: 2016-01-06,收到修改稿日期: 2016-03-14 作者简介:彭新,男, 1980年生,博士生 DOI: 10.11900/0412.1961.2016.00013 第625-631页 pp.625-631