Zirconium Modified Aluminide by a Vapour Pack Cementation Process for Thermal Barrier Applications: Formation Mechanisms and Properties

Abstract

The main mechanism of degradation of thermal barrier systems is the spallation of the thermally grown oxide (TGO) formed at the ceramic/metallic sub-layer. Present trends are the use of a platinum modified nickel aluminide layer as metallic sub-layer. But the effect of few p.p.m. or few % at. of zirconium on the oxidation of hipped or cast nickel aluminide was also studied for higher temperature applications. It has been shown that the system ZrO 2 -Y 2 O 3 (8% mass.) EBPVD / cast NiAl(Zr) had at 1200°C a life durability three times longer than the classical system ZrO 2 -Y 2 O 3 (8% mass.) EBPVD /NiAlPt coating/nickel base superalloy. Similar encouraging results were obtained with the system ZrO 2 -Y 2 O 3 (8% mass.) EBPVD / NiAl(Zr) coating deposited by physical vapour deposition/ nickel base superalloy.In this work, a zirconium modified nickel aluminide coating by vapour pack cementation process was developed. The structure of this modified coating is discussed. Cyclic oxidation test results and microscopic investigations are also presented.

Development of Improved Bond Coat for Enhanced Turbine Durability

“…Additionally, prior work has been conducted on bond coatings with zirconium as the reactive element. Schumann et al and Naveos et al showed that zirconium segregated to the oxide grain boundaries, possibly resulting in reduced aluminum diffusion into the oxide scale [13,14]. Another reported benefit is that reactive elements, including zirconium, interact with deleterious tramp elements such as sulfur that contaminate the coating-oxide interface.…”

Structure And Properties Of Condensed Gradient Metal-ceramic Thermal Barrier Coatings With Nial-bond Coat Alloyed With Y, Hf, Dy

“…С этой ЭЛЕКТРОННО-ЛУЧЕВЫЕ ПРОЦЕССЫ целью связующий слой NiAl дополнительно легируют введением небольшого количества (от 0,01 до 1 мас. %) различных активных к кислороду химических элементов, например Y, Zr, Ce, La, Hf, Dy [8][9][10], которые позволяют замедлить скорости роста слоя окалины Al 2 O 3 на поверхности NiAl, а также повысить адгезию слоя окалины. Позитивный эффект от введения указанных активных элементов (АЭ) связывают прежде всего с образованием «клиновидных» выделений на границе раздела окалины и NiAl, которые увеличивают сцепление слоя окалины с металлом, формированием слоя окалины с более совершенной структурой, а также с подавлением роста пустот/пор на межфазной границе и уменьшению «вспучивания» (rumpling) слоя окалины [11][12][13][14].…”

Formation and growth of protective alumina scales

“…Two other solutions can be considered in order to improve the aluminide mechanical properties: by modifying their microstructure using an innovative elaboration process [241][242][243], or by applying the intermetallic compounds directly on a metal or alloy surface [33,[244][245][246][247][248][249][250][251].…”