Thermal stability of Al–O–N PVD diffusion barriers

CVD of Al2O3 Thin Films Using Aluminum Tri‐isopropoxide

“…The continued interest in corundum alumina is based on its high performance in wear and corrosion resistance, [1±3] its high temperature insulating properties, [4] and its diffusion barrier properties. [5,6] Thin films of a-Al 2 O 3 are deposited using wet processes such as sol±gel, [2,3] spray coating, [7] or physical vapor deposition, [1,8,9] the thermal CVD process being the most often used. The classic way of producing alumina thin films by CVD is based on the hydrolysis of AlCl 3 with a mixture of H 2 and CO 2 gases at temperatures between 700 C and 1000 C.…”

Tie-Line Compositions of the σ and (γ,δ) Phases in the Re-Cr-Ni System at 1573 K

“…It has also been reported that diffusion of alloying elements in the substrate could lead to decrease in the mechanical properties of the Ni-based superalloy. 6) To prevent diffusion of Al into the substrate, a number of diffusion barrier coatings have been proposed; [7][8][9][10] however, after a relatively short oxidation time the barrier layer loses the layer structure, resulting in rapid, catastrophic oxidation behavior. Narita et al proposed a diffusion barrier coating with a duplex layer structure, containing the -phase of Re-Cr-Ni as the diffusion barrier layer.…”

Effect of diffusion barrier on the high-temperature oxidation behavior of thermal barrier coatings

“…An increase of the thermal efficiency in gas turbines is directly connected with a high gas inlet temperature and, therefore, leads to the increased thermal loads on the materials used for turbine components [1,2]. The use of the advanced Ni-based superalloy singly as turbine blade material is becoming difficult.…”

“…However, it has been observed that the alloying elements in bond coat would interdiffuse towards the substrate above 1273 K, leading to the undesired coating failure [2]. The bond coat serves as the reservoir of Al and Cr for the formation of the thermally grown oxide (TGO) which is a thin oxide layer between bond coat and the top ceramic coat.…”

“…Although there is clearly a significant need of effective hightemperature diffusion barriers to extend the lifetime of TBCs, the development of such materials is still a big challenge. In recent 0925 [2,5,6]. In contrast to other metastable materials, ␣-Al 2 O 3 seems to be the most promising, because it has a dense hexagonal close-packed crystal structure and, as a stable modification, it does not have phase transition between room temperature and its melting point [4,5].…”