Chemical vapor deposition of smooth α-Al2O3 films on nickel base superalloys as diffusion barriers

CVD of Al2O3 Thin Films Using Aluminum Tri‐isopropoxide

“…[6] This may be a significant issue whenever the substrate is not able to withstand aggressive by-products, such as HCl.…”

“…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.…”

“…[6] Alternative precursors have been investigated, in particular aluminum alkoxides which undergo a pyrolytic decomposition forming alumina even at low temperatures, and in the absence of an oxidizing gas. [10] Efforts have been made to synthesize highly volatile and non-pyrophoric liquid precursors to deposit dense alumina films free from carbon.…”

Synthesis of α-Al 2 O 3 thin films using reactive high-power impulse magnetron sputtering

“…Industrially, α-alumina coatings are commonly deposited using chemical vapour deposition at elevated substrate temperatures (~ 1000 °C) [1]. The high temperatures, of course, put limitations on the substrate materials that are possible to use and might in addition cause unwanted effects such as chemical reactions between the coating and substrate materials [2], or cracks in the coatings arising due to different thermal expansion of substrate and film [3].…”

Optimization of Deposition Parameters for α-Al2O3 Coatings by Double Glow Plasma Technique

“…Normally, α-alumina coatings can be obtained when the substrate temperature is above 1000 °C in the CVD process. [7][8][9] However, this causes unwanted effects limiting the application of substrate materials, such as steel and glass, 7 and cracks owing to thermal expansion mismatch, 10 which can be avoided by reactive diffusion through post-deposition annealing. Meanwhile, post deposition oxidation after direct Al deposition on 316 L stainless is an efficient way to form (Al 2 O 3 + Fe 2 O 3 ) interface layers.…”