Diffusion barrier effect of Al2O3 layer at the interface between Mo-Si-B coating and Nb-Si based alloy

Qiao, Yanqiang; Chen, Tao; Guo, Xiping

doi:10.1016/j.corcom.2021.10.003

Cited by 7 publications

(2 citation statements)

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“…Applying a diffusion barrier between the MoSi 2 -based coating and the refractory metals substrate is another way to improve the stability and serving life of the coating. Many kinds of materials, including oxides (Al 2 O 3 diffusion barrier for the Mo-Si-B/Nb-Si system [ 33 ], Y 2 O 3 diffusion barrier for the MoSi 2 /Nb-Si system [ 34 ]), carbides (Mo 2 C diffusion barrier for the MoSi 2 /SiC-Mo 2 C/Mo system [ 35 ], SiC-glass diffusion barrier for the MoSi 2 /Nb-Si system [ 36 ]), borides (MoB diffusion barrier for the MoSi 2 /Mo system [ 8 , 37 ], Nb 3 B 2 -NbB 2 diffusion barrier for the Si-Mo-W-ZrB 2 -Y 2 O 3 /Nb system [ 38 ]) and silicides (TaSi 2 diffusion barrier for the MoSi 2 /Nb system [ 39 ], WSi 2 diffusion barrier for the MoSi 2 /Nb-Ti-Si system [ 40 ]) have been used as diffusion barriers between the coatings and the substrates, thereby effectively lengthening the lifetime of these coatings. Reference [ 25 ] demonstrated that the Mo 2 C barrier layer plays a key role in slowing down the diffusion of C and Si toward the inner Mo substrate at high temperatures, which led to less cracks in the surface and a thinner Mo 5 Si 3 layer at high temperatures in air and thus brought about better oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

“…Reference [ 25 ] demonstrated that the Mo 2 C barrier layer plays a key role in slowing down the diffusion of C and Si toward the inner Mo substrate at high temperatures, which led to less cracks in the surface and a thinner Mo 5 Si 3 layer at high temperatures in air and thus brought about better oxidation resistance. References [ 8 , 34 ] reported that the MoSi 2 /MoB coating (MoB as a diffusion barrier) possesses a longer service life compared to the single MoSi 2 coating on the Mo substrates, owing to the diffusion barrier effect of the MoB layer on the Si element diffusion into the Mo substrate.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

et al. 2023

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To enhance the oxidation resistance of Mo-based TZM alloy (Mo-0.5Ti-0.1Zr-0.02C, wt%), a novel MoSi2-ZrB2 composite coating was applied on the TZM substrate by a two-step process comprising the in situ reaction of Mo, Zr, and B4C to form a ZrB2-MoB pre-layer followed by pack siliconizing. The as-packed coating was composed of a multi-layer structure, consisting of a MoB diffusion layer, an MoSi2-ZrB2 inner layer, and an outer layer of mixture of MoSi2 and Al2O3. The composite coating could provide excellent oxidation-resistant protection for the TZM alloy at 1600 °C. The oxidation kinetic curve of the composite coating followed the parabolic rule, and the weight gain of the coated sample after 20 h of oxidation at 1600 °C was only 5.24 mg/cm2. During oxidation, a dense and continuous SiO2-baed oxide scale embedded with ZrO2 and ZrSiO4 particles showing high thermal stability and low oxygen permeability could be formed on the surface of the coating by oxidation of MoSi2 and ZrB2, which could hinder the inward diffusion of oxygen at high temperatures. Concurrently, the MoB inner diffusion layer played an important role in hindering the diffusion of Si inward with regard to the TZM alloy and could retard the degradation of MoSi2, which could also improve the long life of the coating.

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