Characterization of silicide phases formed during pack siliconizing coating on the Nb-1Zr-0.1C alloy

Vishwanadh, B.; Majumdar, S.; Orsborn, Jonathan; Banerjee, Rajarshi; Tewari, R.; Fraser, Hamish L.; Dey, G.K.

doi:10.1016/j.intermet.2015.03.007

Cited by 20 publications

(3 citation statements)

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“…33 Due to the inward diffusion of silicon atom perpendicularly to the surface, it reveals a typical column crystallization for NbSi 2 coating as shown in Figure 4c. Vishwanadh et al 44 detected the crystallization growth of HAPC-coating with vertical column crystal grains in the deposited coating through transmission electron microscope. Column structure, which is vertical to the substrate surface, benefits adhesion between the coating and the substrate.…”

Section: Resultsmentioning

confidence: 99%

“…The formation of Nb 5 Si 3 could result from the depletion of Si atoms in the coating due to the outward diffusion of Si leading to the formation of silica on the NbSi 2 coating surface. 44 According to the XRD patterns (Figure 7d), Nb 2 O 5 and SiO 2 are the predominant phases of the surface oxide scale. In Figure 7c, it can be found that the shape of Nb 2 O 5 is rod with a length of 5−10 μm and width of 1−3 μm.…”

Section: Resultsmentioning

confidence: 99%

“…They grew continuously toward the coating-substrate interface and stopped their propagation at the front of Nb 5 Si 3 , which was a new interdiffusion zone with relatively compact structure (Figure b). The formation of Nb 5 Si 3 could result from the depletion of Si atoms in the coating due to the outward diffusion of Si leading to the formation of silica on the NbSi 2 coating surface . According to the XRD patterns (Figure d), Nb 2 O 5 and SiO 2 are the predominant phases of the surface oxide scale.…”

Section: Resultsmentioning

confidence: 99%

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Silicide Coating Fabricated by HAPC/SAPS Combination to Protect Niobium Alloy from Oxidation

Sun

Guo

et al. 2016

ACS Appl. Mater. Interfaces

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A combined silicide coating, including inner NbSi2 layer and outer MoSi2 layer, was fabricated through a two-step method. The NbSi2 was deposited on niobium alloy by halide activated pack cementation (HAPC) in the first step. Then, supersonic atmospheric plasma spray (SAPS) was applied to obtain the outer MoSi2 layer, forming a combined silicide coating. Results show that the combined coating possessed a compact structure. The phase constitution of the combined coating prepared by HAPC and SAPS was NbSi2 and MoSi2, respectively. The adhesion strength of the combined coating increased nearly two times than that for single sprayed coating, attributing to the rougher surface of the HAPC-bond layer whose roughness increased about three times than that of the grit-blast substrate. After exposure at 1200 °C in air, the mass increasing rate for single HAPC-silicide coating was 3.5 mg/cm(2) because of the pest oxidation of niobium alloy, whereas the combined coating displayed better oxidation resistance with a mass gain of only 1.2 mg/cm(2). Even more, the combined coating could significantly improve the antioxidation ability of niobium based alloy at 1500 °C. The good oxidation resistance of the combined silicide coating was attributed to the integrity of the combined coating and the continuous SiO2 protective scale provided by the oxidation of MoSi2.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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