Microstructure and Oxidation Resistance of a Si Doped Platinum Modified Aluminide Coating Deposited on a Single Crystal Superalloy

Abstract

A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si doped Pt modified aluminide coating consisted of singular β-(Ni, Pt)Al phase, and no PtAl 2 phase was detected, which might be due to the fact that the addition of Si retarded the formation of PtAl 2 phase in the outer layer. Si was dissolved in the β-(Ni, Pt)Al phase in the outer layer and might form silicide with refractory elements in the inter-diffusion zone. The Si doped Pt modified aluminide coating possesses a better oxidation resistance than the Pt modified aluminide coating since Si could promote the formation of α-Al 2 O 3 and inhibit the diffusion of the refractory elements, reducing the formation of detrimental volatile phase.

Interdiffusion Behaviour of NiCoCrAlY Coating and N5 Single Crystal Superalloy

“…The thickness of IDZ and SRZ is also significantly affected by the oxidation time, as shown in Figure 5. It can be seen that the thickness of IDZ and SRZ is sharply increased during the oxidation Coatings 2020, 10, 393 6 of 10 process from 0 h to 100 h, but the growth rate for both zones is obviously slowed down in the next 100 h [34,35]. In order to analyse the interdiffusion behaviour, the distribution of elements was characterised using EDS every 5 μm from coating sub-surface (20 μm away to coating surface) to the interior substrate after oxidation for different time, as presented in Figure 6.…”

“…The thickness of IDZ and SRZ is also significantly affected by the oxidation time, as shown in Figure 5. It can be seen that the thickness of IDZ and SRZ is sharply increased during the oxidation process from 0 h to 100 h, but the growth rate for both zones is obviously slowed down in the next 100 h [34,35]. Figure 4 presents the cross-sectional morphology of NiCoCrAlY coating/N5 single crystal superalloy after static oxidation at 1100 • C for 0, 50, 100 and 200 h. Generally the Al in the coating will diffuse into the substrate because of the high concentration of Al in the coating, resulting in the following phase transformation in the substrate [33]: Figure 4 presents the cross-sectional morphology of NiCoCrAlY coating/N5 single crystal superalloy after static oxidation at 1100 °C for 0, 50, 100 and 200 h. Generally the Al in the coating will diffuse into the substrate because of the high concentration of Al in the coating, resulting in the following phase transformation in the substrate [33]:…”

“…The thickness of IDZ and SRZ is also significantly affected by the oxidation time, as shown in Figure 5. It can be seen that the thickness of IDZ and SRZ is sharply increased during the oxidation process from 0 h to 100 h, but the growth rate for both zones is obviously slowed down in the next 100 h [34,35]. According to the above-mentioned phase transformation process, after static oxidation for 50 h, an interdiffusion zone (IDZ) with a thickness of 17 µm was first formed at the coating/substrate interface, and the dark phase in the IDZ was the γ -Ni 3 Al phase, while the secondary reaction zone (SRZ) was not found.…”

The effect of precious metals in the NiAl coating on the oxidation resistance of the Inconel 713 superalloy

“…Due to the fact that the γ՛-Ni3Al phase formed as a result of the depletion of aluminum from the β-NiAl phase, the content of aluminum was too low in this area to keep an oxide that consisted exclusively of α-Al2O3, so oxides containing nickel were formed as well. Fan et al [35] suggested that carbides dissolved gradually when the β-NiAl →γ՛-Ni3Al phase transformation occurred. It may be due to the higher refractory elements solubility in the γ՛-Ni3Al phase than in the β-NiAl phase.…”

Study on High-Temperature Oxidation Behavior of Platinum-Clad Nickel Composite Wire

“…Scientists have produced a significant amount of research on high-temperature protection coatings of nickel and nickel alloys, including the selection of coating materials [7,8], coating preparation [9,10], coating modifications [11,12], properties [13,14], and oxidationresistance mechanisms [15,16]. These research results have promoted the development of high-temperature protection fields and also provided guidance for the development of this project.…”