1. Protection behavior of Ti-SiO2 modified potassium silicate coating on K447a alloy at 1000 °C.
- Author
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Du, Yao, Chen, Zheng, Lu, Yiliang, Yang, Lanlan, Wang, Cheng, Zhu, Shenglong, and Wang, Fuhui
- Subjects
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POTASSIUM silicate , *DIFFUSION coatings , *SUBSTRATES (Materials science) , *X-ray diffraction , *CALCIUM phosphate - Abstract
Potassium silicate coatings cured by calcium hydrogen phosphate and modified by fillers of Ti and SiO 2 powders were prepared on K447A alloy at 120 °C. The influences of Ti, SiO 2 and both powders on the oxidation behavior of the coated specimens were investigated at 1000 °C for 100 h in static air by thermogravimetry, SEM, XRD and EPMA. The bare K447A alloy suffered severe oxidation at 1000 °C, and the TGO was found to be composited of an outer layer of mixtures of NiCr 2 O 4 , CoAl 2 O 4 and rutile TiO 2 , and an inner α-Al 2 O 3 layer. The potassium silicate coating without filler showed local damages where formation and rapid rupture of bubbles occurred and consequently the local substrate was oxidized. The SiO 2 powder in the coatings is more capable of reducing O diffusion thru the coatings than the Ti powder, while the latter is more effective in getting rid of bubble rupture than the former. Thus, the coating modified by 10 wt% Ti and 20 wt% SiO 2 showed the best protective performance. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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