Y ₂ O ₃-Al₂ O ₃-SiO₂ (YAS) Glass ceramics in 1350℃ Water-oxygen environment in the Long-term corrosion behavior and Mechanism

Digital Object Identifier ：10.1016/j.ceramint.2023.06.089

Laboratory of Thermal Structural Composite Materials Science and Technology, Northwestern Polytechnical University Professor Fan Shangwu’s team in the journal A paper titled ... was published in Ceramics International. “ Corrosion behavior and mechanism of the Y ₂ O ₃ –Al ₂ O ₃ –SiO ₂ system during long-term corrosion in water-oxygen environment at 1350 degrees Celsius   “of the paper. The study analyzes high temperatures Water - In an oxygen atmosphere ( 1350℃ ) Long-term decay Y ₂ O ₃-Al₂ O ₃-SiO₂

 ( YAS ) glass Ceramics of Mechanism 。

Research Background

Y ₂ O ₃-Al₂ O ₃-SiO₂ ( YAS ) Glass ceramics possess numerous outstanding properties, such as oxidation resistance, high hardness at elevated temperatures, and chemical durability, making them suitable for use as protective coatings in high-temperature environments. Therefore, research Y ₂ O ₃-Al₂ O ₃-SiO₂  (YAS) The microstructural evolution and corrosion mechanisms of glass-ceramics are critical to their application in high-temperature water–oxygen corrosion environments.

Research Methods

1. YSA Preparation method for glass-ceramics: 11.1% Y ₂ O ₃ -12.3% Al ₂ O ₃ -76.6% SiO ₂( mol% ) Powder Magnetic mixing combined with alcohol ， Grind to obtain a uniform powder. 5°C/min Heated to at a heating rate of 1650°C , heating 120 minutes, followed by quenching to obtain the glass sample. ， Subsequently Grind to a particle size of less than 30 μm glass powder. The powder is cold-pressed into a size of 8.0 × 8.0 × 3.0 mm ³ the raw billet, and then in 1370°C Post-heat treatment 2 hours, to obtain a highly pre-crystallized YAS Glass-ceramic.
2. Water-oxygen experiment: Temperature is 1350 °C, 50 vol% H ₂ O + 50 vol% O ₂ the water-oxygen environment Testing is conducted in the medium, with a carrier gas flow rate of 200ml/min . Corrode separately within the effective insulation zone 5、30、60 and 100 Hours.
3. Corrosion Mechanism  ：

• Initial stage: The tridymite in the surface layer is destroyed, Y ₂ Yes ₂ O ₇  and mullite decomposes into Y ₂ O ₃  and All ₂ O ₃ , with a slower corrosion rate.
• Intermediate stage ： The residual glass phase crystallizes rapidly, resulting in Y ₂ Yes ₂ O ₇  With the growth of mullite crystals, the glassy phase decreases.
• Final stage: YAS The glass phase is fully crystallized and no longer contains the self-healing phase. Surface corrosion and internal stresses induced by internal crystallization lead to cracking of the ceramic, while corrosive gases readily penetrate into the ceramic interior, increasing the reaction surface area and accelerating the corrosion rate.

Research Results

Silicon dioxide ₂、 Y ₂ Yes ₂ O ₇ When reacting with steam, the primary consumption is Yes , leading to certain enrichments in the ceramic Yes Region “ Silicon depletion ” , form YAl _1.4 Yes _1.7 O ₇。

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