Corrosion behavior of alumina‐based ceramic core materials in caustic alkali solutions

Abstract

Corrosion behaviors of the porous alumina‐based ceramic core materials in KOH and NaOH solution were investigated. Corrosion tests were carried out at 100°C, 150°C, and 200°C, and the concentration of KOH and NaOH was 50, 67, and 75 wt%, respectively. The results indicated that the optimal concentration was 67 wt% for KOH solution and 50 wt% for NaOH solution, respectively. Increasing corrosion temperature and prolonging corrosion time were helpful to enhance the corrosion effect, and temperature played an extra important role during the whole corrosion process. NaOH solution was better than KOH solution for corrosion at the same temperature and concentration.

Preparation and characterization of tubular cermet membrane for microfiltration separation: application to the treatment of textile wastewater

“…Actually, it was the SiO 2 in the glass phase that hardly reacted with HNO 3 . In line with Gao et al [20], the Gibbs free energy between Al 2 O 3 and H + obtained from the Microsoft "HSC Chemistry 6" was equal to −112 KJ•mol −1 while that of Al 2 O 3 and OH − was equal to −10.56 KJ•mol −1 . However, the SiO 2 value contained in the glass phase was higher than the Al 2 O 3 value, due to the relatively low dissolution and diffusion rates of the coarse alumina.…”

Corrosion Resistance Properties of Porous Alumina–Mullite Ceramic Membrane Supports

“…Figure 3a,b shows the mass loss of the porous ceramic supports corroded in acidic and alkaline solutions for different times at 80 C in oil bath. It is shown that the mass loss of the samples increased rapidly at the first stage, but changed quite slowly after 12 h, and almost turned into a constant for the 87.2/12.8 sample that corroded in 10 wt% NaOH solution for more than 20 h. Moreover, the mass loss was merely 0.35 wt% for all the ), [10] the SiO 2 content contained in the glass phase was higher than the Al 2 O 3 content, due to the relatively low dissolution and diffusion rates of the coarse alumina. That is to say, the reaction between SiO 2 and OH À (Gibbs free energy: À1075 KJ mol À1 ) was dominant, so the mass loss was lower in H 2 SO 4 than in NaOH.…”

“…Actually, it was the SiO 2 in the glass phase that hardly reacted with H 2 SO 4 . Although the Gibbs free energy between Al 2 O 3 and H + (–112 KJ mol −1 , obtained from the Microsoft “HSC Chemistry 6”) is less negative than that between Al 2 O 3 and OH − (–10.56 KJ mol −1 ), the SiO 2 content contained in the glass phase was higher than the Al 2 O 3 content, due to the relatively low dissolution and diffusion rates of the coarse alumina. That is to say, the reaction between SiO 2 and OH − (Gibbs free energy: −1075 KJ mol −1 ) was dominant, so the mass loss was lower in H 2 SO 4 than in NaOH.…”

“…Numerous works have focused on the corrosion behaviors of the ceramic membrane supports such as alumina, [8][9][10][11][12] cordierite, [13,14] Al 2 O 3 -TiO 2 or mullite or Al 2 TiO 5 -mullite, [15][16][17][18] mineral-based ceramic (kaolin, dolomite, pyrophyllite, ballclay, and feldspar), [19][20][21] and SiC, [22] under various corrosion media including H 2 SO 4 , HCl, HNO 3 , H 3 PO 4 , HF, NaOH, KOH. The results show that the corrosive attack generally occurs at grain boundaries, in which impurities/glass concentrated, [11,12,23] leading to the deteriorations of mechanical properties and chemical stability of the ceramics.…”

Effect of calcination temperature on friction and wear behavior of α–alumina (α‐Al2O3) for biomedical applications

“…Ceramics are one such class of materials which have been researched extensively for total hip prosthesis applications due to their high scratch and wear resistance and low friction . However, a new class of materials called nanocrystalline ceramics is being developed by reducing grain sizes and are evaluated for improvement in their mechanical properties . However, there are counterclaims in the literature contradicting these observations …”