Medium-Entropy Monosilicates Deliver High Corrosion Resistance to Calcium-Magnesium Aluminosilicate Molten Salt.

For decreasing the global cost of corrosion, it is essential to understand the intricate mechanisms of corrosion and enhance the corrosion resistance of materials. However, the ambiguity surrounding the dominant mechanism of calcium-magnesium aluminosilicate (CMAS) molten salt corrosion in extreme environments hinders the mix-and-matching of the key rare earth elements for increasing the resistance of monosilicates against corrosion of CMAS. Herein, an approach based on correlated electron microscopy techniques combined with density functional theory calculations is presented to elucidate the complex interplay of competing mechanisms that control the corrosion of CMAS of monosilicates. These findings reveal a competition between thermodynamics and kinetics that relies on the temperatures and corrosion processes. Innovative medium-entropy monosilicates with exceptional corrosion resistance even at 1500 °C are developed. This is achieved by precisely modulating the radii of rare earth ions in monosilicates to strike a delicate balance between the competition in thermodynamics and kinetics. After 50 and 100 h of corrosion, the thinnest reactive layers are measured to be only 28.8 and 35.4 µm, respectively.

Bioactivity and cytocompatibility of silicon wafers treated by water.

A range of bioactive ceramics can induce bone-like apatite to deposit on their surface in simulated body fluid (SBF). In this work, the silicon wafer was treated using deionized water to improve its bioactivity. The morphology and chemical composition of the treated silicon wafer was examined using Fourier transform infrared spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Field emission scanning electron microscopy was used to observe the surface morphologies of silicon wafers soaked in SBF. The results indicated that a hydrated sub-oxide film having Si--OH groups formed on the surface of the silicon wafer after the water treatment. The amount of Si--OH groups increased with raising the treatment temperature or prolonging the immersion time. Apatite was deposited on the surface of water-treated silicon wafers immersed in SBF. The apatite deposition was correlated with the amount of Si--OH groups. Human mesenchymal stem cells cultured on the surface of the water-treated silicon wafers showed good adhesion and spread, indicating that the cytocompatibility of silicon wafer was enhanced by this water treatment.