Corrosion of Ceramic Silicon Carbide in Hydrofluoric Acid

Abstract

Silicon carbide usable in mechanical or electrical engineering is produced in various purity grades and exhibits a large number of crystal structure variants. As for use in the chemical field, it is commonly stated that it is highly resistant in acid media but not suitable for use in alkaline media. This paper discusses the resistance of compact silicon carbide to hydrofluoric acid. The compact silicon carbide has been prepared by sintering using the SSiC method with or without binders based on scandium oxide Sc 2 O 3 and calcium fluoride CaF 2 . The purest silicon carbide sample of cubic 3C structure sintered without a binder was almost insoluble in hydrofluoric acid. It has been shown, however, that pure silicon carbide is perfectly insoluble in hydrofluoric acid irrespective of the structure variants detected in the samples (3C, 4H, 6H, 15R). The corrosion stability of the compact ceramics is affected by the residual SiO 2 content (together with other impurities) in imperfect SiC preparations, and it is influenced by the choice and chemical properties of the chosen ceramic binder as well.

Effect of hBN on Corrosion and Wear Performances of DC Electrodeposited NiW and NiW–SiC on Brass Substrates

“…The performance of passive layer in corrosive media is affected by many factors, such as pH, temperature, and dissolved oxygen content [40][41][42][43]. The increase in corrosion potential of NiW toward positive values with the addition of SiC could be attributed to a uniform distribution of SiC particles within the NiW, surface oxidation of SiC particles or presence of SiO 2 in the interplanar layers of individual SiC [32,33]. As well, formation of double layer of NiWO 4 due to the oxidation of the NiW when exposed to corrosive media.…”