The effect of method of preparation on the corrosion resistance and catalytic activity during corrosion of tungsten carbide I. Corrosion resistance of tungsten carbide in sulfuric acid

Abstract

The corrosion resistance in 4.5N and 9.9N H2SO4 of tungsten carbide synthesized under different conditions has been investigated. The amount of oxides in both electrolytes increases linearly with time, suggesting that during the corrosion process the catalyst surface is not passivated. The corrosion rate depends on the method of preparation of the tungsten carbide. Under identical preparation conditions, carbides synthesized from H2WO4 displayed the lower corrosion resistance. The corrosion resistance of carbides synthesized from identical starting materials depends on the carburation temperature: carbides synthesized at elevated temperatures display higher corrosion resistance. The different corrosion rates are explained by the variations in the specific surfaces, the grain size, and the different extent of segregation of the tungsten carbide particles, respectively. It is shown that the corrosion rate in 4.5N H2SO4 is twice that in 9.9N H2SO4. This observation is discussed in terms of differences in the rate of the anodic process and the lower solubility of the corrosion process depolarizer (oxygen) in highly concentrated solutions. © 1980.