Resistance of Reinforcing Fibers

Solid glass and glass fibers are attacked by acids, alkalis, and also by water. Here, the attack mechanisms of acids and alkalis are fundamentally different. While glass fiber corrosion by acids is diffusion-controlled following 7f-kinetics, attack by water and alkali is more linear and controlled by interfacial properties. 

Glass is mainly leached by acids, i.e., cations in the glass are substituted by H ions from the acid  

In thermo-dynamical terms, this is an equilibrium reaction. In addition to ambient pressure and temperature, corrosion resistance in the glass fibers is also critically dependent on their composition and the aggressiveness of the acting acid. Invest - 

Very weak and very strong mineral acids are less aggressive. Different concentrations initiate different conversions. In addition, complexing and the formation of insoluble salts on the glass surface create substances that may act as diffusion barriers. In terms of reaction kinetics, the ion substitution reaction, which causes acid corrosion of individual fibers is determined by a diffusion process ( /f-kinetics). 

The increasing leaching of E-glass fibers by acid attack can be easily observed optically, because it changes the index of refraction in the leach zone. 

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Since the long term durability of CMCs is dominated by strength and creep resistance of reinforcing fibers, fibers are exposed to several tests to evaluate... 

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