Rate of oxide thickness growth

The purpose of this review paper is to survey the principles of high temperature oxidation or high temperature corrosion. A typical situation is that of a metal exposed to a hot gas which can act as an oxidant. In many cases the oxidation product forms a layer which separates the reactants, the metal and the gas atmosphere. Under special conditions, the kinetics are diffusion controlled, i. e,, the rate of the reaction (the rate of oxide thickness growth) depends on the diffusion of species, ions and electrons, through the layer (sometimes called a tarnish layer). Actually when a metal or alloy is exposed to a corrosive gas, the reaction kinetics may be controlled by one or more of the following steps ... 

The mathematics of oxidation kinetics involves diffusion and migration mass transfer. According to Pick s first law of diffusion, the molar flux is related to the rate of oxide thickness growth (dx/dt) is given by... 

In fact, X in eq. (10.19) represents an external thickness in most cases. Now, the generalized equation for die rate of oxide thickness growth takes the form... 

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