Reaction Rate
The study of the rate at which a material reacts with oxygen provides the basis for predicting the growth of oxide layers on metal or semiconductor surfaces. Understanding oxidation kinetics allows for the selection of materials that can withstand harsh environments without failing due to surface degradation. The process follows specific mathematical laws that describe how the oxide thickness changes over time.
Transport Law
Linear, parabolic, cubic, or logarithmic growth patterns define how oxygen atoms reach the unreacted material. Parabolic growth often indicates that the reaction is limited by the diffusion of ions through an existing oxide layer. In contrast, linear growth occurs when the reaction at the interface is the slowest step.
Component Degradation
Thin films used in sensors are particularly vulnerable to surface reactions because a small amount of oxide can consume a large percentage of the total thickness. This loss of functional material changes the electrical resistance and mechanical properties of the sensing element. When the oxide layer becomes too thick, it may crack or delaminate due to internal stress, exposing fresh material to the atmosphere.
Engineers must account for these changes by applying protective coatings or choosing materials that form a stable, self-limiting oxide layer.
Lifetime Modeling
Data from these studies feed into reliability models that predict when a sensor will drift out of its specified tolerance. Accurate kinetic data prevent the premature failure of monitoring systems in power plants or jet engines.
