Definition - What does Internal Oxidation mean?
Internal oxidation is the process of oxide formation away from the material's surface, through diffusion of oxygen within the material. It generally occurs in metals, alloys and composites.
Corrosionpedia explains Internal Oxidation
Internal oxidation is significant because it is used for the study of microstructures of materials such as metals, alloys and composites, so as to:
- Predict the functional as well as structural properties of materials
- Control the manufacturing and treatment processes to optimize the combination of electrical, mechanical and other functional properties
- Develop materials for high-temperature engineering applications
- Detect corrosion products and their impact, away from the surface
While normal oxidation occurs on the surface of solids, internal oxidation occurs due to diffusion of oxygen, away from the surface and also well isolated from the surface. It occurs at high temperatures of 600°C and above. When a component of an alloy oxidizes in preference to the bulk material, then it is a case of internal oxidation. This process is monitored and controlled in the dispersion hardening method of heat treatment of metallic alloys.
Structural and mechanical properties, such as fatigue and tensile strength of materials, are predominantly dependent upon the microstructure of the materials. Internal oxidation affects this microstructure of the material significantly. By controlling internal oxidation during the manufacturing and various heat treatment stages, we can induce desirable microstructure changes and improvements. Thus, it is possible to improve quality and optimize a combination of properties of the materials for critical applications where very high temperatures and pressures exist, for engineering and construction.
Creating beneficial microstructure changes involves:
- Controlling internal oxidation during fabrication
- Plastic deformation
- Surface treatment
- Heat treatment
- Surface engineering stages