Define oxidation process, Mechanical Engineering

Q. Define Oxidation Process?

Oxidation is defined as a loss of electrons, as when a metal goes from the metallic state to the corroded state. When a metal reacts with oxygen, it forms an oxide and the metal is said to be oxidized. Elevated temperatures can significantly increase the rate of oxidation.

Generally speaking, scale growth due to oxidation is proportional to the square root of the exposure time (i.e. it is a parabolic relationship). Three different forms of iron oxide may form, depending on the temperature and the concentration of oxygen available, FeO (wustite), Fe2O3 (hematite) and Fe3O4 (magnetite). The growth of the oxide scale is based on the diffusion rate of oxygen through this layer, which can then continue to react with the iron. In order for the scale to provide a protective layer, the oxide must be tightly adherent and occupy a greater volume than the metal from which it is formed.

The addition of alloying elements such as chromium (Cr), nickel (Ni), as well as small quantities of silicon (Si) and aluminum (Al) improves the oxidation resistance of iron-base alloys. The formation of a stable oxide layer on high temperature materials is a significant factor in providing an acceptable service life. Service conditions that are likely to disrupt the formation of such scales are detrimental (e.g. reducing atmospheres). Unexpected catastrophic failures from oxidation are very unlikely for most high temperature alloys.

Posted Date: 7/5/2013 7:52:37 AM | Location : United States

Related Discussions:- Define oxidation process, Assignment Help, Ask Question on Define oxidation process, Get Answer, Expert's Help, Define oxidation process Discussions

Write discussion on Define oxidation process
Your posts are moderated
Related Questions
Explain about the pedestals as construction engineering. Introduction of pedestals enables the construction engineers to make up levels to supply larger bearing areas to the fo

brifely explain 2r-2p invertion

Q. What is the use of welding electrode? An electrode is a piece of wire or a rod (of a metal or alloy), with or without flux covering, which carries current for welding. Its o

Q. Define Gas Welding? Metal joining process in which the ends of pieces to be joined are heated at their interface by producing coalescence with one or more gas flames (such a

Q. Explain Coating Repairs? Any coatings found to be damaged or that do not pass the inspection stage shall be recoated or repaired at the expense of the Applicator. The entire

What are the advantages and disadvantages hard working over cold working

What do you understand by straight line mechanism ? Describe with a neat sketch the working and construction of any three types of straight line mechanism. Derive a mathematical

Derive the relation for a fin insulated at the tip and the heat dissipation?

In hydrostatic we consider that fluids were at rest. Now we relax this consideration but with caution. We will discuss the flow of an real fluid. There are the assumptions about pe

Calculate the KIC from the data - thick cylinder: In a fracture test a 3-point bend specimen of thickness 20 mm and depth 25 mm is supported over a span of 100 mm. The specime