ABSTRACT
Corrosion is the chemical or electrochemical reaction of a material with its environment. Common types of corrosion of metals include general corrosion, galvanic corrosion, crevice corrosion, pitting, and intergranular corrosion. Plastics resist a variety of chemicals but are usually attacked by organic solvents. Glasses resist most chemicals but are attacked by HF acid. Corrosion can be controlled by good design, galvanic protection, corrosion inhibitors, material selection, or protective coatings. In metals, the degree of protection of an oxide layer depends on its volume relative to the volume of metal consumed in forming it, P–B ratio. Metals with P–B ratios close to unity have protective oxides. Adhesive wear (scoring, galling, or seizing) occurs when two surfaces slide against each other under pressure. Abrasive and erosive wear result from contact with hard particles. Wear can be reduced by selecting a hard surface and using a lubricant. Radiation damage can be caused by electromagnetic waves (UV, x-rays, γ-rays) or particles (neutrons, α or β particles). Damage by radiation depends on its energy, density, time of exposure, and the bond strength of the material receiving radiation.
