CorrosionCorrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. There are factors that accelerate corrosion, such as, water, salts and other pollutants.

RustThe conversion of a

metal to its original state of an oxide. A humidity of 65%+ is needed for iron to rust.

4Fe + 3O2 + 6H2O --> 4Fe(OH)3

Chemical Equation

FatigueFatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading.

Micrographs showing how surface fatigue cracks grow as material is further cycled

Fatigue life ( Nf ) - the number of stress cycles of a specified character that a specimen sustains before failure of a specified nature occurs.

Effects of weathering on plasticsMost plastics subjected to weathering deteriorate from the oxygen and the uv (ultra-violet) light from the sun.

WhyWhen polymers absorb uv light it excites the molecules this causes them to vibrate so that the chemical bonds break and chains shorten. The oxygen forms other chemical groups and sometimes cross links.

OutcomesThe plastic have reduced flexibility and strength and increases brittleness.