Materials degradation

weakening of a material caused by repeatedly applied loads

Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the c

the tendency of a solid material to move slowly or deform permanently

thumb|Rear (driven) bicycle sprockets. Left, new, shows no wear. Right, used, shows obvious wear from being driven clockwise.

thumb|200px|Ablation near the electrode in a flashtube. The high-energy electrical arc slowly erodes the glass, leaving a frosted appearance.

reduction in ductility of a metal exposed to hydrogen

mechanical property of materials

Form of insidious localized corrosion in which a pit develops at the anode site

growth of cracks in a corrosive environment

alteration in the polymer properties under the influence of environmental factors

thumb|right|Image of fretting on a bearing

physical process in which a thermal gradient causes different parts of an object to expand by different amounts

way that brittle materials break or fracture when they do not follow any natural planes of separation

Expansive chemical reaction damaging concrete

severe form of highly localized corrosion attack resulting from the presence of an electrolyte in a crevice

thumbnail|right|Broken crankshaft failed from a surface defect at lower centre. The semi-elliptical beachmarks near the origin, indicate crack growth from Fatigue (material)|fatigue. Hachures are the lines on fracture surface that can be traced back to the origin of the fracture.

fatigue in a corrosive environment

thumb|Heavy foxing on the title page of an 1832 [[textbook]]

damages inflicted to concrete by various harmful physical phenomena and chemical or biological processes

thumb|Galling on the threads not protected by PTFE tape on a NPT fitting (zoom in on first few threads for better view). thumb|250px|An electron microscope image shows transferred sheet-material accumulated on a tool surface during sliding contact under controlled laboratory conditions. The outgrowth of material or localized, roughening and creation of protrusions on the tool surface is commonly referred to as a lump. thumb|250px|The damage on the metal sheet, wear mode, or characteristic pattern shows no breakthrough of the oxide surface layer, which indicates a small amount of adhesive mater

thumb|Very high-speed photography of a small projectile striking a thin [[aluminium plate at 7,000 m/s. The impact causes the projectile to disintegrate, and generates a large number of small fragments from the aluminium (spallation). This can occur without penetration of the plate.]]

process of scuffing, scratching, wearing down, marring, or rubbing away

damage to materials due to cyclic mechanical loads

theory

type of deterioration of film stock

Mechanical erosion of a material, or of the protective oxide layer on its surface

Bands of plastic deformation in metals

Neurolysis is the application of physical or chemical agents to a nerve in order to cause a temporary degeneration of targeted nerve fibers. When the nerve fibers degenerate, an interruption in the transmission of nerve signals occurs. In the medical field, neurolysis is commonly used to alleviate pain, such as in people with various forms of cancer, chronic osteoarthritis or spasticity.

applies cyclic loading to a coupon or structure to determine the rate of growth of cracks and fatigue life.

sound made by bending tin

physical degradation process

photo-oxidation of polymers

thumb|Embrittled Pinch Roller|pinch roller Embrittlement is a significant decrease of ductility of a material, which makes the material brittle. Embrittlement is used to describe any phenomena where the environment compromises a stressed material's mechanical performance, such as temperature or environmental composition. This is oftentimes undesirable as brittle fracture occurs quicker and can much more easily propagate than ductile fracture, leading to complete failure of the equipment. Various materials have different mechanisms of embrittlement, therefore it can manifest in a variety of way

cracks in many different elastomers due to ozone attack