hiertyminen

Hiertyminen is the material loss that occurs when two surfaces rub against each other. The term is derived from the Finnish verb hiertyä, meaning to rub, with the suffix -minen to denote a process. In engineering and materials science, hiertyminen is commonly described as wear caused by sliding contact and is a central concern of tribology, the study of friction, lubrication, and wear.

The mechanisms of hiertyminen include several distinct pathways. Adhesive wear occurs when bonding entities form between contacting surfaces and material transfers from one surface to the other during sliding. Abrasive wear happens when harder asperities or particles plow and remove material from a softer surface. Fatigue wear results from cyclic stresses at the contact that create cracks, which progressively detach material chunks. Tribochemical wear involves chemical reactions at the interface that weaken surfaces and promote removal, often accelerated by temperature, lubrication, or environmental species.

Many factors influence the rate and character of hiertyminen. Contact pressure, sliding speed, temperature, and normal load interact with material properties such as hardness, toughness, and microstructure. Surface finish and roughness, presence of lubrication, environmental conditions (temperature, humidity, contaminants), and the presence of hard third-body particles are also critical.

Measurement and control of hiertyminen rely on wear testing, such as pin-on-disk or block-on-ring experiments, to determine wear rate and specific wear rate. Surface analysis after testing, including profilometry and microscopy, helps identify dominant wear mechanisms. Prevention strategies include selecting harder or tougher materials, applying protective coatings, improving lubrication, controlling surface roughness, and engineering contact geometries to minimize detrimental sliding conditions.

See also tribology, friction, lubrication, and wear.