tvrdnutí

Tvrdnutí is a general term used in Czech and Slovak to describe the process by which something becomes hard or stiffer. It is applied to physical materials, biological tissues, and geological formations, and often denotes a transition from a softer to a more rigid state that may be temporary or permanent.

In materials science, tvrdnutí can refer to solidification, curing, or hardening. Examples include cement hydration, which forms calcium-silicate-hydrate and yields concrete; polymer curing through cross-linking; metals hardened by heat treatment or work hardening; and drying or aging processes that reduce mobility and increase rigidity. The exact mechanism varies: chemical reactions, phase transformations, or physical changes can all produce increased hardness.

In medicine and biology, induration (tvrdnutí) means an abnormal hardening or thickening of tissue. Causes include inflammation, infection, fibrosis, scarring, or tumor infiltration. Clinically, induration is detected by palpation and may accompany changes in skin, lymph nodes, lungs, or other organs. Diagnoses often rely on patient history, imaging studies, and sometimes biopsy.

Hardness, closely related to tvrdnutí, is also a measurable property. It is quantified by indentation tests such as Rockwell, Vickers, or Brinell to assess resistance to deformation. Thus, tvrdnutí encompasses both the causes of a transition to rigidity and the observable or measurable outcomes across different disciplines.