qattiqlik

Qattiqlik, or hardness, is a material property describing resistance to localized plastic deformation, scratching, or indentation. In engineering and geology, it is used to compare how easily a substance can be dented or worn. The exact meaning of hardness depends on the test method and the type of deformation considered, so there is no single universal value for 'hardness'.

Common hardness tests include Mohs scale for minerals, which ranks scratching resistance from 1 to 10. For metals and ceramics, indentation tests such as Rockwell, Vickers, and Brinell are used. These tests apply a defined load and measure the size or depth of an impression to assign a numerical value.

Hardness often correlates with wear resistance and some strength measures, but it is not a direct indicator of toughness. Materials can be very hard yet brittle. Results depend on surface condition, temperature, anisotropy, and microstructure, so different tests may yield different conclusions for the same material.

Practically, qattiqlik informs material selection for cutting tools, molds, gears, and wear parts, and it is a standard check in quality control. Engineers use hardness data to estimate performance and to compare candidate materials for a given application.

In Uzbek, qattiqlik can also mean mental or moral firmness, such as determination, though the term in scientific contexts refers to the material property described here.