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Cobalt is also used in the petroleum industry as a catalyst when refining crude oil. This is to purge it of sulfur, which is very polluting when burned and causes acid rain. [11] Cobalt is the active center of a group of coenzymes called cobalamins. Vitamin B 12, the best-known example of the type, is an essential vitamin for all animals.
Elastic properties describe the reversible deformation (elastic response) of a material to an applied stress.They are a subset of the material properties that provide a quantitative description of the characteristics of a material, like its strength.
Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale. The Mohs scale (/ m oʊ z / MOHZ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.
A variety of hardness-testing methods are available, including the Vickers, Brinell, Rockwell, Meyer and Leeb tests. Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material-specific comparison table for steels.
The addition of cobalt increases heat resistance, and can give a hardness up to 70 Rockwell C. [14] M35 M35 is similar to M2, but with 5% cobalt added. M35 is also known as Cobalt Steel, HSSE or HSS-E. It will cut faster and last longer than M2. [15] M42 M42 is a molybdenum-series high-speed steel alloy with an additional 8% cobalt. [14]
Less common materials in blades include cobalt and titanium alloys, ceramic, obsidian, and plastic. The hardness of steel is usually stated as a number on the Rockwell C scale (HRC). The Rockwell scale is a hardness scale based on the resistance to indentation a material has.
In 1983 Pearson together with Robert Parr extended the qualitative HSAB theory with a quantitative definition of the chemical hardness as being proportional to the second derivative of the total energy of a chemical system with respect to changes in the number of electrons at a fixed nuclear environment: [11]