Hardness refers to something that is hard that lacks flexibility and has a lot of resistance. It is one of the forms of the physical property of matter , it basically consists of the firm and constant union of the molecules that make it up, thus making the penetration, breaking or division process difficult.
In mineralogy it can be defined as the firmness against scratching of the smooth surface of the mineral. This is because a soft surface is easier to scratch than a hard one, in this sense, a firm mineral such as diamond can scratch a soft one, while conversely, a soft mineral can never scratch a hard one.
They are in charge of determining the hardness of the surface. It is in charge of measuring metal, plastic, fabrics, rubber, among others.
Hardness measurement principle
The principle of the measurements of the various hardnesses of the materials is always treated the same. There is only the distinction between the static and dynamic procedure of hardness measurement.
- Shore hardness is an eigenvalue of the custom material for elastomers and plastics. Shore hardness counters for rubber and similar working raw materials are composed of a spring-loaded pencil, the flexibility of which when penetrating the test functions as a measure for the corresponding Shore hardness, which is indicated on a scale from 0 Shore up to 100.
- The hardness calculation studied and exposed by Brinell is usually used for soft and medium-hard metals, unalloyed building steel or aluminum alloys, for wood and work materials with irregular structures, such as cast iron. For this, a steel or carbide ball with a defined measuring force is imposed on the surface of the work material.
- It is named after the British aircraft master builder Vickers . Direct hard working materials are measured, but hardness is also measured in thin-walled or superficially accustomed materials and in marginal areas. Unlike Rockwell hardness measurement, an equilateral diamond pyramid with an opening angle of 136º is pressed with a defined measuring force on the work material.
- The Rockwell HRC hardness of a work material is defined by the penetration depression of a tapered diamond test specimen. With a defined calculation force, this cone is preloaded with a point angle of 120º in the extension of the work material. The depth reached by the penetrator serves as a comparison plane. The indenter is then pressed with the main load for a maximum of six seconds. Then the main load is removed, keeping only the preload.
- Mohs scale: refers to the name of the German scientist who discovered Friedrich Mohs . The hardness of a mineral is determined by evaluating which mineral on that scale scratches it. The index on which this scale is based is determined as follows:
- Talc: 1
- Plaster: 2
- Calcite: 3
- Fluorite: 4
- Apatite: 5
- Ortosa (feldspar): 6
- Quartz: 7
- Topaz: 8
- Corundum: 9
- Diamond: 10