Meaning of Hardness

What is Hardness:

Hardness refers to that which is hard, resistant, and lacks flexibility.

Hardness is the obstacle or impediment that some materials present when you want to alter their physical condition due to the cohesion of their atoms. That is, it is difficult to scratch, penetrate, wear, tear, deform, or burn.

For example, metal is a material that has a great hardness compared to plastic.

Generally, hardness is a term that is used in mineralogy and geology to refer to the hardness and degree of resistance that a mineral has when scratched or penetrated by another material.

For example, "Glass is characterized by its hardness."

Toughness is a word that can be used in different ways, such as indicating the rigorous and severe attitude of a person, "The coach shows his toughness in front of athletes."

Callus that forms on the most superficial part of the skin, usually on the extremities, is also called hardness. In physiology, on the other hand, the term hardness of the belly refers to constipation or difficulties in stool evacuation.

For example, "The new shoes gave me hardness in my heels", "The doctor recommended that I eat foods rich in fiber to avoid the hardness of the belly".

See also Tenacity.

Hardness tests

To determine the hardness of materials, durometers with different types of tips and ranges of loads are used on the various materials. Below are the tests most used to determine the hardness of materials.

Rockwell hardness

It refers to the Rockwell hardness test, a method with which the hardness or resistance of a material when penetrated is calculated. It is characterized by being a quick and simple method that can be applied to all types of materials. No need for an optical reader.

To perform the Rockwell hardness test, a steel ball or a diamond cone can be used as a point for the penetrating equipment, which will indicate the hardness of the material according to the preload, load and discharge ratio used at the time of carrying out the test. test.

Brinell hardness

Brinell hardness is a scale that is used to determine the hardness of a material through the indentation method, which consists of penetrating the hard material with a ball point of tempered steel, a load and during a certain time.

This test is imprecise but easy to apply. It is one of the oldest and was proposed in 1900 by Johan August Brinell, a Swedish engineer.

Vickers hardness

Vickers hardness is a test that is used in all types of solid and thin or soft materials. In this test, a diamond shaped like a pyramid with a square base and an angle at its vertex of 136 ° is placed on the penetrating equipment.

In this test, the hardness measurement is carried out by calculating the diagonal penetration lengths.

However, its result is not read directly from the equipment used, therefore, the following formula must be applied to determine the hardness of the material: HV = 1.8544 · F / (dv2).

Hardness of water

Water hardness is a term used to refer to the concentration of minerals, especially calcium, magnesium and iron salts, which are dissolved in natural water. The hardness of water is represented as Ca CO3.

Now, water acquires these minerals throughout the contact it has with the different types of land through which it circulates, be it a river or reservoir.

In this sense, the degree of hardness depends on the contact that the water has with the ground throughout the journey. Hence there are hard waters and soft waters.

Hard waters are not harmful to health. On the contrary, its daily consumption is recommended since it provides a significant amount of minerals necessary for the body.

On the other hand, there are also soft waters, which are characterized by having few minerals, including calcium and magnesium.

Types of water hardness

Hard water can be differentiated into two main types of hardness which are:

Temporary hardness: produced by acidic calcium or magnesium carbonate and can be removed by boiling water.

Permanent hardness: water composed of calcium sulfate, nitrates, calcium and magnesium chloride. They do not disappear when the water is boiled, but they do disappear using a method that involves the use of sodium carbonate.

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