The Hardness of natural slate

Hardness of natural slate: refers to the slate by other touches (including cutting tools) characterization or cutting resistance, can also be said to be slate resistance to external force damage ability.The hardness of slate is one of the most important physical properties that affect the process of adding slates. Because of the different hardness of the rock, it should be used to adapt to the process of processing, in order to obtain the greatest economic benefits. The hardness of a slate is related to its chemical composition, mineral composition, mineral structure and structure.

Hardness of slate can generally be divided into two kinds of relative hardness and absolute hardness.  

First, the natural slate relative hardness

The relative hardness in general in petrology widely adopted is the foundation's hardness, is made by mineraloge mol, he chose 10 kinds of minerals and rocks as the standard, according to the hardness of the size of order, after a moment ago can scratch the minerals and rocks a mineral rock.

To determine the relative hardness of slates, the hardness of the slate shall be determined by comparing the minerals prescribed by the slate to the Mohs hardness scale. For example, some slate can scratch fluorite and not scratch apatite, then its hardness in Mohs hardness between 4-5, can be set as 4.5 of the hardness of the founder. Another slate and apatite can not be scratched by each other. The hardness of the slate is equal to that of apatite. The hardness of the slate is 5.

In situ measurement, if there are no 10 mineral rocks selected from the hardness scale of the heading, can also be used as a standard for determining the hardness of the slate. For example, the hardness of such things as the copper key is about 3 of Mohs's hardness, and the hardness of steel knives and other articles is about 5.5, and the hardness of glass is about 6 of Mohs's hardness.  

Two, absolute hardness-natural slate

Absolute hardness is the hardness of a slate that has been measured by a hardness tester.  

The value of hardness varies according to the method of measurement, therefore, absolute hardness, in addition to indicating the value of hardness, must also point out the method of measuring hardness. According to the way of loading when measured, it can be divided into two major parts: static hardness and dynamic hardness.  

The static hardness

Static hardness refers to the test of the surface of the material under static load. The hardness is determined by the size of the indentation on the surface of the material. The hardness of the slate plate is measured by the microhardness meter with a pressure head less than 1 kilograms.  

The dynamic hardness of

Dynamic hardness refers to the hardness measured by the impact of the indenter on the surface of the material under dynamic loading. The hardness measurement of slates is usually carried out by shore hardness tester at home.  

"Shore hardness" is indicated by the symbol Hs. The work principle of Shaw hardness test is to raise the diamond punch to the fixed height h. The top pin is tightly pressed, and then the pin mechanism is released. The punch drops to the test table and back up to a certain height H. The value of shore hardness Hs is determined according to the height of the rebound H.

Three, according to the classification of hardness-natural slate

According to hardness classification, facing five materials can be divided into three blocks: hard slate slab, medium hard slate slab and soft slate.  

The hard slate

Hardness is generally Mohs hardness 6 - 7, Shaw hardness is generally 80-100 degrees. Mainly magmatic rocks such as granite (7), syenite and gabbro (Mohs touch 6 - 6.5).  

Hard slate high hardness. The integrity is strong, processing is difficult, as a decorative slate, its gloss. Durable, its durability in about 200-500 years, is the main decoration materials of luxury buildings and ground surface.  

The hard natural slate

Hardness is generally Mohs hardness 3-5, shore hardness is generally 4s-55. Mainly marble, limeslate, and some types of volcanic ash, tuff and dolomite processing panels are also made of hard slate.  

Durability in hard slate is about 100 years, because of its variety of colors, is the luxurious indoor main decorative decoration materials used, its rich and colorful patterns. The processing cost is much lower than the hard slate, so it can be widely used.  

The soft slate

Hardness is generally 2-3 of hardness and 20-40 degree of hardness. The number of varieties including gypsum rock, talc, including some varieties of dolomite and calcareous rock scale etc..  

Because of low hardness, easy processing, and pattern and color variety, low price, is a good slate with interior decoration, due to its loose structure. The texture is soft, so the poor durability generally early syndrome after 25 years or so that damage.