An overview and its properties of carbon

An overview of carbon

It is a suprisingly little-known fact that carbon has excellent characteristics and properties.
Please refer to this page to familiarize yourself with the benefits of carbon.

◆What is carbon? (Carbon: a chemical element with the chemical symbol ‘C’)

This material has a defined level of crystalline structure and is created solely from the chemical element carbon. Graphite and diamond are both crystalline forms of the element carbon.

Although both materials are represented by the chemical symbol C, they have differing atomic arrangements and crystalline patterns, which is why they are known as allotropes* of carbon.

Carbon can be produced by steam baking carbon compounds (excluding some organic compounds), so it includes amorphous carbonsubstances without a proper crystalline structure such as carbon fiber, charcoal/activated charcoal, and coke. Differences in the starting material will lead to a variance in properties and naming.

◆Graphite (the type of carbon used by HOMUSUBI)

A material formed solely from carbon laminated with a sheet of carbon atoms bound to a hexagonal lattice shape; a sintered body of carbon particles with a graphite crystalline structure.

Natural graphite・・・Graphite harvested from natural minerals
Man-made graphite ・・・Can be made from petroleum or charcoal-based raw materials→This is the graphite used by HOMUSUBI

◆Formula for manufacturing a block of man-made graphite

It is extremely time-consuming to produce a block of graphite, taking approximately 3 to 6 months.

1. The raw materials are crushed into particles using a grinder and then classified using mesh.
2. Next, coal tar pitch is added and kneaded together to form a paste.
3. Molding (* Molding method to be discussed below).
4. Firing (approx. 3000 degrees)
5. Graphitization

Properties of carbon

Carbon boasts many excellent properties.
Particular properties and characteristics are described below.

◆Graphite heat properties

The graphite heat properties are described below.
1. Excellent thermal conductivity and resistant to sudden thermal changes.
2. Even at high temperatures, dimensional variation is minimal and strength increases at high temperatures.
3. Can be used up to approx. 3000℃ in a reducing atmosphere, and even in an oxidizing atmosphere, can be used up to approx, 400℃.
4. In a reducing atmosphere, mechanical strengthening is increased together with temperature up to 2500 ℃.
5. The rate of expansion due to heat is minimal, at half the rate or less when compared to other metals such as iron and bronze, and indicating a value equivalent to quartz glass.

◆Graphite characteristics

1. Allows electricity to pass through
2. Light and easy to process (lighter and easier to precision machine than aluminum)
3. Good chemical resistance (resistant to acid and alkali at room temperature, and doesn’t react to glass or quartz)
4. Self-lubricating (does not damage other components, used in applications such as machinery bearings and sliding adhesive material)
5. Produces far infrared rays once 35℃ is exceeded
6. High purity

◆Comparison of types of graphite

Type	Manufacturing method	Properties	Superior feature
CIP	Cold isostatic pressing (CIP): place into a rubber mold and press evenly on all 6 surfaces	Minimal variance in strength between each of the surfaces	Extremely fine, beautiful texture
Extrusion	Place in an extrusion mold and apply pressure from one side	Rough texture (process) but excellent thermal conductivity	Attractively priced
Mold	Place raw materials into a 6-sided metal mold and press	There can be variation between the pressed surface and the other surfaces but produces a strong material	Suitable for volume production

Aside from the above, there are also other promising types of carbon, including C/C composite material, heat insulating material, and ceramic carbon.
CFRP (carbon fiber) has been attracting attention for a considerable time, and is used in a variety of products.

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