According to different application of carbon and graphite product, diiferent physical-chemical standard indicators were stipulated to evaluate quality. Physical-chemical indicators of product is concerned not only with that of raw material, but also with manufacturing technology.There are some rules existing between raw material and manufacturing technology. If we want to keep product be qualified, we should ensure raw material is qualified, manufacturing technology is responsible. This article focus on introducing main physical-chemical indicators. There are six main indicators.
1. True density
True density means the weight of per unit volume of material excluding proportion,who is measured by g/cm³.Usually，we smash assay into 0.15mm, infiltrate assay with alcohol or distilled water, and weight the handled material via comparison weighing method.
By testing true density, we can acquaint basic particle degree and arrange degree of material. As for graphite product and natural graphite sample, true density can reflect the degree of graphite lattice structure.
2. Apparent density
Apparent density means the weight of per unit volume of material including porosity, which is measured by g/cm³ too.
3. Ash content
Most ash contained in Carbon material is Oxidized metal and nonmetal element. Among all kinds of ash, metallurgical coke content(12%-16%) is the highest, the second one is anthracite(7%-12%). Ash of pitch coke and petroleum coke is around 0.5%. The main compound in ash is ferric oxide, aluminum oxide and silicon dioxide, which account for over 80% of the total ash content.
4. Mechanical strength
In carbon and graphite products industry, we are often used to denote the mechanical strength by three indictors: compressive strength, tensile strength and bending strength. The relationship of these three indictors are as follows: compressive strength of graphite product is as twice larger as bending strength. And bending strength is as twice larger as tensile strength.
5. Specific resistance
Most carbon and graphite product appllied to electric conduction, so better the electrical property is, better the material is. That is the date of specific resistance should be as low as possible, lower speific resitance means higher current density.
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