The true density of graphite electrode specimen is the mass per unit volume of specimen without porosity.
The true density of graphite electrode can be determined by X-ray diffraction method and density bottle method. The former is generally used in scientific research, while the latter is widely used in production testing, and is also applicable to the determination of true density of carbon raw materials.
Method will dry graphite electrode sample pieces below 0.15 mm, according to 3 g, in the density of 25 mL bottle, add 15 mL distilled water, on the sand bath (or electric heating board) boil 5 min sample of pore gas, remove the density bottle cooling to room temperature, adding boiling and cooling to room temperature in advance of distilled water to the density bottle scribed line, the density bottle in 20 ℃ + 1 ℃ water bath for 20 min, density bottles of liquid level should be below the water bath liquid level, the last adjustment to the scribed line, take out the density bottle, with a dry towel dry the bottle water, quickly weighed in the balance. The true density is calculated by the following formula:
Dw/dt = m (m + m1, m2)
Where dt is the true density, g/cm3; M is sample quality, g; M1 is the mass of water added to the density bottle, g; M2 is the mass of the density bottle with water and sample, g; Dw is the density of water at 20℃, g/cm3.
In addition to water, as the infiltrating medium there are ethanol, butanol benzene, kerosene, etc., these media is better than water infiltration, the measurement accuracy is slightly higher, but volatile and combustion. In addition, vacuum method can also be used to remove the gas in the sample hole, under the condition of maintaining a certain vacuum degree, the true density can be determined (see the determination of the apparent porosity of the carbon block for vacuum exhaust method).
►Graphite electrode features: Graphite electrode density