Increasing the Density of Graphite Powder
Graphite powders are manufactured to meet various applications. These include casting material, batteries, pencils, thread sealant pastes, etc. They are also used in refractory materials.
High-purity graphite powders can be obtained from natural sources or synthetically produced. Various particle size distributions can be used, but the c/2 value is preferred to be greater than 40 nm.
The particles can be treated according to known fluidization techniques. This method can increase the pressed density of graphite powder by 1% to 8%. In addition, the tamped density can be increased by 10% to 100%. Graphite powders treated according to invention have lower viscosities in liquid media.
Graphite powders with an optimum pitch binder content can achieve a high apparent density. The addition of pitch improves the mechanical strength of the GBs. Moreover, it decreases the porosity. Table 3 lists the physical properties of GBs with different pitch binder contents.
A high pressed density can be achieved with a GF with a particle size distribution of 50:500 mm. This ratio is called the mixing ratio.
Generally, the GF particle size is a function of the GF's specific surface area. Consequently, small-sized GFs have larger surface areas than large-sized GFs. However, the small-sized GFs also have more voids. Therefore, the skeletal density of these particles is less than the theoretical density.
A combination of the bimodal particle size distribution and the autogenous surface treatment increases the tamped density of graphite powders. At the same time, it is possible to increase thermal conductivity.
