Calcination of petroleum coke can yield almost pure carbon or artificial graphite suitable for production of electrodes, motorbrushes, dry cells, etc.
石油焦的煅烧可产出几乎纯的碳或人造石墨，适于生产电极、电机刷和干电池等。
2
Describing the specialities of the starting motorbrushes are of short-time duty system, big current density and the contact voltage drop must be as small as possible.
汽车启动机电刷具有短时工作制、电流密度大及接触压降小的特点。
3
The DC motor without coal brushes is in a new style, with higher work rate, less wear and tear and lower noise.