One explanation for why graphite powder acts so well as a “solid lubricant” is
A、carbon atoms in graphite are covalently bonded within planar layers but have weaker secondary bonds between layers defect
B、finely-powdered carbon has many unsatisfied bonds at the particle surfaces, which act as a “sea of electrons” to cause lubrication
C、when crushed into a fine powder, graphite establishes a “polar” distribution of charge, leading to Coulombic repulsion between powder particles
D、None of above