Formation mechanisms and functionality of boundary films derived from water lubricated polyoxymethylene/hexagonal boron nitride nanocomposite
"...the
friction coefficient of h-BN/h-BN sliding pair in water
was reduced to 0.06–0.12 in comparison to 0.18–0.25 obtained from dry sliding...
...
h-BN reacted with water molecules, and thereby
led to the formation of a tribo-chemical layer, consisting of hydroxide (i.e.,
boric acid (H3BO3)) or boric oxide (i.e., diboron trioxide (B2O3))...
... With respect to
the mechanism of self-lubrication of the tribo-chemical
layer, Erdemir et al...
proposed that the layered triclinic crystal structure of H3BO3 could be the main reason. In summary, the high tribological performance of h-BN in water can be attributed to two aspects: (i) the weaker interplanar forces make the interplanar layers slip easier; (ii) the tribo-chemical reaction products of h-BN provide efficient lubricity.
https://www.sciencedirect.com/scienc...64127516314034