272 Friction-Induced Vibration and Self-Organization
of boric acid was proposed. The atoms constituting each boric acid molecule
were arrayed in closely packed and strongly bonded layers 0.318 nm apart
and held together by weak forces, such as van der Waals. The authors hypoth-
esized that, during sliding, these layers could align themselves parallel to the
direction of relative motion and, once so aligned, could slide over one another
with relative ease to provide low friction (Nosonovsky and Rohatgi 2011).
Boric oxide tends to react with water vapor present in air to form a boric
acid protective coating:
B
2
O
3
+ 3H
2
O → 2H
3
BO
3
(9.1)
The protective coating, in turn, leads to reduced friction and wear. With
its layered crystal structure, boric acid ...