Da Leonardo da Vinci alla nanotribologia: storia delle ricerche e delle teorie sui fenomeni d'attrito. Seconda parte: Le teorie dell'usura, la sintesi di Bowden e Tabor, l'attrito a livello atomico.

The paper present an overview of the history of scientific research concerning friction, lubrication and wear. The most important topics and results of research on friction, from antiquity to now, are outlined. This second part of the work (the first one was published in the previous issue of this journal), concerns the period from 1930 to now: the theories of wear, the synthesis of Bowden and Tabor and the birth of tribology, the more recent developments, friction at the nano-scale and nanotribology. Didactic observations and suggestions introduce and conclude the paper.