In situ examinations of the friction properties of chromium coated tools in contact with wet wood

The study is concerned with in situ examinations of the friction coefficient (mu) of various kinds of wet wood in contact with the active faces of a low-alloy steel cutting tools non-modified and covered with a chromium coating. The variable parameters were: the sliding speed (V) and the normal force (F-N). In all the material pairs examined in friction, the coefficient mu appeared to decrease with increasing V and increasing F-N. Its variation is described by an exponential function. The Cr coating reduces apparently the friction coefficient compared with that of uncoated steel, especially in static friction. The advantageous tribological properties of chromium coating covered with native chromium oxide can be attributed to its weak water wettability and high hardness.