Studying the structure of films generated on HSS-based deformed powder materials cutting tool surface

Abstract

Cutting tools made of high-speed steel based deformed composite powder materials (HSS-based DCPM) are known to develop oxygen-containing films, the so-called “secondary structures” (SS), during the cutting operation. Composition, nearest atomic surrounding, and electron structure of these films were investigated by means of SEM, AES, ELS, and EELFS methods. It was found that structural features of these films differ from those of TiC, TiO 2 (rutile), and of the films developed on the surface of the TiC-powder heated in atmosphere. Lack of order in the arrangement of atoms at remote interatomic distances (beyond the third co-ordination sphere) and low localisation of π-electrons give grounds for inferring the amorphous-like structure of the films. Causes that underlay the development of such formations are discussed in terms of thermodynamics of non-equilibrium processes. Evolution of the atomic structure of DCPM-tools at friction was revealed. It was discovered that favourable frictional properties and high wear resistance of DCPM-tools are determined by developing SSs. Such structures are represented by the oversaturated solid solution of oxygen in titanium. High operational properties of DCPM result, among other things, from metal-type attributes of developing films.