CHARACTERISTIC FEATURES OF WEAR IN TOOLS MADE OF HIGH-SPEED STEELS WITH SURFACE ENGINEERED COATINGS .2. STUDY OF SURFACE ENGINEERED HIGH-SPEED STEEL CUTTING TOOLS BY AES, SIMS AND EELFAS METHODS

Changes in chemical composition and fine (at atomic level) structure c haracteristics of surfaces during the life time of cutting tools were investigated by using AES, SIMS and EELFAS methods. High-speed steels M2 and T15 with coatings incorporating ion nitriding and (Ti, Cr) nitr ide CAPDP (cathode are plasma deposition process) were used. It was fo und that, under the wear conditions studied (such as cutting of medium carbon steels), some components of the protective hard coating dissoc iated, forming quasi-oxide amorphous films. This shows the parallel de veloping processes of: 1. Dissociation of chemical compound in coating material (Ti,Cr)N and intensive diffusion (absorption) of nitrogen in to chip. 2. Creation on tool surface of stable amorphous protecting qu asi-oxide Ti-O films. The discovered changes in chemical and phase com position of contact surfaces of the ''tool-workpiece'' tribopair impro ve service characteristics of the cutting tool and promote its adaptat ion to service conditions (named ''self-organization''). The adaptatio n observed is expressed more on steel T15 with high heat resistance an d leads to a significant increase of tool life.