THE NATURE OF HARD ALLOYS HARDENING DURINGTHERMOHYDROCHEMICAL TREATMENT

Abstract

The studied process of thermohydrochemical treatment involves: 1) hydrochemical treatment of surface in a water-dispersive TiO₂ + MoO₃ medium; 2) heat treatment. The scientific principles for the creation of the thermohydrochemical treatment method are formulated: a) the implementation of mechanisms for obtaining coatings with
a metastable structure with enhanced properties; b) the processing of tool alloys under the influence of a boiling aqueous dispersion medium to create a high chemical gradient and generate pulses of thermal and hydraulic pressures; c) the implementation
of mechanisms for the formation of solid lubricating coatings to prevent adhesive grasping, etc. Tribotechnical researches have shown that the effect of the thermohydrochemical treatment process on the friction coefficient of the hard alloy has a time-deterministic nature of hardening. The optimization of thermohydrochemical treatment of the ТС6 hard alloy has been carried out, which made it possible to reduce the friction coefficient without lubrication of the ТС6 alloy by a 3.8…4.2 times compared to the initial state. A double effect of hardening of hard alloys during
thermohydrochemical treatment due to the deposition of nanostructured solid lubricating coatings and the formation in the sublayer of high compressive stresses (up to 210…235 MPa), comparable to the level of stresses created by the SPD methods, has been established. The developed technology increases the durability of carbide tools by 1.3…4.0 times compared to untreated ones.

Fig. 3. Table 2. Ref.: 12 titles.