INVESTIGATION OF THERMOCHEMICAL CHARACTERISTICS OF MIXTURES OF DISPERSED MATERIALS BY DIFFERENTIAL THERMAL ANALYSIS METHODS

摘要

It is shown that formation of melts as early as at a stage of heating of the powder core up to melting of the sheath of a flux-cored wire and evolution of the gaseous products (H_2O, CO_2, SiF_4) determine shielding functions of an electrode material and exert a substantial effect on the course of metal to gas interaction reactions at the drop and pool stages. Temperature ranges of thermochemical reactions accompanying the heating process overlap, and their thermal effects superimpose on one another, thus stimulating development of some processes and slowing down the other ones. Control of these reactions by varying composition of a mixture allows regulation of the rate of melting of the core to achieve favourable characteristics of melting of the flux-cored wire and transfer of the electrode metal into the weld pool.