ОСНОВИ ВИКОРИСТАННЯ ПОВЕРХНЕВИХ ФІЗИКО-ХІМІЧНИХ ПРОЦЕСІВ ДЛЯ ПРЕЦИЗІЙНОГО ЗВАРЮВАННЯ ТИСКОМ

Abstract

Urgency of the research. The usage of surface physical-chemical processes is the perspective activation method for precision joining of metal materials.Target setting. The modern theory of solid-phase joining concerning to the usage of surface processes cannot fully determine the direct criteria of welding technology with a minimum level of plastic deformation.Actual scientific researches and issues analysis. During the solid-phase welding of various metals and alloys, the usage of preheating of the welded parts in separated state may speed up the recovery process of oxide films and sublimation of one of the materials with subsequent condensation onto the surface of another.Uninvestigated parts of general matters defining. The usage of sublimated layers during the welding of dissimilar materials allows obtaining strength by 15–20 % higher than the strength of joints that welded directly. However, the works have not investigated the possibility of using such layers for precision pressure welding.The research objective. The investigation of the influence of surface physical-chemical processes (self-cleaning of the oxide films, sublimation and condensation) on the ability to precision pressure welding of dissimilar metals in vacuum.The statement of basic materials. The ability of precision pressure welding of copper with molybdenum and chrome through the sublimated copper layer was investigated. The precision weldability of copper and titanium through the sublimated titanium layer was also researched.Conclusions. It was established that the deformation of the basic materials during the welding does not exceed 1 %, and the strength of welded joints of copper with molybdenum and chromium amounts to 85-90 % of the strength of the basic material (copper). The strength of the copper - titanium welded joints amounts to 73-77 % of the strength of copper. A new method of vacuum diffusion welding through the thin sublimated active layers was proposed. A new technological process of vacuum diffusion welding of copper with refractory metals and titanium was developed. Such technological process demands of specialized equipment that allows carrying out of diffusion welding through the sublimated layers in one cycle in the same working chamber. The model of formation of permanent joints during solid-phase pressure welding using surface physical-chemical processes was proposed.