Study of the influence of the controlled gas environment composition and temperature on the quality of solid-state wire bonds in the manufacture of porous mesh materials

Abstract

Porous mesh materials are designed for the manufacture of products with a given shape and size, as well as hydraulic, filtering, thermal and other properties. At the same time, they must have the necessary mechanical and technological properties, which are formed to a large extent by the quality of weld solid-state bonds of mesh wires. Findings of the research that the increase in the strength of wire bonds during manufacture of porous mesh materials is influenced by the conditions for removing oxide layers by means of choosing the optimal protective gas environment and heating temperature during welding. The analysis of the processes occurring at the boundary of the metal–oxide and oxide–gas phases made it possible to establish that, depending on the structure of the alloy, the heating temperature, the composition and partial pressure of the gas protective environment, not only additional oxidation or thinning of the oxide layers but also gas saturation of the work surface are possible. For the manufacture of sizeable sheet porous mesh materials with high accuracy in thickness, the use of welding by rolling in a protective gas environment is the only possible process. Depending on the chemical composition of the wires, it is possible to carry out mesh briquette rolling welding on vacuum rolling mills, in an argon atmosphere of controlled purity and in evacuated envelopes. Within the research, we studied the influence of the composition of the gas environment and the process temperature on the quality of weld bonds and found that it is advisable to manufacture VT2 alloy sheet porous mesh materials by hot rolling in a vacuum mill and in an inert gas environment with a controlled composition. Porous mesh materials made of 12Kh18N10T steel can be made by hot rolling in vacuum envelopes, and products with limited dimensions can be made by diffusion welding. The study also specifies the modes of technological processes for manufacturing porous mesh materials made of VT2 alloy and 12Kh18N10T steel by rolling welding and diffusion welding.