Experiment planning to select soldering parameters of elements made of the powder alloy of the heat-shielding structure

Abstract

The parameters of the soldering technology of the external panel, supports and joining elements made of the (Ni20Cr5.95Al) -Y2O3 alloy of the heat-shielding structure of the windward part of the orbital spacecraft were selected. Based on the microstructural studies for high-temperature vacuum soldering of thin-walled structures of a powder dispersed-cured (Ni20Cr5,95Al) - Y2O3 alloy, it was shown that the adhesive layer is formed if using developed П3 pripium (Ni, 1,5% В, 5% W) in the temperature range 1300-1370°C. The selection of the soldering modes with determination of the soldering temperature, exposure time, clamping forces, geometrical parameters of the workpiece was carried out, using the method of mathematical planning of the experiment according to the scheme of rotatable central compositional planning. As a result of the statistical processing of the experimental data, a second-order regression equation is obtained that adequately describes the dependence of the investigated response function on the selected factors. Based on the numerical experiment, it is shown that temperature and clamping forces have the greatest influence on the strength of the solder joint. The strain value mainly depends on the soldering temperature and geometric parameters. Validation of the calculations was carried out by soldering the (Ni20Cr5,95Al) - Y2O3 alloy plates with a thickness of 0.4 mm and 0.15 mm with П3 solder in vacuum at 1350°C for 20 minutes. The quality of joining was monitored by microstructural analysis. Experimental studies of the feasibility of a mock-up of a heat-shielding structure with (Ni20Cr5,95Al) - Y2O3 alloy components in a high-temperature gas stream have confirmed the viability of selected materials and design of heat protection.