High-Temperature Vacuum Brazing
Thermal joining under technical vacuum at temperatures above 900 degrees Celsius to prevent oxidation. It is particularly suitable for high-temperature resistant alloys.
In vacuum brazing, you join metals in an oxygen-free environment so no oxides form and the joint stays clean and tight. You pull the vacuum until residual gases don't interfere, and heat the parts to brazing temperature until the filler metal flows cleanly into the gaps. If the vacuum isn't right or you get too hot, you'll get porosity or a brittle joint, so ramp the temperature controlled and let the part cool slowly to avoid stresses and cracks. It's important that the parts are grease-free and dry beforehand, otherwise dirt will vaporize in the furnace and ruin the result.