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How to implement brazing process in vacuum furnace

When brazing in the vacuum furnace, put the brazed weldment into the furnace (or into the brazing container), close the furnace door (or close the brazing container cover), and pre vacuum before heating. Start the mechanical pump first, turn the steering valve after the vacuum reaches 1.35pa, turn off the direct channel between the mechanical pump and the brazing furnace, make the pipeline connect with the brazing furnace through the diffusion pump, rely on the mechanical pump and the diffusion pump to work within a limited time, pump the brazing furnace to the required vacuum, and then start the power on heating. During the whole process of heating, the vacuum unit should work continuously to maintain the vacuum degree in the furnace, offset the air leakage at various interfaces between the vacuum system and the brazing furnace, release the gas and water vapor absorbed by the furnace wall, fixture and weldment, and volatilize the metal and oxide to reduce the vacuum drop.

There are two kinds of vacuum brazing: high vacuum brazing and partial vacuum brazing. High vacuum brazing is very suitable for brazing base metal (such as nickel base superalloy) whose oxide is difficult to decompose. Part of vacuum brazing is used for base metal or brazing material volatilizing under brazing temperature and high vacuum conditions.

When special precautions must be taken to ensure high purity, vacuum cleaning method should be used before dry hydrogen brazing. In the same way, using dry hydrogen or inert gas purification method before vacuumizing will help to obtain better resources in high vacuum brazing.