The heater and heat shield of tantalum-niobium vacuum annealing furnace are generally made of high temperature resistant metal and fixed in the furnace body with alumina ceramics, which also play an insulating role. Heater and heat insulation screen commonly used materials for high temperature molybdenum alloy, when the temperature is high and the temperature changes rapidly, molybdenum heater and heat insulation screen is easy to deformation and damage; Alumina ceramic parts will also burst, resulting in reduced insulation performance. According to long-term use experience, if the inert gas is cooled at 1200 ° C ~ 900 ° C, due to the high temperature at this time and the cooling speed is very fast, it can reach 100-200 ° C/minute, which often leads to the deformation of the heat shield and heater in the furnace body, and the heater breaks due to deformation in serious cases, causing unnecessary losses. Unexpectedly, the inventors found that when the inert gas is introduced below 900 ° C, such as in the temperature range of 900 ° C to 600 ° C, it does not cause any substantial effect on the furnace body, especially for the heat shield in the furnace body and the heater does not cause any significant changes. Therefore, the cooling method of the invention can not only shorten the cooling time of tantalum-niobium and its alloy, but also does not affect the service life of tantalum-niobium vacuum annealing furnace.
About 100kg of niobium zirconium wire is loaded into the furnace, and after vacuuming, heating electricity is sent to 1150℃ for 1 hour, and then charged to cool down, cooling speed 20℃/ min, when the temperature drops to 850℃, heating electricity is cut off. Then, close the high vacuum valve, the front valve, the diffusion pump, and the mechanical pump in turn, and keep the cooling water pressure 0.1-0.2MPa. This process is the prior art in this field, and will not be described here.
Ta10W (tungsten mass fraction of 10% tantalum tungsten alloy) bar about 100kg into the furnace, vacuum after the heating electricity, to 1450℃ insulation for 1 hour, off the heating electricity, with the furnace cooling, the temperature drops to 900℃, close the high vacuum valve, valve, diffusion pump, mechanical pump, cooling water pressure to maintain 0.1-0.2MPa. This process is the prior art in this field, and will not be described here.
When the furnace temperature is cooled to about 200 ° C, start the mechanical pump, open the low valve, evacuate 5-30 minutes later, close the low valve and mechanical pump. According to the above aeration method, the mixed gas of argon and helium is filled into the furnace again until the pressure in the furnace body is 0.1MPa. When the furnace temperature is cooled to about 60℃, the cooling water is stopped and the air is broken out. The inspected products were all qualified. The entire vacuum annealing time is about 14 hours. Check heat shield and heater, in good condition, alumina ceramics in good condition.
