91传媒 Brazes Heavy Copper Electrodes
91传媒 took on a very difficult brazing job August 13, 2007. 聽The challenge was to silver braze three 1鈥� diameter copper rounds into a copper bar that measured 3鈥� wide x 3鈥� tall x 71鈥� long and weighed approximately 225 lbs each. 聽The customer had 130 bars that they needed brazed.
After unsuccessful attempts to torch braze these parts by hand, our customer, Clayton H. Landis Company, from Souderton, PA, called Solar for a consultation. 聽Solar has some very large vacuum furnaces capable of vacuum brazing 34 bars in a single furnace run.
The bars were brazed at 1550掳 F using a 72% silver/28% copper (BAg-8) brazing alloy, without the use of braze flux, but rather in soft vacuum in the 10 Torr range using partial pressure nitrogen to avoid copper or braze alloy evaporation. 聽Two thick graphite plates were used to support the 8,000 lb. work load while in the furnace. Since copper melts at 1981掳 F, the bars would be very soft at brazing temperature and would distort if not completely supported and held level. 聽Following brazing, the work load was cooled back to ambient temperature with nitrogen gas at a pressure of 5 PSIG with a 300 HP radial gas blower and water to gas heat exchanger. 聽On removal from the furnace, the copper was completely bright and scale free, so no clean up was required.
These copper electrodes, as an end product, are used in a process to manufacture a toxic gas to produce flat panel television screens. This project was finished in one full day.