Vacuum Brazing is a process to join metal parts together with an alloy, in an environment that is less than normal pressure. Low pressures are created via vacuum pumps on a sealed chamber. Partial Pressure Vacuum Brazing is performed in the 10-2 to 10-4 torr level. The pumps are turned on fully and are set to reach the 10-6 torr range. Meanwhile an inert gas such as argon is flowed into the chamber to increase the pressure to the desired range.
Partial Pressure Vacuum Brazing is usually a better option for copper and copper alloys than Hard Vacuum, due to the low vapor pressure of copper. Other materials where partial pressure is a better environment are brass, silver and nickel.
Hard Vacuum is any vacuum less than 10-4 torr. ThermoFusion routinely brazes in the 10-5 torr or lower range. Metals brazed in this range include stainless steel, titanium, Inconel, Incolloy, Waspalloy, and other high-nickel alloys.
Vacuum Conversions:
| Torr (mm Hg) |
Torr (scientific notation) |
Microns (millitor) |
PSIA (lbs/sq.in. absolute) |
| 760 |
7.6E2 |
760000 |
14.7 |
| 7.6 |
7.6E0 |
76000 |
0.147 |
| 0.76 |
7.6E-1 |
7600 |
0.0147 |
| 0.076 |
7.6E-2 |
760 |
0.00147 |
| 0.0076 |
7.6E-3 |
76 |
0.000147 |
| 0.00076 |
7.6E-4 |
7.6 |
0.0000147 |
| 0.000076 |
7.6E-5 |
0.76 |
0.00000147 |