Effect of oxygen on reaction mechanisms of interface formation in the Cu-Ti-O/sapphire system
- Colorado School of Mines, Golden, CO (United States); and others
It has been reported that in active metal brazing of sapphire using titanium as the active element, titanium segregates to the sapphire-metal interface and reduces the sapphire, forming an intermediate oxide interphase region. In this work, the effect of oxygen on the reaction mechanisms of interface formation by active metal brazing in the Cu-Ti-O/sapphire (single crystal) system was investigated. Spectroscopically pure copper and titanium were used to prepare, in-situ, copper alloys with two different levels of titanium (1 and 2 at.pct). Three brazing temperatures were investigated: 1100, 1150, and 1200{degrees}C. A scavenging system using copper and niobium as getter materials was used to produce atmospheres with a range of oxygen partial pressures covering 1 x 10{sup -5} to 1 x 10{sup -15}atm. Characterization of the interfaces was performed using four techniques: scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray photoelectron spectroscopy (XPS), and oxygen interstitial analysis. The bulk oxygen concentrations in the copper-active metal alloys were determined by a LECO oxygen analyzer, before and after the brazing operation. Wetting of sapphire by Cu-Ti alloys was characterized as a function of time and temperature. Additionally, the work of adhesion in the Cu-Ti-O/sapphire (single crystal) system was found to better correlate with the oxygen concentration in the alloy than with the titanium content itself. The amount of titanium necessary to promote wetting was also optimized to low levels, commensurate with the oxygen content present in the copper alloy.
- OSTI ID:
- 115514
- Report Number(s):
- CONF-9404233-; TRN: 95:002927-0093
- Resource Relation:
- Conference: 75. American Welding Society (AWS) annual meeting, Philadelphia, PA (United States), 10-15 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of 75th Diamond anniversary American Welding Society annual meeting; PB: 273 p.
- Country of Publication:
- United States
- Language:
- English
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