Composition:
Palladium
60%
Silver 28%
Indiun 6%
Tin 5%
Gallium 1%
Balance Ru
Color: White
Applications: TAOS 28 is a white colored noble palladium/silver porcelain-fused-to-metal dental casting alloy. It is designed for single units, 3/4 crowns, and short and long span bridgework.
Physical Properites:
| Casting Temperature | 2480F (1360C) |
| Melting Range | 2175-2355F (1190-1290C) |
| Density (gm/cc) | 10.7 |
| Vickers Hardness | 285 |
| Tensile Strength | 122,000 psi |
| Yield Strength | 95,000 psi |
| Elastic Modulus | 19,000,000 psi |
| Elongation(%) | 15 |
| TCE x 10-6/C(25-600C): | 14.8 |
Recommended Processing:
| Recomended Solders | Pre GPW, Post GPY |
| Recommended Investment | PB-CF |
Soldering: Pre solder using Gateway GPW solder without flux. Post solder using Gateway GPY solder.
Spruing:
Single crowns - Direct method with 8 ga. sprues and adequate resevoirs.
Multiple Units and bridges - Use 6 ga. runner bars with 10 ga. sprues to units and 8 ga sprues to the sprue base.
Investment: Use a high-heat carbon-free phosphate-bonded investment following the manufacturer's instructions.
Burnout: After adequate set-up time, place ring(s) in oven at room temperature and raise temperature to 800F (425C) and hold for 30 minutes. Raise temperature to 1500F (815C) and hold for 1 hour plus ten minutes for each additional ring.
Melting and Casting: TAOS 28 has a casting temperature of 2480F(1360C). Use a fuel/oxygen torch with multiorifice tip. Do not use flux. Allow to bench cool before divesting. Add 50% new material to buttons. Do not use graphite crucibles.
Finishing: Grind metal surfaces for porcelain applications with non-contaminating aluminum oxide stones. Blast with new 50 micron aluminum oxide. Clean in distilled water in ultrasonic cleaner for 10 minutes.
Degassing:Place units in a 1300F (700C) oven and raise temperature to 1900F (1040C) without vacuum. Hold for 10 minutes. Remove and bench cool. Remove all oxide by blasting with 50 micron aluminum oxide.
Opaquing: Follow porcelain manufacturer's instructions.
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