Brazing liquid-phase

Brazing, usually involving a conventional braze alloy in which application involves forming the liquid phase of the braze alloy. 

The wettability of a liquid on a substrate is an important property in a number of ceramic processes. With a decreased wetting angle, i.e. an increased wettability, densification is enhanced in liquid phase sintering and the bonding in brazing or soldering is improved. 

In designing an air braze filler metal, it is critical that there is some degree of mutual solubility between the metal and oxide constituent(s) in the liquid state. Experimental evidence suggests that the likely indicators for this behavior are measurable oxygen solubility (i.e., oxygen activity) in the liquid metal constituent, compatible melting points between the metal and oxide to be alloyed, and multiple valence states in the cation species of the oxide constituent that allow it to serve as an efficient oxygen buffer in the noble metal. Phase formation and phase equilibria in the filler metal system must be appropriate for the application of interest. For... 

Liq = liquid Mech = mechanical Chem = chemical. Notes for Table 4.1 1. Two-phase includes boiling and condensing duties 2. Other special alloys are frequently available 3. The maximum pressure capability is unlikely to occur at the higher operating temperatures, and assumes no pressure/ stress-related corrosion 4. Function of gasket as well as plate material 5. Function of braze as well as plate material 6. Not common 7. Not in a single unit 8. Condensing on gas side 9. PEEK (polyetheretherketone) can go to 250°C continuous use temperature 10. Can be dismantled 11. Polyvinylidene diflouride 12. Polypropylene... 

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