1. Ni-W Liquid Phase Sintering T A B A powder + B powder L T sint A+B

2. LPS as flow through packed beds- the chemical engineering approach The space between particles-the interconnected porosity-are pipes. These pipes have an effective radius (hydraulic radius) given as 2r a 2R

3. 2r a 2R Example 2R2R

4. Example (continued) Now determine the hydraulic radius

5. Example (continued) See Gaskell 2.6 and the Die Cast Mold Filling Example

6. Example (continued)

7. Liquid Polycrystalline particle Grain boundary ‘wetting’ breaks the polycrystalline particle into single crystal particles in the initial stages of liquid phase sintering. These single crystal particles then spheroidize and coarsen.

8. Youngs’ Equation Represent the surface tensions of a multi-phase junction as vectors drawn parallel to the respective surfaces The surface energies for the for the solid/liquid, the solid/vapor and the liquid/vapor interfaces are γ sl, γ sv, γ lv. The vectors representing these surface energies must balance at the three phase triple junction. This equation representing this balance is known as ‘Youngs’ equation” γ sl γ sv γ lv θ

9. γ sl γ sv γ lv θ γ sl γ sv γ lv θ Large γ sl, non-wetting θ Large Large γ sv, wetting θ small

10. Grain A Grain B Liquid γ BL γ AL γ AB θBθB θAθA Grain boundary wetting during LPS occurs when θ A and θ B approach zero.