1. April 8, 2004 Edward Barnard Elizabeth Hager Kevin McComber Jenny Lichter

2. Outline Goal Aluminum Mold and Initial Spin Tests Silicone Mold Ceramic Preform and Binders High Temperature Pressure Vessel Calculations Infiltration Time Calculations Hardness Tests SEM and Etching Schedule

3. Goal The goal of our project is to design a manufacturing process to create a selectively reinforced metal matrix composite. This project will take the theory developed in Jess Wannasin’s thesis work and scale up to part production.

4. Aluminum Mold

5. Centrifuge Setup

6. Initial Spin tests Small amount of Tin-Lead Completed cleared out of runner

7. Silicone Mold Polytek PLATSIL RTV Silicone Rubber 71-10

8. Ceramic Preform SiC 120 Grit (100 µm particles)

9. Wannasin Binder REMET R-25 binder (Prehydrolyzed Ethyl Silicate) Other options: discuss acid phosphate binders with Prof. Cima or look into epoxies Silica

10. Pressure Vessel 0.125 1.5 2.0 Measurements in inches 0.50

11. Wannasin High Temp. Pressure Vessel P max = 730 psi = 50 atm S. F. : safety factor = 2 Material σ UTS r inner r outer S. F. Aluminum45 ksi0.750.821.0020 Aluminum45 ksi0.06250.06460.242560 But…. there’s a catch: as the processing temperature increases, σ UTS decreases

12. http://cyberbuzz.gatech.edu/asm_tms/phase_diagrams/pd/sn_pb.gif Tin-Lead Phase Diagram

13. Swagelok Catalog New Safety Factors High Temp = 250 - 300°C σ UTS, High Temp = [0.2 – 0.3] * σ UTS, Room Temp σ UTS  safety factor Safety factors sufficient r inner S. F. 0.755 0.062515

14. Wannasin Infiltration Time Calculations Darcy’s Law: pressure driven flow Tube-Bundle Theory with Blake-Kozeny equation Assumptions: Laminar flow Particles are uniform spheres S 0 : surface area k: Permeability L: infiltration length

15. Infiltration Time Calculations Values:  = 2*  water, L = 4 inches, D P = 100  m P >> P threshold and infiltration times << 5 mins V P = 0.5V P = 0.7 Threshold pressures1.5 atm3.5 atm Infiltration times<<1 sec

16. Hardness Tests Preparation Cut samples with low-speed saw to obtain smooth surface blade is material specific part is a combination of materials of very different materials Polished with 5-micron polishing paper Results: used Rockwell B and H (low hardness) Pure tin-lead: off-the-scale on the low end hardness MMC: on-scale but low  MMC is harder than plain tin-lead

17. SEM (Scanning Electron Microscopy) Images SiC particles 500-600 microns Fracture behavior 2mm 1mm 100  m

18. Etchers Ceramic particles not visible on all parts Etching may be necessary cutting may have melted metal around ceramic particles and obscured them from view we’d like to see the particles so we can characterize them with SEM Further research into possible etchers

19. Projected Work Schedule