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

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

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.

Aluminum Mold

Centrifuge Setup

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

Silicone Mold Polytek PLATSIL RTV Silicone Rubber 71-10

Ceramic Preform SiC 120 Grit (100 µm particles)

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

Pressure Vessel Measurements in inches 0.50

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 ksi Aluminum45 ksi But…. there’s a catch: as the processing temperature increases, σ UTS decreases

Tin-Lead Phase Diagram

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

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

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

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

SEM (Scanning Electron Microscopy) Images SiC particles microns Fracture behavior 2mm 1mm 100  m

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

Projected Work Schedule