April 8, 2004

Edward BarnardElizabeth HagerKevin McComberJenny 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

0.00

400.00

800.00

1200.00

10 15 20 25

Binder Concentration (%)

Compressive Strength (psi)

No Sintering

Sintering for 1 hourSilica

Pressure Vessel

0.125

1.5 2.0

Measurements in inches

0.50

Wannasin

High Temp. Pressure Vessel

⎟⎟⎠

⎞⎜⎜⎝

⎛

+−

=22

22

max .. io

ioUTS

rr

rr

FSP

σ Pmax = 730 psi = 50 atm

S. F. : safety factor = 2

Material σUTSrinner router router S. F.

Aluminum

45 ksi 0.75 0.82 1.00 20

Aluminum

45 ksi 0.0625

0.0646 0.2425

60

But…. there’s a catch:as the processing temperature increases, σUTS decreases

http://cyberbuzz.gatech.edu/asm_tms/phase_diagrams/pd/sn_pb.gif

Tin-Lead Phase Diagram

Swagelok Catalog

New Safety Factors

High Temp = 250 - 300°C

σUTS, High Temp = [0.2 – 0.3] * σUTS, Room Temp

σUTS safety factor

Safety factors sufficient

rinner S. F.

0.75 5

0.0625 15

Wannasin

Infiltration Time Calculations

Darcy’s Law: pressure driven flow

Tube-Bundle Theory with Blake-Kozeny equation

Assumptions: Laminar flow Particles are uniform spheres

PV

ktL

P

Δ−

=)1(

22

η

220

3

2.4

)1(

P

P

VS

Vk

••−

=

PDS 60 =

S0: surface area

k: Permeability

L: infiltration length

Infiltration Time Calculations

Values: η = 2* ηwater, L = 4 inches,

DP = 100m

P >> Pthreshold and infiltration times << 5 mins

VP = 0.5 VP = 0.7

Threshold pressures

1.5 atm 3.5 atm

Infiltration times <<1 sec <<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 particles500-600 microns

Fracture behavior2mm

1mm

100m

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

2/5 2/12 2/19 2/26 3/4 3/11 3/18 3/25 4/1 4/8 4/15 4/22 4/29 5/6 5/13

MaterialsMetal choiceCeramics choice

Part productionCADAlum. machined mold

Ceramic preform

Volume fraction Time PermittingSize distribution "

Final testing

CODE:Task Sub-task Gradation Testing