April 29, 2004

Edward BarnardElizabeth Hager

Kevin McComberJenny Lichter

Overview• Goal• Etchants• Volume Fraction• Infiltration!!• Backfilling a Preform• Increasing Volume of Tin-Lead• Future Plans• Gantt Chart

Tin-Lead Etchants• Ethanol

• Nital– 1% solution– Approximately 45 seconds– Revealed grain structure of metals

Volume fraction• Why we care:

– High pressure in our process can potentially allow for the the infiltration of higher volume fraction of ceramic particles

– Yields hard, lightweight materials with good fracture toughness properties

• Determined by– Theoretical calculations– Optical imaging and image processing

Calculating Volumes and Average Density

r = (1/6)*h+(1/2)

r

h

Volume = 2*(19π/32) h = 1.5 in

Volume = (4/3)(π)(0.53)= 0.52Volume = 4.25

Calculating volume fraction:- weigh part- MMC weight = part weight – (tin lead)*(Vtin lead )- (ceramic)*(Vceramic ) + (tin lead)*(1-Vceramic ) = MMC

Vceramic = 70 % for sintered SiC, 120 grit

Preparation and Imaging• Tried to cut with hacksaw, band saw

– Was too hard!!

• Cut with diamond-coated wheel• Polished to 4000 grit

– Scratches still remained– Scratches confuse volume fraction calculations based

on images from optical microscope– Thus very good polishing necessary

• Imaged with optical microscope

Image Processing• Used MATLAB• Set threshold brightness to section image into

matrix and ceramic• Integrate and average over many images to get

average area fraction

• For isotropic materials:Area Fraction = Volume Fraction

Infiltrated Al2O3 Preform

Alumina <Vp>= 39 %

Infiltrated SiC preform• 58.9 + 7.1 % Ceramic

Backfilling a Preform• Backfilling important for complicated shapes

• Our plan: insert plate to demonstrate backfilling

Backfilling: red arrows

Backfilling: red arrows

Increasing metal

Alter runner setup toaccommodate metal

Sn-Pb

Mold Mold

Future plans• Further optical imaging

– Fracture behavior– Volume fraction

• As already mentioned– Backfilling– Increasing metal

• Final Prototype

Gantt Chart2/5 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