April 29, 2004 Edward Barnard Elizabeth Hager Kevin McComber Jenny Lichter
description
Transcript of April 29, 2004 Edward Barnard Elizabeth Hager Kevin McComber Jenny Lichter
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