1. Design Review 3-11-04 Group members: Ed Barnard Lizzie Hager
Jenny Lichter
Kevin McComber

2. Overview Goal and Processing Method Ceramic Preform
Pressure Vessel Calculations
Prototype Mold Design
Expected and Threshold Pressures
Infiltration
ASME Standards for Hammers
Methods of Characterization
Risks

3. Goal
The goal of our project is to manufacture a light-weight, high fracture toughness hammer using metal matrix composites.
Halstead

4. Centrifugal Casting Process

5. Ceramic Preform Compression packing Sintering 3D printing Binder
May not produce uniform preform
Can be improved through agitation
Sintering
May form connected ceramic matrix which could require post processing
3D printing
May be time intensive
Binder
Must be able to be burnt out
Initially we’ve been doing compression packing
Purple box shows what we’ll likely use for our final prototype

6. Numerical Simulations
Monte Carlo Simulations
Were considered to model packing density of ceramic powders
Assume spherical particles
Our particles are not spherical

7. Pressure Vessel Calculations
Pmax = 2200 psi = 150 atm
S. F. : safety factor = 2
ri : inner radius = 1.00 inch
Material
σUTS (ksi)
radiusouter
< σUTS >
(σUTS)min
Brass
30-90
1.08
1.16
Stainless steel
60-150
1.04
Aluminum
45-80
1.07
1.10
Graphite
7-10
1.77
2.09
Wannasin

8. Pressure Vessel Calc. Ct’d
Current design: Aluminum 6061
inner radius of 0.75 inches
outer radius of 1.00 inches
Material
σUTS (ksi)
radiusouter
< σUTS >
(σUTS)min
Aluminum
45-80
0.80
0.82
Brass has a low melting temperature and is too soft, and is heavier
S. S. is too hard and too heavy
Graphite would be too large

9. Prototype Mold Two-piece mold Conical shape to aid in the release
Swagelok connector to runner
2.0
1.0
1.5
3.0 .5
.75
1.75
1.0
5.5

10. Release from mold Boron Nitride Spray Coating Graphite powder
Breakaway ceramic
TiC – small particle size
Need a binder
Breakaway ceramic must not be infiltrated so small particles are needed

11. Expected Pressures I1 ω12 = I2 ω22 P = ( ½ ) * (ρω2) * (z22 – z12)
Moment of inertia calculations
Assumption of constant angular energy
I1 ω12 = I2 ω22
ω1 = 2200 rpm, ω2 = 1250 rpm
Pressure calculations:
P = ( ½ ) * (ρω2) * (z22 – z12)
Currently: 2200 psi or 150 atm
New design: 710 psi or 50 atm
Wannasin

12. Threshold Pressures Particulate Size (microns) Threshold Pressure
(atm)
SiC
2 - 22
Al2O3
5 - 20
8 - 11
B4C 9
3 - 4
TiC 30
5 - 6
Based on aluminum infiltration
Generally threshold pressure decreases
with increasing particle size

13. Infiltration Larger particles necessary
Previously used particles a few microns in size
Future Particles (already purchased)
Boron Carbide 100 grit ( microns)
Silicon Carbide 120 grit ( microns)
Silicon Carbide 36 grit ( microns)

14. Safety Requirements (ASME): Design Parameters
Chamfer striking face 45 degrees with length equal to 1/10 of bell (to prevent chipping)
Striking face must be flat or convex
No unnecessary sharp edges, points or surface roughness
Bell
Striking Face
Chamfer
Halstead

15. Safety Requirements (ASME): Mechanical Properties
Hardness Test
Striking face hardness: HRC
Hardness must be maintained at least .75 in. into bell
Striking Test
Average person ( lbs) must strike steel (of hardness HRB) 20 times without causing damage

16. Safety Requirements (ASME): Mechanical Properties Cont.
Assembled Parts Tests
(calculated for hammerhead of grams)
Static Test
556 Newtons or 125 lbs.
Tensile Test (for non-wedged assemblies)
3340 Newtons or 750 lbs.

17. Methods of Characterization
SEM
Estimate ceramic volume fraction
Possible defects – microvoid formation
Incomplete infiltration
Rockwell Hardness
Impact tests
Tensile and compression tests
Plastic deformation

18. Risks Mold leaks Particle size leads to incomplete infiltration
Reduce mold weight
Increase particle size
Different preform production method
Mold leaks
O-ring system
Use outer tube to hold molds

19. Risks, Ct’d Part cannot be removed Low hardness Air pockets
Use stronger mold release spray
Change angle of mold
Low hardness
Choose different ceramic particles with better wettability with respect to metal
Use multiple types of ceramic particles
Air pockets
Design an evacuation system
Multiple types because particles may fit in each other’s interstitial sites

20. Projected Work Schedule

21. Works Cited
Halstead, Gary. “Pictures from Dictionaire Paisonné du Mobilier Français.” Accessed 24 February Medieval and Renaissance Woodworking < >.
Wannasin, Jessada. PhD Thesis. March 2004.