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

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

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

Centrifugal Casting Process

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

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

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

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

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

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

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

Threshold Pressures Particulate Size (microns) Threshold Pressure (atm) SiC 7 - 155 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

Infiltration Larger particles necessary Previously used particles a few microns in size Future Particles (already purchased) Boron Carbide 100 grit (106-150 microns) Silicon Carbide 120 grit (90-125 microns) Silicon Carbide 36 grit (600-850 microns)

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

Safety Requirements (ASME): Mechanical Properties Hardness Test Striking face hardness: 40-60 HRC Hardness must be maintained at least .75 in. into bell Striking Test Average person (160-180 lbs) must strike steel (of hardness 92-105 HRB) 20 times without causing damage

Safety Requirements (ASME): Mechanical Properties Cont. Assembled Parts Tests (calculated for hammerhead of 300-350 grams) Static Test 556 Newtons or 125 lbs. Tensile Test (for non-wedged assemblies) 3340 Newtons or 750 lbs.

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

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

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

Projected Work Schedule

Works Cited Halstead, Gary. “Pictures from Dictionaire Paisonné du Mobilier Français.” Accessed 24 February 2004. Medieval and Renaissance Woodworking. 2003. <http://www.medievalwoodworking.com/vld_tools.htm >. Wannasin, Jessada. PhD Thesis. March 2004.