By: Jacob Scott Advisor: Dr. Rick Reidy

ClassificationProjectile Caliber Projectile WeightVelocity Type II-A.357 Magnum jacketed soft point 9mm full-metal jacketed 10.2 g (158 gr) 8.0 g (124 gr) 1,250 ft/s 1,090 ft/s Type II.357 Magnum jacketed soft point 9mm full-metal jacketed 10.2 g (158 gr) 8.0 g (124 gr) 1,395 ft/s 1,175 ft/s Type III-A.44 Magnum lead semi-wadcutter 9mm full-metal jacketed g (240 gr) 8.0 g (124 gr) 1,400 ft/s Type III*7.62 mm full- metal jacketed 9.7 g (150 gr)2,750 ft/s Type IV* armor- piercing 10.8 g (166 gr)2,850 ft/s *Type III and IV both contain hard or semi-rigid plates, while the rest are “soft/concealable” 3 NIJ Guide US Department of Justice. Selection and Application Guide to Police Body Armor

(Enhanced) Small Arms Protective Inserts (SAPI + ESAPI) First put through a selection of hot, cold, saltwater, oil, fuel, and then dropped SAPI must stop 3 shots “against threats A,B,C” ESAPI must stop 3 shots “against threats A,B,C” and 2 shots “against threat D” Threats A, B, C, D are classified 4 Report No. D Inspector General US:DOD. DoD Testing Requirements for Body Armor

US Patent- US B2 Uses layered tape cast yttria stabilized zirconia (YSZ)/alumina in a strain rate sensitive polymer Recommends minimizing grain growth of YSZ to promote crack deflection Only specifies overall weight percents, does not go into detail on types of YSZ, or casting procedures Item 101- Strain rate sensitive polymer Item 110- Ceramics to break projectile Items 12X- Interconnected ceramics to further break and/or catch fragments Item 140- Ballistic fiber to catch fragments

US Patent- US B1 1. Mixing zirconia with silicon carbide increases controlled defects 2. Leads to increased surface area that is fractured during a ballistic event 3. Leading to the spreading and dispersion of the impact i.e. can disperse a larger projectile

3 mol% YSZ8 mol% YSZ StructureTetragonalCubic Space Group#137- P4 2 /nmc#225- Fm3m Defect Equations: (Anti-Frenkel) ZrO 2 = Zr Zr X +2V O ** +2O i ’’ Y 2 O 3 = 2Y Zr ’ +V O ** +3O O X

Research has shown that 3 mol% YSZ has a 2-3 times higher flexural strength versus 8 mol% YSZ. 1 8mol% is generally used for solid oxide fuel cells The recipe featured in Fabrication of electrolyte materials for solid oxide fuel cells by tape-casting, was investigated and found that the materials used are no longer available. 1 Fabrication of electrolyte materials for solid oxide fuel cells by tape-casting. P. Timakul et al.

Tape casting of 3mol% YSZ with the recipe from C. Suciu et al 2 created thin tapes with minimal cracking, clean burn out. 2 Water-based tape-casting of SOFC…. Of their pellets. C. Suciu et al. PartWeight Percent Powder (TZ-3Y- E) 48.1 Binder (WB4101)21 Defoamer (DF002) 0.3 Solvent (DI Water) 30.1 PH balancer (Ammonium Hydroxide) 0.2

Design a plate that will stop a single 200 joule impact force (equivalent to typical.22LR caliber bullet impact)

The main constraints for this project are the thickness and the weight of the plates.

Tape cast crack-free YSZ tapes Layer tapes to increase thickness Sinter tapes to achieve full tetragonal phase Achieve 95% theoretical density (6.0 g/cm^3) Achieve Vickers hardness value 1250 HV

1. Create and mill slurry of YSZ, binder, defoamer, water 2. Tape cast slurry forming tape 3. Section tape, and layer increasing thickness 4. Sinter layered tapes into plates to join layers 5. Characterize though SEM, XRD, impact testing, hardness testing, density measurements, etc 6. Increase number of layers until design goal met

Appears to have pink tint- Believed to be caused by incorrect amount of ammonia hydroxide added due to calculation error Significant cracking Cracking believed to be caused by too high of bed heat and too large of doctor blade height Large amount of batch wasted from spillage

Changes Lowered bed temperature Lowered doctor blade height Added correct amount of ammonia hydroxide Added slightly more defoamer Used wider film to cast onto to help with spillage Results Cracks formed on thicker side Thickness gradient resulting from unlevel table White color achieved Have a large section of useable crack free tape Still small amount of spillage

Changes Leveled table Created slurry as directed by recipe Used similar doctor blade height as first test to observe if having table level would reduce cracking along with the appropriate amount of ammonium hydroxide added Results No spillage from film, but the slurry did still spread on film Large amount of cracking

Changes Reduced doctor blade height to 0.35 ± 0.02mm Increased casting speed Added similar amount of defoamer as Run 2 Results First ~70% of casting had lots of cracking Last ~30% of casting had a mostly crack free zone of good useable tape

Changes Slightly reduced doctor blade height to 0.25 ± 0.02mm Cast using 12” doctor blade Did not add ammonium hydroxide Results Very small cracking in first few inches Overall very uniform and crack free tape

Changes Raised bed cover to vent humidity Followed recipe from run 5, now standard Increased doctor blade height slightly to 0.30 ± 0.02mm Results Leading edge had some cracking Several small cracks dispersed throughout Tape dried noticeably quicker Overall very good, useable tape Found better way to remove tape from Mylar™ backing

Changes Bed cover was replaced, not vented Doctor blade increased slightly to 0.33 ± 0.02mm Results First ~3 inches and 0.5 inch border cracked, rest of tape was pristine minus a couple small flaws

Schedule: 40*C/hour until 650*C > 145*C/hour until 1200*C/held for 4 hours cooled at 145*C until room temperature Sintering was done in 1 of 4 different batches Time at max temperature not confirmed in first batch Forth batch max temperature time was lengthened 1 hour Strong texturing in first 2 batches from the “sandwich plates” Some plates have small gaps where tapes are layered Tapes that were sintered without weight on top didn’t adhere together

RunAverage Density g/cm 3 Std Dev Green Batch (run) Average Density g/cm 3 Std Dev % Theoretical Density 1 (5) % 2 (5) % 3 (6) % 4 (7) % Sintered The highest density from a single plate came from the third sintering batch with a density of 5.15 g/cm^3 (~85% TD)

Sintering BatchAverage Grain Size (nm)Standard DeviationAppears Porous Yes No No

Values in black represent tetragonal reflections, while values in orange represent monoclinic reflections. Using formulas found in [6] that compare relative intensity ratios, the raw powder was calculated to be 67.5% tetragonal 32.5% monoclinic; the green tape was calculated to be 63.6% tetragonal 36.4% monoclinic. The increase of monoclinic content can be attributed from phase transformation toughening that occurred during ball milling and tape casting. The sintered plates were completely tetragonal as expected based on sintering temperature.

BatchHardness (HV) Standard Deviation Vickers microhardness testing was performed on 3 samples from 3 different sintering batches. The average hardness value is based on 10 tests per sample. The average hardness value in literature ranges from HV.

Impact testing was performed by dropping a rod of ATI 718Plus© that weighed 1.22 kg from various heights. Drop Height (cm)ResultEnergy (J)Thickness (mm)Layers 7.45Pass Pass Pass Fail Pass Pass Pass Pass Pass Fail

Using the 100% success rate of the 16 layer samples stopping 2.57 J at minimum, and assuming a linear trend, it would take 78 plates with combined 1248 layers, with a mass of g, and a total thickness of 8.58 cm to stop a single 200 J impact. Achieving 95+% theoretical density should reduce this thickness dramatically

YSZ was tape casted, sintered, characterized, and impact tested. To meet the design goal it would take an estimated 1248 layers with an estimated thickness and mass off 8.58 cm and g respectively.

I would like to thank Dr. Rick Reidy for his insight and help with the project, Polymer Innovations for supplying a sampling of their products for use, David Bryce for performing SEM and XRD on the samples, Oseoghaghare Okobiah for sputter coating the SEM samples, Dr. Rajiv Mishra for letting me use his Vickers microhardness tester, and the UNT Materials Science department for providing the funding for the rest of the materials and equipment use.

US Patent: US B2 US Patent: US B1 [1] Fabrication of electrolyte materials for solid oxide fuel cells by tape- casting. P. Timakul et al. [2] Water-based tape-casting of SOFC composite 3YSZ/8YSZ electrolytes and ionic conductivity of their pellets. C. Suciu et al. [3] NIJ Guide US Department of Justice. Selection and Application Guide to Police Body Armor [4] Report No. D Inspector General US:DOD. DoD Testing Requirements for Body Armor [5] Tape Casting Theory and Practice. R. E. Mistler, E. R. Twiname. The American Ceramic Society, [6] Quantitative Analysis of Pholymorphic Mixes of Zirconia by X-ray Diffraction. H. K. Schmid. [7] H. McMurdie, Pow. Diff. Jour., 1, 1986, 275. [8] G. Teufer, Acta. Cryst., 15, 1962, 1187.