Transparent Glass-Ceramics as Ceramic Armor Materials

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Transparent Glass-Ceramics as Ceramic Armor
Materials Started March 2007
Core Faculty R. Haber, G. Sigel ARL
Collaborators J. Sands, P. Patel,
J.LaSalvia Industrial Collaborator M.Davis
(Schott), A.Marker (Schott) Post Doc Qiquen Feng
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Objectives

• Investigate the Li-aluminosilicate ternary for
  glass forming systems (collaborating with Schott
  NA)
• Understand the role of crystal size and volume
  fraction on the mechanical and optical properties
• Elastic properties
• Hardness
• Residual Stress and degree of transformation
  (Raman)
• SEM and TEM microstructure
• Evaluate heat treatments to minimize the large
  crystal sizes commonly found within these systems
  (common in the beta-eucryptite)

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Introduction
Transparent Armor A material or system of
materials designed to be optically transparent,
yet protect from fragmentation or ballistic
impact. Application Visors (Riot Visors,
Explosive Ordnance Disposal Visors),
Electromagnetic Windows, Laser Igniter Window,
Ground Vehicles, Air Vehicles. Materials Used for
Transparent Armor Polymeric Materials Glass and
Glass-Ceramics Transparent Crystalline
Ceramics Glass and Glass-Ceramics Soda-lime-silica
Borosilicate, Lithium disilicate, fused silica,
LiAlO2-SiO2 (LAS)
Requirements Transparent, Multi-hit capability,
light-weight, space efficiency, and competitive
cost
Characteristics low cost, ability to form curved
shapes and large sheets, low thermal expansion,
higher strength achieved by chemical and thermal
treatment, thermal stable (compared to glass),
transparent and translucent controlled by
nucleation and crystallization.
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Introduction Structures of high quartz s.s and
beta spondumene
High quartz s.s. (0001) projection P6222 (No.
180) Hexagonal a5.238 Å, c5.472 Å
Beta Spondumene (010) projection P43212 (No.
96) Tetragonal a7.541 Å, c9.156 Å
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Experimental Procedure

• Glass samples with different crystallization
  conditions were supplied by Schott North America
• Elastic properties were measured using ultrasonic
  scanning acoustic imaging
• Hardness was measured using indent method
• Crystal phases in the glass matrix were
  identified using XRD
• Crystalline size and amount were observed using
  TEM. TEM samples were prepared using tripod
  polishing procedures and Ar-ion mill

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Physical Observation of Schott Glass
(SiO2-LiAlO2) with Different Heat Treatments
All the samples have the same thickness (t4.5 mm)
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Elastic Properties and Densities
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Hardness Vs. Loads and Samples
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XRD Phase Identification
The main crystal phases identified by XRD in both
samples are high quartz s.s.
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TEM Micrographs
(a) BF and (b) DF images of sample J (c) BF and
(d) DF images of sample F
Nanoscale TiO2
High quartz regions
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Objectives for Calendar Year 2007-08

• Q4-2007
• Continue TEM evaluation of Schott heat treated
  glass ceramics
• Use XRD to analyze crystal size
• Q1-2008
• Continue TEM evaluation of heat treated glass
  ceramics
• Continue mechanical property evaluation
• Evaluate alternative glass ceramic candidates
• Q2-2008
• Initiate impacted property analyses and
  microstructural analyses of impacted samples