Method of Making Transparent Alumina by Hot-pressing Platelets into an Aligned Grain Microstructure

Back to all technologies
Download as PDF
2020-YOUN-68913
Researchers at Purdue University have developed new highly transparent polycrystalline alumina materials by
hot-pressing platelets alumina crystals and aligning its grain structure to induce low amounts of grain boundary refraction and reflection. This cost-effective transparent alumina processing technique can be used for applications including high-temperature and armored windows, nose cones for rockets, and ballistic blast as well as protective shields. Purdue researchers have fine-tuned fabrication parameters for the new alumina including specified powder and treatment steps sintering temperatures, green-body and hot-pressing geometries, pre-load pressures and hot pressing pressure to achieve a high density of upwards of 99.95%. This allows a real in-line transmission (RIT), defined as a transmission within a 0.5 degree cone of the center beam, of over 70% and a total transmission of over 80 % at 645nm, approaching the theoretical limit of single crystal sapphire (86%). Notably, the aligned grain microstructure limits grain-induced scattering typically seen with polycrystalline translucent alumina with variance of only 15% in RIT over the wavelength range 280 nm to 2500 nm, allowing this material to be continuously effective in a spectral range from UVB to NIR.

Advantages:
-Transparent
-Cost-Effective

Potential Applications:
-Nose Cones for Rockets
-High-Temperature and Armored Windows
-Blast and Protective Shields

Recent Publication:
"Hot-pressing platelet alumina to transparency"
Journal of the American Ceramic Society
DOI: /10.1111/jace.16932
Dec 15, 2020
Utility-Gov. Funding
United States
(None)
(None)

Mar 2, 2020
Provisional-Gov. Funding
United States
(None)
(None)
Purdue Office of Technology Commercialization
The Convergence Center
101 Foundry Drive, Suite 2500
West Lafayette, IN 47906

Phone: (765) 588-3475
Fax: (765) 463-3486
Email: otcip@prf.org