Single crystals are currently the reference materials for optical applications where transparency and high mechanical performance are required. However the production process of single crystals is in most cases much more difficult and costly than their polycrystalline counterparts. Therefore transparent polycrystalline windows and domes in infared and visible wavelengths are very promisiong materials in high added-value products such as airplane countermeasure systems, surveillance cameras, soldier protection googles etc...
There is an increasing need for low-cost, light-weight armor systems that exhibit exceptional multiple-hit performance, have reliable attachment, and show excellent resistance to all hostile environments. Ceramics are used in the fabrication of armors because they are lightweight and extremely hard materials. One of the drawbacks with ceramic armors, however, is that they dissipate the energy of the projectile partially by cracking. Therefore, ceramic armors lack repeat hit capability.
Large, lightweight, high precision mirrors are critical for enhanced surveillance/reconnaissance space missions, directed energy weapons and communication systems, laser radar systems, X-ray and UV telescopes, as well as large astronomical telescopes. Ideal candidate materials for these applications should feature a extremely low thermal expansion in a wide range of temperatures, good thermal conductivity, high strength and good polishability. To date no commercial product fulfill all these requirements.
Historically, soldiers were protected by heavy metallic armors made from, for example, iron or high alloy steels. As more powerful and sophisticated armor piercing projectiles were developed, armors made from these conventional materials had to be made more resistant to penetration. This was generally achieved by making the armor thicker, which had the disadvantage of making the armor heavier. More recently, ceramic-based armors have been developed. Ceramics are used in the fabrication of armors because they are lightweight and extremely hard materials. One of the drawbacks with ceramic armors, however, is that they lack repeat hit capability.
The CINN is working in new nanostructured ceramics for armour applications with enhanced impact resistance.
Polycrystalline ceramics are generally opaque due to light scattering produced by pores, grain boundaries, or impurities. However, when such causes for light scattering are removed, the polycrystalline ceramic may become transparent like a single crystal.
CINN researchers have been studing the relationship between microstructure, processing and optical properies of ceramics since 2005 and the work is currently focused on polycrystalline oxidic ceramics such as alumina (both doped and undoped), YAG and Spinel sintered by Spark Plasma Sintering (SPS) or hybrid SPS-HP techniques.
The current CINN patent's portfolio comprises two patents on innovative processes for obtaining extremely hard transparent alumina materials featuring optical transmitance higher than 70% and 50% in the IR and Vis wavelegths respectively and hardness values higher than 20GPa.
During the last years the CINN has intensively researched new ultra-stable ceramic materials for optical and structural telescope components. This work has resulted in a new and patented family of ceramic materials with null and tailored thermal expansion coefficient.
The combination of oxidic and non oxidic components as well as the use of certain nanoscale reinforcement phases in aluminosilicate ceramic matrixes with negative thermal expansion coefficient, as well as the synthesis and processing of the aluminosilicates, provide these materials with mechanical, electrical and thermal properties otherwise unobtainable in monolithic materials and glass ceramics with similar thermal expansion coefficients.
Lecture: “Materials science: Seeking solutions for the aerospace sector”
On Friday, 22nd July, Dr. Adolfo Fernández is giving a speech on materials science and its applications in the aerospace sector within the frame of the first edition of the
Fabrication of ceramic armors embedding monocrystalline alumina fibers for ballistic protection
A lecture entitled "Fabrication of ceramic armors embedding monocrystaline alumina fibers for ballistic protection" will be given within the