Researchers develop transparent ceramics, reaching theoretical transparency
Transparent ceramics is a new class of advanced materials with unique transparency and excellent mechanical properties.
Indian researchers have developed transparent ceramics, reaching theoretical transparency through a technique called colloidal processing followed by simultaneous application of temperature and pressure, for the first time in India. The material can be used for thermal imaging applications, especially in harsh service conditions and personal protection systems such as helmets, face shields, and goggles.
Transparent ceramics is a new class of advanced materials with unique transparency and excellent mechanical properties. These materials can be designed not only for transparent to visible light but also for ultraviolet (UV), Infrared (IR), and Radiofrequency (RF), giving opportunity for diverse applications. Though produced by different countries globally, transparent ceramics are restricted in supply as they can be used for strategic applications. Though several attempts were made in the country, the transparent ceramics produced were either on a laboratory scale or low transparency. The currently developed process is able to produce the sizes usable for several applications and on a pilot scale.
Generally, prepared from the high purity powders through a line of critically engineered processing steps, transparent ceramics needs preparation processes that will help achieve theoretical transparency by eliminating defects. Chemical Vapour Deposition (CVD) involving reactions of the precursors in the vapour phase at elevated temperatures and HotIsostatic Pressing (HIP) involving simultaneous application of temperature and pressure are a few advanced processing techniques generally practised addressing the above challenges. An enhanced diffusion process at high temperature under pressure is suggested as the possible mechanism to eliminate the defects.
Researchers at the ARCI have produced magnesium aluminate spinel ceramics with colloidal processing followed by the HIP technique which involves the simultaneous application of temperature and pressure. Spinel is currently emerging as a transparent ceramic based on the outstanding optical properties of transmission – more than 75 % in the visible and more than 80% in the infrared range. It also has a higher strength of 200 megapascals and hardness of more than 13 Gigapascal. This research has been published in the journal 'Materials Chemistry and Physics recently.
With potential applications in infantry personal protection systems involving thermal imaging such as helmets, face shields, and goggles, these transparent ceramics developed in India is a step towards Atmanirbhar Bharat.
(With Inputs from PIB)