NUST MISIS scientists have created a composite material containing 40% aluminum nitride to extend the life of solar towers from 2-3 to 5 years.
The material for these solar towers – or installations for collecting solar thermal energy – was developed jointly by NUST MISIS and the Central Metallurgical R&D Institute in Cairo, Egypt.
Solar power plants (SPP) have become increasingly popular, making it possible to collect and process solar energy on an industrial scale.
These so-called solar towers are among the most promising types of SPPs. They consist of a special structure that is a high tower with a water tank and a turbine system inside.
Solar towers are usually surrounded by heliostats – large spinning mirrors that absorb the sun’s rays and concentrate the total beam at a single point on the tower.
The beam lands on the solar absorber which is a heat-absorbing element that in turn heats a special salt solution up to 600°C.
The water in the adjacent tank is heated from the salt solution and the steam rotates the turbines of the power plant.
The porous silicon carbide (SiC) has traditionally been the go-to element for solar absorbers.
However, silicon carbide has certain disadvantages – chief among them is its sensitivity to salt melt environments.
Scientists have of late been considering Aluminum nitride (AIN) as a promising addition to silicon carbide. This is mainly due to its high thermal conductivity, a low coefficient of thermal expansion, and high temperature resistance.
Currently, Sic and AIN composites are mainly used in electronics, but they can potentially be used in a number of other fields, including the thermal transformation of solar energy.
Inspired by this, the NUST MISIS-Central Metallurgical team developed porous composites based on SiC/AIN, which contain up to 40% aluminum nitride.
The optimal compositions of additives and sintering regimes of new composites were selected during the course of the research.
According to the researchers, the new composites exceed the traditional ones due to the formation of a solid solution at the grain boundaries of silicon carbide.
And along with high thermal conductivity and heat resistance, the composites have also proven to have a low coefficient of thermal expansion, which significantly improves their performance.
Image and content: NUST MISIS