The higher the temperature at which an aircraft engine is able to run, the more efficiently it uses fuel. In order to run at those high temperatures, the metal components of airplane engines are presently treated with heat-shielding coatings. Scientists at Sweden's University West, however, are developing a new such coating that is said to be far more effective than anything presently used – it could extend the service life of engines by 300 percent.
The coating consists a powder made up of ceramic and plastic nanoparticles, that is added to a liquid carrier. While the ceramic particles provide insulation against the heat, the plastic allows tiny pores to form within the coating, giving it some elasticity – that's an important consideration, as the coating must be able to expand and contract with the metal that it's covering.
The powder-containing liquid is heated up to 7,000 - 8,000ºC (12,632 - 14,432ºF), causing the ceramic particles to melt, then applied in a process known as plasma spray application. Once adhered to the metal, it takes the form of a 0.5 mm-thick "forest" of tiny standing columns.
Traditional coatings, by contrast, are more like sandwiched layers that are stacked one on top of the other, on top of the metal. According to the scientists, the new coating's structure not only allows it to be more flexible and thus less prone to cracking, but also allows it to adhere better to irregular surfaces.
In thermal shock tests, that simulate the abrupt changes in temperature experienced by aircraft engines, the coating was found to last three times as long as conventional coatings. This means that the engines shouldn't require servicing as often, and should last longer. As a side benefit, the coating itself should be considerably less expensive than coatings currently used.
It is hoped that the technology will find its way into airplane engines and gas turbines within the next two years.
Source: University West
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