Japanese scientists have developed a new coating material to reduce air transport costs

Some parts of an aeronautical gas turbine engine that are widely used on aircraft often reach temperatures above 1,200 degrees Celsius. There is no doubt that any material used in this harsh environment must be durable and competent for this task. Recently, ceramic substation composites made of silicon carbide (SiC) have attracted interest as a candidate for gas turbine engines

.
these materials require a heat-resistant coating to prevent siC oxidation and subsequent evaporation of SiO2, a process that results in a decrease in the volume of the material, such as large cracks or peeling of the top coating. Unfortunately, existing coatings do not completely prevent this oxidation process into SiO2, as oxygen can penetrate through microscopic cracks or simple diffusion in these coatings.
To solve this problem, some scientists use silica(Yb-Si) as a coating material because Yb-Si can reach very high melting points, and their oxides are mainly Yb-silicates, which remain attached as an oxidizing layer and do not evaporate easily. However, little is understood about the basic phenomena that occur in these materials at high temperatures, whether in air or water vapor environments.
a recent paper published in Intermetallics, a team of scientists, including Associate Professor Ryo Inoue of Tokyo University of Science, Assistant Professor Yutaro Arai and Professor Yasuo Kogo, and Senior Researcher Takuya Aoki of the Japan Aerospace Research and Development Agency (JAXA), set out to understand the oxidation mechanisms of Yb-Si. They conducted experiments to gain insight into the high-temperature oxidation and degradation behaviors of different Yb-Si coatings in three atmospheric environments, air, water vapor, and a mixture of the two.
X-ray diffraction analysis, energy dispersion spectroscopy, and scanning electron microscopes, scientists were able to accurately visualize and quantify the shape and composition of Yb-Si samples before and after thermal exposure tests. One of the main findings is that the ratio of Yb to Si is a major factor in determining the oxidation behavior of the material; In addition, in an atmosphere rich in more water vapor, the amount of oxides is greatly reduced.
most importantly, the researchers exploredeffects of high levels on SiO2 formation. "After thermal exposure to these two silicones in steam, we found SiO2 in Yb5Si3, when in fact Si is still in Yb3Si5," said Dr Inoue, who led the study. "Our analysis shows that the growth of SiO2 is inhibited in Yb3Si5 because SiO2 is involved in the reaction to the formation of Yb-silicate and is a limiting factor," he added. Although the exact intermediate reactions that lead to the formation of various Yb-silicates are not fully understood, the team suggests two highly likely response pathways. This is likely to be clarified by future research and more detailed calledtation techniques. "
, this study provides meaningful insights into what happens during Yb-Si oxidation, which will contribute to the development of protective coatings for aeronautical gas turbine engines." If a coating can be achieved that can withstand harsher environments, engine components will become more heat-resistant and naturally lead to higher engine efficiency. Dr Inoue said.
that advances in coating technology will reduce air transport costs and fuel consumption, making flying less costly and less harmful to the environment.
the study was entitled "Oxidation behavior of ytterbium silicide in air and steam."
。