Japanese scientists have found a way to be able to withstand a certain stress at ultra-high temperature metal, the metal provides a broad prospect for the power generation of aircraft jet engines and gas turbines for power generation.
The first study, published in the July 2018 journal "Science Report", the article describes a titanium carbide (TiC) reinforced borosilicate molybdenum (Mo-Si-B) based alloys, namely MoSiBTiC, high temperature strength in 1400oC- at a constant force are detected within a temperature range of 1600oC.
"Our experiments show that MoSiBTiC alloys are more robust than advanced nickel-based single crystal superalloys. The latter are often used in high-temperature areas of thermal engines such as aircraft jet engines and gas turbines," said the first author of the article Professor Kyosuke Yoshimi Division said.
"This research shows that MoSiBTiC, as an ultra-high temperature material other than nickel-based superalloys, is a promising material in the corresponding field," Yoshimi added.
Yoshimi and colleagues reported several parameters that emphasized the alloy's ability to withstand destructive forces without deforming at very high temperatures. They also observed that the cavity in MoSiBTiC was continuously formed and grown with the increase of the applied pressure of the alloy, leading to internal micro-cracks and eventually fracture.
Friction stir welding of Inconel® 600 plates using MoSiBTiC tools.
Source: Kyosuke Yoshimi
The performance of a heat engine is key to future energy harvesting from fossil fuels and subsequent conversion to electricity and power. Performance enhancements can determine their efficiency in terms of energy conversion. Creep behavior or the material's ability to withstand forces at very high temperatures is an important factor, because elevated temperatures and pressures can cause creep deformation. Understanding material creep can help engineers build efficient heat engines that can withstand extreme temperature environments.
The researchers evaluated the alloy creep stress is applied up to 400 hours of 100-300 MPa. (MPa or megapascals is a unit used to measure very high pressures. 1 MPa equals about 145 psi, or pounds per square inch).
All experiments were performed in a computer-controlled test rig under vacuum, which is to prevent material from oxidizing or reacting with any potential air humidity, which may eventually cause rust.
In addition, the study reports that, contrary to previous studies, alloys experience greater elongation with reduced force. They say that this behavior has so far only been observed in superplastic materials. Superplastic materials are able to resist accidental premature failure.
Ultra-high temperature creep testing machine.
Source: Kyosuke Yoshimi
These findings are important indicators of the system MoSiBTiC operate at extremely high temperature, such as energy conversion systems in automotive applications, power plants and aircraft engines and rocket propulsion systems. Researchers expressed as a full understanding of the mechanical properties and the ability to recover from high stress (such as a large stress at high temperature), requires some additional analysis of the microstructure.
They hope that future research will continue to improve their findings. "Our ultimate goal is a new, ultra-high temperature material invention over nickel-base superalloy of the turbine blade and replace our new material ultra-high temperature high pressure turbine blade made of a nickel superalloy," Yoshimi said. "In order to achieve the next step, MoSiBTiC oxidation resistance by alloy design must be improved, it does not reduce their excellent mechanical properties, but this is really challenging."