Scientists announce breakthrough in hypersonic heat shield

In a giant leap for future hypersonic flight, Chinese scientists have turned to multi-scale technology to develop a revolutionary new material that has scored record marks in tests for life-saving strength and thermal insulation properties.

The scientists say their porous ceramic creation opens the door to broader exploration in the fields of aerospace, chemical engineering and energy transfer and production.

“For the first time, multiscale structure design and rapid fabrication of…high-entropy ceramics via an ultrarapid high-temperature synthesis technique that can lead to exceptional mechanical load capacity and high thermal insulation performance,” the report said. researchers said in a paper published Jan. 2 in the journal Advanced materials.

Scientists have long faced challenges in developing strong, lightweight materials with low thermal conductivity, essential especially for hypersonic travel. Ceramic materials are promising because they feature low thermal conductivity, high melting points and corrosion resistance, and they are also non-combustible.

But exploration projects at great depths beneath the Earth’s surface as well as in space face extremely high temperatures and pressures. Traditional ceramic materials are insufficient in these cases.

Lightweight, porous materials offered low heat transfer, but this desirable property often came with a tradeoff: greater fragility.

In their report titled “High-entropy porous ceramics with ultra-strong and high thermal insulation up to 2000°C,” researchers from the School of Materials Science and Engineering at Guangzhou University said: “It It is imperative to find ways to simultaneously improve mechanical strength and thermal insulation. capacity of porous ceramics.

So they turned to the concept of high entropy design to create a porous ceramic material with a good balance of strength and heat resistance, without the usual drawbacks.

High entropy design focuses on using equal measurements of multiple elements that can be used to create stronger, more heat-resistant, and more stable components.

Researchers have developed a material that meets the demanding insulation and weight criteria for aerospace flights. Their new ceramic creation, which goes by the modest name 9PHEB – 9-cation porous high-entropy diboride – offers “exceptional thermal stability” and “ultra-high compressive strength,” the researchers said.

“High-quality interfaces, characterized by strong bonding without defects or amorphous phases, can promote the rapid transfer of force along the building block and to many other blocks via connections during loading, leading to a significant improvement in mechanical strength,” the report states.

Aerospace accidents due to heat and stress have made headlines over the years.

The 1986 Challenger tragedy was blamed on rubber O-rings that formed a seal between rocket boosters. Losing their flexibility in cold weather, their use was limited to temperatures above 53 degrees. The Challenger, however, was launched with temperatures dropping to 36 degrees. The O-rings lost their elasticity, ruptured, and explosive gases escaped, causing a catastrophic explosion that killed all seven astronauts.

A second shuttle disaster occurred 17 years later when foam insulation broke from the space shuttle Columbia’s external tank and struck the thermal shield tiles, compromising the internal heat shield of the wing, leading to the disintegration of the shuttle and the death of all seven astronauts on board.

The researchers say their new material holds promise for advancements in aerospace exploration.

“The excellent mechanical and thermal insulation properties (of 9PHEB) provide an attractive material for reliable thermal insulation in extreme conditions,” they explained.

© 2024 Science X Network