Manufacturing bit: September 28
Texas A&M University has discovered a new self-healing mechanism for ceramics, a technology that could one day be used in jet engines, hypersonic airplanes, and nuclear reactors.
Ceramics involves various materials that are neither metallic nor organic, but rather crystalline and / or glassy, according to the University of Maryland. A common example is clay, which is shaped and then heated in a kiln. This in turn forms bricks, pottery or tiles.
Ceramic materials are also used to make spark plugs, fiber optics, artificial gaskets, space shuttle tiles, cooktops, racing car brakes, chemical sensors, bearings, protective vests. -balls and skis, according to the University of Maryland. Ceramics are also used in the field of electronics. Some integrated circuit and superconducting packages use these materials.
Ceramics are resistant to heat and extreme environments. The problem? They are brittle and crack easily, according to Texas A&M.
In response, Texas A&M demonstrated a mechanism capable of healing cracks as they form in ceramic, even at room temperature. Researchers have discovered a self-healing mechanism within a type of ceramic using MAX phases. Potentially, these materials prevent catastrophic ceramic failures. Self-healing materials resistant to heat and extreme environments such as MAX phases are ideal for next generation technologies such as jet engines, nuclear reactors and other systems.
MAX phases involve a family of materials called ternary carbides. Simply put, atomic layered ternary carbide materials are layered in the ceramics themselves.
“Imagine a loaf of plain bread, it’s smooth, so if I slice it, each slice will look the same – a similar idea to conventional ceramics,” said Miladin Radovic, professor in the Department of Science and Engineering. of materials in Texas. A M. “But the MAX phases are layered like a peanut butter sandwich with peanut butter between two slices of bread.”
“Crystals in this class of ceramic materials easily fracture along weakly bonded crystallographic planes. However, the appearance of an abstruse mode of deformation, called twisting in these materials, induces large crystallographic rotations and plastic deformations which physically heal cracks. This implies that the toughness of many other layered ceramic materials, whose wider applications have been limited by their susceptibility to catastrophic fractures, can also be improved by microstructural engineering to promote twisting and crack healing, ”explained Hemant. Rathod, doctoral student in the Department of Materials Science and Engineering at Texas A&M and lead author of an article in Science Advance, a technology journal.
“This folding or self-healing mechanism can occur repeatedly closing the newly formed cracks, thus delaying the failure of the material,” said Rathod.
“What’s really exciting about MAX phases is that they easily form bend bands under load that can self-repair cracks even at room temperature, making them suitable for a variety of advanced structural applications. Said Ankit Srivastava, assistant professor in the Department of Materials Science and Engineering at Texas A&M, and a corresponding author of the study.
The University of Illinois Urbana-Champaign (UIUC) has developed self-healing polymeric materials for use in the National Laboratory of the International Space Station.
Several thermoplastic materials are used in aerospace applications, such as wire insulation, thermal blankets, and metallic surface coatings. But these materials are known to degrade in space due to radiation and extreme temperatures.
This could be problematic for the International Space Station (ISS). The ISS serves as a research laboratory for businesses, government agencies and universities. For a while, ISS astronauts conducted a plethora of experiments in the orbiting laboratories of various organizations.
The UIUC, meanwhile, has developed a new class of 3D printed thermosetting polymers based on polydicyclopentadiene (pDCPD). These materials harden when heated, which can be a more durable option for space applications. A lightweight thermosetting material, pDCPD is used to manufacture automotive body panels and aviation components.
“The materials we use are novel nanocomposites, based on a thermosetting polydicyclopentadiene (pDCPD) matrix mixed with self-healing components, which can be cured in minutes to hours compared to traditional thermosetting polymers which take days to cure. harden inside an autoclave. In addition, these novel pDCPD-based materials lend themselves to additive manufacturing techniques with the potential for rapid fabrication or repair of parts wherever they are in space, ”said Debashish Das, postdoctoral researcher in the Department of UIUC aerospace engineering.
Researchers will synthesize the test materials in ground laboratories and then launch them to the ISS for testing. “The innovative coupling of high-temperature selective synthesis with 3D printing by UIUC offers a path for the use of in situ resources from space or Earth in the fabrication of new materials,” said Etop. Esen, head of business innovation at the Center for the Advancement of Science in Space (CASIS), head of the national ISS laboratory. “This project will determine whether the pDCPD polymers produced by this method are more durable than conventionally manufactured polymers, such as Kapton or Teflon, currently used in harsh aerospace applications. “
The Indian Institute of Scientific Education and Research, the Indian Institute of Technology in Kharagpur and RWTH University in Aachen have discovered a self-healing piezoelectric molecular crystal.
“The ability to autonomously restore shape or self-healing are useful properties that have been incorporated into a range of materials, including metals and polymers,” according to Science researchers. “Bhunia et al. discovered that both of these capacities could be obtained in piezoelectric molecular crystals, in particular organic bipyrazole crystals. When crystals are fractured, they develop charged surfaces that attract each other, bringing the two faces together to allow self-repair as long as they remain a critical distance from each other. The effect can also be seen in other non-centrosymmetric piezoelectric crystals.
Science X, an online information service, explains how it all works.