Russia has developed a method to improve the fracture toughness of silicon carbide

According to a report on the website of the British airframe manufacturer on August 19, 2020, scientists from the Russian National University of Science and Technology (NUST MISIS) have discovered a kind of silicon carbide (an aerospace structural material with the most potential for the production of refractory parts).
The method to increase the fracture toughness by 1.
5 times-through the formation of reinforced nanofibers in the structure to obtain this result
.
In the future, this technology will expand the application range of silicon carbide as a structural and refractory material, including its use in aircraft manufacturing
.
The relevant results of this research have been published in the British "International Ceramics" and the Swiss "Materials" journals
.
The results described in this article have been published in the April 15, 2020 edition of the British "International Ceramics" journal and the Swiss "Materials" journal in the July 2020 edition.
As of 2019, the global silicon carbide market is estimated to be US$2.
58 billion.
The annual growth rate is expected to be 16%
.
Silicon carbide basically does not exist in nature, so it needs to be obtained by artificial synthesis
.
At present, silicon carbide is increasingly used as semiconductor materials, construction materials, abrasives and refractory materials in various industries
.
For example, silicon carbide is used to manufacture turbine blades and parts for internal combustion engines, which will greatly increase the operating temperature of the engine and significantly improve key performance such as power, traction power, energy efficiency, and environmental protection
.
In addition, silicon carbide ceramics made of low-cost feldspar and quartz sand can successfully replace the alloy parts containing rare elements such as cobalt, nickel and chromium that are often used in the automotive industry
.
Silicon carbide is used in the manufacture of turbine blades and internal combustion engine parts (Photo of the Russian National University of Science and Technology) The key problem of silicon carbide ceramics is that they perform well in compression, but are very sensitive to structural defects, so they usually have low tensile strength and bending.
The strength and crack resistance are poor
.
Scientists from the Russian National University of Science and Technology have found a way to form reinforced nanofibers in silicon carbide ceramics by using self-propagating high-temperature synthesis technology, which significantly improves the sintering ability of silicon carbide ceramics and improves their flexural strength and fracture toughness
.
The synthesis is carried out in several stages
.
First, the silicon, carbon, tantalum and polytetrafluoroethylene powders are mixed in a planetary mill, and then the resulting mixture is burned in the reactor
.
Nanofibers are formed during the combustion process
.
Finally, the finished product is sintered in a vacuum furnace
.
Due to the joint action of tantalum and polytetrafluoroethylene, a silicon carbide nanofiber reinforced silicon carbide matrix material was synthesized
.
Nanofibers prevent fracture propagation, activate ceramic sintering, and improve the strength characteristics of sintered materials
.
The presence of nanofibers reduces the sintering temperature and duration required for the silicon carbide finished product from a few hours at 1800-2000°C to 1450°C for 60 minutes
.
The process diagram in the method described in this article (picture from the Russian National University of Science and Technology).
The researchers plan to continue their efforts to improve the fracture toughness and strength of silicon carbide
.
The combination of good mechanical properties and cost-effectiveness in the production process will continue to expand the application range of silicon carbide as a structural and refractory material
.
The provider of this trend, Mr.
Chen Jiheng, has provided 7 column articles for "Aerospace Defense Observation", which are listed as follows: The first article, Toray Corporation of Japan launched a new generation of carbon fiber prepreg products, with high tensile strength and impact resistance.
Increased by 30%, June 2, 2017; Chapter 2, Composite materials assisting the development of Bell V-280 "Heroic" tiltrotor aircraft, September 22, 2017; Chapter 3, Toray Japan's implementation of mergers and acquisitions to strengthen carbon fiber composite Competitive advantages of materials, August 27, 2018; Part 4, Teijin Corporation develops new heat-resistant and shock-resistant prepregs, April 1, 2019; Part 5, U.
S.
Department of Energy "Using High Performance Computing to Promote Energy Innovation "Analysis of the Strategic Plan, May 17, 2019; Chapter 6, Rare Earth Recycling and Reuse! The United Kingdom launched a rare earth metal recovery pilot project, September 17, 2019; Chapter 7, US Air Force Laboratory scientists discovered a unique stretchable conductor, October 30, 2019
.
(China Aviation Industry Development Research Center? Chen Jiheng)