Development of advanced ceramic material industry（二）

Development of advanced ceramic material industry（二）

Porous ceramics

Porous ceramic is a kind of ceramic material with a large number of interconnected or closed pores, which has the advantages of high temperature resistance, corrosion resistance, thermal shock resistance, structural design diversity, and is widely used in environmental protection, chemical engineering, energy, metallurgy, construction, electronics and other fields.

Porous ceramics were first used on a large scale in the United States and Japan. Its preparation and application technology has developed rapidly and has become mature. There are many kinds of porous ceramics. At present, honeycomb ceramics, foam ceramics, ceramic membranes, foam ceramics, etc. are the main applications. Among them, honeycomb ceramics and foam ceramics occupy a very large share in the international market.

Transparent ceramics

The transparent ceramic is opaque, but the optical ceramic is as transparent as glass, so it is called transparent ceramic. Because of its high strength, corrosion resistance, high temperature resistance and other properties of ceramic materials, as well as its excellent optical properties, the transparent ceramic material industry has developed rapidly in recent years, and the industrial scale has been expanding. According to statistics, the global value of transparent ceramics is up to US $10 billion.

The transparent ceramic material industry has formed a multi-level echelon competition pattern, and each country’s industrial development has its own advantages. The first tier is developed countries and regions such as the United States and Japan, which have absolute advantages in economic strength, core technology, R&D capacity, market share, etc.

The second tier is represented by China, Russia and other countries. The transparent ceramic material industry is in a period of rapid development. Globally, the monopoly of transparent ceramic material industry has intensified, and high-end technical barriers have become increasingly apparent. For example, WordLab of Japan, Hitachi of Japan, General Electric Company (GE) of the United States, Surmet of the United States, Dow Chemical of the United States, Samete Ceramics Co., Ltd. of the United States, Siemens of Germany, etc. have occupied a leading position in most transparent ceramic products with high technology content and high added value by virtue of technological research and development, capital, talent and other advantages, with technology and patents as barriers.

Nuclear ceramics

After nearly 80 years of development, the nuclear industry has become a focus industry worldwide, occupying an indispensable position in the field of national defense and energy development. Driven by application requirements, nuclear materials have been continuously optimized and developed, which has become an important guarantee and driving force for the iterative progress of nuclear technology.

Advanced nuclear ceramic materials are widely used in the nuclear industry because of their high strength, good resistance to high temperature, radiation and chemical corrosion, and unique neutron absorption properties, and become the key basic materials in nuclear reactors, defense and military industries. At present, the whole nuclear material industry is in its infancy, and some research results have not yet been commercialized, with huge market potential.

Key technologies such as high-quality nuclear-grade submicron powder, high-performance fiber, composite materials and corresponding molding and densification are important areas for the development of nuclear ceramic materials industry.

The application of special ceramic fibers and ceramic matrix composites in the field of nuclear energy has always attracted huge investment from technologically developed countries.

Nuclear cells are also one of the key development directions of nuclear ceramics in the future. Isotopic thermal photovoltaic systems have unique advantages in deep space exploration, but the research and development are still in the laboratory prototype stage.

Research institutes and universities in the United States, Japan, Switzerland and other countries have carried out a series of research and development of ceramic-based selective emitter materials and achieved good results, but they have not yet reached the practical level.

At the present stage, the hypersonic vehicle is still in the core technology breakthrough and the experimental stage of the model machine. It is the main arena for various scientific and technological and military powers to compete, and has a milestone significance for the revolutionary development of aerospace and national defense military in the future.

Therefore, heat-resistant materials and their preparation technologies are the key technologies and core materials required for reusable vehicle and hypersonic vehicle, and have extremely important strategic significance.

Ceramic substrate

Ceramic substrates mainly include aluminum oxide substrates, aluminum nitride substrates, silicon nitride substrates and beryllium oxide substrates. They are mainly used in integrated circuits and high-power semiconductor devices. Compared with metal substrates and printed circuit boards (PCBs), ceramic substrates have high thermal conductivity, high insulation and high temperature resistance.

The thermal conductivity is several to dozens times of that of metal substrates and PCBs, and the compressive strength is 3 to 5 times of that of metal substrates, The use temperature can reach hundreds to thousands of degrees Celsius, so the devices made have higher integration, higher power, smaller package volume and wider use temperature range.

With the increasing requirements of electronic circuit devices and power semiconductors for volume and thermal conductivity, the proportion of ceramic substrates will increase. Ceramic substrate is a key basic material in many fields, and its related devices and products have been widely used in the fields of power transmission, medical equipment, microwave communication, land and water transportation, aerospace and aviation. It is an indispensable key material in various related fields.

Electronic ceramics

Electronic ceramics have a wide variety of applications. Ferroelectric materials with optical, electrical and optoelectronic properties have been widely used in memory, detection, sensor, communication and military; Semiconductor ceramic material is the key of sensor technology and sensitive components, which is closely related to communication and computer technology.

Component manufacturers all over the world have invested heavily in research and development of new products, new technologies, new processes, new materials and new equipment of electronic ceramics and its components, of which the United States and Japan have been in the leading position.

Semiconductor ceramics have a very significant feature, that is, its conductivity is very sensitive to external conditions such as pressure, temperature, humidity, atmosphere, and can change the physical quantity of the external environment into electrical signals. Semiconductor ceramics include thermosensitive ceramics, photosensitive ceramics, gas sensitive ceramics, pressure sensitive ceramics and humidity sensitive ceramics.

Therefore, semiconductor ceramic is the key material of sensitive components and sensor technology, and plays a very important role in modern industrial technology, especially in computer, artificial intelligence and robot pattern recognition technology.

The research, development and even production of semiconductor ceramics involve many disciplines, such as physics, chemistry, material science and engineering. Therefore, semiconductor ceramics are technology-intensive and knowledge-intensive industries. Japanese products occupy an absolute dominant position in the world market, and the United States and Europe also occupy part of the market.

Japan has obvious advantages in the field of microwave dielectric ceramics. It devotes its industrialization advantages to promoting the standardization and high quality of microwave dielectric ceramics. The United States focuses on nonlinear microwave dielectric ceramics and high dielectric constant microwave ceramics. Europe focuses on fixed frequency resonator materials. South Korea has also developed rapidly in this field.

Bioceramics

Bioceramics is an emerging field of materials in recent years, which has received widespread attention from all countries in the world. Bioceramics refers to a class of ceramic materials used for specific biological or physiological functions, and biological, medical, biochemical and other ceramic materials directly used for or directly related to the human body.

They need not only high strength and toughness, but also biocompatibility, mechanical compatibility, antibacterial and other characteristics. At present, bioceramic enterprises are mainly multinational manufacturers, accounting for about 2/3 of the global bioceramic market, and the rest is mainly divided by hundreds of smaller competitors.

The global dental implant market is highly competitive, and there are only a few major companies in the market, namely Zimmer, Dentsply, Straumann and Nobel Biocare. The increase of the world’s aging population, lower tooth transplant rate and longer life span are the main market drivers, while the increase of urban population and consumption level is another market driver.

The largest application market of bioceramics is bioceramics for transplantation and medical equipment with analytical and scientific instruments. Bioceramics for transplantation include bone materials necessary for surgery such as teeth, artificial joints, bones, sensors, etc.

In order to ensure that bioceramics can coexist in the human body for a long time without secondary harm, it is necessary to ensure that the mechanical properties, stability, elastic modulus, etc. of the materials and human bones are not significantly different. For example, zirconia and alumina ceramics can withstand the unfriendly environment of human body, and silicon nitride has good biocompatibility and antibacterial properties, which are the main research fields of bone materials.

Nano ceramic composites have important development potential in the field of bone materials. In vitro experiments have proved that osteoblasts can proliferate on the matrix composed of nano ceramic particles and coatings.

However, some studies have shown that such composite materials have certain biological toxicity and may cause inflammation or immune reaction leading to graft rejection, so they have not been applied in practice for the time being, and more experimental studies are needed to solve this problem in the future.

other

Advanced ceramic materials have high specific strength, high toughness, high chemical stability, and low density, high hardness and other advantages compared with metal materials. They show great application potential in armor materials, and become protective materials for many military equipment such as bullet-proof vests, bullet-proof vehicles, fighter aircraft, etc.

During the Second World War, the protective materials of equipment were mainly metal materials. However, with the improvement of weapon lethality and material development level, traditional materials could not meet the requirements of modern military development. Armor materials should meet the requirements of high hardness, high strength, high toughness and low density as much as possible, namely “three high and one low”.

As early as the middle of the 20th century, B4C materials were used in the field of bulletproof vests, and subsequently in the seat of fighter aircraft. In the 1970s, military powers such as Europe and the United States applied ceramic matrix composites in personnel carriers, tanks, and military aircraft. For example, the British Challenger tank, EE-T1 Osorio main battle tank, etc. At present, a large number of armor ceramics have been used on ships abroad.

The United States has used ceramic composite armor on the antenna and turret of ships, and it is expected that its AAAV amphibious attack ships under research will also use ceramic composite armor;
Armor materials in the new era mainly develop in the direction of resistance to multiple strikes, improvement of protection and mobility, and reduction of self-weight.

The single ceramic material has low density, good compression resistance, good wear resistance and chemical resistance, but it is easy to break and brittle. These shortcomings also limit its application to a certain extent. Therefore, the light composite armor is a multi-layer structure, with ceramic plate as the main body and other composite materials.

Breaking through the structural design of traditional heavy composite armor, replacing the armor steel panel with high hardness ceramic panel, giving full play to the high hardness and high compressive strength of ceramics, can improve the ballistic performance of ceramic composite armor.