With the emergence of new technologies such as energy development, space technology, electronic technology, laser technology, optoelectronic technology, infrared technology, and sensing technology, existing general materials are no longer able to meet the requirements. Ceramic materials have become one of the focuses of the development of new materials due to their unique advantages such as heat resistance, wear resistance, corrosion resistance, light weight, insulation, and heat insulation.
In the world of new materials, ceramic materials, metal materials, and organic polymer materials form a tripartite force. At the same time, they are compounded with each other and learn from each other's strengths to offset their weaknesses, becoming the pillars of the new technological revolution.
Ceramics are mainly composed of some non-metallic minerals, silicon nitride, silicon oxide, etc. It has higher heat resistance and chemical reaction resistance than steel, and is very suitable for replacing various alloys to manufacture high-temperature mechanical equipment such as internal combustion engines. Since the 1990s, further improvements in hot melt technology and spray drying technology have helped people understand the actual composition of ceramics. Using ceramics as a matrix material and compounding them with reinforcing agents such as continuous fibers, whiskers, and particles, the resulting ceramic composite materials can be used to manufacture composite ceramic devices in many aspects such as aviation, precision instruments, mechanical tools, electronics, and the human body.
After high-tech compounding, the fatigue strength and corrosion resistance of ordinary ceramics are even higher than those of steel or high-temperature alloy materials. It is particularly ideal to use it to make engines, aerospace equipment or diving equipment. As microwave drying technology becomes more and more perfect, the performance of composite ceramics continues to improve. German tool manufacturers take advantage of the hardness of composite ceramics to produce cutting tools such as drill bits and knives for cutting metal plates. When British companies produce reduction gears, ball shafts and other products, they have also increased the use of composite ceramics. The goal of the U.S. healthcare sector to use composite ceramics to replace certain metal supports entering the human body has also become a reality. By the end of 2000, the sales of high-tech composite ceramics in the international market reached US$190 billion, including US$55 billion in the Western European market and US$30 billion in the Japanese market. Entering the 21st century, the growth rate of investment in the development of high-tech composite ceramics in the United States, the European Community, Japan and some developing countries will exceed 20%. The U.S. military alone has invested US$200 million in research and development of composite ceramics. Advanced structural ceramics have been widely used in automobiles, aircraft, energy transportation, power equipment and machinery industries, and are gradually being used in chemical industry, nuclear engineering, medical equipment and food machinery and other industries. Its main uses include various high-temperature structural parts (nozzles, heat exchangers, setters, high-temperature filters, high-temperature ball valves, heating elementsetc.), wear-resistant parts (bearings, ball mill media, dewatering plates, etc.), corrosion-resistant parts (such as pipes, ball valves, pump materials, etc.), seals, impact-resistant structural parts (ceramic armor), ceramic parts for engines, etc.
In the 1980s, under the background of the international oil crisis, countries competed to invest huge sums of money in the development of ceramic engines, which led to the development of a large number of advanced ceramics, especially structural ceramic products and preparation technologies. At present, automotive ceramic engine parts developed using high-tech ceramics and automotive parts surface-modified using ceramic powder have entered the market in large numbers, greatly improving the working performance of automobiles.
The military use of ceramic materials has always been a major part of the U.S. advanced materials program. Ceramics are widely used in military equipment, from glass-ceramic armored cockpits to Patriot missiles and Apache helicopters. Lightweight ceramics are also widely used in modern fighter jets. Ceramic armor is often installed on the cabin seats, sides and floor to protect the crew from ground attacks. Ceramics are also used in many military radar communication systems. The radar in the Patriot missile system is constructed from ceramic components. In terms of structural ceramics, the life of cutting tools is dozens of times longer than that of ordinary metal tools. For example, titanium carbonitride-based cemented carbide and single crystal diamond are the best tools for precision processing of non-ferrous metals, ceramics, glass, graphite and other materials.
With the increasing demand for these materials in the energy, transportation, automobile, aerospace, electronics, military and other sectors, the application of high-performance ceramic cutting tools will become more widespread.
Advanced structural ceramics have many excellent properties such as high strength, high temperature resistance, wear resistance, corrosion resistance, small specific gravity, and good chemical stability. Compared with metal and polymer materials, its main disadvantage is that it is brittle and not resistant to impact. Therefore, the scope and speed of application of advanced structural ceramic materials mainly depend on two aspects of work. One is to solve the brittleness problem of ceramics, and the other is the economy of the production process. In particular, the properties of ceramics are very sensitive to the particle size, purity, microstructure after firing and process conditions of the raw materials. Therefore, the research and development of new ceramic materials and the improvement of production processes must be carried out simultaneously, and the two are inseparable.
In the petroleum industry, one of the oil fieldsFor some drilling equipment parts, lifting equipment parts, pumps, ball valves, pipe joints, various pipelines, and many other parts that require corrosion resistance and wear resistance, ceramics can be considered to replace metals to extend their service life and increase recovery rates. In addition, foam ceramics, superplastic ceramics, plastic composite ceramics, ceramic powder lubricants and various fine ceramic materials and components are also widely used in the petroleum industry.
Lightweight foamed ceramics have an independent bubble structure, small specific gravity, good processing performance, good thermal insulation and high temperature resistance. This kind of lightweight foamed ceramic is an inorganic lightweight foam made by heating and foaming the mixed raw materials of ceramic powder and foaming agent. By controlling the sintering process conditions and the blending of raw materials, a structure with uniform independent cells (0.1mm to 3mm in diameter) like polyurethane foam is produced. Its thermal insulation is 8 to 20 times higher than concrete, and its maximum heat-resistant temperature can reach 800°C.
In addition to the development of high-temperature structural ceramic materials, the application scope of surface film ceramic materials is constantly expanding, and the development prospects are very optimistic. It has the tendency of miniaturization, multi-layering, thin film and multi-functionality. In addition to being used in the fields of machinery and chemical industry, metal crafts covered with ceramic films have also been successfully produced. For example, an elastic ceramic material that can be stretched and folded at will was recently launched in Japan. Its length after stretching can be increased by more than 10 times. The sintered silicon nitride ceramics produced by this method can efficiently and economically manufacture various complex-shaped products, such as cutting tools, sealing rings, bearings, nozzles and various high-temperature-resistant, wear-resistant, corrosion-resistant products, etc. . Functional ceramics are now increasingly widely used. For example, superconducting ceramics can make current flow without resistance and heat loss, so that maglev trains can travel at a speed of 200 to 300 kilometers per hour, thus having broad prospects. Desktop-sized computing units in supercomputers will run thousands of times faster than today's computers. Other applications of functional ceramics include: various sensors, actuators, optoelectronic materials, semiconductors and multilayer capacitors. Ceramic coatings are also often used to protect or lubricate many materials, such as metals.
These ceramic coatings can effectively prevent computers and other electronic devices from power outages, component malfunctions and excessive wear. In the processing of high-performance ceramic materials, laser processing technology has become popular in recent years. The technology of laser processing ceramic materials can reduce processing costs by 50%. This skillThis technology is especially suitable for certain ceramic parts of small batches and small specifications that are produced without using molds due to mold manufacturing costs. First, the ceramic material is heated to 1000°C using a laser to soften it. The intensity of the laser and the heated area need to be precisely controlled, and the heated area is limited to a very small part of the material. The hot ceramic material is then moved to a lathe made of super-hard boronized material for processing. One of the great advantages of laser processing is that it can achieve complex geometric dimensions in a single cut, whereas conventional methods require several lathes to shape the material.
