Advanced Ceramics Industry Research

I Classification of ceramics
Broadly speaking, ceramic materials refer to all materials other than organic and metallic materials, i.e. inorganic non-metallic materials. They are mainly divided into traditional ceramic materials and advanced ceramic materials.
(i) Traditional ceramics
Ceramics in the traditional sense refers to various products made of clay and its natural minerals through the process of crushing, mixing, molding and firing. They are usually called "ordinary ceramics" or traditional ceramics, such as household ceramics, architectural and sanitary ceramics.
(B) Advanced ceramics
According to the chemical composition can be divided into oxide ceramics, nitride ceramics, carbide ceramics, boride ceramics, silicide ceramics, fluoride ceramics, sulfide ceramics, etc., according to the performance and use can be divided into two categories: functional ceramics and structural ceramics. Functional ceramics are mainly based on the special functions of materials with electrical properties, magnetic properties, biological properties, thermal sensitivity and optical properties. Mainly including insulating dielectric ceramics, ferroelectric ceramics, piezoelectric ceramics, semiconductors and their sensitive ceramics, etc.; structural ceramics are mainly based on the mechanics and structural use of the material, with high strength, high hardness, high temperature resistance, corrosion resistance, oxidation resistance, etc. Mainly including oxide ceramics, nitride ceramics, carbide ceramics and boride ceramics.
Electronic ceramics among functional ceramics are mainly used for encapsulation of chips, capacitors, integrated circuits, sensors, insulators, ferromagnets, piezoelectric ceramics, semiconductors, superconductors, etc.
Structural ceramics mainly include tools, molds, wear parts, pump and valve parts, engine parts, heat exchangers, biological parts, armor, etc. The main materials are: silicon nitride, silicon carbide, zirconium oxide and boron carbide, titanium diboride, alumina, etc. Their typical characteristics are: high strength, low density, high temperature resistance, creep resistance, wear resistance, corrosion resistance, and good chemical stability. Among them, the excellent comprehensive performance of silicon nitride has attracted much attention. Currently, commercial silicon nitride ceramics are mainly used as tool and bearing materials for high-power wind power generation. In addition, silicon nitride substrates are also an application direction of great interest.
Structural ceramics face the problems of high cost, low reliability and poor repeatability. The high cost is related to the manufacturing process and high scrap rate. Reliability is related to low reproducibility compared to toughness. Ceramics, as a typical brittle material, cannot absorb energy through deformation at low temperatures. Once the crack size reaches a critical value, damage occurs. The commonly used toughening methods are particle toughening, whisker and fiber toughening, and stress-induced phase change toughening.
The applications of advanced ceramics in the electronics industry are as follows.
II. The main process flow of ceramic industry
Ceramic raw materials → powder preparation → slurry → molding → sintering → finishing
(A) Raw material powder preparation process
Physical crushing: Powder material is obtained by mechanical crushing and electric spark explosion. Simple operation, low cost, but the product purity is low, the particle distribution is not uniform. Physical crushing can also be used for post-treatment of chemically prepared powder materials to make the powder material finer. With proper control means, powder materials with uniform particle size distribution and fine particles can also be prepared. Physical crushing method involves equipment such as ball mills, sand mills, airflow crushing.
Vacuum condensation method: Vacuum evaporation, heating, high-frequency induction and other methods are used to vaporize or form plasma of raw materials, and then quenched. It has the characteristics of high purity, good crystal structure, controllable particle size, etc., but requires high process equipment.
Vapor phase deposition: Synthesizing nanomaterials by chemical reaction of metal compound vapor. It is characterized by high purity and narrow particle size distribution.
Precipitation method: The precipitating agent is added to the salt solution for reaction, and then the precipitation is heat-treated to obtain nanomaterials. This method is simple and easy to use, but low purity and large particle radius are suitable for the preparation of oxides.
Hydrothermal synthesis: Nanoparticles are synthesized at high temperature and pressure in aqueous solution or water vapor, and then separated and heat treated. It has the characteristics of high purity, good dispersion and easy control of particle size.
Sol-gel method: Curing metal compounds by solution, sol and gel, and then forming nanoparticles by low temperature heat treatment. It is suitable for the preparation of oxide and metal oxide II - VI compounds.
Microemulsion method: Two insoluble solvents are formed in the presence of surfactants, and nanoparticles are obtained after nucleation, agglomeration, agglomeration and heat treatment in microbubbles. The characteristic particles are monodisperse and have good interfacial properties. This method is mainly used for the preparation of this group II ~ VI semiconductor nanoparticles. Strong and hard, etc.
(ii) Forming process
Dry pressing forming: dry pressing forming, cold isostatic pressing forming.
Plastic forming: extrusion forming, injection forming, hot wax casting into shape, zipping film forming.
Slurry forming: slurry forming, cast forming, gel injection molding and in-situ solidification forming.
Solid moldless forming: fused deposition forming, 3D printing forming, layered solid forming, stereolithography forming, and laser-selected sintering forming.
The object of slurry forming, such as injection molding and flow forming is slurry, the liquid percentage is generally above 30%, which has good fluidity and can fill all corners of the mold; the object of plastic forming, such as extrusion forming and rolled film forming is blank, the liquid percentage is generally between 10% and 30%, which has good plasticity and almost no deformation after forming; the object of dry compression forming, such as dry pressing and isostatic pressing The object of dry pressing molding, such as dry pressing and isostatic pressing, is granulated powder, which generally accounts for less than 10% of liquid and relies on pressure to improve the packing density of granulated powder, with small sintering shrinkage. As for solid moldless molding, it can be understood as the category of 3D printed ceramics.
Part of the molding process characteristics
(iii) Sintering process
Fundamentally, sintering is the process of powder diffusion and mass transfer to densify ceramic materials, giving them a uniform microstructure, stable shape and excellent performance.
The main purpose is to reduce the sintering temperature, shorten the sintering time, refine the grain, and eliminate residual porosity.
Commonly used sintering processes are: atmospheric sintering, pressureless sintering, vacuum sintering, hot pressure sintering, hot isostatic sintering, atmospheric pressure sintering, microwave sintering, combustion sintering, self-propagating high temperature sintering, intelligent sintering, spray sintering, low temperature sintering and pressureless sintering.
The main factors affecting sintering are the generation and action of the liquid phase of the ceramic material at high temperatures, the effect and mechanism of a small amount of additives in the ceramic material, and the effect of the fineness and activity of the raw material on sintering. Sintering process can be divided into three stages: the heating stage from room temperature to the highest sintering temperature; high temperature holding stage; cooling stage from the highest temperature to room temperature; some ceramic materials require heat treatment after sintering.
(D) precision processing
Advanced ceramic materials commonly used subsequent processing methods are surface glazing, mechanical processing and surface metallization. Glazing: ① improve the mechanical strength of ceramics and heat impact resistance; ② prevent the workpiece surface low-pressure discharge; ③ improve the moisture-proof performance of porcelain parts. Machining: It can make ceramic products meet dimensional tolerance requirements, improve surface finish or remove surface defects. Methods include grinding, laser and ultrasonic processing.
Metallization: In order to meet the needs of electrical properties or to achieve a ceramic and metal seal, the ceramic surface should be firmly coated with a metal film. Common methods of ceramic metallization include silver plating and electroplating. The forms of sealing ceramic and metal are vitreous enamel sealing, metal welding, active gold layer sealing, laser welding, solid-phase sealing, etc.
III. Advanced ceramic products hot application direction
1、Electronic atomizer
In 2018, the domestic electronic cigarette industry entered an important stage of product development, brand building and consumer cultivation. Preliminary estimates show that China's e-cigarette production will reach about 2.229 billion units in 2018, and it is expected that China's e-cigarette production will reach 2.898 billion units in 2019 and 4.753 billion units in 2022, of which atomizers account for about 35% of the cost of e-cigarettes.
Similar to activated carbon, porous ceramic materials have strong adsorption properties and good biocompatibility. This is one of the key factors in choosing ceramics as a carrier. Similar materials have many applications in daily life, such as cartridges, refrigerator deodorizers, face masks, toothpaste and other daily chemicals.
In fact, nebulization technology has long been used in medical and other fields, such as the treatment of asthma. In conventional nebulization, the particle size distribution of the particles is very wide. Among them, the particles above 2.5 μ m will be deposited in the human respiratory tract and mouth, and the particles of 1 μ M and below will be inhaled into the human lungs, and the active ingredients can be rapidly absorbed by the body. At present, feelm ceramic atomization core produces atomization particles generally less than 1 μ m. It can bring better taste and more satisfaction.
2、Filter
5g filter is expected to use new technology, mainly to be able to achieve miniaturization of the media filter. This utility product has good performance, small size and low power consumption. With the mature industry chain and the advantage of cost performance, the dielectric filter is expected to become the mainstream choice in the 5g period.
In the 5g era, large-scale MIMO technology will be widely used, and media filters are expected to replace metal cavity filters as the mainstream application of base stations; in addition, with the requirements of 5g smartphones in terms of light weight, high frequency and low power consumption, media filters also have great application space in the cell phone field.
In the four base station terminals, Huawei and Ericsson tend to ceramic media filters. ZTE and Nokia are still mainly miniaturized metal cavity filters. In the future, they will transition to ceramic dielectric filters, and the market share of ceramic filters will continue to increase. China 5 grams to promote the construction + With the maturity of microwave dielectric ceramic filter technology, the space for microwave dielectric ceramic filters continues to increase. It is estimated that from 2019-2023, the market capacity of 5g base station dielectric filters in China will exceed 33.6 billion yuan, with a compound annual growth rate of 80.32%.
3、MLCC
According to Murata's official website, the global MLCC market is forecast to grow at a CAGR of 90% of the ceramic capacitor market from 2019-2024.
The upstream of MLCC industry chain is mainly ceramic powder raw materials and metal materials for internal and external electrodes. The fineness, uniformity and reliability of the ceramic powder directly determine the size, capacitance and performance stability of MLCC products. Barium titanate is the main raw material of MLCC ceramic powder, and its cost accounts for 35-45% and 20-25% of the cost structure of high-capacity MLCC and small-capacity MLCC, respectively. Palladium, which was used as the raw material for the inner electrode of MLCC in the early days, was eventually replaced by base metals (nickel, copper, etc.) due to price increase, which reduced the cost of the inner electrode.
4、Mobile phone backplane
5g era requires faster signal transmission speed, 1~100 times faster than 4G. 5g communication will use spectrum above 3GHz with shorter millimeter wave wavelength. Compared with metal backplanes, ceramic backplanes have no interference with signals and have unparalleled superior performance compared with other materials, so they are favored by cell phone manufacturers.
Among all ceramic materials, zirconia ceramics not only have the advantages of high strength, high hardness, acid and alkali resistance, corrosion resistance, and high chemical stability, but also have the characteristics of scratch resistance, wear resistance, no signal shielding, excellent heat dissipation performance, and good appearance. Therefore, zirconia ceramics have become a new type of cell phone body material after plastic, metal and glass. At present, the application of zirconia ceramics in cell phones is mainly for back plates and fingerprint identification covers.
In the 5g era, cell phone back cover materials will mainly use plastic, glass and ceramic. Among them, plastic has the worst appearance and feel and the lowest cost, so it will be the first choice for low-end cell phones. Compared with glass, ceramic has a higher feel and appearance, better heat dissipation and hardness, and its penetration rate in high-end models is expected to increase significantly. According to Ovi cloud forecast, by 2020 the ceramic backing penetration rate of about 2%, is expected to reach 15 billion - 30 billion by 2023 ceramic backing market size.
5、Ceramic insert core
Ceramic cores are widely used in optical network connection points, branch points and terminals. About 72% of them are used in the manufacture of fiber optic connectors. About 25% of them are used in splitters, transceivers and other optical passive devices. About 3% of them are used in optical active devices. Ceramic cores are the core component of fiber optic connectors, which account for about 50% of the total connector cost. The use of 5g base station investment peak will bring a large number of ceramic plug incremental demand. In addition, the development of 5g will further expand the demand for IDC, fiber optic connectors are widely used in IDC Currently there are also a large number of applications, ceramic inserts are still facing a huge development opportunity.
IV. Main distribution of ceramic industry and future trends
At present, the leading foreign countries in the development of advanced ceramics are the United States, Japan, the European Union, Russia and so on. Among them, the United States in advanced ceramics in aerospace, nuclear energy and other fields of application in a leading position, Japan in the industrialization of advanced ceramic materials and civil field in a leading position, occupying about half of the world's advanced ceramic market share; EU in advanced ceramics and machinery and equipment applications in a leading position; Russia and Ukraine in structural ceramics and ceramic-based composite materials have a strong strength. The domestic advanced ceramics industry is mainly concentrated in Shandong, Jiangxi, Guangdong, Jiangsu, Zhejiang, Hebei, Fujian and other provinces.
The application fields of domestic advanced ceramic systems range from single military aviation to environmental protection, new energy and electronic information, and from structural ceramics and functional ceramics to structural-functional integration. It comes from the continuous development of ceramic systems and the continuous enrichment of preparation technology. At the same time, the requirements of research and development are becoming higher and newer: the research and industrialization of ceramic powder technology will meet the basic needs of the development of more ceramic materials. Through the development of mass production preparation technology, production equipment precision manufacturing technology, ceramic precision processing technology and toughening technology, low cost will achieve the purpose of reducing costs and improving efficiency. Among the molding technologies, injection molding, gel molding and moldless solid state molding will become the molding technologies with the most volume applications. si3N4 is the representative of structural ceramics and alon transparent ceramics is the representative of optoelectronic ceramics with excellent comprehensive performance. The basic theoretical research and structural design need to match the development requirements of advanced ceramics in application fields, and provide technical support for new systems, new products, new applications and batch conversion.