According to the concept and use of ceramics, ceramic products are divided into two categories: ordinary ceramics (traditional ceramics) and advanced ceramics (advanced ceramics). Among them, ordinary ceramics refer to various products made by using clay and its natural minerals as raw materials through processes such as crushing, mixing, forming, and baking.
Advanced ceramics are ceramics that use highly selected or synthetic raw materials, have precisely controlled chemical composition, are processed according to controllable manufacturing techniques, are easy to carry out structural design, and have excellent characteristics compared to ordinary ceramics. Advanced ceramics are widely used in the fields of high temperature, corrosion, electronics, and optics. As an emerging material, with its excellent properties, it is unique in the field of materials and has been highly valued by people. It will play an important role in future society.
Sanxin New Meterials –Advanced ceramics are widely used in the fields of high temperature, corrosion, electronics, and optics. As an emerging material, with its excellent properties, it is unique in the field of materials.
Sanxin New Meterials –Classification of advanced ceramics
1. Classified by chemical composition
Advanced ceramics are divided into oxide ceramics, nitride ceramics, carbide ceramics, boride ceramics, silicide ceramics, fluoride ceramics, and sulfide ceramics according to their chemical composition.
2. Classified by performance and use
Advanced ceramics can be divided into structural ceramics and functional ceramics according to their characteristics and uses. Functional ceramics account for about 70% of the market share of advanced ceramics, and the rest are structural ceramics.
Structural ceramics refer to ceramics that can be used as engineering structural materials. They have high strength, high hardness, high elastic modulus, high temperature resistance, wear resistance, and thermal shock resistance. They are roughly divided into oxide, non-oxide and Ceramic matrix composites for structures.
Structural ceramics mainly include: cutting tools, molds, wear-resistant parts, pump and valve parts, engine parts, heat exchangers and armor. The main materials are silicon nitride (Si3N4), silicon carbide (SiC), zirconium dioxide (ZrO2), boron carbide (B4C), titanium diboride (TiB2), alumina (A12O3), and Sialon.
(1) Si3N4-based ceramic material
C fiber reinforced Si3N4 based ceramic material uses ZrO2 phase transformation effect to prevent cracks caused by the mismatch between the thermal expansion coefficient of the fiber and the matrix, and the fracture toughness of the obtained composite material is increased by 5 times. With its excellent comprehensive performance and abundant resources, silicon nitride ceramics have become one of the most promising cutting tools in high-performance ceramics.
(2) Silicon carbide-based ceramics
The C fiber reinforced silicon carbide composite material prepared by the CVI method, while adding 25 vol% TiB silicon carbide multiphase ceramic, if the initial particle size is strictly controlled, the strength can reach 888 MPa and the breaking strength can reach 8.8 MPa · m. It can be said that silicon carbide is the strongest material in high temperature air, and its thermal conductivity is second only to beryllium oxide ceramic materials.
(3) Zirconia toughened ceramics
Zirconium oxide toughened ceramics have made significant progress in the research of structural ceramics. There are many varieties of toughened ceramics. The additives known to stabilize zirconia are: magnesium oxide, calcium oxide, lanthanum oxide, and yttrium oxide. Single oxides, such as cerium oxide, or their composite oxides. Toughened materials include oxide ceramics such as alumina, hafnium oxide, spinel, and mullite in addition to stable zirconia. Adding 16 vol% zirconia to the alumina to toughen it, the strength of the obtained material was 1200 MPa, and the fracture toughness was 15.0 MPa.m. Zirconia toughened ceramic materials have the highest strength and fracture toughness at room temperature, and will focus on improving its high temperature performance in the future.
Sanxin New Meterials –Functional ceramics
There are many types of functional ceramics. These materials have many excellent functions such as microwave dielectric properties, gas sensitivity properties, superconductivity properties, resistance gradient properties, ferroelectric properties and their phase transition behavior, multilayer driveability, and relaxation properties. It is widely used.
(1) Electronic insulation materials
New types of electronic insulation materials such as AlN ceramics that have appeared in recent years have excellent properties such as high strength, high insulation, low dielectric constant, and high thermal conductivity, and their thermal expansion coefficients can match that of single crystal silicon. They are mainly used in applications It is used as a dispersion of large-scale integrated circuits and power module circuits.
(2) Dielectric materials
The ceramic capacitor dielectric materials used for tuning circuits, protection logic and memory cells are mostly BaTiO3-based materials. In addition, there are high-dielectric composite perovskite materials. When the frequency is 105Hz, the dielectric constant is as high as 105. The appearance of capacitors has increased the dielectric constant of conventional ceramic dielectric capacitors by several times or even tens of times.
(3) Piezoelectric ceramic materials
Commonly used piezoelectric components: sensors, gas igniters, alarms, audio equipment, medical diagnostic equipment and communications.
New types of piezoelectric ceramic materials are: high-sensitivity, high-stability piezoelectric ceramic materials, electrostrictive ceramic materials, pyroelectric ceramic materials, etc.
(4) Magnetic ceramic materials
Magnetic ceramic materials can be divided into two types: hard magnetic and soft magnetic materials. The former is not easy to magnetize and it is not easy to lose magnetism. Representative hard magnetic materials are ferrite magnets and rare earth magnets, which are mainly used for magnets and magnetic storage elements. Soft magnetic materials are easy to magnetize and demagnetize, and the direction of the magnetic field can be changed. It is mainly used for electronic components that respond to alternating magnetic fields.
(5) Superconducting ceramic materials
Since there was a major breakthrough in the research of superconducting ceramics in the 1980s, the research and application of high-temperature superconducting ceramic materials have received much attention. In recent years, the application of high-temperature superconducting materials is developing towards high-current applications, electronics applications, and diamagnetic properties.
(6) Anti-bactericidal ceramic material
Anti-bactericidal ceramic materials are a new generation of functional materials that have emerged with the development of science and social civilization.
Inorganic antifungal agents can be divided into three categories according to the mechanism of action on microorganisms: one is to fix silver, copper, zinc and other bactericidal metals or their ions on zeolite, apatite, Made of silica gel, glass and other inorganic materials;
The second type is titanium dioxide particle photocatalytic antifungal agent. Titanium dioxide can change the oxygen molecules into active oxygen under the light, and the water can produce active oxygen free radicals to play the role of antibacterial and sterilization.
The third type is anti-bactericidal material with far-infrared radiation function. The far-infrared anti-bactericidal effect is limited. Therefore, this material must be used in conjunction with the first two materials to have better application value.
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Post time: Mar-17-2020