Alumina ceramics is the most widely used material in advanced ceramics, the alumina content in alumina ceramics is generally between 75% and 99.9%. Usually to the alumina content in the ingredients to classify and name, for example, the content of about 75%, known as “75” ceramics. In these classifications, the content of 80% or less, known as ordinary alumina ceramics, the content of 85% or more alumina ceramics known as “high alumina ceramics”, 99% or more alumina ceramics known as “corundum ceramics” or “pure Corundum ceramics” or “pure corundum ceramics”. Among them, 99 alumina ceramic materials for the production of high-temperature crucibles, refractory furnace tubes and special wear-resistant materials, such as ceramic bearings, ceramic seals and water valves, etc.; 95 alumina ceramics are mainly used as corrosion-resistant, wear-resistant parts; 85 ceramics are often doped with part of the talc, improve the electrical properties and mechanical strength, and molybdenum, niobium, tantalum and other metal seals, and some of them are used as an electro-vacuum device devices.
Properties of alumina ceramics
1. high hardness: its Rockwell hardness is HRA 80-90, second only to diamond, far more than wear-resistant steel and stainless steel wear resistance. 2. good abrasion resistance: its wear resistance is equivalent to 266 times of manganese steel and 171.5 times of high-chromium cast iron.
2. good abrasion resistance: its abrasion resistance is equivalent to 266 times that of manganese steel and 171.5 times that of high chromium cast iron; under the same working conditions, it extends the service life of the equipment by more than ten times. 3. small specific gravity: its density is more than 10 times that of the steel.
3. small specific gravity: its density is 3.5g/cm3, only half of the steel, can greatly reduce the load on the equipment
4. High temperature resistance: alumina ceramics have a very high melting point of 2,072°C.
5. Good chemical stability: insoluble in water, only slightly soluble in strong acid and alkali solutions, but reacts with hydrofluoric acid (HF); resistant to oxidation and aging.
6. High insulation: high volume resistance, aluminum oxide products are suitable for a variety of high current and high voltage applications.
The attached table shows the technical parameters of our regular alumina ceramics of different purities:
Main products and applications of alumina ceramics
1.1 definition of metalized ceramics: due to the surface structure of ceramic materials and metal materials with different surface structures, welding often can not wet the ceramic surface, but also can not act with the formation of a solid bond, and thus ceramic metallization is firmly adhered to the surface of the ceramic a layer of metal film, so that the realization of ceramics and metal between the welding.
1.2 Ceramic substrate material: 94.4% alumina, 96% alumina, 99% alumina
1.3 Types of Metallization:
A. Ceramic body + Mo/Mn metallization;
B. Ceramic body + Molybdenum-Manganese metallization (Mo/Mn) + Electroplating (chemical) Nickel (Ni)
C. Ceramic body + silver cladding (Ag)
D. Ceramic body + Tungsten metallization (W) + Au electroplating
E. Ceramic substrate + Oxygen-free copper (Cu)
1.4 Main types: ceramic tube, ceramic ring, ceramic substrate, structural ceramics ，as shown in the attached figure:
1.5 Main characteristics:
● Excellent welding strength, ● Ultra-high vacuum tightness, ● Excellent mechanical properties, electrical properties，● Chemical resistance, corrosion resistance, aging resistance
1.6 Key parameters
1.7 General post-processing of metallized ceramics
– Double-sided grinding: Improvement of the flatness of the grinding plane for metallization, thus ensuring the adhesion of the metallization layer.
– Internal/external cylindrical grinding: Ensures internal/external diameter tolerances and concentricity; enables smooth assembly.
– Machining: milling and grinding of the corresponding dimensions to ensure assembly.
– Surface glazing: Improvement of dielectric and mechanical strength, protection against dirt, moisture and dust.
1.8 Applications of metallized ceramics:
Widely used in high-voltage, high-current vacuum breaker, vacuum relay, Vacuum interrupters, vacuum electrical feedthrough,Vacuum electrical switch, Vacuum electrical switch, Vacuum electrical switch, Vacuum electrical switch, Vacuum electrical switch, Vacuum electrical switch，Electron tubes, Gas Discharge Tube, (Vacuum capacitor, vacuum tubes, surge dischargers, thyristor shells, Diode housings, Power grid tubes. Traveling wave tubesX-ray tubes, Insulator rings and cylinders and so on.
2.1 Typical materials: 95% alumina, 99% alumina, steatite
Note: Talc is another advanced ceramic that is relatively inexpensive compared to alumina ceramics.
– Talc is another advanced ceramic that is less expensive than alumina, but the dimensional consistency of the product is more difficult to control.
– Talc ceramic cores are used in disposable grinders, mainly for the low end of the market.
– Alumina ceramic cores are used in multi-use grinders (wood/stainless steel/acrylic grinding jars), for the higher end of the market.
2.2 Main types:
2.3 Main characteristics
● Extraordinary wear resistance and service life
● Environmentally friendly material, meets FDA, LFGB, EEC, RoHS, REACH
Excellent hardness and toughness, can grind all kinds of hard coarse salt and spices.
Easy to mass produce and low cost.
2.4 Applications
● Widely used in pepper, spice, salt, herbal and other grinders.
● Widely used in manual and automatic coffee grinders, coffee machines.
3 Alumina ceramic plate, ceramic sheet, ceramic substrate
3.1 Main materials: 95% alumina, 99% alumina, 99.5% alumina and 99.8% alumina.
3.2 Main types: general ceramic plate, ceramic setter plate, ceramic substrate
3.2.1: General ceramic sheet as insulation, heat dissipation and other structural components, or wear-resistant lining use
3.2.2: Ceramic burner plate, used in a variety of high-temperature furnaces, used to burn a variety of CIM, MIM process molding parts and batteries
3.2.3: Ceramic Substrates: Used as circuit boards in various integrated circuits, standard substrate thicknesses include: 0.25mm, 0.30mm, 0.50mm, 0.635mm, 0.80mm, 1.0mm, etc.
3.3 Ceramic wafers and ceramic substrates are illustrated below:
3.4 Main characteristics of ceramic sheets and substrates:
● High temperature resistance, under inert gas protection (reducing atmosphere), the operating temperature can reach 2000℃.
High insulation strength, good insulation performance, suitable for a variety of high-current, high-voltage devices
High thermal conductivity and similar coefficient of thermal expansion to silicon (Si), often used in electric circuits.
Resistant to strong acid and alkali corrosion, oxidation resistance, good chemical stability, used in various harsh environments.
● High hardness, wear-resistant, service life is greatly improved compared with traditional materials.
Good flatness and curvature of the product, which can ensure the consistency of heat dissipation and the consistency of shrinkage of the sintered product.
3.5 General post-processing
● Double-sided grinding to improve the flatness of sintered products.
Other grinding processes, such as drilling, grooving, and various special shapes to meet customized specifications.
● Laser cutting, mainly for ceramic substrates with thin wall thicknesses.
● Metallization to print circuits on the substrate.
3.6 Applications of Ceramic Sheets and Substrates:
General ceramic sheet: insulating parts, heat dissipation parts and other structural parts, or wear-resistant lining.
Ceramic sintered plates: can be used to sinter a variety of ceramic parts, powder metallurgy injection molding products (Metallurgy injection molding – MIM), piezoelectric ceramic (piezoelectric ceramic) and ferrite products (ferrite), 3D printed products, and batteries.
Ceramic Substrates: Widely used in all kinds of thin film and thick film integrated circuits, all kinds of LED lamps, all kinds of communication devices, ozone generators, smart power semiconductors, automotive industry, all kinds of DBC/DPC substrates.
4 Alumina ceramic tube and ceramic rod
4.1 Main materials: 75% alumina, 95% alumina, 99% alumina, 99.5% alumina, and 99.8% alumina.
4.2 Types of ceramic tubes: ceramic tubes with open ends, ceramic tubes with closed ends, square tubes, semi-circular tubes, threaded tubes, porous ceramic tubes, etc., as well as a variety of shaped tubes and rods.
4.3 The relevant ceramic tube diagrams are as follows
4.4 Main characteristics of ceramic tubes and rods:
● High temperature resistance, under inert gas protection (reducing atmosphere), the operating temperature can reach 2000℃.
● High insulation strength, good insulation performance, applicable to a variety of high-current, high-voltage devices
● Resistant to strong acid and alkali corrosion, oxidation resistance, good chemical stability, used in a variety of harsh environments.
● High hardness, wear-resistant, service life is greatly improved compared with traditional materials.
4.5 General post-processing
● Surface grinding to improve the flatness of both ends of the product.
● Polishing treatment, internal or external hole polishing treatment
● Glazing, which glazes the outer diameter of the ceramic.
● Internal and external cylindrical grinding to ensure dimensional tolerances, concentricity, straightness, perpendicularity, etc.
Other grinding processes, such as drilling, grooving, and various special shapes to meet customized specifications.
4.6 Ceramic Tube Applications:
Widely used as insulation, support, protective tubing for thermocouples, or conduit for wires, wire guides, and so on.
5.Alumina ceramic seal
5.1 Main material: 95% alumina, 99% alumina
5.2 Seal type: ceramic valve plate, ceramic sealing ring/ring, ceramic valve core
5.3 Related seal pictures
5.4 Main features of ceramic valve discs and seals:
● Exceptional wear resistance
● Excellent mechanical strength, hardness and toughness.
● Chemical resistance, corrosion resistance, suitable for applications in various harsh environments.
● Low coefficient of friction and automatic lubrication.
● Low coefficient of thermal expansion, can withstand high and low temperatures
● Environmentally friendly, all materials used meet RoHS, REACH requirements.
5.5 Key Parameter Standards
5.6 General post-processing
● Surface grinding to improve the flatness, parallelism and perpendicularity of the two ends of the product.
● Polishing, mirror polishing of work surfaces.
● Other grinding processes, such as drilling, grooving, and special shapes to meet customized specifications.
5.7 Areas of application
The products are widely used as sealing rings and sealing valve plates in various spool valves, manifolds, water pumps, oil pumps, centrifuges and other products.
6 Textile ceramics
6.1 Main materials: 95% alumina, 99% alumina
6.2 Main types: ceramic eyelet, ceramic roller, ceramic pigtail,ceramic traverse guide,ceramic bobbin，ceramic hook
6.3 Pictures
6.4 Main Properties
Extraordinary wear resistance
● Low coefficient of friction
● High temperature and pressure resistance
● Chemical resistance, corrosion resistance, aging resistance
● Anti-static
● No contamination of the material
6.5 Main post-processing: Polishing
6.6 Application: Widely used in various textile machines as wire and yarn guide elements.
7 Thermostat ceramics, ceramic part for temperature controller
7.1 Ceramic material: 95% alumina,steatite
7.2 Typical types.
Ceramic insulation pin, Ceramic tube, Ceramic ring, Ceramic housing, Ceramic shell, Ceramic spacer.
7.3 Related images:
7.4 Main characteristics
● Excellent dielectric strength
● High temperature and pressure resistance
● Excellent mechanical properties
● Chemical resistance, corrosion resistance, aging resistance
7.5 Application areas
Widely used in bimetallic thermostats, flashing adjustable or fixed thermostats, liquid-expansion thermostats, liquid-expansion temperature switches, and various temperature control devices.
8.1 Main materials: 95% alumina, 99% alumina, 99.5% alumina, 99.8% alumina
8.2 Main types:
High Voltage Electrical insulators, pump components (Ceramic bushing, ceramic piston plunger), Spray nozzles, Ceramic bearings, Dielectric components for semiconductor wafer handling, ceramic robotic arm for semiconductor
8.3 Product Pictures
8.4 Main properties
● Excellent mechanical properties, high hardness
● Excellent thermal properties, heat resistance, high temperature resistance, good heat dissipation
● Chemical resistance, corrosion resistance, aging resistance
● High abrasion resistance
● Excellent electrical properties
8.5 General post-processing
● Grinding processes, such as drilling, grooving, and various special shapes to meet customized specifications
● Polishing
● Glazing
● Metallization
8.6 Areas of application
Alumina ceramics are widely used in electronics, electrical appliances, machinery, chemical industry, environmental protection, new energy, military, aerospace and almost all other modern fields.
The above various alumina ceramics applications are only an example of a part of the industrial field, alumina ceramics is the earliest research, widely used and more mature advanced ceramics, Jinghui Ceramics produces a variety of alumina ceramics products, and can be customized according to customer requirements for processing.
