An overview of the technicail ceramics-Beryllium oxide ceramics (BeO ceramic)

Properties of Beryllium Oxide Ceramics

Beryllium oxide has high thermal conductivity, high insulation, high melting point, high strength, low dielectric constant, low dielectric loss, high chemical and stability, and good process adaptability, The biggest advantage of BeO is great high thermal conductivity-285W. (m/K), Therefore, BeO has been the mainstream ceramic material for the preparation of high thermal conductivity components in high-power semiconductor devices, integrated circuits, microwave electric vacuum devices, and nuclear reactors.

Its excellent electrical properties are also important. The dielectric constant ε is a measure of the ability of a dielectric to store charge, often referred to as the capacitance, and is a characteristic parameter of ceramics. The dielectric loss angular tangent tanδ is part of the power loss of the ceramic in an electromagnetic field and is the key special parameter. Both are affected by chemical composition, bulk density, microstructure, as well as frequency and temperature. For beryllium oxide ceramics, it is usually the case that: as the dielectric loss angular tangent tanδ increases, ε does not change much. However, there are cases where the value of ε becomes slightly larger as the frequency increases; or ε becomes slightly smaller as the frequency increases. So, BeO has an advantage: low dielectric loss!

Production Processes of hyper-pure beryllia.

The methods of producing high-purity beryllium oxide are the beryllium sulfate crystallization method, alkaline beryllium acetate decomposition method, and hydrolysis complexation method.

(1) Beryllium sulfate crystallization method.

The beryllium sulfate crystallization method is a method to crystallize beryllium sulfate and leave the impurities in the solution before removing, the process varies depending on the purity of the raw materials used and the requirements for product purity. If the purity of raw material beryllium hydroxide is low and the product purity is high (BeO≥99.9%), the pre-purification method can be used to remove some impurities first, then evaporate the beryllium sulfate solution, cool the crystallization, and finally decompose and calcine the beryllium sulfate crystals to obtain high purity beryllium oxide of the required purity. Or without the pre-purification process, only the beryllium sulfate recrystallization method is used to produce high-purity beryllium sulfate crystals, and finally decompose and calcine them at high temperature to obtain the desired purity of high-purity beryllium oxide. In the case of high purity of raw material beryllium hydroxide (equivalent to BeO≥99.0%) or low purity requirement of the product, only dissolve the beryllium hydroxide with sulfuric acid and carry out one evaporation crystallization to obtain high purity beryllium oxide of the desired purity.

(2) Alkaline beryllium acetate thermal decomposition method.

The alkaline beryllium acetate thermal decomposition method is to make industrial beryllium hydroxide react with acetic acid to make alkaline beryllium acetate, then sublimate under the condition of vacuum heating, then purify by distillation and thermal decomposition to make high purity beryllium oxide with high purity and dispersion.

(3) Hydrolytic complexation method.

The hydrolytic complexation method is to dissolve industrial beryllium hydroxide in sodium hydroxide solution, then, dilute hydrolysis to precipitate beryllium hydroxide, then dissolve by sulfuric acid, add chelating agent complexation, neutralization, and precipitation, drying and calcination process to produce high purity beryllium oxide. The hydrolytic complexation process is simple and the equipment is less corrosive, but the product purity is low (BeO≥99.50%).

Applications of Beryllium Oxide Ceramics

Application Development Timeline

①1930s: BeO began to be used as a ceramic material, initially for crucibles for metallurgy and earlier for fluorescent lamp manufacturing.

②1940s: BeO ceramics were used in large quantities for certain reactors as moderators and reflectors.

③In the 1970s, BeO ceramics were more widely used in electronic devices and the electronics industry.

④In the 1980s, the most important use of BeO ceramics was applied to the electronic ignition system of automobiles; in addition, it was also used in IC substrates for high-speed signal transmission, laser tubes on gyroscopes, automotive parts and braking devices, etc.

⑤ In the 1990s, with the rapid development of science and technology, communication technology, and other fields, the application of BeO ceramics in areas such as communication and the microelectronics industry has been expanding.

⑥In the 21st century, BeO ceramics are expanding their applications in the increasingly progressive development of electronic packaging materials and technologies because of their high thermal conductivity and excellent electrical properties.

1. High-power electronic devices/integrated circuit field

The high thermal conductivity and low dielectric constant of beryllium oxide ceramics are the key reasons why this material can be widely used in the field of electronic technology.

(1) In the application of electronic substrates, compared to our more recognized alumina substrates, beryllium oxide substrates can be used at 20% higher frequencies with the same thickness and can operate at frequencies up to 44 GHz, often used in communications, live satellite, cell phones, personal communications, base stations, satellite reception and transmission, avionics, and global positioning systems (GPS).

(2) Compared with alumina ceramics, the high thermal conductivity of beryllium oxide ceramics can make the heat generated in high-power devices conduct out in a timely and effective manner, and can withstand greater continuous wave output power, thus ensuring the stability and reliability of the devices. Therefore, it is also widely used in broadband high-power electronic vacuum devices, such as the energy transfer window of traveling wave tubes, support poles, and buck collection poles.

2. Nuclear technology material field

The development and utilization of nuclear energy is an important way to solve the problem of energy shortage today. The rational and effective use of nuclear energy technology can provide great energy for social production to supply electricity and heat. Some ceramic materials are also important in nuclear reactors, for example, the neutron reflector and decelerator (moderator) of nuclear fuel is usually used by using BeO, B4C, or graphite materials. Beryllium oxide can be used as a neutron reducer and radiation protection material for atomic reactors. In addition, BeO ceramics have better high-temperature irradiation stability than metallic beryllium, higher density than metallic beryllium, higher strength and thermal conductivity at high temperatures, and beryllium oxide is cheaper than metallic beryllium. This makes it more suitable for use as a reflector, reducer, and dispersive phase fuel matrix in reactors. Beryllium oxide ceramics can be used as control rods in nuclear reactors, and it can be used in combination with U2O (uranium oxide) ceramics as nuclear fuel.

3. Refractory material field--the crucible can work at temperatures up to 2000°C.

Due to their high melting temperature (~2550°C), high chemical stability (alkali resistance), thermal stability and purity, BeO ceramics are used to melt glazes and plutonium. In addition, these crucibles have been successfully used to produce standard samples of silver, gold, and platinum, and the high "transparency" of BeO to electromagnetic radiation allows induction heating to be used to melt the metal samples in them.

Beryllium oxide ceramics are used as refractory materials for refractory support rods for heating elements, thus protecting shields, furnace linings, thermocouple tubes as well as cathodes, thermal heating substrates coatings, etc.

4. Other fields

In addition to the above examples, there are many other applications of beryllium oxide ceramics.

①BeO can be added as a component to glasses of various compositions. Glass containing beryllium oxide can transmit X-rays, and X-ray tubes made from this glass can be used for institutional analysis and in medicine to treat skin diseases. Beryllium oxide affects glass properties, such as increasing the specific gravity, water resistance, and hardness of the glass, improving the coefficient of expansion, refractive index, and chemical stability. It can be used not only as a component of special glass with a high dispersion coefficient but also as a component of glass that transmits ultraviolet light.

②High-purity BeO ceramics have good heat transfer performance and can be used to make rocket head cones, etc.

③ BeO can be made with Be, Ta, Mo, Zr, Ti, Nb, and other metals with a specific line (expansion) coefficient and special thermal properties of metal-ceramic products, such as Ford and General Motors in the automotive ignition device using a sprayed metal BeO liner.

Although BeO is a very toxic substance, its dust and vapor is a level of high toxicity, it is preventable, and beryllium oxide ceramics as a sintered body is non-toxic, with the continuous development of related science and technology, the application scale of beryllium oxide products will be further expanded, we should not "talk about beryllium".

Coraynic is one of the professional Beryllium oxide ceramic suppliers, with a complete industrial chain from high-purity beryllium oxide raw materials to beryllium oxide ceramics. With complete production facilities, professional testing equipment, Strict quality control instruments, an Experienced R&D team, and skilled production staff. We produce beryllium oxide ceramic substrates with excellent thermal conductivity, low dielectric constant and dielectric loss, reliable insulation performance, high-temperature resistance, corrosion resistance, thermal expansion coefficient close to that of silicon, and high reliability of packaging. Beryllium oxide ceramic clamping rod has low dielectric constant, low microwave loss, high strength and good thermal conductivity, high processing accuracy and good consistency, applied with traveling wave tube, supporting its spiral type structure and providing good heat dissipation channels. Beryllium oxide ceramic crucibles can be used for melting rare and precious metals, especially for applications requiring high-purity metals or alloys, and can be used at working temperatures up to 2000 C°. Due to its high melting temperature (2550 C°), high chemical stability (alkali resistance) thermal stability, and purity, beryllium oxide ceramics can also be used for melting uranium and plutonium. Beryllium oxide ceramic cylinder, ceramic tile, and ceramic plate, according to the different structure designs for the traveling wave tube collection pole, receive electron injection and will be converted into heat energy to pass out, and can achieve multi-stage voltage reduction. Beryllium oxide attenuating ceramic is used in microwave electric vacuum devices such as traveling wave tubes, speed modulation tubes, etc. It is an indispensable key material in traveling wave tubes for total signal absorption, reflection reduction and selective suppression of various modes of spurious waves to ensure a given microwave parameter and improve the stability of the device.