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Tips for using Pyrolytic Boron Nitride Crucibles

Pyrolysis boron nitride (PBN) crucible has the advantages of high temperature resistance, high mechanical strength, high purity, and is in contact with acids, bases, and salts without chemical reactions. It has significant anisotropy in mechanical, thermal, and electrical properties, and also has excellent microwave and infrared transmittance.

When using a pyrolysis boron nitride crucible, precautions should be taken:

1. Boron nitride is prone to moisture, and crucibles should not be stored in damp areas and should not be washed with water. Before use, it must be slowly baked to 500 degrees Celsius before use. It can be directly wiped with sandpaper or wiped with alcohol.

2.When removing the molten metal material, it is best to use a spoon to scoop it out and avoid using calipers as much as possible. If using calipers or other tools, they should match the shape of the crucible to prevent some parts from bearing too much force and shorten the service life.

3. The service life of the crucible is related to its usage, and it should be avoided as much as possible to directly spray strong oxidation flames onto the crucible, which can lead to the oxidation of the crucible raw materials and shorten their lifespan.

4. The material should be loaded according to the capacity of the crucible and should not be squeezed too tightly to prevent thermal expansion and cracking of the metal material in the crucible.

5. The temperature used in the air should not exceed 1000 degrees, as the contact surface between boron nitride and oxygen will be oxidized and peeled off.

Zirconia Grinding Balls: The Secret of Nanoscale Ultrafine Grinding of Battery Materials

As a representative of the latest generation of nano battery materials, zirconia grinding beads have advantages such as high density, high strength, good wear resistance, and long service life, which can achieve nano level ultrafine grinding and dispersion of new energy battery materials.

Lithium compounds in lithium batteries have specific requirements for particle size distribution, so it is necessary to use nanoscale battery materials to improve battery performance. As a representative of the latest generation of nano battery materials, zirconia grinding beads have advantages such as high density, high strength, good wear resistance, and long service life, which can achieve nano level ultrafine grinding and dispersion of new energy battery materials.

The grinding principle of zirconia grinding balls is that the zirconia grinding balls collide and shear the battery material particles under the driving force of the sand mill, thereby achieving the effect of reducing particle fineness. They have distinct characteristics in the grinding application of positive and negative electrode materials.

The application of zirconia grinding balls in positive electrode materials is mainly made of lithium iron phosphate material, while the negative electrode is mainly made of silicon carbon negative electrode. The target fineness of the two is greatly different: the former is worth noting that both lithium iron phosphate and silicon carbon negative electrode materials have a common feature of using a rod pin sander for grinding.

The rod pin sand mill has a high linear speed and a large amount of kinetic energy transmitted to grind zirconia grinding media balls, making it suitable for efficient grinding of battery materials; At the same time, higher requirements have been put forward for the performance of zirconia grinding balls used in it, requiring good wear resistance and less prone to breakage.

From the sky to the land, the four major fields of silicon nitride ceramics fulfill their mission

The Origin and Development of Silicon Nitride Ceramics

Silicon nitride (Si3N4) is a covalent bond compound composed of silicon and nitrogen. It was discovered in 1857, but some scholars, especially German researchers, did not fully agree with its chemical composition. Later, a large amount of research confirmed the correctness of this chemical formula, which has been widely cited until now.

Next, we will introduce the important applications of silicon nitride ceramics from four fields.

The soul of No.1 rotating machinery, the carving knife of mechanical components

Silicon nitride ceramics have a wide range of applications in mechanical fields such as high-speed turning tools, bearings, engine blades, guide blades of gas turbines, and turbine blades.

Among them, bearing balls are the most widely used silicon nitride ceramic products, accounting for three tenths of the world”s high-performance silicon nitride products in annual production. Silicon nitride ceramic bearing balls have outstanding advantages compared to steel balls: low density, high temperature resistance, self-lubrication, corrosion resistance, and the same fatigue life failure mode as steel balls. As a high-speed rotating body, ceramic balls generate centrifugal stress, while the low density of silicon nitride reduces the centrifugal stress on the high-speed rotating outer ring. Dense Si3N4 ceramics also exhibit high fracture toughness, high modulus properties, and self-lubrication, which can resist various types of wear and endure harsh environments that may cause cracks, deformation, or collapse of other ceramic materials, including extreme temperatures, large temperature differences, and ultra-high vacuum. Therefore, silicon nitride ceramic bearing balls can be widely used in fields such as precision bearings for machine tools, automotive bearings, insulated bearings for wind turbines, corrosion-resistant and high-temperature bearings for petrochemical industry.

Especially, in addition to these excellent properties, silicon nitride bearings also have insulation properties, which can solve the problems of electrical corrosion often causing bearing surface damage, premature aging of lubricants, and abnormal noise, avoiding shortening the service life of bearings and lubricants, ultimately leading to bearing failure. They are very suitable for applications in fields such as electric vehicles.

Another classic application of silicon nitride ceramics in the mechanical field is high-speed cutting tools.

NO.2 wear-resistant and corrosion-resistant field, very resistant to beating

Silicon nitride ceramics have excellent corrosion resistance and wear resistance. Their excellent creep resistance, oxidation resistance, and low thermal expansion enable silicon nitride ceramics to meet the harsh conditions of application. In addition to bearings and cutting tools, the wear-resistant and sealing components of silicon nitride ceramic materials can also be applied in many harsh environments. The silicon nitride ceramic prepared by the hot pressing process in Saint Gobain, France has good high-temperature strength, corrosion resistance, and creep resistance. It is an ideal sealing surface material in the nuclear industry and can be applied to boiler reactor water pumps, pressure water reactor water pumps, and corrosive boric acid water treatment, It can also be applied to rotating components such as compressors, engines, generators, motors, and turbines.

In addition, silicon nitride also holds a place in the field of ultrafine grinding. Silicon nitride has high hardness, second only to a few superhard materials such as diamond and cubic boron nitride, and has low friction coefficient and self-lubricating properties. In the ultra-fine powder and food processing industries, the performance of silicon nitride ceramic grinding balls is higher in hardness and superior in wear resistance compared to traditional grinding balls.

NO.3 Aerospace field, very reliable in harsh environments

Silicon nitride ceramic materials have advantages such as high strength, high temperature resistance, and good chemical stability, which can meet the stringent requirements of materials in the aerospace industry. Silicon nitride ceramics have two classic applications in the aerospace field:
firstly, silicon nitride is considered one of the few monolithic ceramic materials that can withstand severe thermal shock and thermal gradients generated by hydrogen/oxygen rocket engines, and is used in rocket engine exhaust nozzles. In 2010, the tail nozzle of Japan”s space probe Akatsuki thruster was made of silicon nitride material, and the silicon nitride tail nozzle prepared by Kyocera has been successfully applied to small aircraft and rocket engines. Compared to metal materials, silicon nitride ceramic nozzles can withstand higher combustion temperatures, allowing the thruster to obtain greater thrust. The high stability of the nozzle edges makes the jet airflow more uniform.

The second is to serve as bearings for aviation engines. In the design of aircraft engines, bearing materials and technology always account for over 90% to 95%. It can be said that bearing technology represents the ultimate speed, temperature resistance, and reliability level of the engine. Ceramic bearings, with their excellent performance, can provide important basic technical support for the development of the aviation equipment field, especially the hot isostatic pressing sintered silicon nitride ceramic bearings, which provide core technical support for the development of aerospace. After more than 50 years of research and accumulation, Si3N4 ceramic bearings have been applied in helicopter main transmissions, aviation APUs, aircraft accessory transmissions, missile engines, rocket engines, and aerospace satellites, becoming standard bearings for high-speed and high-power spindles in high-end manufacturing equipment.

NO.4 chemical and metallurgical industry, fearless of 1400 ℃ high temperature test

Silicon nitride ceramic materials have excellent chemical stability and mechanical properties, and can be used as components in thermal equipment such as crucibles, combustion nozzles, and aluminum electrolytic cell liners in the metallurgical industry. Silicon nitride ceramics have good oxidation resistance, with an oxidation resistance temperature of up to 1400 ℃. They remain stable in a dry oxidation atmosphere below 1400 ℃ and can be used at temperatures up to 1300 ℃. And silicon nitride materials can be applied in environments with rapid cooling and heating, so they also have extremely wide applications in the metallurgical industry.

Aluminum nitride: a material that has been “conquered” in the semiconductor field

Aluminum nitride is a typical third-generation semiconductor material. It has an extremely wide band gap and very large exciton binding energy, of which the band gap width is 6.2 eV, which belongs to a direct band gap semiconductor. As aluminum nitride has a variety of outstanding physical properties, such as high breakdown field strength, thermal conductivity, resistivity, etc., it has always been concerned in the semiconductor field, and is also a material that has been “conquered” in the semiconductor field.

Performance characteristics of aluminum nitride

ALN is a crystal dominated by covalent bonds and belongs to hexagonal diamond-like nitride. Its theoretical density is 3.26g/cm3, and its Mohs hardness is 7~8. It has high strength at room temperature, and its strength will decline slowly with the increase of temperature.

Compared with several other ceramic materials, aluminum nitride has excellent comprehensive properties, especially its excellent thermal conductivity, which is very suitable for semiconductor substrates and structural packaging materials, and has great application potential in the electronic industry.

Application of aluminum nitride in semiconductor field：

1. Ceramic packaging substrate

Ceramic packaging substrate With the vigorous development of microelectronics and semiconductor technology, motors and electronic components step into the era of miniaturization, lightweight, high energy density and high power output. The heat flow density of electronic substrate has increased significantly, and maintaining a stable operating environment inside the equipment has become a technical problem that needs to be focused on. ALN ceramic is considered as an ideal material for new generation heat dissipation substrate and electronic device packaging because of its high thermal conductivity, thermal expansion coefficient close to silicon, high mechanical strength, good chemical stability, environmental protection and non-toxic characteristics.

Compared with Al2O3 ceramic substrate and Si3N4 ceramic substrate, ALN ceramic substrate has these advantages: using ALN ceramic substrate as the carrier of the chip can isolate the chip from the module heat dissipation backplane, the ALN ceramic layer in the middle of the substrate can effectively improve the insulation capacity of the module (ceramic layer insulation withstand voltage>2.5KV), and aluminum nitride ceramic substrate has good thermal conductivity, and the thermal conductivity can reach 170-260W/mK. In addition, the expansion coefficient of ALN ceramic substrate is similar to that of silicon, which will not cause stress damage to the chip. The peel resistance of aluminum nitride ceramic substrate is>20N/mm2, which has excellent mechanical properties, corrosion resistance, is not easy to deform, and can be used in a wide temperature range.

2. Semiconductor equipment components

The semiconductor equipment parts are very important for the heat dissipation of the silicon wafer in the semiconductor processing. If the uniform temperature of the silicon wafer surface cannot be guaranteed, the uniformity of the processing will not be ensured during the processing of the silicon wafer, and the processing accuracy will also be affected.

The advantages of using aluminum nitride as the main material for the aluminum nitride electrostatic chuck are that: a wide range of temperature range and sufficient adsorption force can be obtained by controlling its volume resistivity, and the electrostatic chuck can achieve good temperature uniformity through the high degree of freedom heater design; The aluminum nitride is formed through integrated co firing, which will not cause lasting changes due to electrode degradation, and will ensure the product quality to the maximum extent; Lasting operation in plasma halogen vacuum atmosphere to withstand the most demanding process environment of semiconductor and microelectronics, it can also provide stable adsorption and temperature control.

3. High temperature structural materials

Aluminum nitride ceramics have good corrosion resistance, stability and insulation at room temperature and high temperature. It will decompose at 2450 ℃. It can be used as high-temperature refractory materials, such as crucibles and casting molds. Aluminum nitride ceramics can not be wetted by copper, aluminum, silver and other substances, and can resist the corrosion of aluminum, iron, and aluminum alloys. It can become a good container and high-temperature protective layer, such as thermocouple protective tubes and sintering appliances; It can also resist the erosion of high-temperature corrosive gas, and is used to prepare aluminum nitride ceramic electrostatic chuck, which is an important high-end component of semiconductor manufacturing equipment. As aluminum nitride is stable to molten salts such as gallium arsenide, such as aluminum nitride crucibles, thermocouple protection tubes and sintering appliances, it can also be used as containers and processors for corrosive substances instead of glass to synthesize gallium arsenide semiconductors, which can eliminate silicon pollution from glass and obtain high-purity gallium arsenide semiconductors. The aluminum nitride is very stable under the non oxidizing atmosphere until 2000 ℃, so it can be used as the aggregate of refractories used under the non oxidizing atmosphere.

Why is the grinding efficiency of the ceramic grinding bowl on a planetary ball mill higher than that of a common grinding machine

The reason why ceramic ball mills on planetary ball mills perform well in terms of grinding efficiency is closely related to their unique structure and working principles.

The main reasons:

1.Multidimensional motion: The planetary ball mill uses grinding balls fixed to a turntable to cause complex, multidimensional movements inside the mill bowl when they are subjected to rotating and autorotating motion at various speeds. This multidimensional movement not only enables more uniform mixing of the grinding medium and samples, but also enables more efficient collisions and milling processes, thus increasing grinding efficiency.

2.High collision energy: The collision energy between balls and between balls and samples in planetary ball mill cylinder is higher, as the combination of multidimensional motion and high speed rotation, larger impact and shear forces are produced, which can accelerate grinding and mixing processes and improve grinding efficiency.

3.Small sample particle size: Planetary ball mills are suitable for grinding small particle samples, because with multiple dimensions of movement, small particles are able to undergo more substantial impaction and milling to reach the required fineness level of polishing.

How can ceramic alumina balls improve grinding performance in ball mills

Ball mills are used to grind botanical (or other) material to a desired particle size. The particles can then be used in later processing.

Industrial-grade efficiency and consistency are the key advantages of a bill mill or ball grinder. Even a novice end user can use a ball grinder to quickly output material at the chosen particle size.

Ceramic alumina grinding balls is characterized by high hardness, high density, low wear, good regularity and corrosion resistance. It is ideal and efficient grinding medium for grinding glaze, blank and various mineral powders.

The Advantages of Ceramic alumina grinding balls in Ball Mills:

1. Enhanced Grinding Efficiency

Ceramic alumina balls possess an innate ability to withstand extreme mechanical forces and maintain their structural integrity. This resilience translates to efficient grinding, as the balls effectively break down particles, ensuring thorough comminution and reducing processing times.

2. Reduced Contamination

In industries where purity is paramount, such as pharmaceuticals and advanced ceramics, ceramic alumina balls shine. Their chemical inertness minimizes the risk of cross-contamination, ensuring that your materials maintain their integrity throughout the milling process.

3. Extended Lifespan

Thanks to their remarkable wear resistance, ceramic alumina balls exhibit prolonged lifespan even under harsh milling conditions. This longevity translates to cost savings and reduced downtime for ball mill maintenance and replacements.

BN crucible, an essential production component in the semiconductor industry

Boron Nitride is an advanced ceramic material with broad application prospects. It is a crystal composed of nitrogen and boron atoms, with a chemical composition of 43.6% boron and 56.4% nitrogen. It has four different variants: hexagonal boron nitride (HBN), cubic boron nitride (CBN), rhombic boron nitride (RBN), and wurtzite boron nitride (WBN).

Due to the fact that boron nitride material has a thermal expansion coefficient comparable to quartz, but a thermal conductivity that is 10 times that of the latter, it has excellent thermal shock resistance and can reduce the risk of cracking due to rapid temperature changes. It can be cycled several times at 20-1200 ℃ without any problem. In addition, boron nitride does not react with acids, alkalis, glass, and most metals, and has low mechanical strength, only slightly higher than graphite. However, there is no load softening phenomenon at high temperatures, and it can be processed by general metal processing machines. Therefore, it is indeed suitable for use as crucibles, vessels, liquid metal conveying pipes, and molds for casting steel for melting and evaporating metals.

Boron nitride can be used to manufacture crucibles for melting semiconductors, high-temperature vessels for metallurgy, semiconductor heat dissipation insulation parts, high-temperature bearings, thermocouple sleeves, and glass forming molds.

Currently, there are two types of boron nitride crucibles on the market:

1. PBN crucible

Usually, boron containing gas (BCl3 or B2H6) is used as the raw material and produced by chemical vapor deposition method. However, due to the high toxicity of B2H6, BCl3 is currently mostly used as the raw material. The boron containing gas undergoes pyrolysis (1500-1800 ℃) and reacts with NH3 in a high-temperature reaction chamber to form boron nitride solid. The chemical equation is as follows. Because pyrolysis reactions occur during the reaction, it is also known as a boron nitride crucible for pyrolysis (commonly known as a PBN crucible).

BCl3+NH3=BN+HCl

The growth process of PBN materials is similar to “falling snow”, where hexagonal BN flakes grown during the reaction continuously pile up on the heated graphite matrix (core mold). As time goes on, the stacking layer thickens, forming the shell of PBN. After demolding, it becomes an independent and pure PBN component, and when left on top of it, it becomes a PBN coating.

Due to the fact that PBN crucibles do not need to undergo traditional hot pressing sintering processes and do not require the addition of any sintering agents, they have a high purity (over 99.99%) and can be used at temperatures up to 1800 degrees Celsius under vacuum, with a maximum temperature of 2100 ℃ under atmosphere protection (usually using nitrogen or argon gas). They are mostly used for vapor deposition/molecular beam epitaxy (MBE)/GaAs long crystals and other purposes. In addition, due to the slow deposition rate, PBN crucibles are quite expensive (mostly small-sized crucibles).

2. Sintered BN crucible

The sintered BN crucible is made from hexagonal boron nitride and sintering aids (Y2O3, etc.) as raw materials. After forming, it is produced by high-temperature sintering, and also has good heat resistance, thermal stability, thermal conductivity, and high-temperature dielectric strength, which can resist the erosion of most molten metals.

However, due to the presence of sintering aids (1-6wt%) in the sintered BN crucible, its purity is not as high as that of PBN crucible. However, the price is relatively much cheaper and suitable for making large-sized crucibles, which can be used in inert gases such as argon or nitrogen at a maximum temperature of 2800 ℃; The stability in oxygen is poor and can only be used below 900 ℃.

In summary, although boron nitride crucibles may have a higher cost, they are quite practical in specific fields due to their excellent thermal shock characteristics, corrosion resistance, lubricity, high-temperature insulation, and high-temperature non reactivity.

For example, due to the excellent chemical stability of P-BN, as well as the high-temperature insulation characteristics, high thermal conductivity, and low thermal expansion performance mentioned above, it is very suitable for use as a material in strict environmental conditions such as semiconductor manufacturing, such as gallium arsenide, gallium phosphide, and indium phosphide. Meanwhile, due to its excellent mechanical processing performance, extremely high temperature resistance, and dielectric strength, boron nitride crucibles can also be used to make insulation materials or glass fixtures for various heaters, heating tube sleeves, and high-temperature, high-frequency, and high-pressure heat dissipation materials.

Precautions for product application and use:

1. Boron nitride is prone to moisture absorption, and the crucible cannot be stored in damp areas and cannot be washed with water. It can be directly wiped with sandpaper or wiped with alcohol.

2. The temperature used in the air should not exceed 1000 degrees, and the contact surface between boron nitride and oxygen will oxidize and peel off.

Ceramic Grinding Balls Series-Zirconia Toughened Alumina

Zirconia Toughened Alumina balls are a type of ceramic grinding media commonly used in ball mills for various industrial applications. They are made by blending alumina and zirconia powders, which results in a material that combines the high hardness and wear resistance of alumina with the toughness and fracture resistance of zirconia.

Zirconia Toughened Alumina (Zirconia Toughened Alumina balls) balls have several distinct differences compared to other types of grinding balls:

1. Composition: Zirconia Toughened Alumina balls balls are made by blending alumina and zirconia powders, whereas other grinding balls may be composed of different materials such as steel, ceramic, or glass.

2. Mechanical properties: Zirconia Toughened Alumina balls balls combine the high hardness and wear resistance of alumina with the toughness and fracture resistance of zirconia. This unique combination gives Zirconia Toughened Alumina balls balls superior strength and durability compared to other grinding balls, allowing them to withstand heavy impacts and high stress conditions without breaking or chipping easily.

3. Wear resistance: Zirconia Toughened Alumina balls balls are known for their exceptional wear resistance. The alumina component provides high hardness, which helps in maintaining the shape and integrity of the balls even under abrasive conditions. This results in reduced wear on the balls themselves and the grinding equipment, leading to longer lifespan and lower maintenance costs.

4. Grinding efficiency: Due to their hardness and wear resistance, Zirconia Toughened Alumina balls balls offer improved grinding efficiency compared to other grinding media. They can effectively grind and reduce the particle size of various materials, resulting in finer and more consistent product output.

5. Contamination: Zirconia Toughened Alumina balls balls have low levels of contamination, making them suitable for applications where purity is important. Unlike steel grinding balls, they do not introduce metallic impurities to the processed material. This feature is particularly beneficial in industries such as pharmaceuticals, food processing, and electronics manufacturing.

Zirconia Toughened Alumina balls stand out from other grinding balls due to their unique composition, mechanical properties, wear resistance, grinding efficiency, low contamination levels, and customization options. These factors make them a preferred choice for various industrial grinding and milling applications.

Aluminum Nitride Crucibles For Vacuum Evaporation And Metal Smelting Containers

Aluminum Nitride, represented by the formula AlN, belongs to the family of advanced technical ceramics and possesses a covalent bond with a hexagonal crystal structure. This material boasts exceptional thermal, mechanical, and electrical properties, including high thermal conductivity, low dielectric constant, high electrical resistivity, low density, and a thermal expansion coefficient that closely matches that of silicon. Its primary application is as a substrate for electronics or chip carriers, and it is also utilized, alongside PBN crucibles, in the construction of crucibles for growing GaN (gallium nitride) crystals.

Aluminum nitride crucibles demonstrate remarkable resistance to oxidation in air up to 1300°C, though oxidation initiates after 700°C. In a vacuum environment, AlN decomposes at 1800°C, while its melting point is 2200°C under inert atmosphere protection. Generally, AlN products can be safely used up to 800°C in air, 1700°C in vacuum, and 2100°C in an inert atmosphere.

These ceramics find applications as containers for vacuum evaporation and metal smelting, particularly well-suited for vacuum evaporation crucibles for aluminum. This is due to their ability to resist decomposition in a low vapor pressure vacuum, preventing aluminum contamination. In the semiconductor industry, substituting quartz crucibles with aluminum nitride crucibles for synthesizing arsenide eliminates Si pollution on GaAs, ensuring the production of high-purity products.

However, it is important to note that aluminum nitride ceramics react chemically with inorganic acids, strong bases, water, and other liquids, causing slow dissolution. Thus, they should not be directly immersed in such substances. On the contrary, these ceramics can withstand the corrosion of most molten salts, including chlorides and cryolite (Na3AlF6).

Due to the small bottom size of aluminum nitride crucibles, they are typically placed on a clay triangle during heating and should not come into direct contact with metal or wooden supports after intense heating. Furthermore, sudden cooling after heating should be avoided, and instead, the crucibles should be allowed to cool naturally on the clay triangle or gradually on asbestos gauze before handling them with a crucible tong.

Stirring the substance until nearly evaporated, then turn off the heat, and steam it with the remaining heat.

How Ceramic Utility Knives Bring Safety to the Laboratory Oratory

All Advanced utility knives Have Great Properties.

Blade will never rust. Chemically inert blade won”t react with material it”s cutting. No oil coating or maintenance required. Blade is safe up to 1600 degrees, Celsius.

Although Utility Knives were not designed exclusively for use as Laboratory knives, In an industrial setting, such a cut is not only debilitating, but it can hurt your company’s safety record and bottom line.

Unlike metal knives, our Utility Knives never rust. This can be especially critical when working with blood samples to perform blood typing, cross-matching, and screening processes. Rust creates pits in the metal that can retain microscopic residue of prior blood samples, even after the instrument has been cleaned. This results in an increased potential for cross-contamination of blood samples, invalidating results. Utility Knives are made from 100-percent zirconium oxide, an material that is:

Non-sparking

Non-conductive

Non-magnetic

Chemically inert

Not only do our safety blades never rust, but also they’re very easy to clean. The same engineered ceramics used in our knife blades are used in our ceramic utility knives. Cleaning these ceramics is easy.