Introduction
One advanced ceramic material that stands out particularly well when discussing electrical insulation and thermal conductivity is Boron Nitride. It possesses a lot of impressive qualities that ceramic engineers and manufacturers look out for. Interestingly, technology has now made it so easy for you to maximize all the amazing properties of boron nitride. So, if you’re wondering, what can I do with this boron nitride? Or what is boron nitride used for aside from electrical insulation and thermal conductivity? Then today’s article comes in handy to explain its uses and why it has become so relevant to manufacturing industries globally. Here, you will also learn about the various ways industries produce boron nitride. Let’s Go!
What is Boron Nitride?
Boron Nitride (BN) is a powdered crystalline compound formed from the industrial combination of boron and nitrogen under high-temperature conditions. It’s colorless and extremely hard with an impressive crystal structure that is covalently bonded. Most traders fondly call it white graphite due to the close properties it shares with graphite, especially in terms of lubrication. Boron nitride hardness and thermal stability are almost the same as diamond and silicon carbide.
You can find various forms of it in the ceramic market. Forms like - hexagonal boron nitride (Hbn) and cubic boron nitride (CBN), are two of the most common grade types. However, most manufacturers tend to use the hexagonal boron nitride form in metal casting and nanotechnology due to its similarity to graphite, unique stability, low friction, and excellent heat dissipation. While cubic boron nitride is also a very desirable option because of its exceptional hardness. Therefore, one major area cubic boron nitride can help you is in the production of high-grade cutting tools.
Generally, boron nitride is known for its high strength, lightweight, and great resistance to rusting, high temperatures, wear, and tears. It’s a highly refractory ceramic material used by many manufacturing industries due to its thermal stability. They use it mostly in the powdered state (boron nitride powders) to produce high-temperature materials and equipment. Some of these are: glass, heat sinks, LED lights, solid lubricants, electric furnaces, spare parts used in automotive and aerospace industries, heaters and crucibles used in the lab or production houses, etc. One way they achieve this with boron nitride powders is by sintering it under high temperatures and pressure vacuum within a given time frame depending on the quantity produced.
Properties of Boron Nitride
Some of the exciting properties of boron nitride are:
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It is insoluble in water
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It is highly resistant to extreme temperatures, acids, and other strong chemicals.
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It has a knoop hardness of about 45 GPa.
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The hexagonal boron nitride form has a density of 3.45 g/cm³ while the cubic nitride form has a slightly reduced density of 2.1 g/cm³
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It has an electron mobility of 200 cm²/V. S
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It has a refractive index reaching about 2.1
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It has a very high melting point of around 2,900°C
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It has a specific heat capacity of 19.7 J/K.mol
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At threshold temperatures of about 1,400 - 1500°C, Hbn reacts well with solids like Iron (Fe), Nickel (Ni), and Cobalt (Co)
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It has a molar mass of 24.82 g/mol
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It has a maximum band gap of 10.7 eV
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It has a thermal expansion coefficient of about 2.7
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It has a high thermal conductivity of 740 W/m.K
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It has a bulk modulus of 400 GPa
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It is a solid abrasive with a high wear resistance.
Industrial Uses of Boron Nitride
What is boron nitride used for? The truth is, that boron nitride can be used for so many applications in a wide variety of industries. Some of them include:
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The production of high-temperature furnace linings and elements.
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Nanotechnology uses boron nitride powder to produce high-precision nanotubes for ceramic fillers.
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The production of high-performance heating elements like electric furnaces, heaters, and heat sinks.
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Biomedical engineering and medicine use it for bioimaging and the production of chemotherapeutic drugs used in the diagnosis of certain diseases.
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Electrical industries use boron nitride to produce some of the best electrical components and electrical insulators available today due to the absence of free electrons in the crystal structure.
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Some of the cutting and grinding tools produced by the metallurgical industries you see today use boron nitride powders due to their wear-resistant property.
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Boron nitride can help you produce MOSFETs, vacuum systems, power electronics, strong li-ion batteries, and LED Lights.
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Manufacturing companies use boron nitride to produce heavy industrial machines utilized in injection molding, metal casting, crucibles, and glass.
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Boron nitride powder (Hbn) is a form of solid lubricant used in production machines and tribology.
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Boron nitride powder can help you coat virtually any kind of material and it would last long enough without rusting.
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Hexagonal boron nitride is used in the cosmetics industry for the production of high-purity cosmetics products.
Boron Nitride Manufacturing Process
Any high-purity boron nitride manufacturing process is a high-cost effective procedure. With boron nitride reacting poorly to sintering at times, it can pose some technical challenges especially when trying to maintain uniformity in large-scale productions. However, here are four main boron nitride manufacturing processes you can choose from:
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Chemical Vapour Deposition (CVD):
One of the most common boron manufacturing processes you can find is chemical vapor deposition. It’s a versatile method that can help you produce high-purity boron nitride powders. In this procedure, precursors from boron and nitrogen like ammonia borane are vaporized with a hot filament. The product obtained from the vaporization is reacted with a pure substrate to give boron nitride. You can use different types of substrates depending on the level of thickness or roughness you are looking to get. While this boron manufacturing process is a very costly one, it can easily help you synthesize films/substrates with defects.
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Physical Vapor Deposition (PVD):
You can also synthesize boron nitride using this method. It’s less expensive and straightforward compared to CVD. Here, all you need to do is to bombard ions on a boron nitride target which then leads to an automatic ejection of the atoms hitting the boron nitride target surface. This procedure is more of evaporation, afterwards, you can heat these ejected atoms (under high temperatures) on any substrate of your choice, preferably silicon substrates till they vaporize. Then, get a thin film and deposit the resulting boron nitride. The major technical challenge here is controlling the deposited boron nitride film. However, you can still get high-purity boron nitride from this procedure.
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Sol-Gel Method:
The sol-gel boron nitride manufacturing process is used mostly in small-scale production of Bn because it can be time-consuming. It involves the mixing of an inorganic or in some cases organic precursors of nitrogen and boron into a solution, then hydrolyzing it till you get a liquid colloidal particle suspension. Next up, add citric acid to form a gel and then evaporate the solvent. With spin coating or dip coating techniques, you can get thin boron nitride films from this gel solution. This method is not as expensive and widely used as CVD or PVD, but it’s still a reliable process to produce high-quality nanoparticles of boron nitride. The evaporation process can take up to a day or two. So, for someone not in a hurry and also not looking to spend so much, this is a very suitable boron manufacturing process you could take advantage of.
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Hydrothermal Synthesis:
This method involves very high temperatures and pressure. As such, it could be risky due to possible explosions if not properly controlled. Here, you will need to get a pure solution of nitrogen and boron compounds in a hydrothermal reaction vessel containing metal ions. However, you must ensure you’ve heated and pressurized the solution before placing it in the completely sealed hydrothermal vessel for a maximum of 24 hours. Add reagents that would increase the speed of the reaction and also maintain a consistent pH. The best temperature range to use in this method is 250°C or lower. After the necessary reactions have taken place, you will get flat, long boron nitride nano-sized precipitates.
Frequently Asked Questions
What are the best forms of boron nitride?
The best forms of boron nitride are the cubic and hexagonal boron nitride grade types.
At what temperature can hexagonal boron nitride be produced industrially?
Hexagonal boron nitride can be produced industrially under high temperatures reaching over 900°C. This makes them capable of withstanding extreme temperatures.
Why is boron nitride considered one of the best ceramic materials for electrical insulation?
Boron nitride is considered one of the best electrical insulators because it has a complex structure that lacks free charge carriers or free electrons.
Why is boron nitride doped?
Boron nitride is doped by some manufacturers because they want to improve some of its magnetic, electronic, and adsorption properties. Examples of these dopants (impurities) are phosphorus, oxygen, iron (Fe), carbon, etc.
Conclusion
Boron nitride’s importance to so many sectors especially the electrical and metallurgical industry cannot be overemphasized. So far, you’ve seen some of the most sought-after qualities ranging from electrical insulation to high-temperature resistance. Whether it’s in the production of high-precision cutting tools, high temperature, and wear-resistant machines and devices, Boron Nitride has got you covered. It’s also capable of handling whatever production method you choose to go with. Quick update for you; The global boron nitride market is rising at a very fast pace. So do well to quickly place your orders now at GGSCeramics, we offer some of the best boron nitride products.