Introduction
Pyrolytic Boron Nitride (PBN) and Pyrolytic Graphite (PG) have taken center stage when dealing with the functionality of high-temperature applications. This is because they are very efficient refractory materials. In this article, you will learn about PBN, and PG, their differences, real-world applications and how lucrative the business is in case you’re looking to invest.
Difference Between Pyrolytic Boron Nitride (PBN) and Pyrolytic Graphite (PG)
Pyrolytic boron nitride is a high-purity ceramic material produced through chemical vapor deposition. It is odorless and has a crystal structure that is hexagonal which makes people easily mistake it for Graphite. It goes by the trade name, PBN. Pyrolytic Boron Nitride is one of the strongest and purest forms of boron nitride (about 99.9% purity). The reason for this is because of the closely packed anisotropic structure and the intense heat it undergoes while being produced.
Pyrolytic graphite is a special graphite produced by decomposing hydrocarbon gas at extremely high temperatures in a vacuum furnace.
Characteristics of Pyrolytic Boron Nitride And Pyrolytic Graphite
PBN mostly has an orange or whitish appearance with a density of 2.15 g/cm3. The surface is smooth and without pores. The tensile strength of PBN is an impressive 153.84 N/mm2 and its elastic modulus is 235690 N/mm2. It has a dielectric strength of 56k V/mm and a very high thermal shock resistance which makes it able to withstand mechanical stress.
PBN’s strength increases with a rise in temperature until it reaches 2473o K. When the temperature rises to 3273o K, the pyrolytic boron nitride compound disintegrates into boron and nitride. Pyrolytic boron nitride has a low coefficient of expansion (2.1 x 10-6°/C) which makes it maintain a stable shape even under extreme temperatures and pressure.
Furthermore, the fact that it is chemically inert means it doesn’t get rust easily. Why? It’s sufficiently able to resist attacks from chemicals or acids.
Fig 1: Pyrolytic boron nitride (PBN)
PG is a black solid that occurs mostly in the form of a disc, sheet, or plate. It has an ultimate tensile strength of 200 MPa. Its density falls between 1.30 and 2.265 g/cm3. It also has a perpendicular thermal conductivity of 80 W/m·K
Additionally, PG can withstand thermal expansion of up to 20 µm/m·°C. Its perpendicular electrical resistivity falls between 0.15 and 0.25 Ω·cm. Thus, its ultimate strength under compression, bending, and tension rises with increased temperature.
Fig. 2: Pyrolytic graphite (PG)
Applications of Pyrolytic Boron Nitride (PBN) and Pyrolytic Graphite in High-Temperature Environments
High-Power Electronics
PBN comprises ceramic matrix nanocomposites making it good for electrical insulation and allowing it to be stable and function effectively in high temperatures. It also means PBN can also help you produce high strength wafers for any high temperature demanding - power electronics device.
Pyrolytic Graphite tends to act more as an efficient heat dissipator in high-energy electronics you see today. It can make your equipment and gadgets last longer without overheating. PBN can also help you manufacture OLED Displays and LED Lights for electronics.
Fabrication de semi-conducteurs
PBN and PG also play a significant role in the semiconductor industry. Crystal growth and efficient heat dissipation in semiconductors is enhanced using a PBN crucible because of its pure properties and capacity to ensure thermal stability. This allows electronic components to perform optimally due to the absence of contamination.
Uniform heating in the wafer manufacturing process of semiconductors is the function of highly oriented pyrolytic graphite (HOPG). It’s this function that ensures the process of semiconductor fabrication. 
Fig 3: PBN crucible
Nuclear Reactor Components
The refractory ceramic material in PBN and PG allows them to hold out under extreme radiation and heat. PG particularly has a high level of stability, making it a suitable material for designing reactor cores. In contrast, the properties of thermal insulation and chemical stability in PBN ensure the safety and efficiency of reactor components.
Aerospace Engineering
The refractory linings of aerospace machines, aeroplanes and jets make use of pyrolytic boron nitride materials because they tend to facilitate seamless function during flight and re-entry.
In particular, PG is composed of cmc composites that reinforce its capacity for thermal conduction which makes it a good heat shield to sensitive spacecraft components.
Medicine
Most equipment used in sterilization use components made from PBN and PG due to the thermal stability it can provide as well as its biocompatible nature. This thermal stability allows for the production of medical implants that can survive intense conditions without being mordant.
Microwave and RF Applications
The thermal stability and insulation properties of PBN allows it to function as major components of windows and substrates in microwaves. Highly Ordered Pyrolytic Graphite (HOPG) can also efficiently dissipate heat in RF devices and make them function at an optimal level.
The Lucrative Business of PGN and PG
Pyrolytic boron nitride (PBN) and pyrolytic graphite (PG) carry huge potentials for major innovations in several lucrative industries. For instance, being in the PBN and PG business gives you an edge in the electrical industry. This is because of the rise in the interest of PBN-PG composite heating elements.
PBN-PG composite heating elements are very durable. Chemical-vapor deposition (CVD) is used to place PG on the PBN elements to create durable ceramics used in semiconductors. These semiconductors are components of microchips in laptops, mobile phones, robots, etc. This means that PBN-PG composite heating elements are in high demand.
If you want to venture into this business, then you are sure of great profit and growth. PBN-PG composite heating elements offer more efficient options to engineers, especially producers of laptops, mobile phones, tablets, etc. giving them an option to create products that easily dissipate heat.
Fig 4: PBN-PG Composite heating element
PBN is an ideal product component of break rings for horizontal casting machines. If you also need an insulator for a high-temperature furnace or vacuum system, you would be better off using PBN.
Furthermore, highly oriented pyrolytic graphite (HOPG) is utilized in x-ray spectrometry as a dispersive component. Manufacturers in the plastic industry use PG to reinforce plastic products. PBN also plays a key role in the automotive industry due to its effective wear resistance as it helps to increase the longevity of motor spare parts or even the engines by reducing wear and tears from friction.
Frequently Asked Questions (FAQs)
What is the Key Distinction Between Pyrolytic Boron Nitride (PBN) and Pyrolytic Graphite (PG)?
The key distinction between PBN and PG lies in their composition. PG has a significantly higher thermal conductivity than PBN – PG is an electrical conductor while PBN is an insulator. Due to those properties, PBN is more efficient in terms of high thermal resistance.
What Is A Refractory Material?
A refractory material is simply a thermal insulator. They are materials with properties that enable them to withstand extremely high temperatures. They are also highly resistant to chemical attacks and shocks.
Conclusion
Pyrolytic boron nitride and pyrolytic graphite are making giant strides in the electronic and aerospace industries. Particularly, PBN ensures thermal resistance, shielding components of high-temperature devices from damage due to high temperatures. PG dissipates heat in electrical components.