Boron nitride nozzles (BNN) are the ideal industry choice because of their ability to withstand high temperatures. But before learning about the advantages and applications of boron nitride nozzles. Let us first understand- in detail everything about the BN compound.

Boron nitride (BN)

Boron nitride is a refractory compound of Boron and Nitrogen. It exists in various forms that are isoelectronic to carbon lattice. The most stable BN polymorph is hexagonal. Its structure is analogous to that of crystalline graphite. The cubic BN(c-BN) has a diamond-like crystalline arrangement but is softer than the diamond. The abrasive properties of c-BN make it useful in cutting and drilling tools.

Properties

1. High heat resistance - The strength of the boron nitride is twice that of room temperature at 1800c, and sublimation occurs at 3000c. It doesn’t cool from 1500c to room temperature.

2. Excellent electrical properties - Provide electrical insulation up to 10^14 Ω-cm at 25c and 10^3 Ω-cm at 2000c. Hence this is the best high-temperature insulating material.

3. Strong corrosion resistance - BNN doesn’t react with common metals, semiconductor metals, rare earth metals, precious metals, alkalis, etc.

4. Low thermal coefficient - The thermal coefficient of BNN is 2*10^-6. It has the lowest thermal coefficient among ceramics. Moreover, its high thermal conductivity makes it tolerate thermal shocks.

5. It is machinable - It can be processed easily to build high precision parts and components as its hardness is 2 Mohs.

Hexagonal boron nitride ( h-BN)

h-BN is the most widely used polymorph because it works as a good lubricant in high and low temperatures. It is widely popular in such applications where the chemical reactivity of graphite is causing problems. The hexagonal boron nitride polymorphs offer several benefits over graphite, such as its lubricity does not need gas or water molecules to trap in between the layers. Due to this, it is possible to use h-BN in a vacuum. The cosmetic industry has leveraged the benefits of its lubricating properties for some time. However, because of the high price it usage soon stopped.
The h-BN polymorphs are similar to aromatic compounds. Its high ionic character makes it the best proton conductor and electric insulator. Of all electrical insulators, hexagonal boron nitride has the highest thermal conductivity. Due to its high thermal conductivity and chemical stability- it is used in high-temperature equipment.
Hexagonal BN is suitable for constructing ceramics, alloys, plastics, rubber, resins, bearings because of its lubricating properties, higher electrical resistivity and conductivity. Its excellent dielectric properties make it suitable to use in electronics for constructing microwave transparent windows and a lot more.

Cubic boron nitride (c-BN)

Cubic BN is insoluble in iron, nickel and other alloys. Diamond, on the other hand, is soluble in these metals. Being an excellent abrasive, they are employed in machining steel, whereas ceramics and aluminium alloys mostly use diamond abrasives.
BN forms a passive layer of boron oxide when it comes in contact with oxygen. This boron oxide layer prevents further oxidation. However, cubic BN affinity for moisture will dissolve the boron oxide layer and create conditions for hydrolysis, which sometimes seems like a drawback. The sulfurized mineral is the best, and the sulfochlorinated oil emulsion (mixed with 10% water) is the second-best coolant to use with BN.

Boron nitride nozzles

BNN unique properties make it a preferable material in manufacturing industrial nozzles. Here are five benefits of using BN nozzles in industries:

1. No-preheating
Unlike alumina and zirconia, BN nozzles do not require preheating. It can handle thermal shock every smoothly.

2. No- clogging
Most of the metals can’t wet the boron nitride nozzles, due to which there are no or rare chances of clogging.

3. High working temperature
Boron nitrides can tolerate temperatures up to 1800c in a vacuum and inert atmosphere. It is higher than most of the ceramics available.

4. Customizable
By changing the grades of BN, such as BN-2800 and BN-2300, one can alter the thermal conductivity and corrosion resistance of Boron nitride.

5. Easy prototyping
One can make small prototype runs on BNN without spending extra money on tools and equipment. This assists in the development of different nozzle designs.