Boron Nitride Tube

The hot-pressed hexagonal boron nitride ceramic produced by UNIPRETEC uses the international advanced vacuum hot-pressing sintering technique. The material possesses fine structure, high density, exceptional mechanical, chemical, electrical, and thermal properties, and the performance is stable, making it suitable for a series of high-performance industrial applications. The product features and benefits are as follows:

High Temperature Resistance

Excellent High-Temperature Resistance (1900℃ under vacuum, 2100℃ under the protection of nitrogen, argon, and other inert gases; oxidation resistance temperature of 900℃).

High Thermal Conductivity

High thermal conductivity, and low thermal expansion.

Thermal Shock Resistance

Excellent thermal shock resistance, rapid cooling from 1000℃ to room temperature for a hundred times within 15 minutes without cracking.

Electrical Insulation

Excellent electrical insulation at high temperatures; electrical performance does not degrade significantly as temperature rises; the breakdown voltage is 3K/MV; the low dielectric loss is 2.5 X 10-4 at 108HZ; and the dielectric constant is 4, making it transparent to microwave and infrared rays.

Resistance to Infiltration

High resistance to molten metal, slag, and glass infiltration.

Corrosion Resistance

Extremely high resistance to corrosion.

Machinability

Machinable and simple to process into the needed shape and size.

The features of shapes

The usual tubular construction of boron nitride tubes may be modified to meet the requirements of the application for wall thickness. Here, the structure has to be changed.

Boron nitride tubes may be made in a wide range of inner and outer diameters, which makes them excellent performers in many different industrial applications.

The exact use scenario being assessed will specify the length of the boron nitride tube, which may be adjusted to suit the needs of the application.

Surface features: To enhance the bonding qualities with other materials, the surface of the boron nitride tube may be polished or roughened, depending on the situation. The tube is improved in its capacity to create connections with other materials by doing this.

Porous forms are given to boron nitride tubes to suit specific uses such as catalytic processes or filtration. Certain programs are made to fit inside certain ones.

To suit more difficult installation requirements, boron nitride tubes may be made straight or with a certain curvature.

Factors of design

Thermal stability: To prevent structural distortion, the boron nitride tube's design must take high temperature settings into account.

Chemical compatibility: To guarantee no unfavorable reactions, the boron nitride tube's compatibility with the chemicals that could come into touch with it must be taken into account during design.

Mechanical strength: Pressure resistance and a particular mechanical strength are required for the boron nitride tube.

Thermal conductivity: Boundary nitride tubes may have their thermal conductivity tailored to suit the requirements of heat exchange or heat dissipation.

Processing precision: To guarantee form consistency and dimensional correctness, boron nitride tube production calls for exact processing technologies.

Application Areas

Superior furnace tubes Because boron nitride tubes have a high temperature resistance, they may be used in heat treatment and sintering procedures, making them excellent for use as furnace tubes in high temperature furnaces.

The semiconductor industry uses boron nitride tubes to either transmit high purity gases during the semiconductor production process or to function as a part of the reaction chamber.

High-temperature, high-pressure fluid delivery systems in the petroleum and chemical sectors may find use for boron nitride tubes.

Boundary nitride tubes' excellent thermal conductivity makes them useful in heat exchanger construction, which raises the efficiency of heat exchange processes.

Hard wearing components Because of its great degree of hardness, boron nitride tubes are regarded as wear-resistant components and may be used in mechanical seals and bearings.

Boundary nitride tubes find use in electronics to manufacture heat dissipation components or high-performance insulators for electronic devices.

Because boron nitride tubes are lightweight and heat-resistant, they may be used in aircraft thermal protection systems.

Medical equipment made of boron nitride tubes might include biocompatible implants and high temperature-resistant devices.

In environmental engineering, boron nitride tubes may improve the efficiency with which contaminants are removed from high-temperature filtration and flue gas treatment systems.

The nuclear industry uses boron nitride tubes to make radiation and high temperature resistant components.

Boron Nitride Thermocouple Protection Tube

Boron nitride tubes are typically used as thermocouple protection tubes to replace the alumina ones, overcoming the disadvantages of poor thermal conductivity of the latter. Boron nitride has a high thermal conductivity and can withstand temperatures as high as 2200° C (melting point). At 2200℃, it has an equivalently high thermal conductivity to stainless steel. As a result, the BN tube allows for quick heat transfer from the furnace to the thermocouple, leading to quick changes in the thermoelectric potential and increased temperature control precision.

BN material is inert in chemical environments, has excellent corrosion resistance to molten metal, neither wets nor reacts, and can be used up to 2800°C in a N2 atmosphere without failures like breakage and melting of alumina tubes, which will cause the whole furnace product scrap. The physical property comparison of alumina and BN is shown below:

Physical Property Comparison of Al2O3 and BN

BN has four times the electrical breakdown strength of alumina. The temperature will rise abruptly when the thermometer is immersed in the molten metal; therefore, the outer casing of the spray gun should be made of heat-resistant boron nitride to avoid thermal shock from breaking the thermocouple and contaminating it.

Boron Nitride High-Temperature Insulation Tube

In addition to being a good heat conductor, boron nitride tube also acts as an electrical insulator. It has a dielectric constant that is half that of alumina and a breakdown voltage that is four times that of alumina at high temperatures. It maintains its electrically insulating properties up to 2000°C, and its service temperature in nitrogen or argon atmosphere can reach 2100°C. It is an excellent high-frequency, high-voltage, and high-temperature insulation material that is frequently used in high-temperature furnace insulation tubes.

Sintering Methods of Boron Nitride Tube

Pressureless sintering calls for high sintering temperatures and results in poor densification; reaction sintering generates boron oxide, which is easily deliquescent; and in self-propagating synthesis, insufficient contact between internal raw materials and gas released during the reaction frequently affects the conversion rate and density of the product. As the hot pressing sintering is done under high pressure, the synthesis temperature is relatively low and the densification effect is good; there isn't a clear melting point in the N2 or Ar atmosphere, and the highest operating temperature is 2800 ° C, this technology has become a popular method to prepare h-BN ceramics.

Hot pressing sintering is a technique of loading dry powder into a specific graphite mould, applying bidirectional or unidirectional pressure to pressurise the mould uniaxially, and heating in a certain temperature range meanwhile so that the moulding and sintering can occur simultaneously. During hot pressing sintering, the green body will be affected by the increase of temperature and pressure simultaneously. This external pushing force is capable of breaking the card support structure of sheet-like h-BN, encouraging grain rearrangement, and significantly lowering the sintering temperature and cutting the sintering time, ultimately obtaining the ceramic products with high density, uniform grain size, and outstanding mechanical characteristics. Moreover, it can satisfy the purity standards of ceramic products without the addition of sintering or forming aids.