Silicon Nitride

Silicon Nitride vs. Boron Nitride Ceramic Shafts: A Comprehensive Comparison and Applications Overview

In the vast field of advanced materials, silicon nitride and boron nitride (BN) ceramic shafts are emerging as representatives of high performance and are widely used in many industries with demanding material properties. With their unique physicochemical properties, they play a key role in their respective application scenarios.

Comparison of the characteristics of Silicon Nitride and Boron Nitride Ceramic Shafts Mechanical Properties

Silicon nitride ceramic shafts are known for their high strength and hardness, which can reach a hardness of HV1200 or more (Vickers hardness), a bending strength of 800 – 1000MPa, and a compressive strength of 600MPa or more. This makes it perform well under high loads and high stresses and can effectively resist wear and deformation, suitable for heavy-duty mechanical components. For example, in some key rotating parts of automotive engines, silicon nitride ceramic shafts can operate stably and ensure efficient engine operation.

The mechanical properties of boron nitride ceramic shafts are different. Hexagonal boron nitride ceramic hardness is low, and Mohs hardness is only 2, which makes it easy to carry out mechanical processing and can be made into a variety of complex shapes of ceramic products. However, its strength and modulus of elasticity are relatively low, and it withstands higher loads than the silicon nitride ceramic shaft. However, some of the hardness requirements are not high, but the material processability and self-lubricating needs of the occasion, boron nitride ceramic shafts show unique advantages.

Thermal Performance From the point of view of thermal stability, silicon nitride ceramic shafts can maintain good performance in high-temperature environments; its oxidation temperature can be as high as 1400 ℃, in the dry oxidizing atmosphere below 1400 ℃ can remain stable, the use of the temperature is generally up to 1300 ℃ and can be applied even to 1800 ℃ in a neutral or reducing atmosphere. Moreover, silicon nitride has a low coefficient of thermal expansion, good dimensional stability in temperature change, and can effectively avoid material rupture due to thermal stress, which is widely used in high-temperature furnaces, heat exchangers and other equipment.

Boron nitride ceramic shaft also has excellent high-temperature resistance; in the oxidation atmosphere of 900 ℃, a nitrogen atmosphere of 2800 ℃ can be used. Its thermal conductivity is high, and hot-pressing boron nitride ceramics have excellent thermal shock resistance and can be used for rapid cooling and heating environments of the structural components. However, under vacuum conditions, boron nitride ceramics are prone to decomposition, which, to some extent, limits its application in some special environments. Chemical stability Silicon nitride ceramic axis of good chemical stability, in addition to hydrofluoric acid, does not react with other inorganic acids; a variety of non-ferrous metal solutions, especially aluminum solution, do not wet, can withstand strong radiation, in the chemical industry, metallurgy, and other corrosive environments have good applicability. Boron nitride ceramic shafts in chemical stability also have a good performance, just compared to its corrosion resistance is slightly inferior in some strong corrosive environments and is not as resistant as silicon nitride ceramic shafts.

Comparison of Silicon Nitride and Boron Nitride Ceramic Shafts in applications

In the aerospace field, silicon nitride ceramic shafts are widely used in engine parts, thermal protection systems and other key components to ensure reliability under extreme conditions due to their high strength, high-temperature resistance and good dimensional stability. Boron nitride ceramic shafts, due to their low hardness, good processability and lubrication performance at high temperatures, can be used in parts that require high precision in shape and self-lubrication, such as some of the special rotating parts inside some aviation engines.

In the manufacture of electronic equipment, silicon nitride ceramic shafts can be used to manufacture insulators, substrates and other components, with good electrical insulation and thermal conductivity, to ensure that the equipment is in a high-power, high-temperature environment, safe and stable operation. Boron nitride ceramic shafts are commonly used in the production of heat-dissipation structures and insulated heat-dissipation substrates in electronic equipment due to their high thermal conductivity and good electrical insulation.

In the machinery industry, silicon nitride ceramic shafts are often used as key materials for cutting tools, grinding tools and wear-resistant parts due to their excellent wear resistance. Boron nitride ceramic shaft of self-lubricating properties in mechanical seals. High-temperature solid lubricants play an important role in the 100 – 1200 ℃ air, inert gas, and hydrogen environment; the use of performance is better than some other solid lubricants.