Application of silicon nitride ceramics in high temperature resistance

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Silicon nitride (Si ∝ N ₄) ceramics are known as the “king of structural ceramics” and have become an ideal material for extreme working conditions due to their high strength, toughness, and excellent thermal shock resistance even at high temperatures of 1400 ℃. Unlike the brittleness of traditional ceramics, silicon nitride is not easily cracked when subjected to drastic temperature changes, and is widely used in fields such as aerospace, metallurgical casting, and semiconductors.

Frequently Asked Questions (FAQ)
Q: What is the maximum temperature that silicon nitride ceramics can withstand?
A: Silicon nitride ceramics can work stably in an environment of 1200 ℃ -1400 ℃ for a long time in air, and can even withstand temperatures exceeding 1600 ℃ in the short term. More importantly, its high-temperature strength at 1200 ℃ is basically the same as its room temperature strength, and it will not soften or creep like metals.
Q: What are the unique advantages of silicon nitride ceramics in terms of heat resistance compared to alumina or silicon carbide ceramics?
A: The biggest advantage of silicon nitride is its extremely low coefficient of linear expansion (2.8 × 10 ⁻⁶/K) and high fracture toughness. This means that it is less likely to explode than aluminum oxide and silicon carbide when facing severe thermal shocks such as sudden cooling and heating (such as being directly immersed in water from 1000 ℃), and has unparalleled thermal shock resistance.
Q: How does this material behave in a molten metal environment?
A: Excellent performance. Silicon nitride has strong non wettability (non adhesion) and corrosion resistance to molten metals such as aluminum, copper, and zinc. It will not be corroded by aluminum liquid and can effectively prevent the adhesion of metal slag, making it an ideal material for the metallurgical industry.

Core requirements and solutions
For enterprises operating in high temperature, high pressure, and highly corrosive environments, the stability of equipment directly determines production efficiency. Our silicon nitride ceramic products are designed to address the following core pain points:
Solving the problem of “thermal shock cracking”: In scenarios with severe temperature fluctuations such as casting and heat treatment, replacing traditional materials to prevent component explosion and shutdown caused by thermal expansion and contraction.
Addressing the issue of “high temperature softening” failure: providing mechanical support that is more stable than metal under high temperature conditions above 1000 ℃, ensuring that equipment accuracy does not decrease due to high temperatures.
Solving the problem of “molten metal adhesion”: In the process of aluminum and copper smelting, preventing the adhesion and corrosion of molten metal greatly extends the service life of consumables such as crucibles and thermocouple protection tubes.

High temperature resistance and application value of silicon nitride ceramics
The reason why silicon nitride ceramics can become the “savior” in the high-temperature field is due to their unique crystal structure and physicochemical properties.

1. Excellent Thermal Shock Resistance
   The coefficient of linear expansion of silicon nitride ceramics is extremely low (about 2.8 × 10 ⁻⁶/K), only one-third of that of alumina ceramics and one-fifth of that of stainless steel. This low expansion characteristic enables it to withstand rapid temperature changes exceeding 800 ℃.
   Application value: Under frequent heating and cooling cycles (such as induction heating, continuous casting and rolling), silicon nitride components can maintain structural integrity and have a lifespan several times longer than traditional materials.
2. Excellent high-temperature mechanical strength
   Most materials experience a significant decrease in strength at high temperatures, but silicon nitride is an exception.
   Data support: At a high temperature of 1200 ℃, its bending strength can still reach over 900MPa, and its fracture toughness can reach 6-7 MPa · m ¹/².
   Application value: Suitable for high-speed rotating and high load components, such as turbocharger rotors, which can prevent fracture at extremely high speeds and temperatures.
3. Extremely strong chemical stability and corrosion resistance
   Silicon nitride has a dense three-dimensional network structure, with an oxidation resistance temperature of up to 1400 ℃, and strong resistance to inorganic acids and molten metals other than hydrofluoric acid.
   Application value: In scenarios such as temperature measurement of aluminum liquid and flow guidance of copper liquid, no chemical reaction occurs, no pollution of metal liquid occurs, and product purity is guaranteed.
4. Flexible precision customization services
   We are well aware of the differences in operating conditions of different equipment and provide comprehensive customized processing services:
   Shape customization: Can process tubular, plate-shaped, ring-shaped, and irregular structural components (such as turbine rotors, sealing rings, and bearing balls).
   Precision customization: Through precision grinding and polishing, the dimensional tolerance can be controlled within ± 0.01mm, and the surface finish can reach mirror level.
   Composite process: supports metalized coatings or special sintering processes to meet specific welding or assembly requirements.

Customer Application Cases
We not only provide materials, but also offer engineering solutions for extreme working conditions. The following are real cases of our customer service (anonymized):
A large non-ferrous metal smelting plant – solving the problem of frequent explosion of aluminum liquid temperature measuring tubes
Customer pain point: During the continuous temperature measurement process of aluminum liquid (about 750 ℃), the corundum ceramic protective tube used by the customer has poor thermal shock resistance and frequently explodes. On average, it needs to be replaced every 3 days, and the broken ceramic fragments are prone to contaminating the aluminum liquid, causing huge losses.
Our solution: We recommend customers to use reaction sintered silicon nitride (RBSN) thermocouple protection tubes.
Application results: Silicon nitride tubes, with excellent thermal shock resistance, did not crack at the moment of contact with high-temperature aluminum liquid. The dense oxide film generated on its surface prevents further erosion of the aluminum liquid. Actual test data shows that the protective tube has a continuous service life of over 120 days, and the aluminum slag does not adhere during disassembly, greatly reducing the labor intensity and consumable costs of workers.

Whether it’s extreme temperature shock or harsh corrosive environments, silicon nitride ceramics can provide you with reliable solutions. We have mature sintering technology and precision machining capabilities, and can quickly provide samples and technical support according to your drawings or working conditions.
Welcome to contact us for exclusive customized quotes for high-temperature resistant ceramic components!

Brudeze Ceramics supplies and sells a wide range of high-quality quartz glass, including alumina ceramics, zirconia ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, boron carbide ceramics, bioceramics, machinable ceramics, etc. We can meet the customization requirements of various ceramic products.