Resistant Materials for Average-Temperature Furnaces
Average-temperature furnaces are used in a wide range of high-temperature processing operations such as heat treating, annealing, and brazing. Since furnace temperatures can easily reach 1600°C (2900°F), the number one priority for such industrial processes is that the furnaces need to be equipped with materials capable of withstanding the high temperatures while still maintaining their structural integrity. There are a variety of resistant materials on the market that are suitable for such applications.
Silicon carbide (SiC) is a man-made ceramic material that is most commonly used in average-temperature furnace applications. Silicon carbide is an extremely hard material and its strength is ideal for resisting high temperatures and protecting the furnace walls from heat damage. As an additional benefit, silicon carbide’s crystalline structure has a low thermal expansion coefficient which helps the furnace walls from becoming distorted due to thermal expansion and contraction.
Graphite is another popular material for use in average-temperature furnaces. Graphite is extremely heat resistant, and because it is both non-conductive and non-absorptive of heat energy, it helps to prevent heat damage to furnace walls, as well as improve the efficiency of the furnace by reducing thermal energy losses. Graphite can be formed into several different shapes to suit various applications.
Boron nitride (BN) is a specially engineered form of quartz that is often used as a furnace lining material. Boron nitride is highly resistant to heat damage and can withstand temperatures of up to 2800°F (1540°C). Its unique combination of high thermal conductivity, low thermal expansion coefficients, and low density makes it an ideal material for insulation and prevents heat loss.
Mullite is an alumina-silica composite material that is increasingly being used in average-temperature furnace applications. Mullite is highly heat resistant and can withstand temperatures up to 1800°F (980°C) without breaking down. This makes it an ideal choice for protecting against heat damage and ensuring the reliability of furnace walls for longer periods of time.
Alumina is a crystalline form of aluminum oxide and is one of the most popular choices for average-temperature furnace applications. Alumina is highly resistant to heat damage and can withstand temperatures up to 2400°F (1300°C). Its high density and thermal inertia make it an ideal material for protecting furnace walls from heat damage and improving the efficiency of the furnace by conserving energy.
Finally, for applications requiring a high degree of thermal shock resistance, alumino-silicate bricks are often used. Alumino-silicate bricks are highly heat resistant and can withstand rapid temperature changes up to 1800°F. This makes them an excellent choice for protecting furnace walls against thermal shock and ensuring the reliability of the furnace over extended periods of time.
Overall, average temperature furnaces can benefit from the use of several different resistant materials. Silicon carbide is a popular choice due to its strength and low thermal expansion coefficient. Graphite is also a good choice due to its non-conductive and non-absorptive properties. Boron nitride is well-suited for lining the furnace due to its high thermal conductivity and low density. Mullite and alumina are excellent choices due to their high heat resistance. Finally, alumino-silicate bricks are a good choice for applications that require high thermal shock resistance. By selecting the right resistant material for the job, operators can ensure the reliability and efficiency of their average-temperature furnaces.
