The core material of ceramic tubes typically consists of high-performance ceramic materials such as alumina, zirconia, and silicon carbide; among these, alumina ceramic tubes are the most prevalent due to their exceptional combination of properties.
As the name suggests, alumina ceramic tubes are primarily composed of aluminum oxide (Al₂O₃). Depending on their purity level, they are classified into various grades-such as 95%, 99%, and 99.5%. Generally, the higher the purity, the superior the performance; however, this also entails a corresponding increase in cost. Alumina ceramic tubes possess an exceptionally wide operating temperature range, capable of withstanding continuous use temperatures ranging from -200°C to 1600°C, and even enduring temperatures as high as 1800°C for short durations. This characteristic renders them indispensable in high-temperature environments.
In terms of mechanical properties, alumina ceramic tubes demonstrate outstanding performance. They exhibit high compressive strength: the 95% purity grade achieves a compressive strength of ≥250 MPa, while the 99% purity grade reaches an even higher level of ≥300 MPa. Regarding flexural strength, they attain ≥180 MPa at room temperature and maintain a strength of ≥120 MPa even at elevated temperatures of 1000°C. Furthermore, alumina ceramic tubes feature high bulk density, low apparent porosity, a low coefficient of thermal expansion, and moderate thermal conductivity; these combined attributes ensure their exceptional thermal stability.
Beyond their fundamental mechanical and thermal properties, alumina ceramic tubes also possess excellent electrical insulation, corrosion resistance, and wear resistance. They exhibit superior high-frequency dielectric properties, making them ideal for use as insulating components in high-frequency heating equipment. They are capable of withstanding corrosion from molten metals, high-temperature gases, and most acidic and alkaline solutions (with the exception of hydrofluoric acid). Moreover, with a Mohs hardness of 9-second only to that of diamond-their surface is highly resistant to abrasion and scratching.