Roller hearth kilns (RHK) are used to fire a variety of consumer products, including porcelain, tiles, and Lithium Ion batteries. A hearth made of rotating rollers moves such products through the kiln. As rollers constitute a major component of the RHK, it is vital that they function with complete accuracy.
Rollers are usually made from high alloys or various ceramic materials such as Mullite and Alumina. Certain factors must be considered when choosing an effective roller material, including thermal conductivity, load volume, corrosion and erosion resistance, bending strength, and cost. Ultimately, these factors can impact the overall accuracy and stability of the roller.
Rollers made from the ceramic material Silicon Carbide are increasingly being used in a variety of commercial applications. In particular, SiC rollers, such as Hexoloy® by Saint Gobain, are considered to be highly advantageous for use in RHKs.
Silicon Carbide
Silicon Carbide (SiC) was first founded by Edward Acheson in the late 19th century whilst trying to produce synthetic diamonds. Nowadays, this material is thought of as optimal for a wide variety of industrial applications. For example, SiC is an ideal material to produce rollers for RHKs, as it has a unique combination of all the major mechanical, chemical, and thermal properties that rollers require.
Hexoloy SiC Rollers
Saint-Gobain Engineered Ceramic has been producing accurate, high quality rollers for over 20 years. They currently offer two types of Silicon Carbide rollers for use in industry, Hexoloy SE SiC and Silit SiSiC.
Silit, Silicon Carbide infiltrated with silicon metal, generally functions at temperatures up to 1350 °C.
Hexoloy®, on the other hand, is a special sintered SiC which offers increased strength and reduced bending at very high temperatures of up to 1650 °C. This means that, in addition to functioning in raised-temperature environments, Hexoloy rollers also offer the same load capability as thicker Silit rollers but with thinner walls.
A further benefit of Hexoloy SiC rollers is that they can be manufactured to much larger sizes than that of their Silit counterparts. Typical rollers are 34 mm in diameter, 5 mm in wall thickness, and measure 2,220 mm in length. However, as the push for higher kiln throughput continues, Hexoloy SiC rollers can measure up to 50 mm in diameter with 7-8 mm thick walls in lengths up to 3,350 mm.
Following an increase in the use of Lithium Ion batteries in consumer electronics and electric vehicles, battery makers are now consistently looking for rollers that can function at a range of temperatures, with large loads to enable higher productivity, and produce a long, reliable service life. With properties including excellent hardiness, light-weight nature, raised temperature and high load capability, as well as flexible size offering, rollers made from Saint-Gobain’s Hexoloy SiC are ideal for use in RHKs.
This information has been sourced, reviewed and adapted from materials provided by Saint-Gobain High-Performance Refractories.
For more information on this source, please visit Saint-Gobain High-Performance Refractories.