Common Ceramic Wear Surface Definitions: A Quick Reference Guide
Ceramic wear surfaces are used in paper machine applications and can reduce energy consumption and increase wear life. The following provides a quick reference of common ceramic wear surface materials and definitions.
Coefficient of Friction: The amount of drag the surface exerts on the fabric. Higher friction coefficients mean more machine fabric wear and more energy required for machine drives.
Cost: The price of a ceramic is only one variable to consider when determining total cost-effectiveness. Others must also be considered, like ceramic wear life, fabric wear, and ceramic replacement costs.
Density: The weight of the material. An especially dense ceramic, like Zirconia, may prove too heavy for the existing support system.
Flexural Strength: The ability of the material to withstand torsional and deflection loads found in applications like forming board lead blades and where foils are frequently handled.
Fracture Toughness: A measurement of how a material withstands physical shock. This property is important for positions like the forming board, where vibration and shock are present.
Surface Finish: This is a smoothness scale for ceramic surfaces. A smoother ceramic surface results in less drag load and lower energy consumption. Silicon nitride and silicon carbide offer the best surface finishes.
Thermal Conductivity: A material’s ability to conduct, rather than absorb, heat. Higher conductivity will prevent unnecessary heat build-up that can damage fabrics. Zirconia, for example, has a very low conductivity rate.
Thermal Expansion: The degree to which the material expands under heat. Matching coefficients of expansion between ceramic and ceramic carrier is critically important. Differing rates of thermal expansion can cause ceramic to crack.
Thermal Shock Resistance: The extent to which a ceramic can withstand a sudden temperature change without cracking. Silicon nitride has the greatest resistance to thermal shock.
Vickers Hardness: This hardness scale can indicate wear life expectations. Silicon carbide has the highest Vickers hardness, and zirconia has the lowest.
