Zirconia is a white powdered material commonly used to produce dental frameworks for dental substructures such as crowns, bridges, etc. Unlike standard ceramics that tend to be brittle and hard, Zirconia has excellent wear resistance and strength, and comes with a flexibility which is far better than those of other technical ceramics.
Pure Zirconia
Pure zirconia is found in three crystal phases at different temperatures and they include Monoclinic, Cubic and Tetragonal. The fine grain size enables the material to have sharp edges and very smooth surfaces. In order to prevent and control structural changes, several different oxides can be dispersed into the zirconia crystal structure during production. These oxides include Ceria, Magnesia and Yttria.
Zirconia-based ceramics are also used in many other applications. For instance, they can be used as auxiliaries in welding processes, as tools for wire forming, as oxygen measurement cells, as insulating rings in thermal processes (Figure 1), and as materials for crowns and bridges in the dental industry (Figure 2), as mentioned above. These ceramics have been developed to such an extent that infinite designs of micro structure are now possible by controlling fabrication route, composition, thermal treatment, and final machining.
Properties of Zirconia
Zirconia has excellent resistance to chemicals and corrosion without the typical brittleness common in technical ceramics. When compared to other advanced ceramic materials, zirconia has exceptional strength at room temperature. Other principal properties of this material include high fracture toughness, high density, high hardness and wear resistance, good frictional behavior, high temperature capability up to 2,400ºC, non-magnetic, low thermal conductivity, electrical insulation, coefficient of thermal expansion similar to iron, and modulus of elasticity similar to steel. Over the years, a new name was coined for zirconia called ‘ceramic steel’.
Applications of Zirconia
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Figure 1. Insulating rings
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Figure 2. Dental frameworks
Zirconia is used in a wide range of applications, such as precision ball valve (seats and balls), valves and impellors, pump seals, oxygen sensors, high density grinding media, fuel cell membranes, thread guides, medical prostheses, cutting blades, gears, metal forming, radio frequency heating susceptors, metrology components, bearings, bushes and drive shafts.
Manufacture of Zirconia Components
Small-scale production of zirconia depends on the component’s geometry. As such, three common processing routes are used: injection moulding, precision grinding and laser cutting. Injection moulding is suitable for large-scale production of zirconia and laser cutting is a relatively simple process. The laser is typically limited to a 1mm thickness that its can go through. This form of zirconia is extensively used in the electronics industry. With expensive tooling, a high degree of dimensional precision can be obtained.
Conclusion
Precision Ceramics has more than two decades of experience in developing high-quality technical ceramic components for use in a wide range of applications. In-depth ceramic material knowledge together with experienced group of engineers and operators allows the company to provide advanced and cost-effective technical ceramic solutions for customers. Precision Ceramics also operates ultra-precise machining centres to address specific application needs.
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This information has been sourced, reviewed and adapted from materials provided by Precision Ceramics.
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