Zirconia Properties

 

Zirconia is a zircon sand-derived synthetic mineral. It is a fundamental asset in a broad variety of sectors and finished products, varying from sophisticated ceramics and refractories, due to its hardness and extremely high thermal stability. The ceramic substrate Zirconia is one of the most well enough on the globe.

Zirconia contains a natural mineral called Baddeleyite. It is a white powdered substance that is frequently used to make dental foundations for dentistry constructions like crowns and bridges. Unlike traditional ceramics, which are brittle and rigid, Zirconia offers great wear resistance, hardness and durability, as well as superior flexibility.

Properties

• Formula: ZrO₂
• Density: 5.68 g/cm³

• Melting point: 2715^oC

• Boiling point: 4300^oC

• Solubility: Soluble in hydrofluoric acid and hot sulphuric acid

• Mohs Scale Hardness: 8 – 8.5

• Molar mass: 123.218 g/mol

• Bulk modulus: 72.3 – 212 Gpa

• Elastic Modulus: 100 – 250 GPa

• Fracture toughness: 1 – 8 MPa

• Compressive strength: 1200 – 5200 MPa

• Modulus of rupture: 177 – 1000 MPa

• Tensile strength: 115 – 751 MPa

• Thermal expansion: 2.3 – 12.2 * 10^-6 K

• Thermal conductivity: 1.7 – 2.7 W/m.K

• Zirconia offers high chemical as well as corrosion resistance even at high temperature.

• At room temperature, it acts as an insulator. If temperature is greater than 600^oC, it starts to behave as a conductor.

• It has high hardness, high toughness, high density, low thermal conductivity, high resistance to molten metals.

• It has high heat resistance, higher resistance to propagation of crack and higher thermal expansion (to join ceramic and steel).

Crystal structure

• At room temperature, the crystal structure of Zirconia is monoclinic.

• At a temperature range between, 1100^oC – 2300^oC, the structure is tetragonal.

• At a temperature greater than 2300^oC, it has cubic crystal structure.

Demerits of Zirconia

• The main disadvantage of Zirconia is producing different crystal structures at different modes of temperature. So, the material undergoes volume expansion (fatigue) which will lead to “Polymorphic transformation” (same composition with a different crystal structure).

• The range of volume expansion is about 2 – 3%. In order to overcome these disadvantages, the doping of Yttria or Calcia or Magnesia based Stabilized Zirconia is used. Due to this stabilization, there is no volume expansion takes place. 

Applications

• Recently, Zirconia is used as sensors. In earlier method, chicken (bird) is used and put in to the well to check whether the toxic gases were present or not. To overcome this, sensors were used. The emissions of gases were detected by sensors.

• It is used in bleaching powder and manufacturing of crucibles.

• It is used as fuel cell membranes due to non magnetic, higher thermal stability, water insoluble and higher resistance to acid and alkalies.

• It is used in powder compacting dies due to extreme hardness of the material.

• The important application of Zirconia is Dental field. For dental field, there are two categories material such as metal and ceramic. When coming to metal, the problem is the tooth cap undergoes thermal expansion while taking tea or coffee to create sensitivity and easily undergoes corrosion.  In ceramic, the material is long lasting, good wear resistance, no changes in expansion (remaining the same), non conductive, durability and biocompatibility.

• It is used in surgical instruments due to edge retention property and high wear resistance.

• It is used in football shoes and edges to get sufficient strength.

• It is used in Piezoelectronic ceramics and used as catalysis in some reactions.

• The other range of applications such as pump seals, high density grinding media, metal forming, metrology components, bushes, bearings, precision valve and drive shafts.

In this article, you have a learned the basic properties and applications in a simple and better aspect.