Ceramic material is used for such varied tasks as Oxygen Detectors in flues, Heat Protection Sheaths on temperature probes, costume jewellery, bearings and even the body of cell phones.
I think most of us know intuitively what ceramics are, but when we’re forced to describe them it becomes a little more difficult.
One over-simplified, but useful description would be that ceramic is often the oxide of a burned metal.
For example, burn Aluminium and you’ll be left with Aluminium Oxide aka Alumina.
Burn the metal Zirconium (element #40) and you’re left with Zirconium Oxide aka “Zirconia”.
We use Alumina in the temperature protection sheaths as shown below
||DIN type C610
||DIN type C799
Zirconia is used in many applications including Oxygen Detectors for flue gas or for automotive exhausts.
Platinum is used as a Catalyst and the Zirconia as a dielectric between the plates. If there is a difference in concentration of Oxygen outside the cell and inside the cell a concentration Gradient exists and a current flows which is proportional to this gradient.
Homershams have supplied a number of these detectors for flue-gas use, from our supplier Fuji Electric.
Like Carbon, Zirconia can exist in several states. At temperatures below 1000° C, Zirconia is a simple metal oxide as used in the sensors above. But has temperatures increase it changes from its Monoclinic to Tetrahedron and eventually to a Cube shaped molecule, at which point it’s called Cubic Zirconia as used in costume jewellery.
Several cell phones from 2017 had Ceramic backs of Zirconia. Vitreous ceramic as used here, is heated to 975° C and then quickly cooled to form a ‘glass’ with very high hardness/scratch resistance.
Another use of ceramics in our industry, is as a catalyst in Bead Gas Detectors