What is Ceramic?
Definition: Ceramic is a nonmetallic and inorganic material that is hard, brittle, heat resistant & electrical resistant, and is composed of more than one element (e.g two elements in Al2O3).
Ceramic materials have specific properties due to which they are used in various applications including; electric insulation, corrosion resistance, high heat capacity & low heat conduction, artificial joints, crockery, etc.
Well, this was just a simple overview. But further I have discussed how these ceramics are made?
Let’s dive right into it!
How are ceramics made?
Ceramics are made in 3 steps.
- Shaping: The mixture of clay, sand, flint, quartz, silicates, water and other earthen elements is taken and it is given a desired shape.
- Heating: The shaped mixture is then heated at a temperature higher than 1500 °C, due to which a chemical reaction takes place and it produces other chemicals which bind the tiny crystals together.
- Glazing: The ceramic is then glazed and heated again which makes its surface waterproof.
So this is just a simple plain english explanation, but let me give you a detailed scientific explanation for the manufacturing of ceramics (which is also known as ceramic processing).
Ceramic processing (Ceramic manufacturing)
Ceramic processing is a method of producing ceramic components.
Ceramic processing includes many individual steps that differ for different ceramic materials.
Ceramic processing involves 4 steps;
- Raw material selection
- Preparation
- Consolidation
- Sintering
Let’s discuss each of these ceramic processing steps one by one.
#1) Raw material selection
The first step is the selection of raw material, which involves obtaining and preparing the right material to get the desired final product.
For many ceramic manufacturing, different types of clay are selected as a raw material.
The selection of raw material is also done on the basis of required properties of the final component.
Ceramic materials and their uses are given in the table below.
| Material | Uses |
|---|---|
| Al2O3 (Aluminum oxide) | Spark plug insulation, substrate for microelectronics packaging |
| MgO (Magnesium oxide) | Electrical insulators, refractory bricks |
| SiO2 (Silicon dioxide) | Optical fibres, cookware |
| ZrO2 (Zirconium oxide) | Cubic zirconia, oxygen sensor |
| SiC (Silicon carbide) | Heating elements, kiln parts, abrasives |
| Si3N4 (Silicon nitride) | Piston valves, turbocharger motors |
While selecting the raw material for ceramic processing, it is very essential to properly select the grain size of the raw material powder.
This is because the grain size affects the properties of the final components.
Generally, the strength of the ceramic material increases with the decrease in the grain size. So the raw material (or powder) is milled to produce a fine powder having diameter < 1 micrometer.
#2) Preparation
For preparation of the raw material, the additives like water, polymers, etc are added so that the plasticity of material increases.
#3) Consolidation
Consolidation of ceramics involves the shaping of a ceramic mixture.
The ceramics shaping (or ceramic forming) can be following techniques;
- Rubber mold pestel
- Extrusion molding
- Injection molding
- Die pressing
- Slip casting, etc.
#4) Sintering
The final step in ceramic processing is a sintering process.
Sintering process takes place at high temperatures (around 800 °C to 1800 °C), which causes densification of the ceramic material and this ultimately increases its strength.
During the sintering process of ceramics, the pores are eliminated and the particles combine to form a continuous solid network.
In short, the density of the material increases after the sintering process.
Applications of ceramics in daily life
Ceramics are widely used in different fields as mentioned below.
Applications of ceramics in engineering
Engineering applications of ceramics includes;
- Tiles uses in space shuttle
- Gas burner nozzles
- Biomedical implants
- Ceramic disc brakes
- Nose cone of missiles
- Bearings used in rotary parts
- Ballistic protection, etc
Applications of ceramics in construction
In construction field, ceramics are used in;
- Bricks
- Floors and roofs tiles
- Pipes, etc
Applications of ceramics in whitewares
Whitewares including ceramics are;
- Cookware
- Wall tiles
- Pottery products
- Sanitary ware
- Tableware, etc
Applications of ceramics in refractories
For refractories, ceramics are very essential to resist high temperature and hence they are used in;
- Kiln linings
- Gas fire radiants
- Steel and glass making crucibles, etc.
