The ceramics industry covers a wide range of products from traditional ceramics such as pottery and chinaware to modern technical ceramics for chemical, mechanical and other applications.
We are going to provide you a brief overview of the manufacturing process of modern ceramic products, so that you can be familiar with raw materials you need and control the whole manufacturing process.
1. What actually is ceramics?
Ceramics can be defined as a class of inorganic, nonmetallic solids that are subjected to high temperatures for manufacturing use. In this post, the modern technical ceramics are the focus.
The products of technical ceramics include tiles used in Space Shuttle program, gas burner nozzles, nuclear fuel uranium oxide pellets and bio-medical implants.
Its products are often made from materials other than clay, chosen for their particular physical properties. These may be classified as:
- Oxides: silica, alumina, zirconia
- Non-oxides: carbides, borides, nitrides, silicides
- Composites: particulate or whisker reinforced materials, combinations of oxides and non-oxides.
2. General manufacturing process of ceramic products
In order to create end products, the ceramic matter needs to go through the general manufacturing process which goes as follows:
2.1 Milling
Milling is the process by which materials are reduced from a large size to a smaller size.
Milling is generally done by mechanical means, including attrition, compression and impact.
Attrition is particle-to-particle collision that results in agglomerate break up or particle shearing and compression applies a forces that results in fracturing.
Attrition milling equipment includes the wet scrubber, which has paddles in water creating vortexes in which the material collides and break up.
Compression mills include the jaw crusher,roller crusher and cone crusher. Impact mills include the ball mill, which has media that tumble and fracture the material.
2.2 Batching
Batching is the process of weighing the oxides according to recipes, and preparing them for mixing and drying.
2.3 Mixing
Mixing occurs after batching and is performed with various machines, such as dry mixing ribbon mixers, Mueller mixers and pug mills. Wet mixing generally involves the same equipment.
2.4 Forming
Forming is making the mixed materials into shapes, ranging from toilet bowls to spark plug insulators.
Forming can include:
- Extrusion, such as extruding “slugs” to make bricks,
- Pressing to make shaped parts, and
- Slip casting, as in making wash basins and ornamental like ceramic statues.
Forming produces a “green part”, ready for drying. Green parts are soft, pliable, and over time will lose shape. Handling the green product will change its shape.
Once the ceramic powders have been compacted to produce the green-state component, they are approximately 50-70% dense.
They are also relatively weak, but with care can be machined to quite complex geometries. To impart strength, the green state components are usually sintered.
2.5 Drying
Drying is moving from the water or binder from the formed material. Spray drying is widely used to prepare powder for pressing operations. Other dryers are tunnel dryers and periodic dryers.
Controlled heat is applied in this two-stage process. First, heat removes water. This step needs careful control, as rapid heating causes cracks and surface defects.
The dried part is smaller than the green part, and is brittle, necessitating careful handling, since a small impact will cause crumbling and breaking.
2.6 Sintering
Sintering is where the dried parts pass through a controlled heating process, and the oxides are chemically changed to cause bonding and densification. The fired part will be smaller than the dried part.
That is the general manufacturing process of ceramic products and we sincerely hope it’d be helpful. Don’t hesitate to leave you comment below if you have any questions.
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