Ceramics Engineering processing explained with the help of GIFs
This branch of engineering deals with the technology of creating objects from inorganic, non-metallic materials. Ceramics engineering includes the purification of raw materials, the study and production of the chemical compounds concerned, their formation into components and the study of their structure, composition and properties.Image Courtesy: masters.donntu.edu.ua
Ceramic materials are used in a wide range of industries, including mining, aerospace, medicine, refinery, food and chemical industries, packaging science, electronics, industrial and transmission electricity. The feature covers traditional ceramic processes with their respective animations.
-MillingImage Courtesy: aggdesigns.com Image Courtesy: en.trituradoras-de-roca.com
This is a process in which materials are reduced from a larger size to a smaller size and it is usually carried out using mechanical means. The mechanical means involve attrition (which is particle-to-particle collision that results in agglomerate break up or particle shearing), compression (which applies a forces that results in fracturing) and impact (which employs a milling medium or the particles themselves to cause fracturing). The first animation is that of a cone crusher -an example of compression milling. The second is a working animation of a jaw crusher which comes in the impact mills category.
-Mixing and BatchingImage Courtesy: incmachine.com Image Courtesy: ssitechnology.com
Batching is the process of weighing the oxides according to recipes, and preparing them for mixing and drying. After batching, the mixing process takes place and it is carried out using various machines which include dry mixing ribbon mixers, Mueller mixers and pug mills. Even the process of wet mixing is carried out using the same equipment. The animations show the how ribbon mixers work.
-FormingImage Courtesy: schenectady.k12.ny.us Image Courtesy: tumblr.com
Forming is making the mixed material into shapes, ranging from toilet bowls to spark plug insulators. The process of 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. For example, a green brick can be "squeezed", and after squeezing it will stay that way. Forming involves:
i) Extrusion: This involves extruding "slugs" to make bricks as you can see in the first animation.
ii) Pressing: As the name indicates, pressing involves making shaped parts.
iii) Slip casting: Slip casting entails making toilet bowls, wash basins and ornamentals like ceramic statues. The second and third animations show the slip casting process.
-DryingImage Courtesy: kltfiltration.com
Removing the water or other binders from the formed material is known as drying. Most widely used method for preparing powder for pressing operations is known as spray drying. Controlled heat is applied in a 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. The animation shows the water removing process from the ceramics with the help of KLT filter.
-FiringImage Courtesy: steveirvine.com Image Courtesy: sofc.nl
Firing is where the dried parts pass through a controlled heating process, and the oxides are chemically changed to cause sintering and bonding. The fired part will be smaller than the dried part. Firing is done at a temperature below the melting point of the ceramic. Once a roughly-held-together object called a green body is made, it is baked in a kiln, where atomic and molecular diffusion processes give rise to significant changes in the primary microstructural features. The first animation is that of kiln firing. The second animation shows a sinter bonded SOFC.
Ceramics can be used in many technological industries. One of the applications is the ceramic tiles on NASA's Space Shuttle, which are used to protect it and the future supersonic space planes from the searing heat of re-entry into the Earth's atmosphere. They are also used widely in electronics and optics. An example would be a ceramic bearing coating over a titanium frame used for an aircraft. Recently the field has come to include the studies of single crystals or glass fibers, in addition to traditional polycrystalline materials, and the applications of these have been overlapping and changing rapidly.