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ceramic-engineering

Ceramic engineering

Ceramic Engineering is the technology of manufacturing and usage of ceramic materials. Many engineering applications benefit from ceramics characteristics as a material. The characteristics of ceramics have garnered attention from engineers across the world, including those in the fields: Electrical Engineering, Materials Engineering, Chemical Engineering, Mechanical Engineering, and many others. Highly regarded for being resistant to heat, ceramics can be used for many demanding tasks that other materials like Metal and Polymers can not.

Traditional ceramic raw materials include clay minerals such as kaolinite, more recent materials include aluminium oxide, more commonly known as alumina. The modern ceramic materials, which are classified as advanced ceramics, include silicon carbide and tungsten carbide. Both are valued for their abrasion resistance, and hence find use in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are also used in the medicine, electrical and electronics industries.

Ceramic Engineers are found in a wide variety of manufacturing, research and educational fields. These include mining, aerospace, medicine, refinery, food industry, chemical industry, packaging science, electronics, industrial electricity, and transmission electricity.

The Ceramic Process

A general definition of a ceramic material could be: A ceramic is any inorganic crystalline oxide material. It is solid and inert. Ceramic materials are brittle, hard, strong in compression, weak in shearing and tension. They withstand chemical erosion that occur in an acidic or caustic environment. In many cases withstanding erosion from the acid and bases applied to it. Ceramics generally can withstand very high temperatures such as temperatures that range from 1,000°C to 1,600°C (1,800°F to 3,000°F). Exceptions include inorganic materials that do not have oxygen such silicon carbide. Glass by definition is not a ceramic because it is an amorphous solid (non-crystalline). However, glass involves several steps of the ceramic process and its mechanical properties behave similarly to ceramic materials.

The ceramic process generally follows this flow.

Milling→ Batching→ Mixing→ Forming→ Drying→ Firing→ Assembly→

Milling is the process by which materials are reduced from a larger size to a smaller size. Milling may involve breaking up cemented material, thus the individual particle retain their shape or pulverization which involves grinding the particles themselves to a smaller size. Pulverization is actually fracturing the grains and breaking them down.

Generally milling is done through mechanical means. The means include attrition which is particle to particle collision that results in agglomerate break up or particle shearing. Compression which is applying compressive forces that result in break-up or fracturing. Another means is impact which involves a milling media -or the particles themselves- that cause break up or fracturing.

Examples of equipment that achieve attrition milling is a planetary mill or an wet attrition mill, also called wet scrubber. A wet scrubber is a machine that has paddles in water turning in opposite direction causing two vortexes turning into each other. The material in the vortex collide and break up.

Equipment that achieve compression milling include a jaw crusher, roller crusher, and cone crushers.

Finally impact mills may include a ball mill with media that tumble and fracture material. Shaft impactors cause particle to particle attrition and compression which achieve size reduction.

Batching is the process of weighing the oxides according to recipes, and preparing them for mixing and drying.

Mixing occurs after batching and involve a variety of equipment such as dry mixing ribbon mixers (a type of cement mixer), Mueller mixers, and pug mills. Wet mixing generally involve the same equipment.

Forming is making the mixed material into shapes, ranging from toilet bowls to spark plug insulators. Forming can involve: 1) Extrusion, such as extruding "slugs" to make bricks 2) Pressing to make shaped parts. 3) Slip casting, as in making toilet bowls, wash basins and ornamentals 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 product will change its shape. For example, a green brick can be "squeezed", and after squeezing it will stay that way.

Drying is removing 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.

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.

Assembly This process is for parts that require additional subassembly parts. In the case of a spark plug, the electrode is put into the insulator. This step does not apply to all ceramic products.

Ceramics Applications in Engineering

Ceramics can be used in many technological industries. One application are the ceramic tiles on NASA's Space Shuttle, used to protect it and the future supersonic space planes from the searing heat of reentry into the earth's atmosphere. They are also used widely in electronics and optics. In addition to the applications listed here, ceramics are also used as a coating in various engineering cases. An example would be a ceramic bearing coating over a titanium frame used for an airplane. 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.

Aerospace:

  • Engines; Shielding a hot running airplane engine from damaging other components.
  • Airframes; Used as a high-stress, high-temp and lightweight bearing and structural component.
  • Missile nose-cones; Shielding the missile internals from heat.
  • Space Shuttle tiles
  • Rocket Nozzles; Withstands and focuses the exhaust of the rocket booster.

Biomedical:

  • Artificial bone; Dentistry applications, teeth.
  • Biodegradable splints; Reinforcing bones recovering from osteoporosis
  • Implant material

Electronics and Electrical Industry:

Optical/Photonic:

History of Ceramics in Engineering

Ceramics Engineering, like many sciences, evolved from a different discipline by today's standards. Materials Engineering is grouped with Ceramics Engineering to this day. Universities with ceramics programs include a curriculum saturated with materials engineering classes.

The modern day ceramic engineer may find themselves in a variety of industries. Similar to other disciplines a ceramic engineer may find themselves in mining and mineral processing, pharmaceuticals, foods, and chemical operations.

Abraham Darby first used coke in 1709 in Shropshire, England, to improve the yield of a smelting process. Coke is now widely used to produce carbide ceramics. Potter Josiah Wedgwood opened the first modern ceramics factory in Stoke-on-Trent, England, in 1759. Austrian chemist Karl Bayer, working for the textile industry in Russia, developed a process to separate alumina from bauxite ore in 1888. The Bayer process is still used to purify alumina for the ceramic and aluminum industries. Brothers Pierre and Jacques Curie discovered piezoelectricity in Rochelle salt circa 1880. Piezoelectricity is one of the key properties of electroceramics. E.G. Acheson heated a mixture of coke and clay in 1893, and invented carborundum, or synthetic silicon carbide. Henri Moisson also synthesized SiC and tungsten carbide in his electric arc furnace in Paris about the same time as Acheson. Karl Schröter used liquid-phase sintering to bond or "cement" Moissan’s tungsten carbide particles with cobalt in 1923 in Germany. Cemented (metal-bonded) carbide edges greatly increase the durability of hardened steel cutting tools. W.H. Nernst developed cubic-stabilized zirconia (CSZ) in the 1920s in Berlin. CSZ is used as an oxygen sensor in exhaust systems. W.D. Kingery and others in the 1950s developed partially-stabilized zirconia (PSZ), greatly increasing its toughness. PSZ is used to make cutlery and other tools. Lead zirconate titanate (PZT) was developed at the United States National Bureau of Standards in 1954. PZT is used as an ultrasonic transducer, as its piezoelectric properties greatly exceed those of Rochelle salt.

The first ceramic engineering course and department in the United States were established by Edward Orton, Jr., a professor of geology and mining engineering, at the Ohio State University in 1894. Orton and eight other refractory professionals founded the American Ceramic Society (ACerS) at the 1898 National Brick Manufacturers' Association convention in Pittsburgh. Orton was the first ACerS General Secretary, and his office at OSU served as the society headquarters in the beginning. Charles F. Binns established the New York State School of Clay-Working and Ceramics, now Alfred University, in 1900. Binns was the third ACerS president, and Orton the 32nd. The Ceramic Society of Japan was founded in 1891 in Tokyo. Deutschen Keramischen Gesellschaft, the ceramic society of Germany, was founded in Berlin in 1919.

The military requirements of World War II (1939-1945) encouraged developments, which created a need for high-performance materials and helped speed the development of ceramic science and engineering. Throughout the 1960s and 1970's, new types of ceramics were developed in response to advances in atomic energy, electronics, communications, and space travel. The discovery of ceramic superconductors in 1986 has spurred intense research to develop superconducting ceramic parts for electronic devices, electric motors, and transportation equipment.

Preceding the spark of the ceramic industry in the late 19th century, there was the study of materials closely associated with chemistry. Since Ceramics are comprised of a crystalline structure, the knowledge of crystal formation and the strengths involved was important in the development of ceramics as a standalone scientific field.

Present Day Ceramics Engineering

Now a multi-billion dollar a year industry, ceramics engineering and research has established itself as an important field of science. Applications continue to expand as researchers develop new kinds of ceramics to serve different purposes. An incredible number of ceramics engineering products have made their way into modern life. The largest producers of engineered ceramics--and largest employers of ceramic engineers--include AVX, CeramTec, CoorsTek, Corning, EDO, Kohler, Kyocera, Morgan Crucible, Murata, Saint-Gobain and 3M.

Education

Many educational institutions in the United States offer degrees in this field, examples being the New York State College of Ceramics located at Alfred University, and Rutgers University, and there are several in other countries. Some of these institutions are planning to change the names of their disciplines to Materials science, "Materials engineering" or Materials Science and Engineering (MS&E). Clemson University and the Missouri University of Science and Technology offer Ceramic Engineering Major & Materials Minor.

See also

Further reading

  • Engineered Materials Handbook, Volume 4: Ceramics and Glasses, ASM International, 1991, ISBN 0-87170-282-7.
  • M.W. Barsoum, Fundamentals of Ceramics, McGraw-Hill Co., Inc., 1997, ISBN 978-0070055216.
  • W.D. Callister, Jr., Materials Science and Engineering: An Introduction, 7th Ed., John Wiley & Sons, Inc., 2006, ISBN 978-0471736967 .
  • W.D. Kingery, H.K. Bowen and D.R. Uhlmann, Introduction to Ceramics, John Wiley & Sons, Inc., 1976, ISBN 0-471-47860-1.
  • M.N. Rahaman, Ceramic Processing and Sintering, 2nd Ed., Marcel Dekker Inc., 2003, ISBN 0-8247-0988-8.
  • J.S. Reed, Introduction to the Principles of Ceramic Processing, John Wiley & Sons, Inc., 1988, ISBN 0-471-84554-X.
  • D.W. Richerson, Modern Ceramic Engineering, 2nd Ed., Marcel Dekker Inc., 1992, ISBN 0-8247-8634-3.
  • W.F. Smith, Principles of Materials Science and Engineering, 3rd Ed., McGraw-Hill, Inc., 1996, ISBN 978-0070592414.
  • L.H. VanVlack, Physical Ceramics for Engineers, Addison-Wesley Publishing Co., Inc., 1964, ISBN 0201080680.

References

External links

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