Basic Technology

Ceramics, Types and Characteristics of Ceramics

len Alfred Ajibola - Fri, 25th January, 2019 @ 02:09:28 AM

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What are Ceramics?

Ceramics are not metals, neither are they plastics. They are all around us and include things like tile, bricks, spark plugs, diamond and glass.

Ceramics as a topic and a product is indeed very broad; and this had made it's defination somewhat complex. Infact, often times, It is defined as what it's not.

Defining ceramics by it's characteristics can be a little complicated because not all of them share the same feature. For instance ceramics like glass and mugs tend to be hard; and are also bad conductor of electricity. Graphite on the other hand is a ceramic, although it's brittle (soft) and also a good conductor of electricity.

From the above instance, the ceramics; Graphite and Glass share different characteristics. A major reason why both are classified as ceramics is because: "They are inorganic and non-metallic".

ceramics are simply defined inorganic and non-metallic materials.

Inorganic imply that they they do not have their origin from living organisms

Refratory means that they are capable of withstanding a variety of abuses like high temperatures and chemical attacks.

Please read on Organic Chemistry here.

Note: Ceramics are refractory by nature and require a very high amount of heat and subsquent cooling to be formed.

Ceramics are generally made by taking clay from the ground and mixing it with water. It is then shaped into any form and fired inside an oven (called kiln) at a very high temperature. They may then be decorated with a waterproof, paint-like substances called glazes.

Types of Ceramics

Ceramics may be classified into two. These are:


(A) Traditional Ceramics

They are made completely from clay. We can Categorize them into the followings:

  1. Earthenware: These are clay fired at a fairly low temperatures of about 900°C – 1,150°C. The result is the formation of a partially porous and rough object.
    As a fix for it's porosity, the resulting product is covered with a waterproof, paint-like substance or "powered glass substance" suspended in water. (This substance is called glaze). It is then fired a second time.
    Delft and Majolica are examples of earthenware.

  2. Stoneware: They are clay fired at a temperature of about 1,250°C until they become vitrified, that is; glass-like.
    Stoneware is non-porous and if glazes were to be used, then it's only for decorative purposes.
    The products of stoneware are strong and durable materials which can be used as cooking pots, jugs and plates.

  3. Porcelain: They are made from kaolin clay, glass, granite, feldspar and water.
    Please read on the Types of Rocks here.
    Once made into desired shape, they are fired in a kiln between the temperatures 1,200°C – 1,450°C. It may be decorated with glazes by additional firing.
    By characteristics, they are very hard, translucent white ceramic.
    Procelain is sometimes referred to as fine china because it had it's origin from China.
    They are used as vaces, jugs and plates.

 

(B) Advanced Ceramics

They are based on metallic oxides or non-oxides (or combinations of both) and are not generally clay based.

The main oxides used in advanced ceramics are aluminium oxide (Al2O3), Magnesium oxide (MgO) and zirconium oxide (ZrO2).

The non-oxides are mainly carbides, borides and silicides; for example, boron carbide (B4C) and silicon carbide (SiC).

With regards to how they are produced, firstly, these oxides are thoroughly grounded into very fine powders and then shaped into a green body fired at a very high-temperature (1,600–1,800°C) in an oxygen-free atmosphere; (and allowing the tiny grains of each ceramic components to join together. This aformentioned process called sintering).

The end result is a very hard, durable and corrosion-resistant product.

Note: Advanced ceramics are used in metal production and electronics.

 

Please read on Characteristics of Hardwood and Softwood here.

Characteristics of Ceramics

Ceramics may have constrasting physical and chemical properties/characteristics; but in general,

  1. They have high melting points.
  2. They are heat resistant.
  3. They can be very hard with great strength; although a few are brittle or soft; for example, graphite.
  4. They are durable (last for a long time).
  5. Most are electrical insulators (cannot conduct electricity) but graphite is an electrical conductor.
  6. They are chemically unreactive or inert.
  7. They are not easily oxidized.
  8. Most are non-magnetic.

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len

Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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