One of the commonly used materials is ceramics. It is a widely used material. Our first thought of ceramics probably would be pottery or dishes. But, ceramics is more than pottery and dishes: clay, bricks, tiles, are all examples of ceramic.
In this lesson, we are going to learn about CERAMICS and we will discuss:
Thousand so years ago, humans discovered that clay could be found in abundance and can be formed into objects by first mixing with water and then firing. This is when ceramic appears as a material. It is considered one of the oldest materials created by man. The earliest ceramics made by humans were pottery objects, like pots, vessels, or figurines made from clay.
The word ceramics is derived from the Greek word keramos which means "potter’s clay". However, many compounds which are classified as ceramics today contain no clay.
Today, ceramics is everywhere around us. It can be defined as an inorganic non-metallic solid made up of either metal or non-metal compounds that have been shaped and then hardened by heating to high temperatures.
Both pottery and ceramic are general terms that describe objects which have been formed with clay, hardened by firing, and decorated or glazed.
Ceramics are generally made by taking mixtures of clay, earthen elements, powders, and water and shaping them into desired forms. Once the desired object has been shaped, it is heated to a very high temperature. The process of heating is usually performed in a high-temperature oven known as a kiln.
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for a long time to turn objects made from clay into pottery, tiles, and bricks.
During the process of heating, it undergoes a series of chemical reactions and is hardened to form ceramics.
Often, ceramics are covered in decorative, waterproof, paint-like substances. Those paint-like substances are called glazes.
Round-shaped ceramics objects are made with the help of a potter's wheel. The potter's wheel looks like a horizontal revolving disk on which wet clay is shaped into pots or other round ceramic objects.
Types of atoms present, the types of bonding between the atoms, and the way the atoms are packed together determine the properties of ceramics, just like in every other material. Properties of ceramics include:
In general, ceramics is hard, corrosion-resistant, and brittle. It is extremely durable and can resist scratches and common damages. But, due to the molecular structure, it is not resistant to shattering, so if a ceramic object falls onto a hard surface it may shatter.
Ceramics is 100% recyclable material. But actually, many of us wonder if potteries are biodegradable since they are made from earthly materials? The answer is yes, they are biodegradable, but it usually takes a very long time. It can even take as long as a million years for a piece of glazed pottery to biodegrade.
Ceramics is hard, porous, and brittle. As a result, it is used to make pottery, bricks, tiles, cement, and glass. Ceramic products can be structural, refractories, whitewares, or technical. Each of the groups includes:
Types of ceramics vary in accordance to the clay used to create them, as well as the heat required to fire them. They include the following three main types of pottery/ceramic:
Earthenware is clay fired at relatively low temperatures of between 1,000 to 1,150 degrees. Earthenware is pottery that is porous, which means that water gets through tiny holes slowly, therefore, the basic earthenware can not be used to contain water. Basic earthenware is often called terracotta. Earthenware can be glazed. That can make it waterproof.
Stoneware is a rather broad term for pottery or other ceramics fired at a relatively high temperature. A modern technical definition is a vitreous (glossy look) or semi-vitreous ceramic, that has a glossy look made primarily from stoneware clay or non-refractory fire clay. Whether vitrified or not, it is nonporous and it may or may not be glazed.
Porcelain is a ceramic material made by heating clay-type materials to high temperatures. It includes clay in the form of kaolinite. There is a distinction between hard-paste porcelain, fired at 1400 degrees Celsius, and soft-paste porcelain, fired at 1200 oC. The term porcelain refers to a wide range of ceramic products that have been baked at high temperatures to achieve vitreous, or glassy qualities.
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