What Are The Common Ceramics?

Ceramics are inorganic, nonmetallic materials that are hardened by high temperature firing. The word “ceramic” comes from the Greek word “keramos” meaning potter or pottery. Ceramics are compounds formed between metallic and nonmetallic elements such as aluminum, oxygen, nitrogen, silicon, carbon, and boron.

The most common types of ceramic materials are earthenware, stoneware, porcelain, and bone china. Ceramics are used for tableware, sanitaryware, electrical insulators, pipes, building materials, and abrasives. The properties of ceramics vary widely, but they are generally hard, inert, brittle materials that withstand high temperatures.

This article provides an overview of the most common categories of ceramic materials, their properties, manufacturing process, and uses.

Earthenware

Earthenware is made from clay and is fired at lower temperatures, typically between 1000-1200°C. It is porous and slightly permeable to liquids. The most common use of earthenware is for flower pots, dishes, and decorative items. Earthenware can be glazed to provide an impermeable surface. Unglazed earthenware absorbs water and needs to be fired at a higher temperature if it will hold liquids. Earthenware is heavier and thicker than other types of ceramics. It also tends to be more affordable and accessible. According to Soul Ceramics, earthenware has a natural thick cross section, making it suitable for everyday practical uses.

Stoneware

Stoneware is a vitreous or semi-vitreous ceramic made from clay that has been fired at high temperatures ranging from 1200°C to 1300°C. According to The Pottery Wheel, stoneware is less porous than earthenware but more porous than porcelain.

Stoneware is made from refined clay with a high percentage of fluxes. The fluxes help lower the vitrification temperature of the clay so that it can be fired at high enough temperatures to become non-porous and suitable for holding liquids. However, stoneware retains some porosity, making it less glass-like than porcelain.

Stoneware ceramics are valued for their strength and thermal shock resistance. They can withstand rapid temperature changes without cracking, making them ideal for ovenware and dishware. In fact, stoneware was originally developed in Germany and England specifically for producing kitchen and tableware such as jugs, plates, mugs and serving dishes. The fired clay becomes impervious to water and able to withstand freezing, thawing and washing without damage.

Today, stoneware continues to be a popular choice for kitchenware and tableware. It provides a good combination of durability, lower cost than porcelain, and appealing natural colors and textures. The partial vitrification makes stoneware non-porous enough to hold liquids without leaking, while retaining some of the natural charms of an unglazed clay surface. With glazes added, stoneware takes on even more possibilities for functional artistry.

Porcelain

Porcelain is a type of ceramic made from kaolin clay that is fired at very high temperatures between 2,200 and 2,600 degrees Fahrenheit. It is known for being non-porous, translucent, and delicate (The Crucible). Since porcelain can withstand high temperatures and is impermeable to water, it is commonly used to make art objects, dishware, sanitaryware and electrical insulators.

Unlike other types of pottery such as earthenware, porcelain has low porosity, making it less prone to absorbing water and breaking. The kaolin clay used to make porcelain contains minerals that vitrify and become glass-like when fired at high heat. This renders the final porcelain product smooth, brittle, and translucent with a luminous sheen. True porcelain is delicate yet durable.

Translucence is a key property of porcelain that allows light to pass through the material. Thinner pieces used for bone china tea sets often appear nearly transparent. The delicate, translucent nature of porcelain sets it apart from opaque stoneware ceramics. Porcelain’s refined white color also contrasts with the tan or red hues of earthenware. The result is a smooth, delicate, and luminous final product.

Bone China

Bone china is a type of porcelain that is composed of bone ash, feldspathic material, and kaolin. It is known for being translucent, delicate, and expensive compared to other types of ceramics (Ceramics & Tableware).

The bone ash in bone china comprises about 50% of the total composition. The bone that is used comes from cattle and is calcinated at a very high temperature until it becomes bone ash. This bone ash is what gives bone china its milky white color and translucency.

The addition of bone ash also makes bone china thinner, lighter, and more delicate than other ceramics. It has high tensile strength which allows bone china to be fashioned into more intricate shapes. However, its delicate nature also makes it more prone to chipping if handled roughly.

Due to the amount of bone ash required in its production, bone china is usually more expensive than porcelain or stoneware. The cost of bone china also stems from its very refined production process as well as its reputation as a high-class ceramic (components bone china ceramics style Two Eight company). It is prized for its beauty and status, making it popular for fine china dinnerware and tea sets.

Terracotta

Terracotta, from the Italian “baked earth,” refers to a type of unglazed clay that is fired at lower temperatures than many other ceramics. Terracotta clay is very permeable and tends to be reddish orange or brownish red in color after firing due to the iron oxide content in the clay. Some key characteristics of terracotta include:

Terracotta is typically used for items like plant pots and sculptures. The porosity of terracotta makes it great for plant pots, as it allows air and water to pass through. Many garden pots and planters are made from terracotta clay for this reason. Terracotta is also a common material for sculptures, as it can be easily shaped when wet and becomes durable and lightweight after firing. Greek and Roman sculptures were often made with terracotta. Terracotta artwork and architectural decorations remain common in many parts of the world today.

Overall, terracotta represents one of the oldest and most basic forms of ceramic, given its crude clay composition and low firing temperatures. But it continues to be valued for certain uses like gardening and sculpture where permeability and moldability are beneficial properties.

Refractories

Refractories are ceramics specifically designed to withstand very high temperatures, with high heat resistance and strong thermal insulation properties. They are used in applications such as kiln linings, furnace linings, fireplace and chimney components, and other structures exposed to high heat. The key properties of refractory ceramics that enable their use in extreme environments are:

• High melting points – Refractory ceramics have very high melting temperatures, often above 1500°C.
• Good thermal insulation – They function as thermal insulators due to their low thermal conductivity, reducing heat transfer.
• Resistance to thermal shock – They are resistant to cracking under rapid temperature changes.
• Chemical stability – They are resistant to corrosion and chemical attack at high temperatures.

Some examples of refractory ceramics are alumina, silicon carbide, zirconia, and magnesium oxide. They are manufactured in shapes such as bricks, boards, and monolithics. Refractories find major use in applications like linings for kilns and furnaces, incinerators, and reactors across industries such as steel, glass, cement, and ceramics.

Technical Ceramics

Technical ceramics, also known as advanced ceramics or engineered ceramics, are non-clay ceramics that are valued for their mechanical, electrical, thermal, and chemical properties. They are frequently used to replace metals, plastics, and other materials in applications that require high strength, hardness, temperature resistance, electrical insulation, low thermal expansion, or chemical inertness.

Some common uses of technical ceramics include deep sea earthquake observation equipment, spacecraft and satellite components, parts for the Large Hadron Collider, high performance computer components, and medical implants. Electrical applications utilize their insulating properties, while mechanical applications take advantage of their hardness, strength, and ability to withstand high temperatures.

Some of the industries that rely heavily on technical ceramics are electronics, automotive, aerospace, defense, energy, and medical. As technology continues to advance, technical ceramics are replacing traditional materials in more and more applications due to their superior properties and performance.

Glass Ceramics

Glass ceramics are a mixture of glass and ceramic materials. They are produced by controlled crystallization of base glasses, which transforms them from amorphous solids into polycrystalline solids. The crystalline phase is embedded within a vitreous phase resulting in a composite material with improved mechanical, thermal and electrical properties compared to the parent glass.

Some common applications of glass ceramics include cooktops and stovetops. Glass ceramic cooktops use electrical heating elements underneath a smooth glass-ceramic surface to generate heat for cooking. The glass-ceramic surface has high resistance to thermal shock and chemicals, making it durable and easy to clean. Ceramic cooktops are prized for providing even heating across the surface¹.

Glass ceramics are also used for missile nose cones and reentry heat shields on spacecraft. The materials can withstand extremely high temperatures up to 1,000-1,600°C. The addition of crystalline phases imparts increased fracture toughness and thermal shock resistance compared to pure glass. This makes glass ceramics well-suited for applications undergoing rapid heating and cooling cycles.

Conclusion

In summary, the most common types of ceramics are earthenware, stoneware, porcelain, bone china, terracotta, refractories, technical ceramics, and glass ceramics. Each type is characterized by different properties, manufacturing processes, and applications.

Earthenware, the oldest type, is porous, softer, and lower-fired. It’s used for flower pots, dishes, and decorative pieces. Stoneware is water-resistant and durable, making it ideal for cookware and storage containers. Porcelain, the most prestigious ceramic, is highly refined, translucent, and vitreous. It’s valued for tableware, artware, and sanitary ware applications.

Bone china combines calcined bone ash with clay to create a delicate, white, translucent material used for fine china tableware. Terracotta refers to unglazed ceramic clay used for pottery, figurines, and architectural decorations. Refractories withstand extremely high temperatures and are used to line furnaces and kilns. Technical ceramics have advanced engineering properties for applications like ceramics armor, prosthetics, and electronics.

Glass ceramics start as glass and are heat-treated to form crystalline phases, combining glass and ceramic properties. Overall, ceramics are an incredibly diverse material family with ancient origins and modern high-tech applications across countless industries.