Ceramic is one of the most used materials in our day-to-day life. But do we know what is ceramic & why ceramic is a material? This post is all about Ceramic. You will learn about ceramics & their classification, properties, use. You will also get to know about glass & ceramic engineers & their work.
I am a certified Glass & Ceramic Engineer. I think I am the right man to write this kind of post! So stay till the end.
Ceramics and Their classification
First of all the word “ceramic” originated from the Greek word ‘keramikos’ which means “of pottery or for pottery”. From ancient times ceramic is used in pottery objects such as vessels, pots. These were made from clay including silica, alumina, feldspar, and then shaping the clay and lastly hardening in the fire.
This process is very familiar with the modern process of producing ceramics products. Ceramic can be defined as an inorganic, non-metallic solid consisting of metal, non-metal, or metalloid compounds; they are certain oxides, nitrides, sulfides.
Though in the past ceramic was specifically used in pottery, in present days the area of properties and application has expanded, so does the meaning of ceramic. This statement means that there are two different types of ceramic. The first one is traditional ceramic and the other one is Advance ceramic.
It was used in pottery and pottery is one of the oldest human technologies. Pottery is more clay-based. Various composition of clay is used as well as other additives(water and other to give a shape) and they were hardened through firing.
The firing temperature determined the nature of the end product. There are three types of pottery found in present. They are earthenware, stoneware, and porcelain.
- Earthenware: It is used for tableware and decorative objects. The clay of earthenware is fired at a relatively low temperature (1000°-1150°C).
This cause to produce the porous and coarse product. For this reason, the clay is fired a second time with grounding glass powder suspended in water(glaze). Earthenware is the oldest pottery found.
- Stoneware: stoneware is a very hard chip-resistance and very durable material. The clay is fired at a very high temperature which leads to nonporous products. If it is used for decoration then the glaze is applied during the production.
- Porcelain: It was actually coming from China. Many minerals like feldspar, white kaoline, granite are used to produce porcelain. They are fired at around 1200°-1400°C temperature and to add decorative glazes require further firing.
Porcelain is very hard, translucent, and white. As it originated from China, the Chinese are still use porcelain as plates, cups, pots, etc.
Advanced Ceramics :
Advanced ceramics are referred to as technical ceramic or high-tech ceramics. It represents the advancement in the ceramic area. Advanced ceramics are not clay-based like traditional ceramics. It is more likely to composition or compound based.
Over the past decades, the development in the process and manufacture of ceramic materials exhibit special properties such as extreme heat resistance, superconductivity, hardness, biocompatibility, etc. These exceptional qualities make them a more versatile group of materials.
There are two types of advanced ceramics.; oxides and non-oxides. Alumina (Al2O3) and Zirconia (ZrO2) are commonly used oxides ceramics whereas non-oxides are nitrides, carbides, borides. For example Boron Carbide, Silicon Carbide (SiC)
Chemical composition of ceramics
We know that the properties of any material depend on the types of atoms present in it, the bonding between the atoms in ceramics, and the way the atoms are packed together affect the application area as well.
Usually, there are two types of bonds are found in ceramics one is an ionic bond and the other is a covalent bond. The ionic bond propagates between a metal molecule and a nonmetal molecule. This means two atoms with very different electronegativity generate the bond.
On the contrary, a covalent bond occurs between two nonmetals molecules, in other words, two atoms that have similar electronegativity and the intention to sharing of electron pairs between the two atoms.
Though both types of bonds can be found in the chemical composition of ceramic materials, in most of them (Specifically the oxides) the ionic bond is more flourishing.
The ionic and covalent bonds of ceramics are accountable for many unique properties of ceramic materials, such as high hardness, high melting points, low thermal expansion, and good chemical resistance, but also for some unwanted characteristics, like being brittleness, which is the main cause to fractures.
These types of properties can be overcome if the material is toughened by reinforcing agents or by other means.
The properties of ceramic
The properties of ceramics depend on their microstructure. As ceramics are known by definition as natural or synthetic inorganic, non-metallic materials.
The structure of ceramics sometimes is crystalline, polycrystalline, and even monocrystalline (such as diamond and sapphire which are also included under the term ceramics). Polycrystalline materials are shaped by multiple crystal elements linked together during the production process.
Due to these differences in the crystal structure, the properties of ceramic materials are largely affected. Similarly, the grain sizes and shapes, and characteristics such as density, hardness, mechanical strength, and optical properties strongly correlate with the microstructure.
Now let’s see about some key points of the properties of ceramic materials like physical properties, mechanical properties, electrical properties, chemical properties, and optical properties.
- Physical properties:
- Physical properties include the melting point of the material, thermal conductivity. The properties also correlate with all the other properties.
- The melting point of ceramics are effectively very high which means they are heat resistant and the thermal expansion is very low compared to plastics and metals
- But the thermal conductivity stands between the metal and the plastics.
- Mechanical properties:
- These properties include the elasticity (stress, strain) of the material, strength, hardness, brittleness, etc.
- Ceramics are rigid and stiff.
- Generally, they have high compressive strength but the impact strength is comparatively low.
- They have poor thermal shock resistance.
- They have great hardness and considerable durability (long-lasting and hard-wearing)
- They have micro-cracks in the structure which cause brittle fraction and stress concentration.
- Electrical properties:
Ceramics have some serious electrical properties like electrical insulation, piezoelectric effects, semi-conducting behavior, and superconductivity.
- Metals Ceramics have very low electrical conductivity due to Ionic-Covalent Bonding which does not form free electrons. This is why ceramics are used as a grate insulator.
- There are some ceramics possessing superconductivity properties like Lanthanum (yttrium)-barium-copper oxide ceramic can be superconductor a critical temperature around as high as 138 K.
- Some ceramics show piezoelectric properties. They are used for manufacturing various transducers, actuators, and sensors like hydrophones, sonar, strain gauges, medical ultrasound equipment.
- The semi-conducting ceramics are made by liquid phase sintering with control of grain boundary structure. Positive Temperature Coefficient Resistors (PTCM) are formed using the properties of semiconducting ceramics.
- Chemical properties:
Ceramics are very resistant to any kind of chemical reagent and barely react with them. They even remain the same even in higher temperatures.
- Optical properties:
Ceramics contain microscopic grain boundaries and microstructure pores that diffuse the light and it is difficult to transmit the light. So ceramics are mainly translucent in nature. In fact, it is the major optical property in ceramics.
For example, Alumina is a good translucent material and it is used in high-pressure sodium street lamps. In recent decades many types of transparent ceramics have been developed for many usages.
Application of ceramics
Ceramics have way more influence on our daily life. We use ceramics almost every day in our life without even knowing that it is a ceramic material. There are many kinds of ceramics according to their application area. Some of them are whitewares, refractories, abrasives, glassware, cement advance, etc.
To be more clear, we point out to have the full knowledge about those ceramics and the applications.
- Traditional Ceramics: We know earlier about traditional ceramics, they are mainly clay-based. Though the concept is from ancient times, they are widely used these days to make pots, jars, plates, and other kitchen and household products. It is the most common products of ceramics that we already are aware of
- Refractories: Refractories are special kinds of ceramic materials with a high melting point. They have heat resistivity. They are mainly used in many industries like metal industries, plastic industries as a giant pot to melt the metal or plastics.
- Abrasives: An abrasive is a ceramic material that is used to shape or finish a material often means polishing it to gain a smooth surface, the process can also involve roughening as beaded finishes. They are extremely common to be found and are used very extensively in a wide variety of industrial, domestic, and technological applications. Abrasives are used as in many tools to operate cutting, drilling sanding, grinding, sharpening, and polishing.
- Whitewares: whitewares are one of the common ceramics in modern days. It is a wide area of ceramic products with off white color and glossy finish. The products of whitewares include china dinnerware, kitchen sinks, and toilets, dental implants, and spark-plug insulators.
- Cement: We all know about cement for sure. It is a binder material, a substance used for construction work. When it hardens, it adheres to other materials (bricks) to bind them together. Cement is rarely used on its own, but rather to mix with sand and pebbles (aggregate) together. Cement is one of the fundamental elements for building construction.
- Advanced ceramics: Advanced ceramics can revolutionize the modern world towards the future. It already changed the world we see today. Advanced ceramics are used in many fields. A few of them are denoted below:
Advanced Ceramics in the Automotive Industry
- ceramic is used (heat-resistant ceramic) in engine parts like valve components, backings in the crankshaft housing, and components for water and fuel pumps
- Advanced ceramic is used to increased efficiency, less wear, and lower noise outflow
Advanced Ceramics in Equipment and Mechanical Engineering
- It is applied in this sector for its high wear resistance, heat resistance, and high level of corrosion resistance
- To produce cutting tools, mechanical pumps
Advanced Ceramics in Electronics
- ceramic heat-sinks provide the right status for high-power electronics.
- used in Capacitors
- used in Insulators
- used in making miniature circuits
- used in processor (mobile and computers)
Advanced Ceramics in Medical Technology
- The doctors use biocompatible ceramics to help the patient with intensive care to overcome daily challenges.
- used to make Artificial bone
- used to make dental products
- Advanced ceramic is used in Aerospace Engines for protecting a hot-running airplane engine from damaging other materials.
- For Airframes; a high-stress, high-temp, lightweight bearing and structural component of advanced ceramic is used. Also used in missile nose-cones ;
- used in Space Shuttle tiles.
- used in Rocket nozzles, withstands and focuses the exhaust of the rocket booster.
- Modern industry• For the manufacture of ceramic knives Zirconium dioxide ceramics are mostly used. The sharpness of a ceramic knife lasts more than a steel knife.
- To produce bulletproof vest, ceramics such as alumina, boron carbide, and silicon carbide is mainly used,
- Ceramic ball bearings are generally made of silicon nitride.
Distinguish between glass and ceramics
Earlier we knew that ceramic is a nonmetallic, inorganic rigid material and mostly made of oxides, nitrides, or sulfides. Now moving to glass which sometimes can be called a type of ceramics. Glass is almost the same as ceramic except for some properties. It is a non-crystalline amorphous solid. But glass does not have a long-range periodic atomic structure like ceramic and polymer.
The main ingredient for manufacturing glass is silicon dioxide. We can find them as sands. In our nature, we can find glass as it naturally generates when very high temperatures like lava or lightning react with sand. But glass is also manufactured in kilns. When the process of manufacturing is completed, transparent, smooth glass is produced. Though glass is usually transparent in nature, sometimes it is made translucent or opaque. Glass is called supercooled liquid. When it is heated, it behaves like rubber.
Ceramics are opaque in nature since their main component is clay. Light cannot cross them rather form a shadow. The antique and vintage type prospect of ceramics makes them a great option for the aesthetical craft.
When the raw materials of ceramics are heated to high temperatures, they become hard as wanted. This process is costly so they are needed to operate carefully.
To be more specific about glass and ceramic, we denote some affairs:
- Structure: Glass is an amorphous and non-crystalline solid, on the other hand, ceramics are inorganic and can be crystalline or semi-crystalline but never non-crystalline.
The structure affects the glass to be more brittle in nature and the ceramics to be more hardened in nature.
- Ingredients: The main element of glass, most needed while manufacturing is silicon dioxide (sand) whereas the main elements of ceramics are mostly kaolin, feldspar, and other clay-based materials.
- Transparency: Glass is naturally transparent which means light can pass through it. On the contrary, ceramics are opaque. Glass can be transformed to make it translucent or even opaque. Ceramics are usually opaque in nature. So It is not possible for ceramic to be transparent as glass.
- Pricing: Glass is way cheaper as compared to ceramics. Because of the less production cost. Special kinds of ceramics have a higher as compared to glass and rarer to find these days.
- Heating with temperature: When glass is heated to higher temperatures, it behaves like rubber, which causes it to flows and melts as a thick liquid in some ways. Ceramics however when heated to high temperatures, become more harden as the water molecules vaporize.
However, glass is a kind of ceramic because it is made of nonmetallic, inorganic, metal-oxides. So according to the definition, it is a kind of ceramic but the properties and the application of these two are not similar in real life.
Why we need a ceramic engineer and a glass engineer?
Ceramic engineers are the intellectual materials engineers who work with ceramics, that are processed at high temperatures. Glass, porcelain, brick, and cement are the primary examples of ceramics.
Ceramic engineers exhibit new ceramic products as well as process and implement for processing ceramic materials. They usually work with a broad distinction of products, extending from glassware and electronic materials to nuclear reactors and jet engines.
Most ceramic engineers are hired mainly in the stone, clay, or glass industries. A few of them work in industries that use ceramics, such as the aerospace, iron and steel, and chemical industries. Even some ceramic engineers teach and do research in universities.
Ceramic engineers often specialize in research and development. They develop new ceramic components artificially or from minerals found in the earth. Rest ceramic engineers enhance the technology of existing ceramics, such as improving some properties like mechanical properties, electrical properties, etc.
The ceramic engineers who work involve in sales can show customers ways to use ceramics. They sometimes supervise the installation and operation of ceramic equipment in customers’ plants.
Ceramic engineers generally can be experts in one or more of the ceramic products like some assign with refractories, which are fire- and heat-resistant materials and coatings made of refractory materials which are used to defend the metal outer shell of spacecraft.
Dialectical engineers are ceramic engineers who particularly work on electrical ceramic materials. The production of electrical current, thermal nuclear current for generating power includes the criteria of the engineers.
One of the common fields of ceramic industries is whitewares, which is a wide area that includes china dishes and electric insulators. Some other special product fields are including abrasives, cement, structural ceramics, superconducting materials, and nonmetallic nuclear fuels. In these industries, the engineers have plenty of scopes to be shinned.
Now from the glass engineer point of view,
Glass engineering is a special section of materials engineering that concentrates on the design of glass, related composites. Engineers in this branch design and experiment new materials that can replace the traditional glass enhancing the performance or strength where it is required.
A glass engineer may also develop new implements that can be applied to advance the glass production process and manufacturing, Their initial task is to supervise in order to increase the production of glass and glass-related structures or products.
In the modern-day, all the skyscraper buildings are made of glass surfaces instead of bricks and cement. So glass engineers focus on research and develop new materials and technologies to flourish this glass industry. They experiment with existing types of glass to make the mechanical properties even more advance.
In research and development criteria, a glass engineer also generates test structures to see if they can tolerate certain types of forces, temperatures, or other factors. A glass engineer can consult with the companies to arrange materials within the factory to maximize production, and help to train employees to use equipment properly.
A glass engineer may design some advanced glass that has way more strength, hardness than regular glass, for example, bulletproof glass. And to manufacture this type of special glass the engineers has to maintain a strict way. We know that optical fiber is very much used in many ways. It is very thin like hair and made of glass. So to produce and design the fiber we just need a glass engineer.
There are three types of material that exist on the planet; metal, polymer, and ceramic. Ceramics have played a crucial part to make the world a better place. In the stone age, it is used to make fires (stones) from that incident to build civilizations(lost), to develop a modern world, ceramics played a major role.
We live around many ceramics without even knowing about the material. Now, as the world progresses, the ceramic industries are uprising rapidly with their latest innovation. So, the main target is to change the world for a better future.
You can also read: