Ceramics Flashcards
What is a ceramic?
A ceramic is a material that is neither metallic nor organic. It may be crystalline, glassy, or both, and is typically hard, chemically non-reactive, and can be formed or densified with heat.
What are some common examples of ceramics?
Common examples include clay, bricks, tiles, glass, cement, pottery, and dishes.
What are the primary components of traditional ceramics?
generally made from clay, silica (sand), and feldspar.
What distinguishes advanced ceramics from traditional ceramics?
Advanced ceramics are made from highly pure and refined raw materials through precise manufacturing processes that control compositions and microstructures, resulting in superior mechanical strength, temperature resistance, and durability.
What are the main categories of ceramics?
- glasses: optical, containers/household
- clay products: bricks, whiteware
- refractories: bricks for high T
- cements: composites, structural
- advanced ceramics: engine, bearings, sensors
What are the properties of cement ceramics?
Cement ceramics form a slurry that sets and hardens when mixed with water, and they can be used to form virtually any shape.
What is the main ingredient in glass?
silica (SiO₂).
What happens if glass is cooled very slowly?
If cooled very slowly, glass will form a crystalline structure.
What is tempered glass, and how is it made?
Tempered glass is glass that has been heat-treated to increase its toughness and resistance to cracking. It is made by heating the glass to around 650°C to 700°C and then rapidly cooling it.
What are the three common types of glass?
The three common types are soda-lime glass, lead glass, and borosilicate glass.
What is the float glass process?
The float glass process involves floating molten glass on a bath of molten tin to produce flat glass sheets.
What are some common materials used in advanced ceramics?
Common materials include silicon nitride (Si₃N₄), silicon carbide (SiC), zirconia (ZrO₂), and alumina (Al₂O₃).
What are the advantages of using ceramics in heat engines?
Advantages include high-temperature resistance, excellent wear and corrosion resistance, low frictional losses, and the ability to operate without a cooling system.
What are the disadvantages of using ceramics in heat engines?
Disadvantages include brittleness, difficulty in machining, and the potential for voids that can weaken the engine.
What are the main ceramic fabrication methods?
main methods are glass forming, particulate forming, and cementation.
What is slip casting?
Slip casting involves pouring a liquid clay mixture (slip) into a mold, allowing the mold to absorb water, and then removing the formed “green” ceramic.
What is sintering in ceramic fabrication?
Sintering is a process where ceramic particles are heated to a high temperature to form a solid piece by reducing pore size and forming necks between particles.
What is tape casting used for?
Tape casting is used to produce thin sheets of green ceramic for applications like integrated circuits and capacitors.
What is the purpose of annealing in glass fabrication?
Annealing removes internal stresses caused by uneven cooling, making the glass more durable.
What are the mechanical properties of ceramics?
Ceramics are characterized by high-temperature resistance, high strength, super hardness, wear resistance, and corrosion resistance.
How do ceramics compare to metals in terms of electrical conductivity?
Ceramics are generally poor electrical conductors, while metals are good conductors.
What is the difference between the tensile strength of metals and ceramics?
Metals have high tensile strength, while ceramics have poor tensile strength and are brittle.
What is the difference between the shear strength of metals and ceramics?
Metals have low shear strength, while ceramics have high shear strength.
What is the difference between the ductility of metals and ceramics?
Metals are ductile and can undergo plastic flow, while ceramics are brittle and have poor ductility.
What is the significance of porosity in refractories?
Porosity in refractories helps with thermal insulation and resistance to thermal shock, but it must be controlled to maintain strength.
What is the purpose of adding water to clay in ceramic fabrication?
Adding water to clay allows the material to shear easily along weak van der Waals bonds, enabling processes like extrusion and slip casting.
