Ceramics Lecture Notes

What are ceramics?

Compounds formed between metallic and nonmetallic elements, commonly including oxides, nitrides, and carbides.

List examples of ceramics

Aluminum oxide (alumina, Al2O3); Silicon dioxide (silica, SiO_2); Silicon carbide (SiC); Silicon nitride (Si*3N_4); Clay minerals (e.g., porcelain); Cement; Glass

What do silicates primarily consist of?

Silicon and oxygen

What are some applications of silicate ceramics?

Early Ming Dynasty Bowls; Brick walls; Tile patterns; Electric fuses

List some applications of advanced ceramics

Si3N_4 gas turbine rotor; WC blast nozzle; MgO refractory bricks (furnace liners); Al2O*3 structural parts

Describe the elastic behavior of ceramics.

A linear relationship exists between stress and strain. The elastic moduli range from approximately 70 to 500 GPa. Porosity significantly influences the modulus of elasticity.

Why are tensile tests not commonly used for brittle ceramics?

Difficulty in preparing specimens; Challenges in gripping brittle materials; Ceramics failing at approximately 0.1% strain, necessitating perfect alignment.

What is flexural strength?

The stress at fracture in a three-point bending test.

Why does fracture strength vary in brittle ceramics?

Due to the dependence of fracture strength on the probability of flaws initiating cracks.

What are examples of ceramic materials?

Glasses; Clay products; Refractories; Abrasives; Cements; Ceramic biomaterials; Carbons; Advanced ceramics

How are clay-based products divided?

Structural clay products (bricks, tiles, sewer pipes) and Whitewares (porcelain, pottery, tableware, china, plumbing fixtures)

List key properties of refractory ceramics.

Ability to withstand high temperatures without melting or decomposing; Inertness and unreactivity in severe environments.

What are abrasive ceramics used for?

To wear, grind, or cut other, softer materials.

List some desirable properties for ceramic biomaterials.

Chemical inertness; Hardness; Wear resistance; Low coefficient of friction.

What are some applications of ceramic biomaterials?

Implants, load-bearing, orthopedic applications, and femoral heads for hip replacements.

Describe annealed glass.

Untreated glass with standard grains that is weak and prone to chemical attack.

Describe tempered glass

Tempered (safety) glass: created by quickly cooling heated glass with superior strength.

What is glass laminating?

Involves placing a thin layer of ductile polymer between glass layers to hold the glass in place after fracture.