06 Ceramics and Glasses Free Online FlashCards

How does the atomic structure of glass differ from crystalline ceramics?

Crystalline ceramics have ordered atomic arrangements; glass is amorphous, with no repeating long-range order.

Which material families commonly make up ceramics?

Ceramics commonly include oxides, carbides, and nitrides, held together mainly by strong ionic or covalent bonds.

What are grains and grain boundaries in a crystalline ceramic?

Crystalline ceramics consist of small crystals, or grains, with different orientations; the interfaces between them are grain boundaries.

What is the structure of ordinary silica glass?

Ordinary silica glass has a silicon–oxygen network that is disordered rather than crystalline.

Why is borosilicate glass useful where temperatures change?

Borosilicate glass has relatively low thermal expansion, making it useful where temperature changes are expected.

How is a glass-ceramic made?

A glass-ceramic starts as glass and is heat-treated to form fine crystals within it.

Which useful properties do strong bonds give many ceramics?

Strong bonds give many ceramics high hardness, stiffness, wear resistance, and chemical resistance.

What does brittleness mean for a ceramic?

Many ceramics are brittle: they undergo little plastic deformation before fracture. Strong bonds and limited atomic-plane slip help explain this behavior.

How can a small flaw cause a ceramic to fracture?

Cracks, pores, and surface damage can concentrate stress and trigger sudden fracture.

How does ceramic strength generally compare in compression and tension?

Ceramics and glasses are generally much stronger in compression than in tension, so tensile loading is a key design concern.

What causes thermal shock in ceramics or glass?

Thermal shock occurs when rapid temperature change creates internal stress from uneven expansion or contraction, and that stress exceeds resistance to fracture.

How can thermal-shock risk be reduced?

Low thermal expansion and carefully controlled heating or cooling can reduce thermal-shock risk.