Materials A: Lecture 16- Ceramics

What are some applications of ceramics in technology?

Ceramics find diverse applications in technologies such as refractories, spark plugs, capacitors, sensors, abrasives and magnetic recording media. Notably, the space shuttle utilizes reusable, porous ceramic tiles for heat protection during re-entry.

How is the synthesis and processing of ceramic powders typically carried out?

Due to the high melting point and brittle nature of ceramics, traditional methods like melting and casting are impractical. Instead, ceramics are processed from ceramic powders, involving activities such as crushing, grinding, blending, and shaping using techniques like compaction, tape casting, extrusion, and slip casting.

What is the purpose of sintering in ceramic processing?

Sintering involves a high-temperature treatment that further consolidates a green ceramic, resulting in a dense material. This process contributes to obtaining the desired properties for final applications.

How is slip casting used in ceramics, and what are its applications?

Slip casting involves pouring an aqueous slurry of ceramic powder into a mould, allowing the formation of ceramics through drying and subsequent firing. This technique is widely employed in creating ceramic art, sanitaryware, and other products like sinks.

How are Miller-Bravais indices determined for hexagonal unit cells?

Miller-Bravais indices for hexagonal unit cells involve a special four-axis coordinate system due to the unique symmetry of the system. The designation for planes and directions includes four intercepts, with the first three integers related by h+k=-i

What are the key considerations for the characteristics of sintered ceramics?

For sintered ceramics, factors such as average grain size, grain size distribution, porosity level, presence of second phases, and orientation effects are crucial. The properties of ceramics are affected by these factors, influencing their mechanical and functional attributes

How is porosity measured in ceramics and why is it important

Porosity in ceramics, affecting mechanical properties is measured through apparent and true porosity. Apparent porosity involves interconnected pores and determines permeability, while true porosity includes both interconnected and closed pores, providing a more accurate representation of the ceramic properties