1. Chapter 12 Characteristics of Ceramic Materials

2. Objectives Divisions of ceramic – clay and glass. Ceramic stock including synthetic materials such as high temperature carbide and natural materials such as soapstone and clay. Traditional ceramics. Industrial ceramics.

3. Background Ceramic products are made of clay, an inorganic, nonmetallic solid material that is derived from naturally decomposed granite. Ceramic products such as brick, pottery, and art ware have been made from sand and clay since the Iron Age and Bronze Age. Advanced ceramics companies are manufacturing high temperature cutting tools, artificial joints, and much more. In the telecommunications industry, glass fiber cables, about the thickness of a human hair carry more than 50,000 telephone conversations. Conventional copper wires are able to carry 24 simultaneous telephone conversations.

4. Unique Characteristics of Ceramics The advantages of ceramics are high melting temperatures, high hardness, high compressive strength, and low electrical and thermal conductivity. Ceramics are able to survive corrosive gases, molten metals, and acids. The disadvantages are low impact strength and a high degree of brittleness. Uses include diesel engine exhaust valves and heat exchange tubes, hot gas filters, and gas turbine combustion chamber liners.

5. Ceramics in Space The heat resistant tiles on the underside of the shuttle are part of the thermal protection system (TPS) that protect the shuttle as temperatures reach 3000 0 F as the orbiter returns to earth. The quality of materials are greatly improved when produced in the weightless environment of space.

6. Other Applications of Ceramics Ceramics are used for gun liners, ceramic armor, and ammunition parts. The NATO C-130 aircraft are equipped with fiber and glass ceramic cockpit armor. Doctors are experiencing success with ceramics in hip and knee joint replacements. Ceramics are also used of heart valves, and dental implants. Containment booms suing ceramic material are being used to surround oil spills. Ceramics are also used for floor tiles, brick, gypsum board, sewer pipes and glass.

7. Ceramics Traditional Ceramics: include clay and glass products - structural clay products, white ware, refractories, glass, abrasives, and cement. Advanced Ceramics: include 4 major industry segments – structural, electrical, coatings, chemical and environmental ceramics. Companies are now able to combine metals and ceramics to make cermet (ceramic/metal composite) cutting tool inserts. They are made either from aluminum oxide or titanium carbide to create a very hard shock resistant cutting surface.

8. The Nature of Industrial Stock Long before the pyramids, craftsmen combined local clay and water, shaped the plastic material by hand to make pottery to store food and water, and then permanently removed the water using direct fire or heated furnaces. Egyptian glass beads were discovered that date back to about 2500 BC. The basic raw material for glass is silica. Soda-lime glass is used extensively for light bulbs, bottles, and windows.

9. Summary Ceramic products are made of clay, an inorganic, nonmetallic solid material that is derived from naturally decomposed granite. In the telecommunications industry, glass fiber cables, about the thickness of a human hair carry more than 50,000 telephone conversations. The advantages of ceramics are high melting temperatures, high hardness, high compressive strength, and low electrical and thermal conductivity. Ceramics are able to survive corrosive gases, molten metals, and acids. The heat resistant tiles on the underside of the shuttle are part of the thermal protection system (TPS) that protect the shuttle as temperatures reach 3000 0 F as the orbiter returns to earth. Doctors are experiencing success with ceramics in hip and knee joint replacements. Ceramics are also used of heart valves, and dental implants. Companies are now able to combine metals and ceramics to make cermet (ceramic/metal composite) cutting tool inserts.

10. Home Work 1. What is the advantage of glass fiber cables? 2. What are the advantages of ceramics? 3. What are cermets?