Chapter 27

Processes Used to Fabricate Ceramic Materials

Objectives

• Direct Bonding and Mechanical Attachment.• Metallizing techniques to provide conductive

pathways.• Glass to glass and metal to glass bonds.• Metal coatings.• Refractory ceramic materials.

Direct Bonding Processes

• Metallizing is often used to provide a transmission path on ceramics for electrical current.

• Hermetic seals are painted on by hand or sprayed on to prevent movement of gases or liquids into or out of a product. Many medical products require hermetic seals.

• Glass to ceramic seals are used to bond unlike materials in products such as spark plugs and electronic components.

Fusion Sealing

• Many electronic products require pressure tight seals between metal and ceramic materials.

• The fusion sealing method uses special glass compositions to make direct glass to metal seals.

• The critical sealing temperature required must take into consideration the expansion and contraction requirements of both materials.

Laminating

• One of the most common glass products produced using lamination is the automobile windshield.

• A polyvinyl butyl plastic interlayer is placed between two pieces of curved glass and the sandwich is pressed together in an autoclave furnace to bond under heat and pressure.

• The vinyl layer holds the glass together and keeps the glass from shattering on impact.

Refractory Materials

• The most common material for making refractory products is clay.

• Refractory products are installed as linings for industrial furnaces or in similar high temperature environments.

• The metal casting industry is the largest user of refractory material.

Mechanical Attachment Process

• Mechanical attachment of one or more materials is often used when the product being manufactured may eventually need to be disassembled.

• An example is a unit that may need periodic servicing.

• It is important when working with ceramics not to apply too much pressure when joining parts together.

Summary

• Metallizing is often used to provide a transmission path on ceramics for electrical current.

• The fusion sealing method uses special glass compositions to make direct glass to metal seals.

• One of the most common glass products produced using lamination is the automobile windshield.

• Refractory products are installed as linings for industrial furnaces or in similar high temperature environments.

• Mechanical attachment of one or more materials is often used when the product being manufactured may eventually need to be disassembled.

Home Work

• 1. What keeps a glass windshield from shattering on impact?

• 2. Where is mechanical attachment often used?