Mechanical joining of ceramics
A range of mechanical techniques can be used to incorporate ceramic components into metallic structures. Technically, mechanical joints are simple in design, using bolts or screw threads. However, even simple design requires complex diamond machining, which makes such joints expensive; moreover, they will not be gas tight.
Shrink and taper fitting exploit the difference in thermal expansion between the metal and ceramic components. The joint is formed at high temperatures; the metal surrounds the ceramic component and contracts on cooling. As the temperature falls the metal clamps the ceramic, so forming a strong joint. Obviously, this kind of bond can be used only at low temperatures and can be subject to failure at local stress concentrations.
A metal flow process can produce a mechanical bond around a ceramic component. The metal, under applied stress and pressure, deforms plastically and flows into recesses in the ceramic surface. Such mechanical keying can form a reasonably strong gas-tight bond.
Further information
Best practice guides
Staff papers
- Techniques for bonding ceramics (Bulletin, September/October 1990) Industrial Members Only
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