WELDING OF CERAMICS.
Abstract
All known work on the welding of refractory ceramics is reviewed and summarized. Oxides, carbides, and borides, as well as graphite, have been welded to themselves or to some metals (usually refractory metals) by either solid-state or fusion welding, or both. Of the two techniques employed, solid-state, or diffusion, welding is conducted below the melting point where sintering, diffusion, and/or reaction phenomena lead to bonding. This is generally done by means of pressure applied across the joint, and often with a fine powder in the seam. This technique will generally give the finest weld grain size, and hence higher strengths (e.g., 50,000 psi or more in Al2O3). But the total elimination of porosity can be very difficult and thus limit the use of this technique for applications in which a fraction to a few percent porosity is detrimental (e.g., to optical transmission properties). On the other hand, fusion welding is accomplished by the solidification of molten edges of the parent material or of a filler using electron-beam, optical (laser or arc-image furnaces), arc (for conductors like most carbides and borides), and flame torches, as with metals. This gives moderate (20,000-30,000 psi in Al2O3) to good (40,000-60,000 psi in some carbides and borides) weld strengths and is potentially the most economical welding method for many purposes. Other relative limitations and merits of diffusion and fusion welding are discussed along with some of the work needed to apply this technology on a broader scale. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 06, 1970
- Accession Number
- AD0710359
Entities
People
- Roy W. Rice
Organizations
- United States Naval Research Laboratory