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- 1972 (24) (entfernen)
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Particle boards are of increasing economic importance. Without special treatment they are destroyed by termites. Deterioration of unprotected material as well as possibilities and present knowledge of preservation against termite attack are briefly described. Recent laboratory experiments with particle board treated to make it resistant to humidity and basidiomycete fungi showed that only one organic preservative out of four protected the boards also against termite attack; one of two water-soluble preservatives gave promising results. Heterotermes indicola (Wasmann) from India proved to be more aggressive and resistant to the preservatives than Coptotermes amanii (Sjöstedt) from Kenya and Nasutitermes nigriceps (Haldemann) from Guatemala. Kalotermes flavicollis (Fabr.) from Italy was also very tolerant to the fungicidal preservatives. Further development of treatments of particle board against termites is required.
Adhesion bonding at a bimetallic interface is considered in terms of the electronic structure of combined metals in a highly simplified model. If specific surface properties are neglected, the contact area may be interpreted by a `jellium' model of thinned atom cores smeared on the interface and imbedded in a thinned sea of electrons. Adhesion bond strength will then depend primarily on free-electron density. In addition to the free-electron `jellium' formalism, the electronic structure of metals and the character (s, p, d) of electrons free for adhesion bonding must be considered. For metal single crystals an influence of the structure of the Fermi surface can also be pointed out. The adhesional pairs of dissimilar metals are assumed to fall into line with groups of `donor-acceptor' combinations of different strengths of adhesion.