Background Research and Development of the Department of Supply

Another, and most surprising manifestation of biological activity was revealed in the attack by micro-organisms on the walls of aircraft fuel tanks,[43] which at that time were lined with organic self-sealing material. Investigations carried out, many years previously of corrosion of ships' fuel tanks had indicated the presence of bacteria which survived in the water layer at the bottom of these tanks. The first action was, therefore, to sample aircraft fuel tanks where it was most difficult to exclude water of condensation. A fungus -Cladosporium resinae was detected here as well as in the slime removed from infected tank linings. While careful housekeeping by aircraft operators alleviated the problem, a satisfactory solution was arrived at only when a treatment, advocated in the United States, of adding fuel icing inhibitor, was carefully investigated. A concentration of about 25 per cent of ethylene glycol monomethyl ether in the minute amount of water present completely inhibited biological action.

Machining

Metallurgists, led by L. E. Samuels were interested in the processes of metal removal during the actions of abrasion, cutting and polishing.[44] They found that, contrary to the theory of Beilby, in the latter case, actual removal of metal took place. The disposition of the cutting medium, (an abrasive material such as silicon carbide for example), with respect to the metal surface was studied and optimum angles of attack to form a continuous metal chip were determined. The cutting process operated on a microscopic scale and D.S.L. pioneered the use of the scanning electron microscope in Australia to demonstrate them. These investigations of the behaviour of metals during the removal process clarified the changes in structure which occurred at the metal surface and indicated situations which could lead to damage affecting subsequent behaviour of machined parts.

Xerography

During the war, MSL had become a centre for industrial radiography, and this work-load continued.[45] The use of silver-halide photographic film was slow, expensive and often did not yield adequate resolution. K. A. Metcalfe, at MSL's Adelaide branch, began to experiment with the ideas of Carlson for making images with dry powders on photosensitive material. (This, it will be recalled, was to spawn the xerographic -i.e. dry process photocopying industry.) Dissatisfied with the results of dry powders, Metcalfe conceived the idea of using photosensitive paper coated with zinc oxide and developing the electrostatic images from suspensions of resins and dyes in organic fluids.

Australian Academy of Technological Sciences and Engineering