together with an adhesive thermoplastic may be selected for particular applications. The invention applies to a laminate which does not "spring back" to its original unbent form. A formula is provided for calculating from the radius of recovery the required core thickness. Suggested applications include vibration damping, model prototypes in making complicated ducts, pattern shapes, moulds, boat hulls and automotive body parts.
Improvements in fibre-reinforced materials and their manufacture Rudloff, B. UK Patent Specification,
1,1 71,349 (19 November 1969) By charging a sheet of fibres with two or more resins in powder form, the invention allows a choice of resins and the use of curved moulds, because of the flexibility of the charged fibrous sheet. Additives may be incorporated including fireproofing agents, fungicides, germicides and colourants. Hot pressing achieves melting and polymerization, at 120°C to 290°C under a pressure of 400 to 600mg per square centimetre, the pressure being maintained until polymerization is complete, preferably. Cooling may be accelerated by natural or forced air flow around the article. Good economy is claimed when the percentage by weight of resin does not exceed 20% of the composite.
Metal-polymer compositions Saunders, F. L., Rieke, J. K. and Twining, J.W. UK Patent Specification,
1,172,629 (3 December 1969) A metal powder-polymer composition is described, having improved modulus, and greater tensile and impact strength. 40% to 60% of the total volume is metal powder, the particle size ranging from 5 to 300 microns, the preferred range being 13 to 20 microns. The polymer, also in powder form is irradiated and dry blended with the metal powder. The composition can be cast, extruded and moulded, with uniform distribution of the filler. Suitable fillers include aluminium, lead, iron, carbon blade, and other metal powders. Examples of possible applications include magnetic cores for electromagnets, machined parts, housings, gears, bearings and pulleys.
COMPOSITES June 1970
Improvements in or relating to fibrecontaining formed structures Selwood, A. UK Patent Specification,
1,1 74,263 (17 December 1969)
Solid solution carbide-graphite composites United States Atomic Energy Commission UK Patent Specification,
1,180,332 (4 February 1970J Improvements in fibre reinforced rigid synthetic foams are achieved with continuous filaments distributed throughout the foam and oriented along the length of the structures. More uniform properties are made possible across the cross sections and can be tailored to requirements by arranging the filaments in greater numbers where higher loads are to be carried. The production of different foams for differing requirements are described and seven fabrication methods for the composite are given. Particular application is envisaged in the construction industry.
Tantalum and niobium in powder form, or their alloys or carbides are mixed with powdered graphite. The composite is formed by hot-pressing at 3050°C at 32001b/in2. The presence of tantalum carbide in this solid solution composite increases its resistance to deformation at high temperatures, tests being carried out to 2700°C with a load of 2,0001b/in 2. Details of the preparation of the metallic powders by various methods are included. Applications in high pressure, corrosive environments are suggested.
Electrical insulators reinforced with glass fibres Siemens Aktiengesellschaft UK Patent
Treatment of carbon fibres and composite materials including such fibres Wadsworth, N.J. and Watt, W. UK
Specification, 1,180,489 (4 February 1970)
Patent Specification, February 19 70)
A glass fibre member, treated with an unfilled epoxide resin, is placed in the cavity of a mould and dilated to fill the mould by the addition of a second epoxide resin and hardener. The glass fibre member dilates to four times its original volume. This method is applied to the fabrication of electrical insulators, giving good resistance to surface leakage current and arcing and is stable in the open air.
To improve shear strength properties, carbon fibres are heated in either air, oxygen or nitrogen dioxide, in the temperature range 3 5 0 - 8 5 0 ° C . Microscopic examination of oxidised fibres shows pitted surfaces, thus providing a good key for the matrix. This is believed to produce the improved interlaminar shear strengths. Polyester resin, epoxy resin, and Friedel-Crafts type resin are alternatives used for the matrix.
Improvements in and relating to an apparatus and a method for producing boron-coated filaments United Aircraft Corporation UK
Patent Specification, 1,177,854 (14 January 1970) A vertical reactor for the pyrolytic deposition of boron on a metallic substrate is described. In earlier rigs the reactor had to be tilted for continuous operation and end-seals were rapidly worn. Both these problems are overcome. Mercury reservoirs both seal the vessel and act as electrodes, heating the metallic substrate filament by resistance heating. The reactant gas, usually boron halide, is thermally decomposed to produce a coating with a thickness up to 2,54/a, dependent on the rate the filament is driven through the reactor.
Composite materials Webber, H. H. UK Patent Specifica-
tion, 1,174,292 (17 December 1969) The invention relates to metallic fibre reinforced composites. The matrix may be of thermoplastic and thermosetting resins, rubber, ceramics and glass. The fibres, which have a rough surface and a mean diameter of lmil or less, may consist of stainless steel, niobium, nickel, tungsten, iron, aluminium, carbon steel and chrome nickel alloys. The rough surface of the fibres, which may be improved by texturizing, provides mechanical interlocking with the matrix. With the fibres in the form of a knit fabric, high abrasion resistance is achieved.