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Compatibility studies of carbon fibres with nickel and cobalt
oxidation it was possible to obtain different degrees of chemical bonding between them and the glass matrix. When good bonding occurred, the strength of all three types of glass was improved. The bond counteracted the micromechanical stress concentrations set up during loading. The strength was found to be dictated by a Griffith mechanism. By examination of the fracture surfaces with a scanning electron microscope it was found that fracture occurred through the Ni in the high-expansion glass composites and through the glass close to the Ni-glass interface in the low-expansion glass composites. The strength was independent of the fracture path. (70/2/15)
Metal matrices Fracture behaviour of an Fe-Cu microduplex alloy and Fe-Cu composites FLOREEN, S., HAYDEN, H. W. and PILLAR, R. M. Transactions AIME, Vol 245, No 12, pp 2529 2536 (December 1969) The fracture behaviour was studied of materials formed of 50% Cu and 50% Fe mixed in different ways. The materials were a conventional microduplex alloy formed by induction melting, Cu-Fe laminates formed by roll bonding, and composites of the elemental powders formed by extrusion. For all the materials the ductile/brittle transition temperature was lowered to about 300°F as compared with about 0°F for annealed pure Fe. Crack propogation was prevented by different mechanisms in the different types of material. In the alloy it was prevented by the small spacing of the two phases, in the laminates by delamination and in the powder composites by deflection along pre-existing flaws. (70/3/33)
Compatibility studies of carbon fibres with nickel and cobalt JACKSON, P. W. and MARFORAM, J.
R. Journal o f Materials Science, Vol 5, No l, pp 9 - 23 Techniques by which single carbon and graphite fibres are coated with nickel or cobalt are described. These coated fibres are subjected to heattreatments in the temperature range
254
COMPOSITESJune 1970
500°C to 1100°C and results obtained are stated to be valid for bulk composites. These results show that carbon fibres undergo structural recrystallization at these temperatures, when in contact with nickel or cobalt. The mechanism by which this occurs is by diffusion of carbon atoms from one fibre surface through the matrix, followed by a reciprocation on another fibre at a site which allows growth in a more fully graphitic form. Graphitized fibres resist recrystallization better than carbonized fibres. (70/3/34)
Fabrication and mechanical properties of sapphire whisker/aluminium composites MEHAN, R. L. Journal o f Composite Materials, Vol 4, pp 90 101 (January 1970) Air elutriation and semi-automatic methods for aligning discontinuous alumina whiskers for the fabrication of aluminium matrix composites have been developed. Elastic modulus, tensile strength, creep rupture strength and fatigue strength have been determined for the composite materials. Significant improvement over matrix properties, especially at elevated temperatures, can be achieved. (70/3/35)
The wetting of carbon by copper and copper alloys MORTIMER, D. A. and NICHOLAS,
M. Journal o f Materials Science, Vol 5, No 2, pp 149 155 (1970) Pure molten copper does not wet graphite and so a survey was carried out to determine whether alloying constituents could improve the wetting characteristics of copper on graphite. Ordinary bulk graphite and vitreous carbon substrates were used, the latter in an attempt to imitate carbon fibre crystallite size more closely. The survey revealed that chromium caused copper to wet both substrates and vanadium enhanced wetting on the vitreous carbon only. The authors interpret their data in terms of the wetting behaviour of the alloy being dependent on the reaction product carbides of the alloying addition. (70/3/36)
Whiskers challenge composites
fibre-in-metal
PETERS, D. The Engineer, p 42 (March 1970) It is thought that a Swiss firm is very close to being able to market tonnage quantities of silicon carbide whiskers using the growth and aligning process developed by the Explosives Research Centre, Waltham Abbey. ERDE have suggested prices as low as £1 per lb with large scale production but this is thought to be an optimistic view by others. Envisaged applications such as turbine blading, rocket nose cones, filtration, welding, and the manufacture of electric motors and artificial limbs are briefly reviewed. (70/3/37)
Resin matrices Veroudering van gewapende kunstoffen ALGRA, E. A. H. and VAN DER BEEK, M. H. B. Plastiea, Vol 23, p 45 55 (February 1970) The long term resistance of six polyester and epoxide resin]glassfibre laminates prepared by normal hand-lay-up techniques has been investigated. Changes in flexural properties and appearance after, 5 0 - 10 years outdoor exposure, 5 - 10 years immersion in water at 20°C, and accelerated aging in water at high temperatures, were studied. It is suggested that the long term resistance of laminates in water at 20°C can be predicted from accelerated tests in water at 100°C by use of an acceleration factor of about 1 000. (70/4/56)
Properties of unit composites as determined by properties of the interface part 111: Experimental study of unit composites without a perfect bond between the phases AMIRBAYAT, J. M. and HEARLE, J. W.S. Fibre Science and Technology Vol 2, No 3 p 223 (January 1970) The experimental work described is concerned with systems which have limited friction at the fibre]matrix interface and the object was the evaluation of the deficiencies of reinforcement attributable to fibre shippage. The results of tests on perspex, nylon fibre, nylon fibre and polythene
Metal matrices Fracture behaviour of an Fe-Cu microduplex alloy and Fe-Cu composites FLOREEN, S., HAYDEN, H. W. and PILLAR, R. M. Transactions AIME, Vol 245, No 12, pp 2529 2536 (December 1969) The fracture behaviour was studied of materials formed of 50% Cu and 50% Fe mixed in different ways. The materials were a conventional microduplex alloy formed by induction melting, Cu-Fe laminates formed by roll bonding, and composites of the elemental powders formed by extrusion. For all the materials the ductile/brittle transition temperature was lowered to about 300°F as compared with about 0°F for annealed pure Fe. Crack propogation was prevented by different mechanisms in the different types of material. In the alloy it was prevented by the small spacing of the two phases, in the laminates by delamination and in the powder composites by deflection along pre-existing flaws. (70/3/33)
Compatibility studies of carbon fibres with nickel and cobalt JACKSON, P. W. and MARFORAM, J.
R. Journal o f Materials Science, Vol 5, No l, pp 9 - 23 Techniques by which single carbon and graphite fibres are coated with nickel or cobalt are described. These coated fibres are subjected to heattreatments in the temperature range
254
COMPOSITESJune 1970
500°C to 1100°C and results obtained are stated to be valid for bulk composites. These results show that carbon fibres undergo structural recrystallization at these temperatures, when in contact with nickel or cobalt. The mechanism by which this occurs is by diffusion of carbon atoms from one fibre surface through the matrix, followed by a reciprocation on another fibre at a site which allows growth in a more fully graphitic form. Graphitized fibres resist recrystallization better than carbonized fibres. (70/3/34)
Fabrication and mechanical properties of sapphire whisker/aluminium composites MEHAN, R. L. Journal o f Composite Materials, Vol 4, pp 90 101 (January 1970) Air elutriation and semi-automatic methods for aligning discontinuous alumina whiskers for the fabrication of aluminium matrix composites have been developed. Elastic modulus, tensile strength, creep rupture strength and fatigue strength have been determined for the composite materials. Significant improvement over matrix properties, especially at elevated temperatures, can be achieved. (70/3/35)
The wetting of carbon by copper and copper alloys MORTIMER, D. A. and NICHOLAS,
M. Journal o f Materials Science, Vol 5, No 2, pp 149 155 (1970) Pure molten copper does not wet graphite and so a survey was carried out to determine whether alloying constituents could improve the wetting characteristics of copper on graphite. Ordinary bulk graphite and vitreous carbon substrates were used, the latter in an attempt to imitate carbon fibre crystallite size more closely. The survey revealed that chromium caused copper to wet both substrates and vanadium enhanced wetting on the vitreous carbon only. The authors interpret their data in terms of the wetting behaviour of the alloy being dependent on the reaction product carbides of the alloying addition. (70/3/36)
Whiskers challenge composites
fibre-in-metal
PETERS, D. The Engineer, p 42 (March 1970) It is thought that a Swiss firm is very close to being able to market tonnage quantities of silicon carbide whiskers using the growth and aligning process developed by the Explosives Research Centre, Waltham Abbey. ERDE have suggested prices as low as £1 per lb with large scale production but this is thought to be an optimistic view by others. Envisaged applications such as turbine blading, rocket nose cones, filtration, welding, and the manufacture of electric motors and artificial limbs are briefly reviewed. (70/3/37)
Resin matrices Veroudering van gewapende kunstoffen ALGRA, E. A. H. and VAN DER BEEK, M. H. B. Plastiea, Vol 23, p 45 55 (February 1970) The long term resistance of six polyester and epoxide resin]glassfibre laminates prepared by normal hand-lay-up techniques has been investigated. Changes in flexural properties and appearance after, 5 0 - 10 years outdoor exposure, 5 - 10 years immersion in water at 20°C, and accelerated aging in water at high temperatures, were studied. It is suggested that the long term resistance of laminates in water at 20°C can be predicted from accelerated tests in water at 100°C by use of an acceleration factor of about 1 000. (70/4/56)
Properties of unit composites as determined by properties of the interface part 111: Experimental study of unit composites without a perfect bond between the phases AMIRBAYAT, J. M. and HEARLE, J. W.S. Fibre Science and Technology Vol 2, No 3 p 223 (January 1970) The experimental work described is concerned with systems which have limited friction at the fibre]matrix interface and the object was the evaluation of the deficiencies of reinforcement attributable to fibre shippage. The results of tests on perspex, nylon fibre, nylon fibre and polythene