reactive metal to increase the wettability of the alloy and the graphite particles. The melt is cleaned and degassed with dry nitrogen to remove aluminium oxide and dissolved hydrogen, it is treated with flux and surface activated graphite powder is then gradually added whilst the melt is stirred at 500600 rpm at a temperature of 700-730°C. Method for preparing dense, pressureless sintered SiC whisker reinforced composite ceramics Wei, W.-C. and Novich, B.E. (Ceramics Process Systems Corporation, Milford, MA, USA) US Pat 4 946 808 (7 August 1990) A slip containing (1) solids, the major proportion of which is a pressureless-sinterable material with an average particle size ~< 5 lxm but also including 5-10 volume % whiskers, 2-10 volume % of a sintering aid, (2) a vehicle and (3) a dispersant is formed into the desired shape and then densified by pressureless sintering at a temperature greater than or equal to the eutectic temperature of the sintering aid and the matrix material. A whisker-reinforced composite is formed that has a density which is at least 99% of the theoretical density.
Discrete, single, reinforcing fibres and thermoplastic fibres are uniformly blended to produce a loose, non-woven admixture. This is then heated to at least the melting point of the thermoplastic fibres and pressurized to produce a thermoplastic matrix containing reinforcing fibres. The pressure applied is limited so as to result in minimal fibre breakage. Fibre-reinforced composite comprising mica matrix or interlayer Beall, G.H., Chyung, K., Dawes, S.B., Gadkaree, K.P. and Hoda, S.N. (Coming Incorporated, Coming, NY, USA) US Pat 4
948 758 (14 August 1990) A coating of sheet silicate crystals or an oxide precursor thereof is applied to the surfaces of amorphous or crystalline inorganic fibre reinforcements which are then combined with a ceramic, glass-ceramic or glass matrix. The whole is consolidated into a dense, fibrereinforced composite. Process for making a silicon carbide composition Hida, G.T. (Benchmark Structural Ceramics Corporation, Amherst, NY, USA) US Pat 4
948 761 (14 August 1990) Composites of in-situ exfoliated graphite Chung, D.D.L. (UCAR Carbon Technology Corporation, Danbury, CT, USA) US Pat 4
946 892 (7August 1990) A suspension of intercalated unexfoliated graphite flakes in a liquid polymeric thermoset resin matrix, which has a curing temperature greater than graphite exfoliation onset temperature, is heated to a temperature sufficient to cause onset of the exfoliation and to initiate curing of the matrix. This temperature is maintained until a solid composite of graphite flakes with an expanded exfoliated structure dispersed in a solid polymer matrix is produced. Metal-ceramic composite and method of producing the same Morita, Y., Seguchi, M., Okamura, K., Hikami, F., Ishihara, K. and Hara, K. (Sumitomo Metal Industries, Ltd, Osaka, Japan) US Pat 4 947 924 (14 August 1990) Ceramic particles with a specific gravity less than one half of a cobalt-based metal are placed in chamber which has an opening in the lower portion through which the molten cobalt-based metal is introduced when the whole (the ceramic and the metal) is heated, thus producing a cobalt-based metal-ceramic composite. Glossy finish fibre reinforced moulded product and processes of construction Smith, R.W. and Miller, G.W. (C.H. Masland & Sons, Carlisle, PA, USA) US Pat
4 948 661 (14 August 1990)
. JULY 1992
A composite material containing 25-45% 0~-SiC and 63-71% Ai203, with the total amount of these two components being at least about 85% and at least 80% of the SiC is present as whiskers, is heated to 350-500°C at a rate of 15-30°C min i under a pressure of less than 20 Pa. It is maintained at this temperature and pressure for at least 5 minutes and then is further heated in an inert atmosphere to 1250-1450°C at a rate of 15-25°C min -1. This temperature is maintained for at least 30 minutes whilst a pressure of 34.5-103 kPa is applied. The inert atmosphere and pressure are maintained whilst the temperature is further increased to 16501900°C at a rate of 7-15°C min-1. It is maintained under an inert atmosphere at this temperature and pressure for 30-90 minutes before cooling. Process for producing glass fibre reinforced thermoplastic compression moulded materials and said moulded materials Das, B., Raghupathi, N. and Thimons, T.V. (Azdel, Inc, Shelby, NC, USA) US Pat 4 950
such that the laminate expands. The heated laminate is compression moulded at 3.4541.3 MPa with at least one mould surface at a temperature between T~ (of the polymer) and Tg-39°C, thereby reducing the shear modulus at the surface of the laminate contacting the mould to produce a reinforced, predominantly amorphous thermoplastic part. Method of producing a deposition film of composite material Kawabata, H., Kudoh, Y., Murakami, M., Miyatake, N. and Yamamoto, M. (Matsushita Electric Industrial Co, Ltd, Osaka, Japan)
US Pat 4 952 295 (28 August 1990) A vacuum sputtering method is described for producing a protective film, in which ZnSe and sin2 are uniformly distributed, for a magneto-optical recording medium. The method comprises moving a substrate sufficiently rapidly under sputtering targets of ZnSe and SiO2 such that alternate thin layers of the two materials are deposited on the substrate, each layer having a thickness which is the order of the inter-atom distance. Process for the hot press moulding of moulded articles Kiss, G . H . (Societe Generale, Paris, France)
US Pat 4 952 356 (28 August 1990) Binder-impregnated fibrous mat is adhered to a stabilizing support which comprises fibrous sheet material and a curable thermosetting resin. The two are then steam-treated before being press moulded. During the latter process the thermosetting resin cures to form a dimensionally stable, inflexible covering on the binder-impregnated fibrous mat. Dental composite material and process Brosnan, D.A. and Colarusso, L.J. (Erico International Corporation, Solon, OH, USA) US Pat 4 952 530 (28 August 1990) A glass material with a softening range of at least 10°C with a less than 250 mesh particle size is mixed with a fugitive pore-forming material and a binder. The resulting mixture is pressed at a pressure in excess of 35 MPa and then sintered for a sufficient time to remove the fugitive pore-forming material and to form a sintered mass which is then crushed to form particles less than 250 ~tm in size for incorporation in a dental composite.
532 (21 August 1990) At least one laminate of predominantly amorphous thermoplastic polymer, copolymer, terpolymer, blend or alloy reinforced with less than 40 weight % of either continuous glass fibre strand mat (needled or nonneedled) or chemically bonded glass fibre strand mat, is preheated to a temperature sufficient to at least soften the amorphous polymer (and melt any semicrystalline polymer) without any polymer degradation
High strength AI203 Block, J. (W.R. Grace & Co-Conn, New York, NY, USA) US Pat 4 952 536 (28 August
1990) A mixture of 0~-AI203 powder, an organic dispersing agent and a zirconia sol is formed and extruded. The extruded body is sintered to produce a high flexural strength AI203 body containing no more than 1 weight % ZrO 2.