Patent GB-1064932-A (GB)
Title: Coloured metal-glass composites
IPC: B22F3/24
Filed: 1964-06-01
Abstract: A composite material consisting of a sintered intimate mixture of metal particles and coloured glass particles may be anodized or may be mixed with powdered metal followed by sintering. Anodization may be performed if Al is the metal ingredient; dye treatment may be performed thereafter.  If mixed and sintered with a powdered metal, this metal, which forms a matrix throughout which the composite is distributed, has a sintering temperature not exceeding the melting temperature of the metal component of the composite. The glass component of the composite is such that in its softened state its temperature is within \sB100 DEG C. of the sintering temperature of the metal component.  The metal component may be e.g. Zn, Al, Mg, Cu, Fe, or alloys thereof, and may constitute by volume e.g. 30-90% of the composite.  Sintering is effected at 500 DEG -550 DEG C. in H2 and the compact may be hot forged or hot extruded.  The glass constituents are SiO2, PbO, Na2O, K2O, Li2O, B2O3, P2O5, Al2O3, TiO2, BaO, MgO, Sb2O3, SnO, CaF2, CrO3, CaO.  A colourant e.g. CoO, Cr2O3, Fe2O3, CaS or CaSe may be added.ALSO:A composite material consists of a sintered intimate mixture of metal particles and glass particles. The glass when softened has a temperature within \sB100 DEG  C. of the sintering temperature of the metal but below the M.P. of the metal, and contains a colourant which survives the maximum temperature of the glass when in its softened state.  As shown in Fig. 1, the material consists of two fine, continuous, highly irregular matrices of metal 10 and coloured glass 11.  The glass colourant may be added to the melt in the course of manufacture of the glass frit, or unpigmented glass frit may be milled with pigment, e.g. in the presence of a 10% aqueous solution of Na2SiO3. <PICT:1064932/C1/1> The metal and dry glass powders may be mixed, cold-pressed into billets, sintered, e.g. at 500-550 DEG  C., and hot-forged, e.g. in an atmosphere of H2, or hot-extruded.  The surface may then be wet-ground.  Surface etching, which may be partial, may then be performed, e.g. by brushing with or dipping in aqueous solutions or slurries of e.g. Ca(OH)2, Ca(OH)2+NaOH, Na2SiF4+NH4NO3, H3PO4+CrO3, K2CrO4+NH4OH, or Na2CrO4+Na2CO3+NaOH, MgO, CaO, SrO, or HNO3; MgO, CaO, SrO, ZnO or BaO may be incorporated in situ in the composites.  Further treatments applicable to either component may be performed; thus, if Al is the metal ingredient, anodization may be performed, and may be followed by dye treatment. Composites may also be formed by partially mixing two or more distinctively coloured metal-glass powder mixtures and sintering; or a sintered composite may be ground and mixed with ground glass, or powdered metal; followed by sintering.  The metal employed may be e.g. Zn, Al, Mg, Cu or Fe, or alloys thereof, and may form e.g. 30-90% by volume of the composite.  The colourant may be e.g. CoO, Cr2O3, Fe2O3, CdS or CdS plus CdSe, and may be present in concentrations of e.g. 0-40% by weight of the frit.  Glasses exemplified comprise without colourant constituents whose percentages by weight fall in the following ranges: SiO2, 24.6-74.2; PbO, up to 48.2; Na2O, up to 19.0; K2O, up to 22.9; Li2O, up to 6.4; B2O3, up to 16; P2O5, up to 41.3; Al2O3, up to 24.7; TiO2, up to 14.5; Sb2O3, up to 2.7; BaO, up to 4.3; SnO, up to 1.0; CaF2, up to 5.5; CaO, up to 13.0; MgO, up to 3.2; CrO3, 4.8; Sb oxide, up to 2.7.  A glass for use with aluminium may comprise, in mole per cent, PbO, 25-55; SiO2, 20-50; TiO2, 1-15; alkali metal oxide, 10-30.  The composites may be applied as coatings on metals or other backings, e.g. by spray-gun or by fluidized solids deposition.