Patent GB-955675-A (GB)
Title: Improvements in or relating to compacts and seals
IPC: C04B37/00
Filed: 1960-06-29
Abstract: A sintered compact comprising a particulate material dispersed in and cemented by a continuous matrix of one or more intermetallic type compounds, or a seal in which the intermetallic type compound forms a continuous cementing phase bonded to another material, is produced in a reaction hot pressing process in which the component powders of the intermetallic type compound are either mixed together with the powders of the dispersed material and hot pressed at a temperature such that reaction occurs to form the intermetallic type compound or the component powders of the intermetallic type compound may be placed as a layer in contact with the other material and hot pressed to form a composite body. The intermetallic type compounds specified are: silicones, borides, aluminides, titanides, zirconides, antimonides, germanides, beryllides, stannides and these are formed in situ from a stoichiometric or non-stoichiometric mixture of the elements or compounds.  The dispersed particulate phase may be a preformed intermetallic compound, oxides, carbides or metals.  Many different examples are given and the intermetallic type compounds formed in situ are NiAl, Ti3Sn, TiB2, ZrB2, MoGe2, CrSi2+B, TiSi2+B, and the silicides of Mo, Ta, Nb, W, Co, Zr, Ti, Cr and V.  The dispersed particulate materials specified are ceramics such as the oxides of Al, Zr, Th, Mg, Eu, Gd, Sm, U, Hf.  For nuclear energy applications U powder may be added and examples are also given in which MoSi2, SiC, B, ZrB2 and Ni powder are used.  The powder mixture of the components of the intermetallic type compound and the dispersed particulate material is heated and pressed in a graphite mould under an atmosphere of helium or argon and the mixture may be precompacted cold. The pressure which is maintained throughout the process may be single-ended or double-ended and may also include lateral pressure. The process is also used for producing ceramic: ceramic, ceramic: metal or metal: metal seals, the components of the intermetallic compound which forms the seal being placed as a powder layer between the bodies to be joined and then reaction hot pressing the assembly.  In a modification one or both of the bodies to be joined may be in powder form so that sintering of the bodies is effected concurrently with the joining during the hot pressing. Examples are given of joining TiC or WC to Al2O3, Cr to Al2O3, M to Al2O3, Nb to Al2O3, Ti to forstenite and P to forsterite.ALSO:A sintered compact comprising a particulate material dispersed in and cemented by a continuous matrix of one or more intermetallic type compounds, or a seal in which the intermetallic type compound forms a continuous cementing phase bonded to another material, is produced in a reaction hot pressing process in which the component powders of the intermetallic type compound are either mixed together with the powders of the dispersed material and hot pressed at a temperature such that reaction occurs to form the intermetallic type compound, or the component powders of the intermetallic type compound may be placed as a layer in contact with the other material and hot pressed to form a composite body. The intermetallic type compounds specified are:-silicides, borides, aluminides, titanides, zirconides, antimonides, germanides, beryllides and stannides and these are formed in situ from a stoichiometric or non-stoichiometric mixture of the elements or compounds.  The dispersed particulate phase may be a preformed intermetallic compound, oxides, carbides or metals. Many different examples are given and the intermetallic type compounds formed in situ are NiAl, Ti3Sn, TiB2, ZrB2, MoGe2, CrSi2+B, TiSi2+B, and the silicides of Mo, Ta, Nb, W, Co, Zr, Ti, Cr and V.  The dispersed particulate materials specified are ceramics such as the oxides of Al, Zr, Th, Mg, Eu, Gd, Sm, U, Hf. For nuclear energy applications, U powder may be added and examples are also given in which MoSi2, SiC, B, ZrB2 and Ni powder are used. The powder mixture of the components of the intermetallic type compound and the dispersed particulate material is heated and pressed in a graphite mould under an atmosphere of helium or argon and the mixture may be precompacted cold. The pressure which is maintained throughout the process may be single ended or double ended and may also include lateral pressure. The process is also used for producing ceramic: ceramic, ceramic:metal, or metal:metal seals, the components of the intermetallic compound which forms the seal being placed as a powder layer between the bodies to be joined and then reaction hot pressing the assembly. In a modification one or both of the bodies to be joined may be in powder form so that sintering of the bodies is effected concurrently with the joining during hot pressing. Examples are given of joining TiC or WC to Al2O3, Cr to Al2O3, Mo to Al2O3, Nb to Al2O3, Ti to forsterite and Pt to forsterite.