Patent EP-1783107-A1 (EP)
Title: Process for the preparation of a ceramic/metal seal resistant to high temperature, composition comprising glass and ceramic and piece comprising a metal-ceramic junction
Inventor: RICHET NICOLAS
IPC: B01J19/24
Filed: 2005-11-08
Abstract: Preparing a ceramic-metal joining, between ceramic and metal (alloy) part, using a sealing material comprising glass (mixture) (G) (10-90 wt.%) and a ceramic material (T) (10-90 wt.%), comprises: either preparing a mixture (M) of (G) and (T) powders, pressing the obtained sealing material preform, densifying, implementing the ceramic joining elements complementary to the preform followed by heat treatment; or pressing a preform of (T), partially densifying, implementing the ceramic-metal joining element complementary to the preform and infiltrating (G) in the porosity of the preform. Preparation of a ceramic-metal joining, between a ceramic and a metal or metal alloy part, using a sealing material comprising glass (mixture) (G) (10-90 wt.%) and a ceramic material (T) (10-90 wt.%) i.e. optionally identical in chemical nature with the ceramic part to be sealed, the process comprises either: preparation of a mixture (M) of powders comprising (G) and (T), pressing of the sealing material preform containing (M), densification of the sealing material preform, implementation of the ceramic joining elements complementary to the sealing material preform and heat treatment of implemented sealing; or pressing of a preform of a ceramic material powder (T), partial densification of the preform, implementation of the ceramic-metal joining element that is complementary to the preform and heat treatment of glass (mixture) infiltration in the porosity of the preform, to form the sealing material containing the ceramic-metal joining. Independent claims are included for: (1) a composition comprising glass (mixture) (G) (10-90 wt.%) and a material (10-90 wt.%) (A) comprising a compound (I) (75-100 vol.%) e.g. doped ceramic oxides in the form of a crystal lattice presenting the lacuna in ion oxides of perovskite phase, of formula (Malpha 1-x-uMalpha 1>xMalpha 2>uMbeta 1-y-vMbeta 1>yMbeta 2>vO3-w); a compound (II) (up to 25 vol.%) such as oxide compounds e.g. alumina, cerium oxide, silica, titania, zirconia, zinc oxide, magnesium oxide, calcium oxide (all preferred), boron oxide or gallium oxide, strontium aluminum oxide (SrAl2O4 or Sr3Al2O6), barium titanium oxide (BaTiO3), calcium titanium oxide (CaTiO3), aluminum and/or magnesium silicate e.g. mullite (2SiO2.3Al2O3), cordierite (Mg2Al4Si5O18) or spinel (MgAl2O4), calcium phosphates or their derivatives e.g. hydroxy apatite (Ca10(PO4)6(OH)2) or tricalcium phosphate (Ca3(PO4)2), perovskite materials of formula La0.5Sr0.5Fe0.9Ti0.1O3-d, La0.6Sr0.4Fe0.9Ga0.1O3-d, La0.5Sr0.5Fe0.9Ga0. 1O3-d or La0.6Sr0.4Fe0.9Ti0.1O3-d, or non-oxide compounds such as carbides and nitrides e.g. silicon carbide, boron nitride, aluminum nitride, silicon nitride, silicon aluminum oxynitride, nickel, platinum, palladium, rhodium or metal alloys or metal mixtures; and optionally a compound (III) (up to 2.5 vol.%) obtained from the reaction of (I) and (II) at a ratio of x and y respectively, to obtain z times of (III), where x, y and z are >=0; and (2) a ceramic-metal joining unit (5) comprising a ceramic part (3) appearing as a hollow tube and a cylindrical axis (XX'), closed at one end and opened at another end, defining an interior zone called ceramic zone (ZC) and an external zone called metallic zone (ZM) i.e. (ZC) and (ZM) are not communicating between them and being separated at least partially by the ceramic part tube, at least partially sheathed by at least a metal/metal alloy casing (2) comprising a part i.e. joining zone of considerably hollow cylindrical axis covering at least partially the ceramic part tube and a space (4) considerably annular axis being fixed between the ceramic part tube and the joining zone, where: the sealing between the ceramic part tube and the casing is ensured by at least a ceramic-metal joining element (1) of which are in contact with the ceramic part tube and the joining zone; the joining element is at least partially present in the annular space while occupying some subspace and preferably appearing itself as a considerably annular part (1); the joining element comprises the sealing material containing the composition; and the joining unit is such as the joining zone has a low dimension (I), according to every axis (YY') crossing the joining zone and perpendicular to the axis (XX'). Malpha , Malpha 1> = Sc, Y, lanthanides, actinides or alkaline-earth metals; Malpha 2> = Al, Ga, In, Ti or alkaline earth metals; Mbeta = transition metal; Mbeta 1> (different from Mbeta ) = transition metal, Al, In, Ga, Ge, Sb, Bi, Sn, Pb or Ti; Mbeta 2> (different from Mbeta and Mbeta 1>) = transition metal, alkaline earth metal, Al, In, Ga, Ge, Sb, Bi, Sn, Pb or Ti; x, u = 0-0.5; y, v = 0-0.9; and w = structure to make the compound electrically neutral. Provided the sum of x and u is =0.5. Provided the sum of y and v is 0-0.9. Malpha and Malpha 1> are different from each other.