Vitreous or at least partly crystallised sealing material, joint connection, barrier layer, and layer system comprising the sealing material and integration thereof into components

Abstract

Vitreous or at least partly crystallized sealing material is provided. The sealing material is from the system SiO.sub.2B.sub.2O.sub.3CaOMgO, which is free from BaO and/or SrO and which has an improved coefficient of thermal expansion and improved crystallization properties. The sealing material is employed to produce joint connections, electrical feedthroughs, and/or as a barrier layer.

Claims

1. A vitreous or at least partly crystallised sealing material, comprising: a composition comprising (in mol %, based on oxide): TABLE-US-00002 SiO.sub.2 25-45; B.sub.2O.sub.3 5-less than 20; Al.sub.2O.sub.3 0-5; CaO 4-30; MgO greater than 30-40; CeO.sub.2 0-10; La.sub.2O.sub.3 0-10; Y.sub.2O.sub.3 0-10; TiO.sub.2 0-10; ZrO.sub.2 0-10; SnO.sub.2 0-10; HfO.sub.2 0-10; and R.sub.2O.sub.3 0-10, wherein R.sub.2O.sub.3 is an oxide selected, individually or in any desired combination, from a group consisting of Ga.sub.2O.sub.3, In.sub.2O.sub.3, Dy.sub.2O.sub.3, Yb.sub.2O.sub.3, and any combinations thereof, and wherein the composition is free from BaO and SrO apart from at most impurities.

2. The sealing material of claim 1, further comprising a coefficient of thermal expansion in the at least partly crystallised state of .sub.(20-700)10.0.Math.10.sup.6 K.sup.1.

3. The sealing material of claim 1, wherein the composition comprises (in mol %, based on oxide): TABLE-US-00003 SiO.sub.2 25-45; B.sub.2O.sub.3 5-18; Al.sub.2O.sub.3 0-5; CaO greater than 15-30; MgO greater than 30-40; CeO.sub.2 0-10; La.sub.2O.sub.3 0-10; Y.sub.2O.sub.3 0-10; TiO.sub.2 0-10; ZrO.sub.2 0-10; SnO.sub.2 0-10; HfO.sub.2 0-10; and R.sub.2O.sub.3 0-10.

4. The sealing material of claim 1, wherein the composition comprises (in mol %, based on oxide): TABLE-US-00004 SiO.sub.2 25-less than 35; B.sub.2O.sub.3 5-less than 20; Al.sub.2O.sub.3 0-5; CaO 4-less than 15; MgO greater than 30-40; CeO.sub.2 0-10; La.sub.2O.sub.3 0-10; Y.sub.2O.sub.3 0-10; TiO.sub.2 0-10; ZrO.sub.2 0-10; SnO.sub.2 0-10; HfO.sub.2 0-10; and R.sub.2O.sub.3 0-10.

5. The sealing material of claim 1, wherein the composition has a lower limit of B.sub.2O.sub.3 that is 7% (in mol %, based on oxide).

6. The sealing material of claim 1, wherein the composition comprises (in mol %, based on oxide), individually or in any combination, TABLE-US-00005 Al.sub.2O.sub.3 0-less than 2.1; ZnO 0-less than 5; and Y.sub.2O.sub.3 greater than 0-10.

7. The sealing material of claim 1, wherein the crystalline phase in the at least partly crystallised state comprises at least one compound selected from a group consisting of CaSiO.sub.3 (wollastonite), MgSiO.sub.3 (enstatite), Mg.sub.2SiO.sub.4 (forsterite), CaMgSiO.sub.4 (monticellite), CaMgSi.sub.2O.sub.6 (diopside), Ca.sub.2MgSi.sub.2O.sub.7 (akermanite), and any combinations thereof.

8. The sealing material of claim 1, further comprising up to 30 wt. % of inorganic fillers selected from a group consisting of Al.sub.2O.sub.3, stabilised ZrO.sub.2, MgO, MgSiO.sub.3 (enstatite), Mg.sub.2SiO.sub.4 (forsterite), CaMgSiO.sub.4 (monticellite), CaMgSi.sub.2O.sub.6 (diopside), Ca.sub.2MgSi.sub.2O.sub.7 (akermanite), and any combinations thereof.

9. The sealing material of claim 1, wherein the sealing material is configured for a use selected from the group consisting of a fuel cell, an electrolysis cell, a feedthrough element, a sensor, an actuator, production of sintered bodies, production of sheetings, an additive material glass, an additive material in glass-ceramics, and any combinations thereof.

10. A composition comprising: a component made of metal or ceramic, wherein the metal comprises chromium-containing steel and/or chromium-containing alloy and the ceramic comprises Al.sub.2O.sub.3 and/or stabilised zirconium oxide, wherein the stabilising is effected by one or more oxides selected from a group consisting of Y.sub.2O.sub.3, Sc.sub.2O.sub.3, CaO, MgO and/or CeO.sub.2; and a barrier layer on the component, wherein the barrier layer comprises the sealing layer of claim 1.

11. A joint connection, comprising: a first component; a second component; and the sealing material of claim 1 joining the first and second components, wherein the first and second components are selected from a group consisting of a metal component and a ceramic component, the metal component comprising chromium-containing steels and/or chromium alloys and/or nickel alloys, the ceramic component comprising Al.sub.2O.sub.3 and/or stabilised zirconium oxide, wherein the stabilising is effected by one or more oxides selected from a group consisting of Y.sub.2O.sub.3, Sc.sub.2O.sub.3, CaO, MgO and/or CeO.sub.2.

12. A layer system, comprising: a first element; a second element; the sealing material of claim 1 between the first and second elements; and at least one further glass-based sealing material applied to the sealing material at least in regions, wherein the first and second elements are selected from a group consisting of a metal element and a ceramic element, wherein the metal element comprises chromium-containing steel and/or chromium-containing alloys and/or nickel-containing alloys and the ceramic element comprises Al.sub.2O.sub.3-based ceramics and/or stabilised zirconium oxide.

13. The layer system of claim 12, comprising a layer sequence having the metal and/or ceramic element, followed by the sealing material, followed by the further glass-based sealing material, followed by the sealing material, followed by the metal and/or ceramic element.

14. The sealing material of claim 1, further comprising a ratio of SiO.sub.2/MgO from 0.6 to 1.4.

15. The sealing material of claim 1, further comprising a ratio of MgO/CaO of from greater than 1.1 to less than 10.

16. The sealing material of claim 1, wherein the composition comprises more than 31.1 of MgO (in mol %, based on oxide).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained further with the aid of the drawings. The figures show:

(2) FIG. 1a: The barrier layer 1 on a component made of metal 2;

(3) FIG. 1b: The barrier layer 1 on a component made of ceramic 3;

(4) FIG. 2a: A joint connection with a component made of metal 2 and a component made of ceramic 3 joined with the sealing material 1;

(5) FIG. 2b: A composite system in the layer sequence component made of metal 1 and ceramic 3layer of sealing material 1further joint partner 4;

(6) FIG. 3a: The recurring unit of a fuel cell

(7) FIG. 3b: A fuel cell stack

(8) FIG. 4a: The recurring unit of an alternative fuel cell

(9) FIG. 4b: An alternative fuel cell stack

(10) FIG. 5a: A section through a feedthrough element

(11) FIG. 5b: A feedthrough element in plan view

(12) FIG. 6a: An alternative feedthrough element in cross section

(13) FIG. 6b: An alternative feedthrough element in plan view

(14) All the drawings are purely in schematic form, and the dimensions and proportions of the actual objects may deviate from those of the drawings.

DETAILED DESCRIPTION

(15) FIG. 1a shows a barrier layer of the vitreous or at least partly crystalline sealing material 1 according to the invention on a component of metal 2. As can be seen the barrier layer 1 can be on any desired regions of the surface of the component made of metal and in any desired thickness. This naturally equally includes a coating over the entire surface. The barrier layer 1 is joined to the metal 2 by fusing the sealing material 1. A glass-metal join has formed. A joint system or also joint bond can also be referred to in the case of FIG. 1.

(16) FIG. 1b shows a barrier layer of the vitreous or at least partly crystalline sealing material 1 according to the invention on a component made of ceramic 2. The same principles and information disclosed in the case of FIG. 1a are also applicable with respect to FIG. 1b.

(17) FIG. 2a shows a joint connection with a component made of metal 2 and a component made of ceramic 3 joined with the sealing material 1. This joint bond shown represents as an example a base unit for producing any desired joined components. In particular, it is possible to join a component element 1 made of metal to a component element made of ceramic 2 with the vitreous or at least partly crystalline sealing material according to the invention. In particular, a hermetically tight joint is possible. As already described, it is of course also possible to join component elements made of metal, include different metals, or component elements made of ceramic, including different ceramics, to one another.

(18) FIG. 2b shows a joint system in the layer sequence component made of metal 1 and ceramic 3layer of vitreous or at least partly crystallised sealing material 1 according to the inventionfurther joint partner 4. In contrast to FIG. 2a, a hybrid component element comprising metal 2 and ceramic 3 is shown as a joint partner. The sealing material 1 according to the invention joins this to the further joint partner 4, which can comprise any desired suitable material. For example, the joint partner 4 can be a further glass-based sealing material, so that the layer of sealing material 1 can fulfil the function of a barrier layer, but also generally can act as a bonding promoter between the materials 2 and/or 3. As is known to the person skilled in the art, the joining strength and/or other properties of the joint of a sealing material with another material can depend on surface effects of the materials, in particular on chemical bridging bonds or adhesive forces at the interface. Consequently, it may be that a material is not optimal and/or is even incompatible with respect to the surface effects. The properties of the individual joint partners can be matched to one another by suitable layer sequences. The invention therefore also provides the provision of such layer sequences. As can be seen from the principle of 2b, this likewise represents a base unit for producing any desired components in which the sequence of the elements and/or layers shown can also recur in a modified form.

(19) A use example of such joint connections and/or layer sequences is shown in FIG. 3a and/or FIG. 3b. FIG. 3a shows purely in schematic form the recurring unit of a fuel cell. The electrode 31 is held between the interconnectors 30. The electrically insulated joining of the interconnectors 30 is effected via the cell frame 35. The cell frame 35 and the interconnectors are joined to one another by means of the vitreous or at least partly crystallised sealing material 1 according to the invention. Contacting of the electrode is effected via the electrode contacting elements 32, 33, which represent the anode or cathode contacting elements.

(20) Essential criteria in selecting the material are, as described, in addition to the coefficients of thermal expansion, which must be matched to the materials of the interconnectors and/or cell frame, the heat resistance, in particular the ability to soften, but also the compatibility with the materials of the interconnectors and/or cell frame and/or operating substances, which may weaken and/or damage the sealing materials 1 by migration of material constituents. The use of the sealing material 1 according to the invention renders possible, as already described, the use of standard materials for e.g. the interconnectors 30 and/or cell frame 35.

(21) FIG. 3b shows a fuel cell stack constructed by means of the recurring unit according to FIG. 3a. This can be extended or shortened as desired.

(22) FIG. 4a shows an alternative recurring unit of a fuel cell. Representation of the electrode contacting elements 32, 33 has been omitted for clarity. In actually existing objects they are of course present. In contrast to the recurring unit according to FIG. 3a, the vitreous or at least partly crystallised sealing material according to the invention is provided here as a barrier layer 1 which separates a joint material 10, which joins the interconnectors 30 and/or the cell frame 35 to one another, from the materials thereof. In particular, the further joint material 10 can be a glass-based sealing material. As already described, it is possible in this manner to be able to produce the interconnectors 30 and/or the cell frame 35 from the standard materials described, and also for the joint material 10 to be e.g. a standard glass, the diffusion of harmful constituents from the interconnectors 30 and/or the cell frame 35 into the standard joint material 10 being prevented or at least suppressed by the sealing material 10 according to the invention.

(23) FIG. 4b shows in turn a fuel cell stack constructed by means of the recurring unit according to FIG. 4a. This can also be extended or shortened as desired.

(24) FIG. 5a shows the section through a feedthrough element according to the invention. Feedthrough elements are known in general from the field of the art and are contained in many devices. Generally, such feedthrough elements conventionally comprise a functional element 51, e.g. an electrical conductor, which is fixed by an electrically insulating material 1, here the vitreous or at least partly crystallised sealing material 1 according to the invention, in a feedthrough opening of a carrier element 50. The parameters which distinguish the performance of such feedthrough elements are essentially the electrical resistance of the insulating material 1 and the resistance towards heat and pressure, which tend to cause the insulating material 1 and/or the functional element 51 to tear out of the feedthrough opening of the carrier element 50. The carrier element can be made of metal and/or ceramic or at least comprise these, in particular in regions which are provided with the sealing material 1.

(25) FIG. 5b shows the plan view of a feedthrough element according to FIG. 5a. As can be seen, the functional element 51 is arranged in particular concentrically in the circular feedthrough opening. Other geometric arrangements are nevertheless possible and included in the invention. The sealing material 1 holds the functional element 51 in the feedthrough opening and seals this off, in particular hermetically tightly.

(26) The functional element 51 can generally perform various functions in a feedthrough element according to the present invention. The functional element 51 is most often an electrical conductor. In this case the functional element can be a filled or hollow pin or a tube. Such a pin can be produced from metal or other suitable conductors. In the context of the present invention the functional element 51 can also fulfil other functions, e.g. it can be a wave guide for e.g. microwaves or sound waves which are to be conducted through the feedthrough element. In these cases the functional element can usually be a tube, which is preferably produced from metal or ceramic. The functional element 51 can also be used to conduct a cooling fluid, such as cooling water or cooling gases, through the feedthrough element. A further possible embodiment of the functional element 51 is simply a holding element which holds further functional elements, e.g. thermocouples or fibres, such as optical wave guides. In other words, in this embodiment the functional element 51 can function as an adapter for functional elements which cannot be fixed directly in the electrically insulating glass or glass-ceramic material. In these cases the most suitable functional element is a hollow element or a tube.

(27) Not only the geometric shape, such as the thickness of the sealing material 1 in the feedthrough opening, but also the joint strength of the sealing material 1 in the feedthrough opening, defines the maximum pressure to which the feedthrough element according to the invention could be exposed. When such a material is used in order to seal off a feedthrough opening, chemical and physical joint phenomena exist in the contact region of the sealing material 1 and the internal wall of the feedthrough opening or the external surface of the functional element 51. These joint phenomena can be chemical reactions or physical interactions between on the one hand the material of the internal wall of the feedthrough opening and therefore the material of the carrier element 50 and/or of the functional element 51 and on the other hand the components of the sealing material 1. If the composition of the sealing material 1 is selected in a suitable manner, these joint phenomena contribute significantly to the connecting strength between the fixing material and the materials to be fixed.

(28) FIGS. 6a and 6b show an alternative feedthrough device. This substantially corresponds to that shown in FIGS. 5a and 5b, so that for explanation of the corresponding elements reference is made to the statements made in the case of FIGS. 5a and 5b. In contrast to the embodiment of a feedthrough device described above, the vitreous or at least partly crystallised sealing material 1 according to the invention in this case is present as an intermediate layer to a further fixing material 10, that is to say forms a barrier layer 1 on the internal wall of the feedthrough opening of the carrier element 50 and/or the external wall of the functional element 51. The function of the barrier layer is therefore the same as or at least similar to that described in the case of FIGS. 4a and 4b and for this reason reference it made at this point to the corresponding statements regarding FIGS. 4a and 4b.

(29) The advantages of the invention have been acknowledged in detail in the description. In particular, due to omission of BaO and SrO the sealing material 1 according to the invention renders possible a sealing joint with materials of high chromium content since it is chemically compatible with these. The sealing material 1 according to the invention is self-crystallising and crystallises in a shortened time interval, and it therefore can be employed efficiently and with a lower outlay on production in production processes for components which comprise the sealing material 1 according to the invention. Due to its improved coefficient of thermal expansion, it is possible to employ standard materials known for the uses, in particular steels. The sealing material according to the invention adheres very well to the materials in question and in this way renders possible the production of a joint which is stable in the long term. The sealing material 1 according to the invention moreover has a very good chemical resistance to attack by acid, alkali and water, so that the components produced with the sealing material 1 according to the invention can be employed in chemically aggressive environments.

(30) With the sealing material according to the invention the inventors have succeeded in meeting the following criteria which are decisive for the use: The sealing-in temperature is less than 1,000 C., operating temperatures of up to 1,000 C. are rendered possible, a short half-life at the sealing-in temperature is required for the crystallisation (advantageously less than one hour, particularly advantageously less than 0.5 hour, the sealing material thus behaving similarly to conventional amorphous solder glasses during processing), the sealing material shows a very good wetting and adhesion on steels and chromium and nickel alloys, and also a very good chemical compatibility with the metals and a very good stability to hydrolysis and acid, the sealing material has very good electrical insulation properties, which manifests itself in a very high ohmic resistance even at high temperatures, and the at least partly crystallised sealing material has a very high mechanical strength.

(31) TABLE-US-00001 TABLE 1 Example No. 1 2 3 4 5 Glass SiO.sub.2 34.0 32.0 30.0 31.1 32.5 composition B.sub.2O.sub.3 8.0 8.0 7.0 7.5 8.5 [mol %] Al.sub.2O.sub.3 1.5 1.5 1.5 1.5 1.5 Y.sub.2O.sub.3 4.5 4.5 4.5 4.1 La.sub.2O.sub.3 CeO.sub.2 MgO 32.0 33.0 34.0 32.0 35.0 CaO 20.0 21.0 23.0 23.9 22.5 ZrO.sub.2 Sum 100 100 100 100 100 SiO.sub.2/MgO 1.06 0.97 0.88 0.97 0.93 MgO/CaO 1.60 1.57 1.48 1.34 1.56 SiO.sub.2/(MgO + CaO) 0.65 0.59 0.53 0.56 0.57 Bulk CTE(300 C.) [ppm/K] 8.49 8.81 9.15 9.13 8.71 T.sub.g [ C.] 687 696 706 697 663 Properties T.sub.g [ C.] 707 717 725 726 682 powder T.sub.x,onset [ C.] 907 906 894 886 848 T.sub.x,peak [ C.] 938 931 916 912 872 Start sintering [ C.] 740 744 tbd tbd 674 Softening temp. [ C.] 784 tbd tbd 770 Spherical temp. [ C.] 885 879 tbd tbd 810 Half sphere temp. [ C.] 1157 1139 tbd tbd 1144 Flowing temp. [ C.] 1168 1166 tbd tbd 1168 Crystallised CTE(300 C.) [ppm/K] 9.22 9.42 9.76 9.58 9.2 CTE(750 C.) [ppm/K] >T.sub.g >T.sub.g 11.03 10.82 10.75 CTE(300 C.) [ppm/K] 0.73 0.61 0.61 0.45 0.49 T.sub.g [ C.] 615 604 >800 low Dilat. softening [ C.] >800 >800 >800 >800 >800 Example No. 6 7 8 9 10 Glass SiO.sub.2 31.0 31.1 31.5 30.0 31.0 composition B.sub.2O.sub.3 8.0 7.5 8.5 18.0 7.0 [mol %] Al.sub.2O.sub.3 1.5 1.5 1.5 1.5 1.5 Y.sub.2O.sub.3 3.5 4.1 3.5 4.5 La.sub.2O.sub.3 CeO.sub.2 MgO 34.0 32.0 34.0 35.0 34.0 CaO 22.0 23.9 21.5 10.0 22.0 ZrO.sub.2 3.0 2.0 Sum 100 100 100 100 100 SiO.sub.2/MgO 0.97 0.93 0.86 0.91 MgO/CaO 1.34 1.58 3.50 1.55 SiO.sub.2/(MgO + CaO) 0.56 0.57 0.67 0.55 Bulk CTE(300 C.) [ppm/K] 8.93 9.02 9.51 7.15 9.01 T.sub.g [ C.] 682 690 616 659 703 Properties powder T.sub.g [ C.] 705 717 694 679 724 T.sub.x, onset [ C.] 885 896 867 876 891 T.sub.x, peak [ C.] 937 939 893 912 912 Start sintering [ C.] tbd 731 684 711 729 Softening temp.[ C.] tbd 812 778 777 829 Spherical temp. [ C.] tbd 860 821 852 878 Half sphere temp. [ C.] tbd 1130 1126 1043 1163 Flowing temp. [ C.] tbd 1153 1147 1057 1194 Crystallised CTE(300 C.) [ppm/K] 9.48 9.58 9.18 7.94 9.74 CTE(750 C.) [ppm/K] 10.83 10.42 >T.sub.g 11.00 CTE(300 C.) [ppm/K] 0.55 0.56 0.33 0.79 0.73 Tg [ C.] low >800 >900 661 >800 Dilat. softening [ C.] >800 >800 >1000 >850 >800 Example No. 11 12 13 14 15 Glass SiO.sub.2 38.7 40.0 36.0 36.0 32.0 composition B.sub.2O.sub.3 8.9 9.0 8.0 8.0 15.0 [mol %] Al.sub.2O.sub.3 1.6 1.5 1.5 1.5 3.0 Y.sub.2O.sub.3 3.4 4.5 4.5 4.5 La.sub.2O.sub.3 CeO.sub.2 MgO 39.1 39.0 36.0 36.0 35.0 CaO 4.3 6.0 14.0 14.0 13.0 ZrO.sub.2 4.0 2.0 Sum 100 100 100 100 100 SiO.sub.2/MgO 0.99 1.03 1.00 1.00 0.91 MgO/CaO 9.00 6.50 2.57 2.57 2.69 SiO.sub.2/(MgO + CaO) 0.89 0.89 0.72 0.72 0.67 Bulk CTE(300 C.) [ppm/K] 6.56 6.88 7.98 7.98 7.03 T.sub.g [ C.] 685 687 690 690 645 Properties T.sub.g [ C.] 713 715 705 705 669 powder T.sub.x, onset [ C.] 895 879 889 889 852 T.sub.x, peak [ C.] 917 902 915 915 884 Start sintering [ C.] 762 761 748 748 725 Softening temp. [ C.] 802 870 797 797 815 Spherical temp. [ C.] 1042 910 893 893 851 Half sphere temp. [ C.] n.d. n.d. 1160 1160 1076 Flowing temp. [ C.] n.d. n.d. 1174 1174 1087 Crystallised CTE(300 C.) [ppm/K] 8.81 8.95 8.97 8.97 7.8 CTE(750 C.) [ppm/K] >T.sub.g >T.sub.g >T.sub.g >T.sub.g >T.sub.g CTE(300 C.) [ppm/K] 2.25 2.07 0.99 0.99 0.77 T.sub.g C. 622 626 630 630 635 Dilat. softening [ C.] >900 >900 >900 >900 >800