Ceramic product and method for its manufacture

Abstract

A ceramic product includes a first ceramic part and a second ceramic part, wherein the first ceramic part is connected with the second ceramic part via a joint, wherein the joint comprises an active hard solder, or braze, characterized in that the joint has an inhomogeneous distribution of the components of the active hard solder, or braze, wherein at least at an interface between the active hard solder, or braze, and the ceramic, the at least one active component of the active hard solder, or braze, is enriched. For manufacture of the product, the active hard solder, or braze, material is provided in such a manner, that at least one surface section of at least one of the ceramic parts is first coated with at least one active component of the active hard solder, or braze, and that on the coated section, an alloy is provided, which, by melting of the alloy during the heating, alloys with the coating and forms a metal joint between the two ceramic parts.

Claims

1. A ceramic product, comprising: at least a first ceramic part and a second ceramic part, wherein: said first ceramic part is connected with said second ceramic part via a joint; said joint having a thickness; said joint comprises an active hard solder, or braze, said active hard solder, or braze, comprising at least one active component, said active component having a location-dependent concentration said joint has an inhomogeneous distribution of the components of the active hard solder, or braze, and at least at an interface between the active hard solder, or braze, and the ceramic, said active component of the active hard solder, or braze, is enriched, wherein: $\frac{{}_{-d/2}^{d/2}.Math.x.Math..Math.c_i\left(x\right)x}{{}_{-d/2}^{d/2}{c}_i\left(x\right)x}\frac{a.Math.d}{4},$ wherein a>1.0, wherein d is said thickness of said joint, wherein x is an integration variable, said integration variable having a zero point, wherein said zero point of said integration variable, x, lies in the middle of the joint between the ceramic parts, and wherein c.sub.i(x) is the location-dependent concentration of said at least one active component in mass %.

2. The ceramic product as claimed in claim 1, wherein: a>1.1.

3. The ceramic product as claimed in claim 1, wherein: a>1.3.

4. The ceramic product as claimed in claim 1, wherein: the ceramic product is a pressure sensor; and the ceramic parts comprise a platform and a measuring membrane.

5. The ceramic product as claimed in claim 1, wherein: the joint comprises a ternary ZrNiTi alloy with c.sub.Zr mass % Zr, c.sub.Ni mass % Ni and c.sub.Ti mass % Ti, wherein 100>c.sub.Zr+c.sub.Ni+c.sub.Ti100R, with R<0.5.

6. The ceramic product as claimed in claim 5, wherein: R<0.3.

7. The ceramic product as claimed in claim 5, wherein: R<0.25.

8. The ceramic product as claimed in claim 5, wherein: concentrations of components of the alloy lie in the ranges, 55<c.sub.Zr<65.5, 20.5<c.sub.Ni<27.5 and 14<c.sub.Ti<17.5.

9. The ceramic product as claimed in claim 5, wherein: concentrations of components of the alloy lie in the ranges, 61<c.sub.Zr<63.5, 21.5<c.sub.Ni<24 and 14.5<c.sub.Ti<15.5.

10. The ceramic product as claimed in claim 1, wherein: said first ceramic part and/or said second ceramic part comprise aluminum oxide, said aluminum oxide comprising aluminum atoms; a boundary region is present, in which a concentration of aluminum atoms in the active hard solder, or braze, diffused in from said first or second ceramic part is larger than the concentration of Ni-atoms in this region, wherein said region extends not less than 10 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

11. The ceramic product as claimed in claim 10, wherein: said boundary region extends not less than 40 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

12. The ceramic product as claimed in claim 10, wherein: said boundary region extends not less than 80 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

13. A ceramic product, comprising: at least a first ceramic part and a second ceramic part, wherein: said first ceramic part is connected with said second ceramic part via a joint; said joint having a thickness; said joint comprises an active hard solder, or braze, said active hard solder, or braze, comprising at least one active component; said at least one active component having a location-dependent concentration; said joint has an inhomogeneous distribution of the components of the active hard solder, or braze, and at least at an interface between the active hard solder, or braze, and the ceramic, said active component of the active hard solder, or braze, is enriched, wherein: $\frac{{}_{-d/2}^{d/2}.Math.x.Math..Math.\left(c_i\left(x\right)-c_i\left(0\right)\right)x}{{}_{-d/2}^{d/2}{c}_i\left(x\right)-c_i\left(0\right)x}\frac{a.Math.d}{4},$ wherein a1.25, wherein d is the thickness of the joint, wherein x is an integration variable, said integration variable having a zero point, wherein said zero point of said integration variable, x, lies in the middle of the joint between the ceramic parts, and wherein c.sub.i(x) is the location-dependent concentration of the at least one active component in mass %.

14. The ceramic product as claimed in claim 13, wherein: a>1.5.

15. The ceramic product as claimed in claim 13, wherein: a>1.7.

16. The ceramic product as claimed in claim 13, wherein: the ceramic product is a pressure sensor, wherein the ceramic parts comprise a platform and a measuring membrane.

17. The ceramic product as claimed in claim 13, wherein: the joint comprises a ternary ZrNiTi alloy with c.sub.Zr mass % Zr, c.sub.Ni mass % Ni and c.sub.Ti mass % Ti, wherein 100>c.sub.Zr+c.sub.Ni+c.sub.Ti100R, with R<0.5.

18. The ceramic product as claimed in claim 17, wherein: R<0.3.

19. The ceramic product as claimed in claim 17, wherein: R<0.25.

20. The ceramic product as claimed in claim 17, wherein: concentrations of components of the alloy lie in the ranges, 55<c.sub.Zr<65.5, 20.5<c.sub.Ni<27.5 and 14<c.sub.Ti<17.5.

21. The ceramic product as claimed in claim 17, wherein: concentrations of components of the alloy lie in the ranges, 61<c.sub.Zr<63.5, 21.5<c.sub.Ni<24 and 14.5<c.sub.Ti<15.5.

22. The ceramic product as claimed in claim 13, wherein: said first ceramic part and/or said second ceramic part comprise aluminum oxide, said aluminum oxide comprising aluminum atoms; a boundary region is present, in which a concentration of aluminum atoms in the active hard solder, or braze, diffused in from said first or second ceramic part is larger than the concentration of Ni-atoms in this region, wherein said region extends not less than 10 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

23. The ceramic product as claimed in claim 22, wherein: said region extends not less than 40 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

24. The ceramic product as claimed in claim 22, wherein: said region extends not less than 80 nm from the interface between the ceramic part and the active hard solder, or braze, in the direction of the active hard solder, or braze.

Description

BRIEF DESCRIPITION OF THE DRAWINGS

(1) The invention will now be explained in greater detail on the basis of the appended drawing, the sole figure of which shows as follows:

(2) FIG. 1 illustrates components of a pressure sensor of the invention.

DETAILED DISCUSSION IN CONJUCTION WITH THE DRAWINGS

(3) The components of a ceramic pressure sensor 1 illustrated in FIG. 1 comprise a circular, disk shaped measuring membrane 2 and a circular, disk shaped platform 3 made of corundum. The measuring membrane 2 and the platform 3 have, for example, a diameter of 20 mm. The measuring membrane 2 and the platform 3 are to be pressure-tightly connected by means of a ZrNiTi active hard solder, or braze, in a high vacuum soldering/brazing process.

(4) In contrast to the previous standard method, however, an annular coating 4, 5 of an active component is deposited, respectively, on the measuring membrane 2 and on the platform 3 in the region of the joint. This can be, for example, a titanium layer in each case with a thickness of, for example, 150 nm. The coatings 4, 5 can be deposited, for example, in a sputtering process.

(5) Between the two coatings is then arranged an annular active hard solder, or braze, preform 6, which aligns with the coatings, and which has, for example, a thickness of 20 m. In the alloy of active hard solder, or braze, preform 6, the concentration of titanium can be reduced, for example, to about 10%, in order to approach the ideal alloy with c.sub.Zr=63, c.sub.Ni=22 and c.sub.Ti=15 in the average across the joint after the soldering/brazing process. An example of the composition of the active hard solder, or braze, preform would be: C.sub.Zr=64, c.sub.Ni=22.5 and c.sub.Ti=13.5.

(6) After the active hard solder, or braze, preform is arranged between the coatings, the components are connected with one another in a soldering/brazing process, especially a high vacuum soldering/brazing process.

(7) Instead of a coating with titanium, a coating with zirconium or with a mixture of titanium and zirconium can also be used.

(8) Via the coatings with the active component, an improved control of the interaction between the active component and the corundum is obtained.