LAYER AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The invention relates to a layer having piezoelectric properties and a method for producing a layer having piezoelectric properties, in particular by means of aerosol deposition method (ADM).

Claims

1. A layer having piezoelectric properties, wherein no temperature treatment >500? C. takes place during and after coating.

2. The layer having piezoelectric properties according to claim 1, wherein the piezoelectric properties of the layer are formed at room temperature or by annealing at temperatures up to a maximum of 350? C.

3. The layer having piezoelectric properties according to claim 2, wherein the coating is applied to a substrate or a carrier by way of an aerosol deposition method of the powdered raw materials.

4. The layer having piezoelectric properties according to claim 1, wherein the layer is made of PZT or PZT-containing material or lead-free piezoceramics.

5. The layer having piezoelectric properties according to claim 1, wherein the substrate or the carrier is made of ceramic, plastic, glass, metal, semiconductor or a composite of the aforementioned materials.

6. The layer having piezoelectric properties according to claim 5, wherein the substrate or the carrier has a lower hardness than the bulk material of the powdered raw materials used for the aerosol deposition.

7. The layer having piezoelectric properties according to claim 1, wherein the bonding strength between the layer and the substrate or carrier is achieved by a microstructural plastic deformation of the surface of the substrate or of the carrier (mechanical anchoring).

8. The layer having piezoelectric properties according to claim 1, wherein the layer has a thickness <100 ?m.

9. The layer having piezoelectric properties according to claim 1, wherein the layer has a porous to dense structure.

10. The layer having piezoelectric properties according to claim 1, wherein the particle sizes in the layer are less than 1 ?m.

11. The layer having piezoelectric properties according to claim 1, wherein the layer entirely or partially covers the substrate or the carrier after the coating process.

12. The layer having piezoelectric properties according to claim 1, wherein the carrier is provided with an intermediate layer, to which the layer is deposited.

13. The layer having piezoelectric properties according to claim 11, wherein electrodes are arranged beneath or on top of the layer across the full surface, partial surface or in an interdigital structure, which allow the operation.

14. The layer having piezoelectric properties according to claim 1, wherein the substrate or the carrier has an arbitrary shape, such as curvatures.

15. The layer having piezoelectric properties according to claim 1, wherein the layer is structured or polarized during deposition or thereafter.

16. A method for producing a layer having piezoelectric properties, wherein no temperature treatment >500? C. takes place during and after coating since this would result in the formation of the piezoelectric properties.

17. The method according to claim 16, wherein the piezoelectric properties of the layer are formed at room temperature or by annealing at temperatures up to a maximum of 350? C.

18. The method according to claim 16, wherein the piezoelectric properties of the layer are formed at room temperature or by annealing at temperatures up to a maximum of 350? C., and the coating is applied to a suitable substrate or a suitable carrier by way of an aerosol deposition method of the powdered raw materials.

19. The method according to claim 1, wherein the layer is made of PZT or PZT-containing material or lead-free piezoceramics.

20. The method according to claim 1, wherein the powder and/or the substrate or the carrier are not heated by means of an external heat source to high temperatures above 350? C. during coating.

21. The method according to claim 1, wherein the substrate or the carrier is made of ceramic, plastic, glass, metal, semiconductor or a composite of the aforementioned materials.

22. The method according to claim 21, wherein the substrate or the carrier has a lower hardness than the bulk material of the powdered raw materials used for the aerosol deposition.

23. The method according to claim 1, wherein the bonding strength between the layer and the substrate or carrier is achieved, among other things, by a microstructural plastic deformation of the surface of the substrate or of the carrier (mechanical anchoring).

24. The method according to claim 1, wherein the layer has a thickness <100 ?m and a porous to dense structure, and the particle sizes in the layer are less than 1 ?m.

25. The method according to claim 1, wherein the layer entirely or partially covers the substrate or the carrier after the coating process.

26. The method according to claim 1, wherein the carrier is provided with an intermediate layer, onto which full or partial deposition takes place.

27. The method according to claim 1, wherein electrodes are arranged beneath or on top of the layer across the full surface or partial surface, which allow the operation.

28. The method according to claim 27, wherein electrodes are arranged beneath or on top of the layer in an interdigital structure, which allow the operation.

29. The method according to claim 1, wherein the substrate or the carrier has an arbitrary shape, such as curvatures.

30. The method according to claim 1, wherein the layer is structured during deposition or thereafter.

31. The method according to claim 1, wherein the layer is polarized during deposition or thereafter.

Description

EXEMPLARY EMBODIMENT: PZT ON STAINLESS STEEL

Aerosol Deposition:

[0012] An aerosol is generated from PZT powder and a carrier gas in an aerosol generator. The aerosol is sprayed onto the stainless-steel substrate to be coated in a deposition chamber, in which negative pressure is generated with the aid of a vacuum pump, using a (slot-shaped) nozzle. The aerosol is accelerated due to the pressure difference between the aerosol bottle and the deposition chamber and impinges on the stainless-steel substrate at high speeds. The PZT particles break during impact, adhere to the substrate, and form a layer there, as shown in FIG. 2. Due to the movability of the stainless-steel substrate, which in contrast to the fixedly positioned nozzle is located on a movable table, coating can take place in a planar (large-surface-area) manner.

Annealing

[0013] Some of the PZT-coated samples are annealed in the furnace at 300? C. for approximately 2 h.

Metallizing

[0014] The stainless-steel substrate can be used as an electrode for the polarization process. The counter electrode is generated by sputtering a metal layer onto the PZT layer. Care must only be taken that an insulating PZT edge is preserved between the stainless-steel substrate and the sputter layer. This may be ensured through the use of an appropriate mask.

Polarizing

[0015] An approximately 30 ?m-thick PZT layer is polarized by a trapezoidal voltage signal.

Measurement Results

[0016] The d33 value was determined on the polarized layers by means of a Berlincourt meter. The minima and maxima of the d33 measurement values ascertained in different locations of the sample surface are listed in Table 1.

TABLE-US-00001 TABLE 1 d33 measurement values (day 1 after polarization); RT: room temperature (no annealing). Annealing Layer thickness temperature d33 min d33 max No. Material [?m] [? C.] [pC/N] [pC/N] 6 FeNi 28 300 26 38 8 FeNi 26 RT 10 17 9 FeNi 24 RT 5 14 10 FeNi 23 300 61 78 14 FeNi 18 300 37 43

[0017] The piezoelectric data show that a usable piezoelectric effect is successfully achieved under the above-described deposition conditions, despite the low temperatures.