Slip and process for producing an oxidation- and corrosion-resistant diffusion layer

Patent metadata

Field	Value
Publication number	US-10316198-B2
Application number	US-201514886381-A
Country	US
Kind code	B2
Filing date	Oct 19, 2015
Priority date	Oct 29, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

The present invention relates to a process for producing a diffusion layer for protecting temperature-stressed components, in particular of turbomachines, against oxidation and corrosion. The process comprises application of at least one slip to a component surface on which the diffusion layer is to be produced, and drying and/or hardening of the at least one slip by a heat treatment at a first temperature and diffusion heat treatment at a second temperature. The slip comprises Al-containing powder, Si-containing powder and a binder and also a Cr-containing powder which does not comprise any hexavalent chromium. In addition, the invention provides a corresponding slip.

First claim

What is claimed is:

1. A process for producing a diffusion layer for protecting a temperature-stressed component against oxidation and corrosion, wherein the method comprises:
application of at least one slip to a component surface on which the diffusion layer is to be produced,
drying and/or hardening of the at least one slip by a heat treatment at a first temperature and diffusion heat treatment at a second temperature;

and wherein a base slip comprising at least one halide, a Cr-containing powder and a binder is applied in at least one first layer and at least one second layer is applied to the first layer using a slip comprising Al-containing powder, Si-containing powder and a binder, neither the Cr-containing powder nor the halide comprising hexavalent chromium.

2. The process of claim 1 , wherein the second layer is applied onto the base slip of the first layer before or after a heat treatment of the base slip or before or after a heat treatment for reactive bonding of the base slip or before or after a diffusion heat treatment of the base slip.

3. The process of claim 1 , wherein the halide of the base slip comprises a metal chloride compound or chromium halogen compound.

4. The process of claim 1 , wherein the base slip comprises from 0.1% to 10% by weight of CrCl 2 and/or CrCl 3 and from 25% to 95% by weight of binder, the balance being Cr particles and/or chromium alloy particles.

5. The process of claim 1 , wherein the base slip comprises a binder having an acrylic basis or a glycol basis or a polyvinyl basis.

6. The process of claim 2 , wherein the heat treatment of the base slip is carried out at a temperature in ranging from 50° C. to 600° C. and/or for a time in ranging from 5 minutes to 240 minutes.

7. The process of claim 2 , wherein the heat treatment of the base slip for reactive bonding is carried out before the diffusion heat treatment and/or at a temperature ranging from 900° C. to 1160° C. and/or for a time ranging from 15 minutes to 15 hours.

8. The process of claim 1 , wherein the diffusion heat treatment of the base slip is carried out for a time ranging from 30 minutes to 12 hours and/or at a temperature ranging from 800° C. to 1200° C.

9. The process of claim 1 , wherein the diffusion heat treatment of the base slip is carried out in a halide atmosphere, a hydrogen atmosphere or an inert gas atmosphere and/or at a pressure ranging from ambient pressure to an industrial vacuum.

10. The process of claim 9 , wherein the hydrogen atmosphere or the inert gas atmosphere comprises a gaseous addition of metal halides or an aerosol comprising metal halides and the metal halides comprise CrCl 2 and/or CrCl 3 .

11. The process of claim 1 , wherein the slip of the second layer, which is applied onto the base slip, comprises a slip which comprises Al-containing powder, Si-containing powder, Cr-containing powder which does not comprise any hexavalent chromium, and a binder.

12. The process of claim 1 , wherein the surface to be treated is blasted with particles before application of the base slip.

13. The process of claim 1 , wherein the process is carried out in such a way that the diffusion layer on the surface and/or averaged over the thickness of the diffusion layer comprises from 10% to 30% by weight of Cr, from 20% to 35% by weight of Al and from 5% to 20% by weight of Si.

14. The process of claim 1 , wherein the process is carried out in such a way that the diffusion layer has a thickness of from 10 μm to 200 μm.

15. A process for producing a diffusion layer for protecting a temperature-stressed component against oxidation and corrosion, wherein the method comprises:
application of at least one slip to a component surface on which the diffusion layer is to be produced,
drying and/or hardening of the at least one slip by a heat treatment at a first temperature and diffusion heat treatment at a second temperature;

and wherein the at least one slip comprises from 20% to 40% by weight of Al powder, from 5% to 8% by weight of Si powder, and from 1% to 20% by weight of Cr powder or from 1% to 25% by weight of Cr(II) compounds and/or Cr(III) compounds, the balance being one or more organic binders.

16. The process of claim 15 , wherein the at least one slip comprises from 1% to 25% by weight of Cr(II) compounds and/or Cr(III) compounds.

17. The process of claim 15 , wherein the heat treatment of the at least one slip is carried out at a temperature in ranging from 50° C. to 600° C. and/or for a time in ranging from 5 minutes to 240 minutes.

18. The process of claim 15 , wherein the diffusion heat treatment of the at least one slip is carried out for a time ranging from 30 minutes to 12 hours and/or at a temperature ranging from 800° C. to 1200° C.

19. The process of claim 15 , wherein the diffusion heat treatment of the at least one slip is carried out in a halide atmosphere, a hydrogen atmosphere or an inert gas atmosphere and/or at a pressure ranging from ambient pressure to an industrial vacuum.

20. The process of claim 19 , wherein the hydrogen atmosphere or the inert gas atmosphere comprises a gaseous addition of metal halides or an aerosol comprising metal halides and the metal halides comprise CrCl 2 and/or CrCl 3 .

Assignees

• MTU Aero Engines AG

Inventors

• Lopez Lavernia Natividad
• Hillen Michael
• Pillhoefer Horst
• Kliewe Anja

Classifications

• C22C30/00 Primary

  Alloys containing less than 50% by weight of each constituent · CPC title

• C09D129/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title

• C23C10/26

  more than one element being diffused · CPC title

• C09D5/103 Primary

  containing Al · CPC title