METHOD OF REPAIRING CERAMIC COMPOSITE ARTICLES

Abstract

A method of repairing an article including cleaning a repair area, wherein the repair area comprises a ceramic matrix composite; and depositing a ceramic material in the cleaned repair area using laser assisted chemical vapor deposition. Also disclosed is a repaired ceramic composite produced by this method.

Claims

1. A method of repairing an article comprising: cleaning a repair area, wherein the repair area comprises a ceramic matrix composite; and depositing a ceramic material in the cleaned repair area using laser assisted chemical vapor deposition.

2. The method of claim 1, wherein cleaning the repair area comprises contacting the repair area with an oxidant, halogen, energy from an ultraviolet laser, or combination thereof.

3. The method of claim 1, wherein cleaning the repair area comprises contacting the repair area with energy from an ultraviolet laser.

4. The method of claim 3, wherein the ultraviolet laser is in pulsed mode.

5. The method of claim 1, wherein the deposited ceramic material comprises silicon carbide (SiC), boron carbide (BC.sub.x). boron silicon carbide (BSiC.sub.x), hafnium carbide (HfC), zirconium carbide (ZrC), or a combination thereof.

6. The method of claim 1, wherein the deposited ceramic material has less than 10% porosity.

7. The method of claim 1, wherein the repair area comprises silicon carbide (SiC), boron carbide (BC.sub.x). boron silicon carbide (BSiC.sub.x), hafnium carbide (HfC), zirconium carbide (ZrC), or a combination thereof.

8. The method of claim 1, wherein the repair area comprises a cooling hole.

9. The method of claim 1, wherein the repair area comprises a trailing edge.

10. The method of claim 1, wherein the laser assisted chemical vapor deposition uses a gas nozzle that is colinear with the laser.

11. The method of claim 1, wherein depositing the ceramic material comprises orienting a gas nozzle and a laser relative to the repair area using an articulated arm.

12. The method of claim 1, wherein the article is located in a vacuum chamber with a flowing gas precursor and depositing the ceramic material comprises locally heating the repair area with a laser to convert the gas precursor to the ceramic material.

13. The method of claim 1, wherein the repair area is located below the surface of the article and the method further comprises exposing the repair area.

14. The method of claim 1, wherein the repair area has a size of 50 micrometers to 50 millimeters.

15. A repaired ceramic composite article comprising a repaired area consisting of silicon carbide, boron carbide (BC.sub.x). boron silicon carbide (BSiC.sub.x), or a combination thereof and having a porosity less than 10%.

16. The repaired ceramic composite article of claim 15, wherein the repaired area has a size of 50 micrometers to 50 millimeters.

17. The repaired ceramic composite article of claim 15, wherein the repaired area comprises a cooling hole.

18. The repaired ceramic composite article of claim 15, wherein the repaired area comprises a trailing edge.

19. The repaired ceramic composite article of claim 15, wherein the repaired area corrects a defect located below a surface of the article.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0023] FIG. 1 illustrates a repair of a ceramic matrix composite article; and

[0024] FIG. 2 illustrates another embodiment of a repair of a ceramic matrix composite article.

DETAILED DESCRIPTION

[0025] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

[0026] As discussed above, a ceramic composite erodes quickly under conditions that include mechanical impact damage, a high velocity water vapor-containing flow, and combinations thereof. The eroded area may be repaired by filling with a portion of the barrier material when the barrier material is reapplied but the barrier material typically is different in composition from the ceramic composite. It is more desirable to replace the ceramic composite with a material that comprises a component of the composite, typically the matrix material or a component of the matrix material. This results in a more robust repair. For example, the thermal conductivity of silicon carbide (SiC) is closer than the thermal conductivity of the barrier material to the thermal conductivity of ceramic composite. Accordingly repairing a damaged area with SiC or similar material results in a component with less heterogeneity than one repaired with barrier material.

[0027] Disclosed herein is a method of repairing a ceramic composite article. The method includes cleaning the area needing repair (referred to as the repair area) and then depositing ceramic material in the cleaned repair area using laser assisted chemical vapor deposition. The deposited ceramic material may include material used in the matrix of the ceramic composite article.

[0028] The repair area may be cleaned using a mechanical method such as grinding, an oxidant gas, a halogen gas, an ultraviolet (UV) laser, or a combination thereof. Cleaning removes unwanted oxide or carbide phases that may interfere with the deposition of the ceramic material. Exemplary oxidants include H.sub.2O Exemplary halogens include HCl, Cl.sub.2, and HF. The repair area may be contacted with the oxidant, halogen, UV laser, or combination thereof. The laser may be used in a pulsed mode to deposit energy to a limited depth.

[0029] After cleaning the repair area, ceramic material is deposited using laser assisted chemical vapor deposition. A gas precursor is injected into the area of the repair area and the laser heats the repair area to provide energy to convert the precursor to the deposited ceramic material. Because the precursor is converted to the product on site there are little or no side products. This contrasts with molten methods which can also deposit undesirable side products which can affect the performance of the deposited material. Exemplary undesirable side products include low melting point products from residual molten phases. The ceramic material deposited using laser assisted chemical vapor deposition has less than 10%, or less than 5%, or less than 2% porosity.

[0030] FIG. 1 shows a ceramic matrix composite 10 having a repair area 20. Laser beam 30 heats the repair area 20 and assists chemical vapor deposition of material 40 in repair area 20. Precursor inlet 50 provides the precursor for chemical vapor deposition. Outlet vacuum 60 provides local exhaust for the reaction product and avoids contamination of the part surfaces.

[0031] FIG. 2 is similar to FIG. 1 but shows the precursor inlet 50 as co-linear with the laser beam 30.

[0032] Exemplary precursor materials are those known to be useful in chemical vapor deposition and include methyl trichlorosilane (MTS), vinyltrichlorosilane, hexamethyldisilane, and other chlorides or mixture of gases such as SiCl.sub.4, BCl.sub.3 with CH.sub.4, C.sub.2H.sub.4, typically know to the art of CVD. Exemplary deposited ceramic materials include silicon carbide (SiC), boron carbide (BC.sub.x), boron silicon carbide (BSiC.sub.x), hafnium carbide, zirconium carbide, and combinations thereof.

[0033] The laser may raster the area and/or be used in a pulsed mode to limit the amount of heating of the substrate. As mentioned above a UV laser may be used for cleaning. Exemplary lasers for laser assisted chemical vapor deposition include lasers that couple with the surface of the repair area to heat the surface such as infrared lasers and carbon dioxide lasers. The atmosphere may include inert gases or catalyst gases such as H.sub.2. The pressure of the chamber can be controlled to tailor the rate of reaction. The repair area may be preheated. The nozzle used to provide the precursor material to the repair area may be co-linear or co-axial with the laser. The nozzle and the laser may be oriented relative to the repair area using an articulated arm that can control the orientation of the nozzle and laser independently or jointly. Alternatively, the component can be affixed to an articulated arm and the laser and nozzle fixed. The gas can also be provided in the chamber independently of the laser.

[0034] The repair area of the ceramic composite may include silicon carbide, boron carbide (BC.sub.x), boron silicon carbide (BSiC.sub.x), hafnium carbide, zirconium carbide, and combinations thereof. The repair area may have a size of 50 microns to 50 millimeters (mm) or 100 microns to 5 mm. The repair area may include a feature such as a cooling hole or an edge such as a trailing edge. Repair of such features has previously proved difficult. With laser assisted chemical deposition the laser pattern can be altered for the repair of features without the need for subsequent machining.

[0035] It is further contemplated that the above described repair method may be employed to repair a defect, such as a pore or crack, in a ceramic composite. In these instances the method may further include removing a portion of the barrier material.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

[0037] While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.