IE990654A1

IE990654A1 - Method of Cleaning Metal Components

Info

Publication number: IE990654A1
Application number: IE990654A
Authority: IE
Inventors: Kenneth Gove
Original assignee: Sifco Res & Dev Ltd
Priority date: 1998-07-30
Filing date: 1999-07-29
Publication date: 2000-04-05

Abstract

A process of cleaning components, in particular nickel or cobalt based super alloys which are used for the manufacture of aircraft and land based gas turbine engines, is described. The cleaning of the superalloys usually takes place prior to repair of cracks or other defects in the components. The process involves the placing the components in a furnace retort, or some other similar sealed vessel, heating the components to an elevated temperature, and while at said elevated temperature introducing a geseous mixture of fluoride and chloride ions into the retort. Preferably, the halide gases introduced to the retort are hydrogen fluoride and hydrogen chloride.

Description

“METHOD OF CLEANING METAL COMPONENTS” A process of cleaning components, in particular nickel or cobalt based super alloys which are used for the manufacture of aircraft and land based gas turbine engines, is described. The cleaning of the superalloys usually takes place prior to repair of cracks or other defects in the components. The process involves the placing the components in a furnace retort, or some other similar sealed vessel, heating the components to an elevated temperature, and while at said elevated temperature introducing a geseous mixture of fluoride and chloride ions into the retort. Preferably, the halide gases introduced to the retort are hydrogen fluoride and hydrogen chloride.

Claims

1. A process for cleaning cracks and other surface defects in components made from metallic based superalloys, prior to the repair of the crack by brazing and the like, comprising the steps of: a) placing the component in a furnace retort b) heating the furnace to an elevated temperature, and while at said elevated temperature, c) introducing a gaseous atmosphere into said retort, characterised in that the gaseous atmosphere comprises a mixture of hydrogen, a gaseous source of fluoride ions and a gaseous source of chloride ions.

2. The process as claimed in claim 1, wherein the gaseous source of fluoride ions is hydrogen fluoride and the gaseous source of chloride ions is hydrogen chloride

3. The process as claimed in any preceding claim, wherein the gaseous atmosphere comprises up to 20% hydrogen fluoride, a volume of hydrogen chloride comprising 1 to 2% of the volume of hydrogen fluoride and the balance comprising hydrogen.

4. The process as claimed in any preceding claim, wherein the elevated temperature is substantially in the range 950°C to 1000°C.

5. The process as claimed in any of the preceding claims where the elevated temperature is about 975°C.

6. The process as claimed in any preceding claim wherein the metallic based superalloys are selected from nickel and/ or cobalt based superalloys.

7. The process as claimed in any preceding claim comprising the additional preliminary step of removing any oxide material adhering to the components.

8. The process as claimed in any one of the preceding claims comprising the additional preliminary step of removing sulphide and/or oxy-sulphide deposits from the components by immersing the components in solutions comprising one or more of 5 the following compounds: a) nitric acid, b) acetic acid, c) phosporic acid, and d) ferric chloride.

9. The process as claimed in claim 4 wherein the heating process is carried out for a duration from about 15 to about 60 minutes.

10. A process for cleaning cracks and other surface defects in components made

11. 15 from metallic based superalloys substantially as described hereinbefore with reference to and/ or as illustrated in Figure 1.

12. 20 Tomkins & Co.