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Gas Chemical Cleaning of Service Induced Oxide Filled Cracks Disclosure Number: IPCOM000020436D
Original Publication Date: 2003-Dec-25
Included in the Prior Art Database: 2003-Dec-25

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During operation of a gas turbine parts of the wheels are exposed to material critical high temperatures. Due to the high temperature fine cracks can occur on the surface of these wheels. These component parts are very expensive so it is profitable to repair the surfaces, i.e. to fill such racks with a filling material. In order to braze repair those cracks, the cracks need to be cleaned from residual oxidation, because the soldering metal would not conjoin very well with the oxide. Currently the only known reliable method to remove the oxide is fluoride ion cleaning. It is proposed to use chlorine gas to clean oxide filled cracks. The metal-oxides build a chemical bond with the chloride gas. This chemical bond is volatile. So the cracks are cleaned from the oxides. For example the aluminium- and titanium-oxides react with the chloride gas to Aluminium- and titanium-chlorides. Some oxygen can be added to the process gas in order to create a thin passivating nitride-oxide layer that protects the base material. Ultrasonic agitation of the gas turbine part during cleaning via a sonotrode can be applied.