Industrial gas turbine (IGT) parts with hundreds of thousands of service hours become severely oxidized. To address this issue, service shops fill the cracks with a braze alloy. However, all existing oxidation, sulphidation and hot corrosion must first be thoroughly removed from component surfaces, cooling passages, and cracks that are often very narrow and deep.
The Dynamic Fluoride Ion Cleaning (DFIC) Process from Hi-Tech Furnace Systems is made to clean deep, narrow cracks of oxides by cycling between negative, atmospheric, and positive pressure.
The DFIC process results from the reaction of fluorine with various oxides. At temperatures greater than 1,750° F (950° C), fluoride ions react with oxides that have formed on the crack faces, converting them to gaseous metal fluorides than can then be easily removed.
By varying the pressure between positive, negative, and atmospheric levels, the DFIC system “pulses” HF in and out of cooling channels, deep cracks and small holes to more effectively clean oxidized, hard to reach areas. Control of both HF ratio and atmospheric pressure can help efficiently remove even highly embedded oxidation.