Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-34CLEANING OF CRACK SURFACES OF METAL ALLOY PARTICLESZ.P. Pai 1 , V.N. Parmon 1 and V.V. Pai 21 Boreskov Institute of Catalysis SB RAS, Prosp. Akad. Lavrentieva, 5Novosibirsk 630090, RussiaFax: (383) 330-80-56, E-mail: zpai@catalysis.ru2 Lavrentiev Institute of Hydrodynamics SB RAS, Prosp. Akad. Lavrentieva, 14Novosibirsk 630090, RussiaThe operation of aviation gas turbine engines is accompanied by formation of cracks onthe turbine blades caused by high temperatures, high aerodynamic and mechanical loads, etc.The blades are very expensive. Therefore, the development of repair-recovery technologiesaimed at extending the blade service life is one of the topical problems in the turbineconstruction.At present, the DAYTON method is widely used to recover cracked metallic parts, whichpermits one to considerably prolong service life of the above parts, to save materials and toreduce labour inputs. The DAYTON recovery is performed via two steps:• Cleaning of the crack surface from metal oxides;• High-temperature soldering of cracks using special heat-resistant solders.The key step of the DAYTON technology (developed and patented by the UDRI-University of Dayton, Research Institute in 1980) is the process of qualitative removal ofmetal oxides from the crack mouth surface (FCP-Fluorocarbon Cleaning Process) [1, 2].Thus, the cleaning of cracks from metal oxides is a necessary condition for repair ofdetails with cracks using the high-temperature vacuum soldering method.The researchers of the Institute of Catalysis and the Institute of Hydrodynamics (SB RAS)performed a series of works aimed at developing a new cleaning method of micro cracks ofmetallic materials using a nickel-based alloy as an example [3]. A setup was developed andmanufactured to experimentally substantiate the developed method (Fig. 1). Basic units of thesetup are: reactor supplied with a contact heater with controlled capacity (which is controlledby a thermocouple with digital temperature indication); reservoir for solution with heatsupply; steam-generator supplied with a heating element and temperature and fluid levelsensors; water-cooled condenser.In the experiments, the state of the cracks surface of the samples-simulators wascontrolled by an INCA Energy (X-ray energy dispersion) spectrometer, installed on theLEO-420 focused beam electron microscope. The chosen gas- and hydrodynamics parameters367