Abstract
UDC 621.793
This article introduces certain information on the problem of increasing the service life of steam turbine blades of the last and last-but-one stages. A special technology and equipment for the deposition of composite coatings by the Electro-spark Alloying (ESA) have been developed. It is established that with the ESA protective coating technology we can prevent volumetric heating of the blade over 200°С. That means we can avoid heat treatment. The equipment mentioned above consists of vibrators and pulse sources, which allows us to vary parameters in a wide range. That is why we can make coatings of a high quality. We have manufactured a source of pulses with the frequency from 500 Hz to 12000 Hz and with the duration from 10 ms to 150 ms. In addition, vibrators with the vibration frequency up to 260 Hz have been also made. The main purpose of the application of the ESA protective coating technology is lowering the cost of consumables against that of protection by stellite plates.
Keywords: electro-spark alloying, composite coatings, microstructure, equipment, power, vibrator, impulse, frequency.