Muboyadjyan

This work presents results of thermodynamic studies and searching for a rational chemical activation dopant for deposition of hafnium from the gaseous phase onto the surface of gas-turbine engine’s parts made of heatproof nickel alloys in order to increase diffusion stability of heatproof aluminide coatings. Calculations showed impossibility of using a traditional activation dopant, that is nickel dichloride, for hafnium coating because liberation of gaseous hafnium compounds occurs at temperatures which are beyond reach for modern equipment for thermochemical treatment. During this investigation it was established that ammonium chloride could be used as an activation dopant. If hafnium consists one fifth of ammonium chloride in the saturating mixture, amount of gaseous hafnium chloride reaches its maximum.