Development of Erosion Resistant Coatings by Magnetron Sputtering

Auger Electron Spectroscopy has been used to determine the sputter cleaning time required with a Fast Atom Beam source to remove the oxide layer from steel substrates. Removal of the oxide layer prior to coating resulted in good adhesion between coating and substrate as determined by optical microscopy and adhesion testing. Coatings of Cr, Nb, Ta and W were deposited after sputter cleaning on flat steel coupons and subjected to a severe thermal shock (plasma test). The Cr, Nb and Ta coatings accommodated the effects of the thermal shock and provided an effective thermal barrier whereas W which was much harder and less ductile could not withstand the thermal stresses and fractured and spalled from the substrate.