Abstract: Coatings are described which are particularly suited for the protection of nickel and cobalt superalloy articles at elevated temperatures. The protective nature of the coatings is due to the formation of an alumina layer on the surface of the coating which serves to reduce oxidation/corrosion. The coatings contain aluminum, chromium, and one metal chosen from the group consisting of nickel and cobalt or mixtures thereof. The coatings further contain a small controlled percentage of hafnium which serves to greatly improve the adherence and durability of the protective alumina film on the surface of the coating.

Abstract: In an electro-chemical machine tool electrolyte drainage flow is acted upon, on its way to the sump, by a device which breaks up the flow into isolated droplets, so as to prevent electrical leakage occurring via the electrolyte flow.

Abstract: Coatings are described which are particularly suited for the protection of nickel and cobalt superalloy articles at elevated temperatures. The protective nature of the coatings is due to the formation of an alumina layer on the surface of the coating which serves to reduce oxidation/corrosion. The coatings contain aluminum, chromium, and one metal chosen from the group consisting of nickel and cobalt or mixtures thereof. The coatings further contain a small controlled percentage of hafnium which serves to greatly improve the adherence and durability of the protective alumina film on the surface of the coating.

Abstract: Electro-chemical drilling of small diameter holes is achieved by placing an electrolyte discharge nozzle in fixed spaced apart relationship with a workpiece, heating the electrolyte passing between the discharge nozzle and the workpiece to increase the current conductivity of the electrolyte up to about 70.degree. C and forcing a jet of electrolyte across the space onto the workpiece. The electrolyte pressure and discharge nozzle orifice length are matched so as to provide an unconfined jet of electrolyte which has a constant diameter so as to obviate the necessity of relative movement between nozzle and workpiece. Increased temperature results in a fine non-conductive mist at the end of the electrolytic jet thereby providing a process for drilling holes of smaller size in the workpiece than prior procedures.A novel nozzle assembly is also disclosed adapted to produce holes in a workpiece by directing free streams of electrically charged electrolyte at the workpiece.