Abstract: A method of producing oxide ceramic layers on Al, Mg, Ti, Ta, Zr, Nb, Hf, Sb, W, Mo, V, Bi or their alloys by a plasma-chemical anodical oxidation in a chloride-free electrolytic bath having a pH value of 2 to 8 and a constant bath temperature of -30.degree. to +15.degree. C. A current density of at least 1 A/dm.sup.2 is maintained constant in the electrolytic bath until the voltage reaches a predetermined end value.

Abstract: A method of producing composite oxide ceramic fluorine polymer layers on articles of aluminum, magnesium, titanium or their alloys, particularly of light metal components, includes introducing particles of fluorine polymers into the capillary system of an oxide ceramic layer. The particles have a particle size which at least in one dimension is smaller than the diameter of the capillaries. The article is then subjected to alternating pressure conditions.

Abstract: A method of producing oxide ceramic layers on Al, Mg, Ti, Ta, Zr, Nb, Hf, Sb, W, Mo, V, Bi or their alloys by a plasma-chemical anodical oxidation in a chloride-free electrolytic bath having a pH value of 2 to 8 and a constant bath temperature of -30.degree. to +15.degree. C. A current density of at least 1 A/dm.sup.2 is maintained constant in the electrolytic bath until the voltage reaches a predetermined end value.

Abstract: The invention relates to a cyanide-free electrolyte being harmless to the environment and to health which makes feasible the production of black surface layers on light metals or on alloys of the latter, preferably titanium, remaining deeply-black and adhesive even after extreme changes in the ambient temperature and having nearly equal values of the optical absorptivity of radiation and of the thermal emission capability (the .alpha./.epsilon.-ratio is about 0.95) by means of the anodic oxidation by spark discharge (ANOF-method). These layers are absolutely X-amorphous and show, hence, an ideal optically isotropic behavior regarding the reflection of radiation. Due to their minimum evolution of gases they offer a high thermovacuum stability. The electrolyte consists of an ammoniacal solution of K.sub.2 H.sub.2 PO.sub.4 potssium dihydrogenphosphate and K.sub.2 CRO.sub.4 potassium chromate. The homogeneity of the optically black layers is ensured by not using fluoride ions and employing acetate ions.