Abstract: An aqueous alkaline plating bath for the electrodeposition of a zinc-nickel alloy coating on a substrate is described. The plating bath generally comprise(A) zinc ions;(B) nickel ions; and(C) at least one heterocyclic compound having the general formulaRN.sup.+ --R.sup.1 --Y.sup.(-)a (X.sup.-).sub.b (I)wherein RN is an aromatic heterocyclic nitrogen-containing group, R.sup.1 is an alkylene or hydroxy alkylene group, Y is --OSO.sub.3, --SO.sub.3, --COOH, --CONH.sub.2 or --OH, X is a halide, a and b=0 or 1, and the sum of a+b=1. Preferably, additional additives are included in the plating bath to improve the properties of the deposited alloy. For example, polymers of aliphatic amines may be included to improve the level of the deposits and metal complexing agents such as hydroxyalkyl-substituted polyamines also may be included. The plating baths of the invention are effective depositing bright alloys over a wide current density range.

Abstract: A method is described for preparing a black chromium-containing conversion coating on a zinc-nickel alloy surface containing at least about 8% nickel in the alloy or on a zinc-iron alloy surface. The method of the invention comprises contacting said surfaces with an aqueous acidic solution comprising trivalent chromium and an amount of a phosphorus acid selected from phosphoric acid, phosphorous acid, hypophosphorous acid, and mixtures thereof effective to provide a solution having a pH of from about 1.0 to about 2.5. Metal articles having zinc-nickel alloy surfaces containing at least about 8 % nickel in the alloy or having zinc-iron alloy surfaces which have been treated in accordance with the method of the invention exhibit the desired blackened surfaces and are characterized by improved corrosion resistance.

Abstract: A method is described for producing an iridescent chromium coating on a zinc-nickel alloy surface containing at least about 8% nickel in the alloy. The method of the invention comprises(A) contacting said surface with an aqueous acidic solution maintained at a temperature of from about 38.degree. C. to about 75.degree. C., wherein the solution comprises trivalent chromium as substantially the only chromium ion present, and a phosphorus acid selected from phosphoric acid, phosphorous acid, hypophosphorous acid and mixtures thereof in an amount effective to provide a solution having a pH of from about 1.0 to about 2.5; and(B) drying the surface.Metal articles having zinc-nickel alloy surfaces containing at least about 8% nickel in the alloy which have been treated in accordance with the method of the invention exhibit the desired iridescent coating and are characterized by improved corrosion resistance.

Abstract: A method is described for producing an iridescent chromium coating on a zinc-nickel alloy surface containing at least about 8% nickel in the alloy. The method of the invention comprises(A) contacting said surface with an aqueous acidic solution maintained at a temperature of from about 38.degree. C. to about 75.degree. C., wherein the solution comprises trivalent chromium as substantially the only chromium ion present, and a phosphorus acid selected from phosphoric acid, phosphorous acid, hypophosphorous acid and mixtures thereof in an amount effective to provide a solution having a pH of from about 1.0 to about 2.5; and(B) drying the surface.Metal articles having zinc-nickel alloy surfaces containing at least about 8% nickel in the alloy which have been treated in accordance with the method of the invention exhibit the desired iridescent coating and are characterized by improved corrosion resistance.

Abstract: A method is described for preparing a black zinc-nickel alloy surface containing at least about 8% nickel in the alloy. The method of the invention comprises contacting said surfaces with a chromium-free aqueous acidic solution of an inorganic acid. Preferably the inorganic acid is a phosphorus acid selected from phosphoric acid, phosphorous acid, hypophosphorous acid, and mixtures thereof. The aqueous acidic solution can also contain at least one silane. Metal articles having zinc-nickel alloy surfaces containing at least about 8% nickel in the alloy which have been treated in accordance with the method of the invention exhibit the desired blackened surfaces and are characterized by improved corrosion resistance when at least one silane is present in the acidic solution.

Abstract: This invention relates to a method of controlling orthophosphite ion concentration in a hypophosphite-based electroless metal plating bath, comprising the steps of contacting the plating bath with a yttrium or a lanthanide series metal salt, and removing orthophosphite ions from the bath. The methods of the present invention provide effective means for controlling phosphite ion concentration in electroless metal plating baths and especially electroless nickel plating baths. The methods of the present invention provide means for increasing pH and removing orthophosphite ions from the plating bath.

Abstract: This invention relates to a paste composition, comprising:(A) at least 12% by weight of a paste forming compound and(B) at least one oxidizing agent which is a metal oxide or salt;(C) at least one reducing metal wherein (B) and (C) are capable of forming a metal coating;(D) at least one nonreactive, powder material capable of being incorporated into the coating formed from (B) and (C) wherein the material is selected from the group consisting of a metal, a metal alloy and a polymer; or(E) mixture of two or more thereof.The paste compositions control the pyrophoricity and explosive tendencies of the metal powders used in the process. Further, the paste affords easy handling of the materials. Delivery of the paste may be manual or automatic such as with a grease pump.

Abstract: The invention provides an on-stream method and apparatus for analyzing of the concentrations of chemical components in a bath, especially in an electroplating bath, contained in one or more processing tanks. Moreover, the information obtained by such analysis of a single bath or of multiple baths may be efficiently employed to control such concentrations in the bath or respective baths, for example, by controlling the addition of one or more additives. The apparatus comprises a multi-steam sampling value and a computer for controlling the operation of said value. The computer also controls means for adding material to the baths in order to maintain the parameters thereof.

Abstract: A composition is described which provides an improvement in the electrodeposition of zinc from aqueous alkaline plating baths containing cyanide ions. The new composition comprises the reaction product obtained by the process of reacting(a) a polyhydroxyethylated polyamine having a carbon to nitrogen weight ratio of about 2.8:1 to about 3.3:1 and a nitrogen to oxygen weight ratio of about 1:1 to about 2:1, and(b) a 3-halo-2-hydroxypropane sulfonate.Aqueous, alkaline cyanide zinc electroplating baths containing the additive compositions of the invention deposit a bright zinc coating over a wide range of current densities.

Abstract: Aqueous acidic coating solutions are described for treating zinc or zinc alloy surfaces comprising trivalent chromium as substantially the only chromium ion present, fluoride ion, an acid other than nitric acid, and an oxidizing agent. The coating solutions containing trivalent chromium as substantially the only chromium ion present preferably are prepared by reducing an aqueous solution of hexavalent chromium with sufficient reducing agent to reduce all of the hexavalent chromium to trivalent chromium. Chromate coatings on zinc and zinc alloy surfaces are produced by contacting said surfaces with an aqueous acidic solution of the invention.