Abstract: Provided are a treatment liquid for a black trivalent chromium conversion coating, and a trivalent chromium-containing water-soluble liquid for finishing treatment, achieving excellent corrosion resistance and scratch resistance without containing a cobalt compound, with high stability and adequate consideration for environmental issues; and a method for treating a metal substrate using the same. The treatment liquid for a black trivalent chromium conversion coating on the surface of a metal substrate contains a trivalent chromium compound, two or more organic acids or organic acid salts, or one or more organic sulfur compounds, and nitrate ions, and contains no cobalt compound.

Abstract: Provided are a treatment liquid for a trivalent chromium conversion coating, achieving excellent corrosion resistance and scratch resistance without containing a cobalt compound, with high stability and adequate consideration for environmental issues; and a method for treating a metal substrate using the same. Provided is a treatment liquid for a trivalent chromium conversion coating on the surface of a metal substrate comprising: a trivalent chromium compound; titanium lactate; one or more compounds of transition metal other than cobalt; two or more organic acids or organic acid salts, and at least one ion species selected from chloride ions, nitrate ions, and sulfate ions; but no cobalt compound.

Abstract: To provide a high-nickel plating bath which is weakly acidic and can stably form a plating film having a nickel content of 11 to 19% (preferably 12 to 18%) even at a current density of 3 A/dm2 or more. An acidic zinc-nickel alloy electroplating solution which contains an amine compound represented by the formula H2N—R1-R2 {wherein: R1 is [(CH2)M—NH]L or (CH2)N; R2 is H, NH2, or R3; R3 is an alkanol or alkoxyl group having 1, 2, 3, 4, or 5 carbon atoms; L is 2, 3, 4, or 5; M is 2, 3, 4, or 5; and N is 3, 4, or 5}.

Abstract: A zinc-nickel alloy plating solution in an aqueous solution comprising, as represented in terms of ions, 4-30 g/liter of zinc and 0.05-4 g/liter of nickel, together with 50-220 g/liter of an alkali hydroxide, 4-110 g/liter of a complexing agent, 0.1-10 g/liter of a primary brightener, 0.01-0.2 g/liter of a booster brightener and preferably, further, 0.01-0.05 g/liter of a tertiary brightener. The primary brightener is at least one selected from the reaction products of amines such as ethylenediamine or its methyl-substituted derivatives, propylenediamine or its methyl-substituted derivatives, diethylenetriamine or its methyl-substituted derivatives, and the like with epihalohydrin. The booster brightener is at least one selected from aromatic aldehydes such as anisaldehyde, vanillin, heliotropin, veratraldehyde, and the like. The tertiary brightener is at least one selected from tellurium oxide, tellurous acid or its salts, or telluric acid or its salt.