PL86754B1

PL86754B1 -

Info

Publication number: PL86754B1
Application number: PL1974176333A
Authority: PL
Priority date: 1974-12-11
Filing date: 1974-12-11
Publication date: 1977-12-15

Description

Przedmiotem wynalazku jest sposób wytwarzania powlok ze zlota, charakteryzujacych sie duzym polyskiem i wysokimi parametrami mechanicznymi jak mi kro twardosc, odpornosc na scieranie i podobne.Z kapieli znanej z polskiego patentu nr 64.990 uzyskuje sie powloki stopowe z metalami grupy zelaza o podwyzszonej twardosci, jednak kapiel ta wymaga ciaglej kontroli skladu przez utrzymanie scislego stosunku molowego metalu stopowego z EDTA. Ponadto obecnosc soli EDTA w kapieli jest niekorzystna ze wzgledu na obróbke scieków.Celem wynalazku jest opracowanie sposobu wytwarzania powlok blyszczacych zlotych tak aby dobrany sklad elektrolitu nie wymagal czestych korekt technologicznych i byl nietoksyczny.Sposób wedlug wynalazku polega na tym, ze do kapieli kwasnej, zawierajacej zloto w postaci cyjanku zlotowo-sodowego lub zlotowo-potasowego i metal grupy zelaza w postaci soli hydroksykwasu, dodaje sie mieszaniny dwóch hydroksykwasów o róznych ilosciach grup wodorotlenowych, przy czym proces galwaniczne¬ go pokrywania prowadzi sie przy gestosci pradu 0,1-1,5 A/dm2, temperaturze 20-50°C i pH = 3,8-6,0. Jeden z kwasów musi zawierac wiecej niz 2 grupy wodorotlenowe, a ich wzajemny stosunek molowy powinien sie zawierac w granicach 1:1—1:5.Sposób wedlug wynalazku gwarantuje otrzymanie blyszczacych powlok zlotych o dobrej przyczepnosci do metalu podloza i podwyzszonych wlasnosciach mechanicznych.Przyklad I. Przygotowano kapiel o skladzie 10 g/l zlota w postaci cyjanozlocinu sodu i dodano do nie] 0,5 g/l niklu w postaci soli kwasu cytrynowego i podgrzano do temperatury 30°C. Nastepnie dodano mieszaniny hydroksykwasów: 100 g/l kwasu cytrynowego i 20 g/l kwasu trójhydroksyglutarowego. Proces galwanicznego nakladania powloki prowadzono przy gestosci pradu 0,5 A/dm2 i przy pH = 4,0. Otrzymano powloke o grubosci 10 /im o duzym polysku i mikrotwardosci 220 juHV.Przykladll. Przygotowano kapiel o skladzie 10 g/l zlota w postaci cyjanozlocinu potasu i dodano do niej 1 g/l kobaltu w postaci soli kwasu jablkowego i podgrzano do temperatury 40°C. Nastepnie dodano2 86754 mieszaniny hydroksykwasów : 80 g/l kwasu jablkowego i 40 g/l kwasu czterohydroksyadypinowego. Proces galwanicznego nakladania powloki prowadzono przy gestosci pradu 0,8 A/dm2 i pH = 4,5. Otrzymano powloke o grubosci 12 /im i mikrotwardosci 190 uHV. PLThe subject of the invention is a method of producing gold coatings, characterized by high gloss and high mechanical parameters, such as softness, abrasion resistance and the like. The bath known from Polish patent No. 64,990 is used to obtain alloy coatings with metals of the iron group with increased hardness, but the bath this requires continuous composition control by keeping a strict molar ratio of the alloy metal to EDTA. In addition, the presence of EDTA salts in the bath is disadvantageous with regard to the treatment of sewage. The aim of the invention is to develop a method of producing shiny gold coatings so that the selected electrolyte composition does not require frequent technological adjustments and is non-toxic. The method according to the invention consists in the fact that for an acid bath containing gold in the form of gold-sodium or gold-potassium cyanide and the metal of the iron group in the form of a hydroxy acid salt, mixtures of two hydroxy acids with different amounts of hydroxyl groups are added, the galvanic coating process being carried out at a current density of 0.1-1.5 A / dm2, temperature 20-50 ° C and pH = 3.8-6.0. One of the acids must contain more than 2 hydroxyl groups, and their mutual molar ratio should be in the range 1: 1-1: 5. The method according to the invention guarantees obtaining shiny gold coatings with good adhesion to the base metal and enhanced mechanical properties. A bath of 10 g / L of gold in the form of sodium cyanozlocin was prepared and 0.5 g / L of nickel in the form of a citric acid salt was added thereto and heated to 30 ° C. Then mixtures of hydroxy acids were added: 100 g / l of citric acid and 20 g / l of trihydroxyglutaric acid. The process of galvanic coating was carried out at a current density of 0.5 A / dm2 and pH = 4.0. A 10 µm thick coating with a high gloss and microhardness of 220 µHV was obtained. A bath of 10 g / L gold in the form of potassium cyanozlocin was prepared and 1 g / L cobalt as the malic acid salt was added and heated to 40 ° C. Subsequently, 2 86,754 mixtures of hydroxy acids were added: 80 g / L of malic acid and 40 g / L of tetrahydroxyadipic acid. The process of galvanic coating was carried out at a current density of 0.8 A / dm2 and pH = 4.5. A coating with a thickness of 12 µm and a microhardness of 190 µHV was obtained. PL

Claims

1. Patent claim A method of producing shiny gold coatings with increased mechanical properties from an acid bath containing gold in the form of sodium-sodium cyanide or gold-potassium cyanide, and an iron group metal in the form of a hydroxy acid salt, characterized in that the bath is added to mixtures of two hydroxy acids, at least one of which contains more than two hydroxyl groups and their mutual ratio is in the range 1: 1 to 1: 5, the galvanic plating process is carried out at a current density of 0.1 to 1.5 A / dm2, at a temperature of 20 to 50 ° C, with a pH in the range 3.8 to 6.0. Wash. Typographer. UP PRL Mintage 120 + 18 copies Price PLN 10 PL