DE2251103C3 - Acid galvanic zinc bath - Google Patents

Description

example 1

A cold rolled steel plate was made among the following Conditions plated

Composition of the bath Zinc sulfate (ZnSO ₄ · 7 H ₁ O) 450 g / l Zinc chloride (ZnQ _x ) 150 g / l Sodium succinate [(CH _x COONa) _x -

6H ₈ O)] 15g / l

Nicotinic acid amide (ΰ, Η, Ν, Ο ») 3 g / l Ammonium chloride (NH ₁ CI) 40 g / l Ethoxylated a-naphtholsulfone

acid (C ₁₁ H _1x OsS) 0.62 g / l

Current density, .. 100 A / dm * Plating time 5 seconds

Example 2
Composition of the bath

Zinc sulfate (ZnSO ₄ · 7 H ₁ O) 300 g / l Zinc chloride (ZnCl _x ) 80 g / l Ammonium chloride (NH ₄ Ci) 20 g / l Sodium succinate KCH ₈ COONa) _x -OH _x O)] 10 g / l Nicotinic acid amide (CAN _x O _x ) 5 gl / Current density 60 A / dm * Plating time 8 seconds

Example 3
Composition of the bath

Zinc sulfate (ZnSO ₄ -7H ₁ O) 35Og / l Zinc chloride (ZnCl _x ) 200g / l Ammonium chloride (NH ₄ Cl) 50 g / l Sodium succinate

_ [(CH _x COONa) _x - 6 H ₁ O)] 20 gA

Ethoxylated naphtholsulfonic acid

(C ₁₁ H ₁₁ O ₁ S) 0.05g / l

Current density 80 A / dm * Plating time 4 seconds

The plating coatings produced according to the corresponding examples have dense crystal structures with a good appearance and are smooth and shiny.

The electroplating operation was used as a control or reference test with the compositions of Examples 1 to 3, but without a content of nicotinic acid amide and / or ethoxylated «-naphtholsulfonic acid, and it was found that the films formed were coarse and the surface of the Plating does not become smooth and shiny.

Claims (1)

Claim: tration of less from 200 g / l it is impossible to get high Apply current densities as the surface of the Acid galvanic zinc bath with a content of pitting is burned, while with a Konan zinc, ammonium, sulfate and chloride concentration above 650 g / l there is a tendency to erzeulons, an ethoxylated organic compound. These precipitates as well as an organic one Acid, zinc ammonium sulphate, which characterizes the conductor roll, is that the bath is an aqueous solution of 200 to 650 g / l zinc sulphate, 50 to or 200 g / l zinc chloride on the surface of the plating film, poisoning an electric current Separate 10 to 70 g / l ammonium and deteriorate the plating film. ΪΓ "V ^{5 to X} ^ ¹ sodium succinate and 0.1 to io. Zinc sulfate is therefore used in amounts of 200 Ws 650 g / l 10 g / l nicotinic acid amide and / or 0.01 to 0.1 g / l ethoxylated «-Naphtholsulfdnsäure contains At a concentration of zinc chloride of less than 50 g / l, the conductivity is too low to generate high current densities, while at a tv κ, « a · ¹ ^ concentration of more than 200 g / l changes the appearance The invention relates to an acidic galvanic which degrades plating when exposed to a nish zinc bath with a content of zinc, amphosphate or chromic acid can be treated. momum, sulphate and chloride ions, an ethoxy- By adding ammonium chloride, the herten organic compound as well as organic conductivity can be improved. With concentration recess construction. This bath is glossy for the production of less than 10 g / l, this goal of Am- Zender zinc coatings with dense crystal structures cannot be achieved with monium chloride, while with suitable under high current densities. a concentration above 70 g / l a tendency to It is known to use acidic zinc plating baths to deposit deposits. In the apply zinc sulfate, zinc chloride or zinc fluorobo-electrolysis using the electrolysis bath Rat or the like. ^{Contained as a source of Zn s +} ions. The favorable pH value of the is around the »s according to the invention α Jiui *? Ü λ ^{S TO increase} > ^{is often} 8 sulphate electrolysis bath between 3.5 and 4.5 and preferably or Uilond added to the bath. With such a plateau at 4.0. A pH value of the electrolysis bath above It is possible to use plating baths; High density if the plating causes zinc compounds. A pH of the bath is stirred during the plating operation. 30 electrolysis bath below 3.5 would «N increased current densities is however the surface of the material development in the bath, which lead through the Coating coarse and not shiny. In addition, plating film is absorbed and pinholes in the large crystals are formed. To make this difficult- plating film would cause. It has been suggested to avoid small The main function of the sodium succinate is Amounts of organic matter, for example 35 in the stabilization of the pH of the plating ™ "^ i * ^m ' ^{G !? Inil} ^ ^Wc ™ .I>« troee, ^. Naphthol baths. At a sodium succinate concentration of or the like to add to the bathroom. An introduction of less than 5 g / l is its effect to buffer the the pHs does not allow such organic substances to be sufficient, while with a concentration Production of high quality plating within tration above 30 g / l the preference of sodium A certain range of current density, although 40 succinate is not increased. the practical range of the current density is relatively nicotinic acid amide and ethoxylated «-naphthol- and it is impossible, nice coatings with sulfonic acid are added in order to obtain dense and glossy cranuhdites, especially in an area zende plating surfaces. You can get from 50 A / dm to 100 A / dm ² . can be used individually or in combination bo is, for example, an acidic galvanic zinc bath, «introduction creates fine crystals, making them smooth the zinc, ammonium, sulfate and chloride ions, get a shiny and nicely plated surface ethoxylated compound as well as an organic acid S. S ^ VnÄ 'I ^de i ^German Offenlegungs-An amount of 0.1 to 10 g / l nicotinic acid amide has been described in writing 1 521 029. Suitable for this bath. A concentration lower than 0.1 g / l is, however, not effective when using high current densities 50, while a consequence in excess of 10 g / l as a result of the formation of coarse coatings which is not yet freezing does not increase the desired advantage. n «r E,« „j„ i ^ jv ... "A suitable concentration of ethoxylated Λ-naphtha The underlying task is therefore that tholsulfonic acid is in the range from 0.01 g / l to 0.1 g / l an improved zinc electroplating bath at While a concentration of less than 0.01 g / i «Chaffs which the generation of denser and smooth 55 is not effective, leads to a concentration of more ! «Ttings in a wide range of than 0.1 g / l for the formation of pinholes in the plat- from 10 A / dm "to 100 A / dm ² eroded surfaces and opaque-plated surfaces , "" ..,. with an unfavorable appearance. _{7! Λω} , ^the ? ™ ^ηάυη & ^w " ^d em acidic electroplating becomes a plating bath of a composition 2ίHT ίκΤΓ ^{8 named Art} ™ Disposal 60 within the range of the limits described above S IL WHAT? ^a i - is marked ^{> that the κα} used and this bath violently during the sufot 0 hKS ϋΠ T H ⁰⁰ IiI- ⁶ V / ¹ ^ - P ' ^a ttierung _S stirred in operation, it is possible to be plated minLShWH ^? · 5, ^nk ? i? ^nd . · ^{10 bls} . ⁷ ° Zl ^{l Am} "surfaces with dense crystal structure at high ™ 7Ä? V? ^{IS 3} ° ^{8 /} J ^Na V ™ msuccinate and 0.1 current densities of 10 A / dm ² to 100 A / dm ² up to 10 g / 1 nicotinic acid amide and / or 0.01 to 0.1 g / l 65 hold ^at -nSat ^r ÄSl ^ H T ^ « ^{To the better understanding} * * <" Invention When zinc chloride is used as the source of the examples below, the preferred embodiment Ions used. In the case of a zinc sulphate concentration form, listed.