CA1050470A - Process for coloring by electroplating an aluminium or aluminium alloy piece - Google Patents
Process for coloring by electroplating an aluminium or aluminium alloy pieceInfo
- Publication number
- CA1050470A CA1050470A CA193,185A CA193185A CA1050470A CA 1050470 A CA1050470 A CA 1050470A CA 193185 A CA193185 A CA 193185A CA 1050470 A CA1050470 A CA 1050470A
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- time
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- aluminium
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/20—Electrolytic after-treatment
- C25D11/22—Electrolytic after-treatment for colouring layers
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for coloring, by electroplating, an aluminium or aluminium alloy article previously subjected to anodic oxidation, in which co-deposition of at least one metal selected from the group consisting of nickel, cobalt, and cadmium with at least one auxiliary metal is carried out by stirring, applying an alternating voltage between said article and a counterelectrode immersed in a bath containing the salts of the metals; in the process the alternating voltage, for each period, has a zero value for at least a certain period of time, and the bath has a pH below or equal to 1.8 and contains at least a salt of the auxiliary metal selected from the group consisting of the copper and tin salts, the concentration of the auxiliary metal salt in the bath being lower than 2.5 g/l and the concentration in the bath of the salt selected from the Ni, Co and Cd salt being less than 200 g/l.
The present invention provides a process for coloring, by electroplating, an aluminium or aluminium alloy article previously subjected to anodic oxidation, in which co-deposition of at least one metal selected from the group consisting of nickel, cobalt, and cadmium with at least one auxiliary metal is carried out by stirring, applying an alternating voltage between said article and a counterelectrode immersed in a bath containing the salts of the metals; in the process the alternating voltage, for each period, has a zero value for at least a certain period of time, and the bath has a pH below or equal to 1.8 and contains at least a salt of the auxiliary metal selected from the group consisting of the copper and tin salts, the concentration of the auxiliary metal salt in the bath being lower than 2.5 g/l and the concentration in the bath of the salt selected from the Ni, Co and Cd salt being less than 200 g/l.
Description
16~50470 The present invention relates to a process ~r ~olo~i~g, by electroplating, aluminium ~r aluminium a]loy article~ whose surface has previously been subjected to anodic oxidation.
- The term "aluminium" as used herein means the metal and its alloys and "anodized aluminium" means any aluminium or aluminium alloy articles whose surface has been subjected to anodic oxidation.
Various processes are known ~or coloring, by electro-plating, aluminium, amongst which may be mentioned those involving the so-called "two phase" technique comprising formation of an aluminium oxide layer and then electrodeposition of coloured @
metallic compounds.
Norwegian patent No. 69,930, which discloses the "two-phase" technique, discloses in particular the use of an acid electroplating bath through which an alternating current is passed and which contains one or more salts selected from the ~
group Fe, Co, Ni, Mn and Cr salts and, in an amount less than C
10 g/l one or more soluble compounds selected fromthe group of t salts As, Sb, Bi, Se, Te and Sn soluble salts. Using a bath of this type, various bronze tones have been obtained on the surface of the aluminium articles when coloured compounds of metal such as Fe, Co, Ni or Mn were deposited in the pores of the oxide ~
layer. To carry out the co-deposition of the metals of the two .
groups, it was necessary to maintain the As, Sb, Bi, Se and Sn content below a certian limit, in order to maintain a current F
` density which can be used industrially. This process has various drawbacks. The current density, when the electroplating bath contains primarily nickel, must be as low as possible to avoid perforated discharges or a concentric spalling of the oxide layer, - 30 and the duration of the treatment must be increased, to obtain .
adequate coloring, thus decreasing the economical desirability of the process, and increasing the risk of disruptive discharges.
.
~, ' . ' ' ~0470 British Patent No. 1,022,927 discloses a process for coloring, by electroplating, aluminium in which an alternating current is passed between an aluminium article and a counter-electrode, particularly one made of retort carbon or gas carbon, carborundum or aluminium The electroplating bath contains a small amount of Ni, Co, Cr, Cd, V, Au, Ag, Fe or Pb salt.
As this process has the same drawbacks as those indicated previously, consideration was given to French patent 2,011,376 which discloses the application of an assymmetric alternating voltage between an anodized aluminium article and a counterelectrode immersed in a bath containing salts capable of coloring the aluminium oxide layer.
Further, to overcome the above drawbacks and to deposit tin on anodized aluminium, to obtain coloration, by the electro-plating of tin, French patent ~o. 2,047,917 discloses a process in which an acid bath containing tin salts and a tin complexing agent is used to avoid the oxidation of tin (II) to tin (IV).
An alternating current, which is applied across the aluminium article to be treated and a tin or titanium counterelectrode, is passed through said bath. The pH of the bath is preferably in the range of from 0.8 to 1.5 and the current density may vary from 0.2 to 1.0 A/dm , and it can even be above 1.0 ~/dm2. It is evident that only specific coloringsof the tin can be obtained by this process, i.e. bronze colours with greenish tints, which can extend to black. However, at present, the colourings required by the construction and architectural industries have warmer tones which cannot be obtained with the tin salt baths contemplated in French patent 2,047,917.
The present invention provides a process for producing ~0 on the surface of an anodized aluminium article, a bronze tone by the deposition of one or more metals selected from Ni, Co and Cd, so that:
.~, ' ~
~050470 a) said process does not have the aforesaid drawbacks;
b) the shade obtained is uniform and sufficiently dark; and c) the process is industrially economically desirable.
In accordance with the present invention, a solution which differs completely from those contemplated in French patents 2,011,376 and 2,047,917 has been found which overcomes the insufficiency of distributing the current in conventional electroplating baths, which insufficiency is mainly due to the reduced conductivity of said baths. To increase the heat conductivity of the electroplating bath, it is necessary to operate at a very low p~l~ However, this pH does not allow deposition of the metals of the group consisting of nickel, cobalt and cadmium. This group will hereinafter be referred to as the q:
"fundamental group". ~
~ It has surprisingly been found, to obtain the Ni, Co ~ ~;
- or Cd electropl~ating tones, one or more metals of the fundamentalgroup may be deposited at a pH below or equal to 1.8 in the presence of one or more auxiliary metals provided that a special type of alternating voltage is applied.
Thus, since when operating at a pH below or eaual to 1.8, it is not possible to deposit one or more metals of the fundamental group on the anodized aluminium, a co-deposition of I one or more metals of the fundamental group with one or more ~
nobler auxiliary metals should be effected and a portion of r the auxiliary metal or metals deposited on the aluminium oxide layer should be re-dissolved.
The main difficulty of this concept according to which penetration of the ion or ions of the metals of the fundamental group facilitated by the use of one or more auxiliary cations, is that the auxiliary cation is deposited with more ease than the fundamental cation andis preferentially deposited. Therefore, -- ` .
-, ., . . . ~ . . .
..
- ~.
use is made of the favourable action of the auxiliary cation to its utmost. Consequently, it is necessary to use conditions which tend to reduce the effect of the presence of said auxiliary cation in the ~inal deposition.
In practice, to overcome the difficulties posed by the use of an auxiliary metal salt under the relatively unfavourable deposition conditions of said auxiliary metal, it has been necessary to determine the precise operative conditions which permit the exact reproduction of the desired shades, so that:
a) the influence of the color corresponding to the auxiliary metal is as weak and uniform as possible, in the colour obtained; and b) a dissolving effect in ~he bath, due to the auxiliary metal which is deposited, is produced during deposition.
According to the present: invention therefore there is prcvided a process for coloring, by electroplating, an aluminium or aluminium alloy article which has previously been subjected to anodic oxidation, wherein co-deposition of at least one ~ metal selected from nickel, cobalt and cadmium with at least one -I 2~ auxiliary metal is carried out by stirring, applying an alternat-; ing voltage between said article and a counterelectrode immersed in a bath containing the salts of said metals, the , alternating voltage, for each period, having a zero value, at least for a certain period, the pH of the bath being below or equal to 1.8, the bath containing at least one auxiliary metal salt selected from copper or tin salts, and the concentration in the bath of the salt selected from Ni, Co and Cd being less than 200 g/l. The concentration of the auxiliary metal salt is always less then 2.5 g/l, so that its influence on the . 30 coloring obtained is minimum. The practical coloring effectobtained for auxiliary metal salt concentrations of about 10 g/l is that which corresponds to the auxiliary metal, ' ~ - 4 !. : . ~ ` : . ` :
105~)470 primarily that o~ tinr when this is used. It has been obser~ed that with this concentration, when a normal alternatin~ current and only the auxiliary metal cation are used and when the current ceases, the dissolving action of the bath on the deposit obtained is very important and the color obtained can disappear completely. This action is reduced when the concen-tration of the auxiliary metal used alone is higher. Therefore, this action is practically negligible when concentrations of about 10 g/l are used, Therefore, under the operating conditions, in the process of the present invention, the auxiliary metal salt concentrations used are as low as possible, in order to reduce as much as possible the ratio between the elements which are .~. l jointly deposited.
, Thus under these working conditions and to enhance the dissolving action of the bath on the auxiliary cation, it is necessary, once the deposition has started, to have periods of time durlng which current does not flow. Consequently, a normal alternating current is not suitable for this process. A
symmetric alternating voltage is preferably used for each period which has a zero value for a total duration corresponding '~ to hal,f a period. , 1, Suitable pH conditions are obtained by adding acids , which can act on the auxiliary cation, tending to remove it i~ :.
` ,after its deposition. Naturally, the removal or dissolving action of the acid on the auxiliary cation can be promoted by varying the temperature. Likewise, organic acids which favour the stability of the auxiliary cation, when this is necessary, ~ can be added to the bath. Should the auxiliary cation be tin, ,~ 30~ the aforesaid stability can be obtained by conventional means in tinplating deposition, that is by adding organic acids selected from phenols and sulfones mainly sulfophthalic, phenolsulfonic , ' . s '.` ~L9~,...
- lOS0470 and cresolsulfonic acids.
In a particular embodiment of the present invention the temperature of the bath is in the ranye from about 15 to about 25C, i.e. close to ambient temperature.
The alternating voltages are used with time int~rvals during which current does not flow. The accompanying drawings illustrate examples of usable voltages.
In the drawings;
Figure 1 illustrates a voltage which voltage is aiternating for a 0.5 N period and zero for a 0.5 N period, Figure 2 illustrates a voltage which is alternating for an N-period and zero for an N-period and Figure 3 illustrates a square wave voltage which voltage is uniform and positive for a O.S N period, zero for a 0.5 N
period uniform and ~egative for a 0.5 N period and zero for a 0.5 N period.
The voltages of Figures 1 and 2 are obtained according to the technique of controlled diodes, mainly for example by means of thyristors and triads. The square wave represented in Figure 3 is obtained by starting with a tri=phase alternating current, contrary to the conventional practice in the technique ~ of coloring/ by electroplating, which starts with monophasic -~' alternating currents. The use of this type of wave allows a 3 more effective action of the current to be obtained since the wave starts with a constant current value for each polarity.
Further, in practice, the use of triphasic transformers avoids, when their voltage is high, the unbalances between phases produced '~ when tri-monophasic transformers are used.
$: Copper and/or tin salts are the auxiliary metal salts.
, .
30 Under the aforesaid operative conditions neither of these cations ~
' ',J.'~'`' . ' , .: ', . ' . . ~ . . ' ' . , ' ', ' , ~05~470 give rise, independently, to a useful effect. Thus, when the auxiliary cation e.g. the tin cation, is used alone, a colour is produced, but the chemical action of the bath ten~s to remove it. If the nickel cation is used alone, no colour is produced.
` The requirement to operate at low pH values is determined by the need to obtain the highest possible conduct-ivity of the electrolyte, so that the predominant resistance, in the coloring process, is that of the aluminium oxide film.
Consequently, the process is such that deposition is auto-controlled by the resistance of said aluminium oxide film and deposition results in a perfect uniformity even in poorly accessible zones, thus eliminating the shade effect which is an undesirable feature in all galvanizing processes.
According to the process of the present invention, a darker and uniform coloration is obtained even on articles whose anodic film has discontinuities affecting the electrical '1 resistances, as in the case of casting articles, aluminium alloys containing copper, and aluminium alloys having a high silicon content. The importance of operating under pH
conditions below 1.8 is important because if a pH above 1.8 is , used the silicon content of the alloys used in architecture would have such an influence on the coloration that when the ~, silicon content is high, within permissible limits, various ~¦ difficulties appear if one is to obtain dark shades, since the aluminium alloys for use in architecture have, according ! to the diverse international norms, a silicon content of ~ approximately 0.2 to 0.6% in weight.
`~ Furthermore, better results are obtained with the ¦~ 30 process of the present invention than with classic methods of ., coloration by immersion, even with pieces having residues of ~ acids from anodic oxidation baths, as in the case of wedged or s~ :
( ~ , nailed pieces or faulty weldings.
It is desirable to stir the bath during the process of the present invention. ~,enerally, an inert counterelectrode, mainly graphite electrodes, is used. The duration of the treatment, which affects the ~inal result of the colorations and the properties cf the colora~ions, is at least 3 minutes, and is preferably from about 3 to about 30 minutes.
In a preferred embodiment of the present invention the process comprises depositing on the surface of a previously - 10 anodized aluminium article a fundamental metal with a nobler ; auxiliary metal, applying to a bath containing the salts of these metals, at a p~ of no more than 1.5 and a temperature of e about 15 to 25C a symmetric alternating voltage which, during each period, has a zero value for a total time corresponding to half a period, so that:
1) operation is carried out with a square wave voltage or 15 V for 2 minutes and then ., ~,
- The term "aluminium" as used herein means the metal and its alloys and "anodized aluminium" means any aluminium or aluminium alloy articles whose surface has been subjected to anodic oxidation.
Various processes are known ~or coloring, by electro-plating, aluminium, amongst which may be mentioned those involving the so-called "two phase" technique comprising formation of an aluminium oxide layer and then electrodeposition of coloured @
metallic compounds.
Norwegian patent No. 69,930, which discloses the "two-phase" technique, discloses in particular the use of an acid electroplating bath through which an alternating current is passed and which contains one or more salts selected from the ~
group Fe, Co, Ni, Mn and Cr salts and, in an amount less than C
10 g/l one or more soluble compounds selected fromthe group of t salts As, Sb, Bi, Se, Te and Sn soluble salts. Using a bath of this type, various bronze tones have been obtained on the surface of the aluminium articles when coloured compounds of metal such as Fe, Co, Ni or Mn were deposited in the pores of the oxide ~
layer. To carry out the co-deposition of the metals of the two .
groups, it was necessary to maintain the As, Sb, Bi, Se and Sn content below a certian limit, in order to maintain a current F
` density which can be used industrially. This process has various drawbacks. The current density, when the electroplating bath contains primarily nickel, must be as low as possible to avoid perforated discharges or a concentric spalling of the oxide layer, - 30 and the duration of the treatment must be increased, to obtain .
adequate coloring, thus decreasing the economical desirability of the process, and increasing the risk of disruptive discharges.
.
~, ' . ' ' ~0470 British Patent No. 1,022,927 discloses a process for coloring, by electroplating, aluminium in which an alternating current is passed between an aluminium article and a counter-electrode, particularly one made of retort carbon or gas carbon, carborundum or aluminium The electroplating bath contains a small amount of Ni, Co, Cr, Cd, V, Au, Ag, Fe or Pb salt.
As this process has the same drawbacks as those indicated previously, consideration was given to French patent 2,011,376 which discloses the application of an assymmetric alternating voltage between an anodized aluminium article and a counterelectrode immersed in a bath containing salts capable of coloring the aluminium oxide layer.
Further, to overcome the above drawbacks and to deposit tin on anodized aluminium, to obtain coloration, by the electro-plating of tin, French patent ~o. 2,047,917 discloses a process in which an acid bath containing tin salts and a tin complexing agent is used to avoid the oxidation of tin (II) to tin (IV).
An alternating current, which is applied across the aluminium article to be treated and a tin or titanium counterelectrode, is passed through said bath. The pH of the bath is preferably in the range of from 0.8 to 1.5 and the current density may vary from 0.2 to 1.0 A/dm , and it can even be above 1.0 ~/dm2. It is evident that only specific coloringsof the tin can be obtained by this process, i.e. bronze colours with greenish tints, which can extend to black. However, at present, the colourings required by the construction and architectural industries have warmer tones which cannot be obtained with the tin salt baths contemplated in French patent 2,047,917.
The present invention provides a process for producing ~0 on the surface of an anodized aluminium article, a bronze tone by the deposition of one or more metals selected from Ni, Co and Cd, so that:
.~, ' ~
~050470 a) said process does not have the aforesaid drawbacks;
b) the shade obtained is uniform and sufficiently dark; and c) the process is industrially economically desirable.
In accordance with the present invention, a solution which differs completely from those contemplated in French patents 2,011,376 and 2,047,917 has been found which overcomes the insufficiency of distributing the current in conventional electroplating baths, which insufficiency is mainly due to the reduced conductivity of said baths. To increase the heat conductivity of the electroplating bath, it is necessary to operate at a very low p~l~ However, this pH does not allow deposition of the metals of the group consisting of nickel, cobalt and cadmium. This group will hereinafter be referred to as the q:
"fundamental group". ~
~ It has surprisingly been found, to obtain the Ni, Co ~ ~;
- or Cd electropl~ating tones, one or more metals of the fundamentalgroup may be deposited at a pH below or equal to 1.8 in the presence of one or more auxiliary metals provided that a special type of alternating voltage is applied.
Thus, since when operating at a pH below or eaual to 1.8, it is not possible to deposit one or more metals of the fundamental group on the anodized aluminium, a co-deposition of I one or more metals of the fundamental group with one or more ~
nobler auxiliary metals should be effected and a portion of r the auxiliary metal or metals deposited on the aluminium oxide layer should be re-dissolved.
The main difficulty of this concept according to which penetration of the ion or ions of the metals of the fundamental group facilitated by the use of one or more auxiliary cations, is that the auxiliary cation is deposited with more ease than the fundamental cation andis preferentially deposited. Therefore, -- ` .
-, ., . . . ~ . . .
..
- ~.
use is made of the favourable action of the auxiliary cation to its utmost. Consequently, it is necessary to use conditions which tend to reduce the effect of the presence of said auxiliary cation in the ~inal deposition.
In practice, to overcome the difficulties posed by the use of an auxiliary metal salt under the relatively unfavourable deposition conditions of said auxiliary metal, it has been necessary to determine the precise operative conditions which permit the exact reproduction of the desired shades, so that:
a) the influence of the color corresponding to the auxiliary metal is as weak and uniform as possible, in the colour obtained; and b) a dissolving effect in ~he bath, due to the auxiliary metal which is deposited, is produced during deposition.
According to the present: invention therefore there is prcvided a process for coloring, by electroplating, an aluminium or aluminium alloy article which has previously been subjected to anodic oxidation, wherein co-deposition of at least one ~ metal selected from nickel, cobalt and cadmium with at least one -I 2~ auxiliary metal is carried out by stirring, applying an alternat-; ing voltage between said article and a counterelectrode immersed in a bath containing the salts of said metals, the , alternating voltage, for each period, having a zero value, at least for a certain period, the pH of the bath being below or equal to 1.8, the bath containing at least one auxiliary metal salt selected from copper or tin salts, and the concentration in the bath of the salt selected from Ni, Co and Cd being less than 200 g/l. The concentration of the auxiliary metal salt is always less then 2.5 g/l, so that its influence on the . 30 coloring obtained is minimum. The practical coloring effectobtained for auxiliary metal salt concentrations of about 10 g/l is that which corresponds to the auxiliary metal, ' ~ - 4 !. : . ~ ` : . ` :
105~)470 primarily that o~ tinr when this is used. It has been obser~ed that with this concentration, when a normal alternatin~ current and only the auxiliary metal cation are used and when the current ceases, the dissolving action of the bath on the deposit obtained is very important and the color obtained can disappear completely. This action is reduced when the concen-tration of the auxiliary metal used alone is higher. Therefore, this action is practically negligible when concentrations of about 10 g/l are used, Therefore, under the operating conditions, in the process of the present invention, the auxiliary metal salt concentrations used are as low as possible, in order to reduce as much as possible the ratio between the elements which are .~. l jointly deposited.
, Thus under these working conditions and to enhance the dissolving action of the bath on the auxiliary cation, it is necessary, once the deposition has started, to have periods of time durlng which current does not flow. Consequently, a normal alternating current is not suitable for this process. A
symmetric alternating voltage is preferably used for each period which has a zero value for a total duration corresponding '~ to hal,f a period. , 1, Suitable pH conditions are obtained by adding acids , which can act on the auxiliary cation, tending to remove it i~ :.
` ,after its deposition. Naturally, the removal or dissolving action of the acid on the auxiliary cation can be promoted by varying the temperature. Likewise, organic acids which favour the stability of the auxiliary cation, when this is necessary, ~ can be added to the bath. Should the auxiliary cation be tin, ,~ 30~ the aforesaid stability can be obtained by conventional means in tinplating deposition, that is by adding organic acids selected from phenols and sulfones mainly sulfophthalic, phenolsulfonic , ' . s '.` ~L9~,...
- lOS0470 and cresolsulfonic acids.
In a particular embodiment of the present invention the temperature of the bath is in the ranye from about 15 to about 25C, i.e. close to ambient temperature.
The alternating voltages are used with time int~rvals during which current does not flow. The accompanying drawings illustrate examples of usable voltages.
In the drawings;
Figure 1 illustrates a voltage which voltage is aiternating for a 0.5 N period and zero for a 0.5 N period, Figure 2 illustrates a voltage which is alternating for an N-period and zero for an N-period and Figure 3 illustrates a square wave voltage which voltage is uniform and positive for a O.S N period, zero for a 0.5 N
period uniform and ~egative for a 0.5 N period and zero for a 0.5 N period.
The voltages of Figures 1 and 2 are obtained according to the technique of controlled diodes, mainly for example by means of thyristors and triads. The square wave represented in Figure 3 is obtained by starting with a tri=phase alternating current, contrary to the conventional practice in the technique ~ of coloring/ by electroplating, which starts with monophasic -~' alternating currents. The use of this type of wave allows a 3 more effective action of the current to be obtained since the wave starts with a constant current value for each polarity.
Further, in practice, the use of triphasic transformers avoids, when their voltage is high, the unbalances between phases produced '~ when tri-monophasic transformers are used.
$: Copper and/or tin salts are the auxiliary metal salts.
, .
30 Under the aforesaid operative conditions neither of these cations ~
' ',J.'~'`' . ' , .: ', . ' . . ~ . . ' ' . , ' ', ' , ~05~470 give rise, independently, to a useful effect. Thus, when the auxiliary cation e.g. the tin cation, is used alone, a colour is produced, but the chemical action of the bath ten~s to remove it. If the nickel cation is used alone, no colour is produced.
` The requirement to operate at low pH values is determined by the need to obtain the highest possible conduct-ivity of the electrolyte, so that the predominant resistance, in the coloring process, is that of the aluminium oxide film.
Consequently, the process is such that deposition is auto-controlled by the resistance of said aluminium oxide film and deposition results in a perfect uniformity even in poorly accessible zones, thus eliminating the shade effect which is an undesirable feature in all galvanizing processes.
According to the process of the present invention, a darker and uniform coloration is obtained even on articles whose anodic film has discontinuities affecting the electrical '1 resistances, as in the case of casting articles, aluminium alloys containing copper, and aluminium alloys having a high silicon content. The importance of operating under pH
conditions below 1.8 is important because if a pH above 1.8 is , used the silicon content of the alloys used in architecture would have such an influence on the coloration that when the ~, silicon content is high, within permissible limits, various ~¦ difficulties appear if one is to obtain dark shades, since the aluminium alloys for use in architecture have, according ! to the diverse international norms, a silicon content of ~ approximately 0.2 to 0.6% in weight.
`~ Furthermore, better results are obtained with the ¦~ 30 process of the present invention than with classic methods of ., coloration by immersion, even with pieces having residues of ~ acids from anodic oxidation baths, as in the case of wedged or s~ :
( ~ , nailed pieces or faulty weldings.
It is desirable to stir the bath during the process of the present invention. ~,enerally, an inert counterelectrode, mainly graphite electrodes, is used. The duration of the treatment, which affects the ~inal result of the colorations and the properties cf the colora~ions, is at least 3 minutes, and is preferably from about 3 to about 30 minutes.
In a preferred embodiment of the present invention the process comprises depositing on the surface of a previously - 10 anodized aluminium article a fundamental metal with a nobler ; auxiliary metal, applying to a bath containing the salts of these metals, at a p~ of no more than 1.5 and a temperature of e about 15 to 25C a symmetric alternating voltage which, during each period, has a zero value for a total time corresponding to half a period, so that:
1) operation is carried out with a square wave voltage or 15 V for 2 minutes and then ., ~,
2) operation is carried out with a square wave voltage of 18 V for 5 to 25 minutes.
The process of the present invention also allows the simultaneous treatment of articles having different shapes ~-and sizes, precisely due to the ease with which penetration is obtained. This applies to soldered frames, to profiles having different shapes and lengths, open and closed.
The-present invention will be further illustrated by way of the following Examples.
Coloration, by electroplating, of an aluminium plate ' previously subjected to anodic oxidation i5 carried out by i 30 àpplying to the terminals of the bath an alternating voltage, ~.
according to Figure l! wherein each half-period of a pure alternating current is followed by a half~period of zero current.
.
, lOSQ470 The electroplating bath has the following composition and criteria:
NiSO4 150 g/l SnSO4 2 g/l o-Phenosulfonic acid 1 g/l H2SO4 in a sufficient amount for a pH of 1.5 Ambient temperature 15-25C
A root mean square voltage of 15 V, according to Figure 1,¦
is applied for 2 minutes followed by a root mean square voltage of 18 V, always according to Figure 1, for 5 minutes. A uniform bluish-bronze tone differing from the greenish-bronze solely due to the tin is obtained.
:, . .
Coloration, by electroplating, of an aluminium plate previously subjected to anodic oxidation is carried out by applying to the terminals of the bath a voltage, according to Figure 2, which is an alternating wave voltage, wherein each one of the periods is followed by a break having a duration corresponding to said period of the wave voltage. The bath has the following composition and criteria:
,~ CoSO4 160 g/l SnSO4 2 g/l 4-(o-cresol) sulfonic acid 2 g/l H2SO4 in a sufficient amount for a pH of 1.4 Ambient temperature 15-25C
Following the procedure of Example 1, a root mean square voltage of 15 V is applied for 2 minutes followed by a root mean square voltage of 18 V for 5 minutes A uniform bronze tone differing from the greenish bronze due solely to tin, is obtained.
: .
~::
'''''' .
,.-~g _ . ..
_ . .. ..
-~
1051)470 - EX ~ PLE 3 Coloration, by electroplating, of an aluminium plate is carried out using a bath identical to that represented in ; Example 1. The alternating voltage used is that of Figure 3 (direct current which has, with respect to an alternating current which starts with an N period of time, a positive value for a 0.5 N period of time, a break which lasts for 0.5 N of time, a negative value for a 0.5 N period of time and a break which lasts for 0. 5 N of time).
A root mean square voltage of 15 V is applied for 2 ,~
minutes which is converted within 2 minutes to a root mean ,;
square voltage of 18 V, this latter being maintained for 20 to 25 minutes. A blackish-bronze tone is obtained, I
:~ . . I ' .1~ ' . .
.j . .
,~ ~ ,.,~: ' .. " , ' `.
:~ ~ ' .
~ ~ 20 ~ -~ ~`30~
~ ' 10- ' ' t ~
The process of the present invention also allows the simultaneous treatment of articles having different shapes ~-and sizes, precisely due to the ease with which penetration is obtained. This applies to soldered frames, to profiles having different shapes and lengths, open and closed.
The-present invention will be further illustrated by way of the following Examples.
Coloration, by electroplating, of an aluminium plate ' previously subjected to anodic oxidation i5 carried out by i 30 àpplying to the terminals of the bath an alternating voltage, ~.
according to Figure l! wherein each half-period of a pure alternating current is followed by a half~period of zero current.
.
, lOSQ470 The electroplating bath has the following composition and criteria:
NiSO4 150 g/l SnSO4 2 g/l o-Phenosulfonic acid 1 g/l H2SO4 in a sufficient amount for a pH of 1.5 Ambient temperature 15-25C
A root mean square voltage of 15 V, according to Figure 1,¦
is applied for 2 minutes followed by a root mean square voltage of 18 V, always according to Figure 1, for 5 minutes. A uniform bluish-bronze tone differing from the greenish-bronze solely due to the tin is obtained.
:, . .
Coloration, by electroplating, of an aluminium plate previously subjected to anodic oxidation is carried out by applying to the terminals of the bath a voltage, according to Figure 2, which is an alternating wave voltage, wherein each one of the periods is followed by a break having a duration corresponding to said period of the wave voltage. The bath has the following composition and criteria:
,~ CoSO4 160 g/l SnSO4 2 g/l 4-(o-cresol) sulfonic acid 2 g/l H2SO4 in a sufficient amount for a pH of 1.4 Ambient temperature 15-25C
Following the procedure of Example 1, a root mean square voltage of 15 V is applied for 2 minutes followed by a root mean square voltage of 18 V for 5 minutes A uniform bronze tone differing from the greenish bronze due solely to tin, is obtained.
: .
~::
'''''' .
,.-~g _ . ..
_ . .. ..
-~
1051)470 - EX ~ PLE 3 Coloration, by electroplating, of an aluminium plate is carried out using a bath identical to that represented in ; Example 1. The alternating voltage used is that of Figure 3 (direct current which has, with respect to an alternating current which starts with an N period of time, a positive value for a 0.5 N period of time, a break which lasts for 0.5 N of time, a negative value for a 0.5 N period of time and a break which lasts for 0. 5 N of time).
A root mean square voltage of 15 V is applied for 2 ,~
minutes which is converted within 2 minutes to a root mean ,;
square voltage of 18 V, this latter being maintained for 20 to 25 minutes. A blackish-bronze tone is obtained, I
:~ . . I ' .1~ ' . .
.j . .
,~ ~ ,.,~: ' .. " , ' `.
:~ ~ ' .
~ ~ 20 ~ -~ ~`30~
~ ' 10- ' ' t ~
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for coloring, by electroplating, an aluminium or aluminium alloy article previously subjected to anodic oxidation, in which co-deposition of at least one metal selected from the group consisting of nickel, cobalt, and cadmium with at least one auxiliary metal is carried out by stirring, applying an alternating voltage between said article and a counter-electrode immersed in a bath containing the salts of said metals, the alternating voltage, for each period, having a zero value for at least a certain period of time, the bath having a pH below or equal to 1.8 and containing a salt of the auxiliary metal selected from the group consisting of the copper and tin salts, the concentration of the auxiliary metal salt in the bath being lower than 2.5 g/l and the concentration in the bath of the salt selected from the Ni, Co and Cd salt being less than 200 g/1.
2. A process according to claim 1, in which the alternating current is symmetric and, during each period, has a zero value for a total time corresponding to half a period.
3. A process according to claim 1, in which the temperature of the bath is from about 15 to about 25°C.
4. A process according to claim 2, in which the voltage, with respect to an alterating wave voltage of a period of time N is alternating for a period of time 0.5 N and zero for a period of time 0.5 N.
5. A process according to claim 2, in which the voltage, with respect to an alternating wave voltage of a period of time N is alternating for a period of time N and zero for a period of time N.
6. A process according to claim 2, in which the voltage, with respect to an alternating wave voltage of a period of time N, is uniform and positive for a period of time 0.5 N, zero for a period of time 0.5 N, uniform and negative for a period of time 0.5 N and zero for a period of time 0.5 N.
7. A process according to claim 1, in which the duration of the treatment is at least 3 minutes.
8. A process according to claim 7, in which a square wave voltage of 15 V is applied for 2 minutes followed by a square wave voltage of 18 V for 5 to 25 minutes.
9. A process according to claim 8, in which the voltage is passed from 15 to 18 V in 2 minutes.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ES411895A ES411895A1 (en) | 1973-02-21 | 1973-02-21 | Process for colouring by electro-deposition an anodized aluminium or aluminium alloy article |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050470A true CA1050470A (en) | 1979-03-13 |
Family
ID=8463501
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA193,185A Expired CA1050470A (en) | 1973-02-21 | 1974-02-21 | Process for coloring by electroplating an aluminium or aluminium alloy piece |
Country Status (16)
| Country | Link |
|---|---|
| JP (1) | JPS5438983B2 (en) |
| AT (1) | AT328818B (en) |
| BE (1) | BE810682A (en) |
| BR (1) | BR7401314D0 (en) |
| CA (1) | CA1050470A (en) |
| CH (1) | CH606508A5 (en) |
| DE (1) | DE2407860C3 (en) |
| ES (1) | ES411895A1 (en) |
| FR (1) | FR2218405A1 (en) |
| GB (1) | GB1406591A (en) |
| IT (1) | IT1011524B (en) |
| LU (1) | LU69324A1 (en) |
| NL (1) | NL7402384A (en) |
| NO (1) | NO134664C (en) |
| SE (1) | SE407085B (en) |
| ZA (1) | ZA741048B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2110372B1 (en) * | 1996-08-02 | 1999-06-16 | Rodriguez Martinez Dionisio | ELECTROLYTIC PROCEDURE FOR THE COLORING OF THE ANODIZED ALUMINUM, THROUGH THE MODIFICATION AND CONTROL OF THE TRANSMISSION COLOR OF THE ANODIC FILM. |
| PL241203B1 (en) * | 2020-07-29 | 2022-08-22 | Canpack Spolka Akcyjna | Method of producing an interference coating |
-
1973
- 1973-02-21 ES ES411895A patent/ES411895A1/en not_active Expired
-
1974
- 1974-02-04 NO NO740352*[A patent/NO134664C/no unknown
- 1974-02-05 LU LU69324A patent/LU69324A1/xx unknown
- 1974-02-06 BE BE140613A patent/BE810682A/en not_active IP Right Cessation
- 1974-02-07 GB GB570774A patent/GB1406591A/en not_active Expired
- 1974-02-07 SE SE7401636A patent/SE407085B/en not_active IP Right Cessation
- 1974-02-08 CH CH180674A patent/CH606508A5/xx not_active IP Right Cessation
- 1974-02-15 ZA ZA00741048A patent/ZA741048B/en unknown
- 1974-02-18 AT AT126274A patent/AT328818B/en not_active IP Right Cessation
- 1974-02-19 DE DE2407860A patent/DE2407860C3/en not_active Expired
- 1974-02-21 CA CA193,185A patent/CA1050470A/en not_active Expired
- 1974-02-21 JP JP2099274A patent/JPS5438983B2/ja not_active Expired
- 1974-02-21 BR BR1314/74A patent/BR7401314D0/en unknown
- 1974-02-21 NL NL7402384A patent/NL7402384A/xx not_active Application Discontinuation
- 1974-02-21 FR FR7406020A patent/FR2218405A1/fr not_active Withdrawn
- 1974-03-06 IT IT67515/74A patent/IT1011524B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| LU69324A1 (en) | 1974-05-29 |
| FR2218405A1 (en) | 1974-09-13 |
| DE2407860C3 (en) | 1979-04-12 |
| AT328818B (en) | 1976-04-12 |
| NL7402384A (en) | 1974-08-23 |
| BR7401314D0 (en) | 1974-11-05 |
| NO134664B (en) | 1976-08-16 |
| JPS5024126A (en) | 1975-03-15 |
| NO134664C (en) | 1976-11-24 |
| IT1011524B (en) | 1977-02-10 |
| DE2407860B2 (en) | 1978-07-13 |
| ES411895A1 (en) | 1976-01-01 |
| BE810682A (en) | 1974-05-29 |
| ATA126274A (en) | 1975-06-15 |
| GB1406591A (en) | 1975-09-17 |
| DE2407860A1 (en) | 1974-08-22 |
| SE407085B (en) | 1979-03-12 |
| ZA741048B (en) | 1975-06-25 |
| AU6554774A (en) | 1975-08-14 |
| JPS5438983B2 (en) | 1979-11-24 |
| CH606508A5 (en) | 1978-10-31 |
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