DE1496974A1 - Corrosion-resistant, decorative chrome coatings - Google Patents

Description

PATENTANWÄLTE 8902 augsburg-göggingen, the

* - .. "_ * · Eldiendorff-StraB · 10

dr.ing. E. LIEBAU ■ u "," z., *. "R ₅₉₇₀ ■ 'U96974

DIPL.ING. G. LtEBAU '"' Your sign Your message from

DIRECTED BY ITATIOIiALE DEP. USINES REiIAULT Billancourt (Seine) France

Corrosion-resistant, decorative chrome coatings.

So-called decorative chrome coatings are generally the last layers with a gap between them and over them an electrodeposited chrome coating.

For years, the _"view;. Prevalent that the Chror.-layer no contribution to the overall protection deliver only to improve the appearance of the treated parts contribute.

Meuer Recently the investigation of anomalies chrome corrosion resistance die admissions ^ / © idfcöQ _J »S has _f out _i ßhluß

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that the chroir layer, on the contrary, is an essential hell for the. Protection of the object plays that role though is not an increase in protection but, on the contrary, Reason to be more or less obvious depending on the circumstances Acceleration of corrosion. '

The physical state of the chromium layer is of the predominant Meaning »The" metal can be deposited in a dense layer be; i / egen of brittleness electrodeposited Chromium, however, reduces this tightness quite a bit quickly through the formation of cracks and pores. The chromium can also be tiny from the moment it is deposited Have pores and cracks in more or less large Amount per unit area, i.e. consequently as Elements that are more or less closely adjacent to one another;

It has been found that the chrome plating becomes all the faster Corrosion of the nickel leads, the lower the surface density of the pores or cracks, very numerous pores and Rather, cracks leave the corrosive speed of the nickel become very low. . *

Starting from these appearances are a number of methods has been specified to determine the overall behavior of the chrome-plated counter

SQ 9 8 51/14 2 2 _BATHROOM

149697A

to improve permanent corrosion effects. For example, the preparation is a chromium coating with ^T 'ikrorlssen (the cracks are in a mutual distance of a few hundredths millimeters) this purpose. This is achieved either by chrome plating in zv. ^? ei layers that require chrome thicknesses above ο.5 nikron or by chrome plating in a layer in chrome baths that is a little '' tight. Contain selenium, with micro-cracks occurring at a strength of around ο, 3.'jikron.

Another ^T! Ethod for the production of microporous chromium coatings provides (is executed in general as bright nickel) to the last nickel layer, a thin IJickelschicht of about 1 'Likron strength applied, comprising the inclusions of non-conductive particles. The chromium layer applied to this nickel layer is in turn porous because of the presence of these very small, non-conductive particles.

According to the invention, a chromium layer with oil cracks can be created produce in a technically extremely simple way. The procedure consists of putting on the metal, roughly on the nickel, which is usually the last protective layer before the chromium, a thin layer of a metal under conditions aufzubrinp; s where it is very tight and very

909851/1422

BATH ORIGINAL

is little ductile * Formed during the last Venhromen at the same time micro-cracks in this last metal layer vie In the chrome layer, and the object treated in this way has excellent corrosion resistance on «

The thinner the layer of this intermediate metal, which was deposited for the subsequent formation of cracks, the more advantageous it is if its electrochemical potential is between that of the underlying metal and that of the final chromium layer (in the state of superficial oxidation, which normally occurs after a few hours or a few days) "A thin layer should be understood to mean a thickness between fractions of a micron up to about J or 4 microns"

While various metals or alloys _$ are based on nickel or cobalt mainly used nen Kings *, so 1st but a Nickelschloht particularly well suited for ■ ι iiberäSttg, 4 cracking show solli provided · _f is that the potential of this layer something "noble? ^{11 is} than that of the previous layer. In addition, the layer must not have the final appearance of the chrome-plated object.} <·

affect · Γ '

In the following, non-limiting beings are used as the ancestor

9098517 U22

two methods are given * which allow a chrome coating with microcracks to be produced according to the principle of the invention. · * Those who are oily milk «those with the formation of microrissors? not

example 1

- Nickel plating as the main protective layer, e.g. glossy nickel plating,

- Wash,

- Deposition of cracked nickel in the following «it @ jt» Conditions:

.- Nickel acetate "anhydrous" 50 g / l to

for saturation loo g / l

• Nickel chloride, containing water, 100 g / l

up to saturation 375 g / l

.pH 2 to 6 6 to 5.5

. Current density 1 to 15 A / dm ² Io A / dm ²

§09851 / U22 ^{ßAD 0RfGIN} AL

. Duration 15 sec to 2 min 3o see

♦ Temperature below 35 ⁰ C 2o to 25 ° C

. Move in any way, for example with

Compressed air

- Wash

- Chrome plating,. "

- Wash,

- Dry*

Example 2

- Nickel plating as the main protective layer, e.g. bright nickel plating,

- Wash,

- Deposition of cracked nickel under the following conditions:

optimal . Nickel chloride, containing water, 100 g / l to

for saturation * loo g / l, ammonium acetate, anhydrous, 50 g / l to

for saturation loo g / l

.pH 2 to 6 5 to 5.5

. Current density 1 to 15 A / dm ² Io A / dm ²

. Duration 15 to 2 min. 3o

BAD OBiGlNAL

U96974

optimal

.Temperature below 35 ⁰ C 2o to 25 ⁰ C

. Move in any way, such as wit

Compressed air,

- Wash,

- Chrome plating,.

- Wash,

- Dry·

Be nickel or Ammoniumaoetftfc can be replaced by other compounds, "In general, can be added to one of the enumerated below links the nickel chloride: acetic acid, nickel acetate, gluconic, Hickelgluconat _e tartaric acid, Nickeltartrat, formic» nickel formate, lactic acid, Nlckellactat "citric _s Nickeleitrat, succinic acid, Nlckelsuceinat , the mixture of at least two of the compounds mentioned, ammonium acetate "

Baths that contain acetic acid, gluconic acid, formic acid and succinic acid in connection with their nickel salts and combined with nickel chloride, create chromium layers with micro-cores Ir, the entire range of current densities in which the shiny chrome layers are shiny. These baths are within the scope of the invention most suitable"

909851 / U22 bad o _RIQ , _NAt

. . ■ U96974

. -8- ■■ *

• -

But also the other acids or salts listed above , deliver very useful results if the shape of the Oegeft » . Estates flees AnIaE for «ti grotae St ^ mdlc ^ teuiiter differences there.

In this case it is possible to use the nickel chloride Replace nickel sulfamate or nickel fluorate, with the the latter substance is preferable

The bathrooms for cracked nickel plating when they deliver operated under the conditions as described above are, for deposition tents less than 2 minutes, a coating of a shine, which is then a chrome layer of to achieve excellent gloss.

In certain cases, however, it may still be necessary to considerably extend the period of exposure for the formation of a cracked patch. This is for example:

necessary if the to-be protected for deep recessed areas J have, as the layer thickness increases at these points slower zn as the projecting points} it can also happen that the installations becoming due to their design not reduce the duration for the formation of a crack \. Never allow for 2 minutes «i

: '■■ ^; ■ ■ ■: - - ■■ '". ■' - ■ ■ '- ■ · -. ■' -.» ■ -: *. \

One or more suitable brighteners can now be added to the baths

909851 / U22

BATH

'·' '. "H96..974

■ add. These Qlanzbliciner are said to have the potential of being cracked nascent nickel does not look noticeably stubborn, so that the electrochemical vision process as described above, is sustained * Outside of this, they should have the tendency to Crack formation in the strips, which then cause the crack formation In the upper ear it triggers, not diminishes.

Sulphonates, sulphonamides and sulphonimides can be used as brighteners aromatic compounds can be selected «Specifically, the sodium salt of o-benzoic acid sulfimide (saccharin) can be used in quantities between 0.5 and 3 g / l are added; the optimal one, by no means critical amount is l g / l,

Also provides a Zueatz Butin-2-DLCL-l _t 4 $ Mrtywe I ** "4 x 4) to baths for cracked expectant Niekelüberauge high-gloss coatings of this type any Stärk ·" The connection to the bath with about o, l to 3 g / l added

Other common substances with the same effect are the amine derivatives heterossyklisefeer 7trbinda «n such as a-amino-thiaiicle. Cobalt, as an additive to baths for cracked nickel layers, also enables a gloss improvement in the layer

are 1 to 3o g / l ₀

As further examples of nickel plating fider to achieve risk

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In the context of the invention, the following compositions and methods of operation were specified:

optimal

Niekelaeetat,

So g / l up to
Saturation loo g / l

Niekeleftlorid, water-containing loo g / l up to

Saturation 375 g / l

Butyne-2-di-i _t ii

Current density farmer
temperature

0.1 to 3 g / lo.2 g / l 2 to 6 2 to 5.5 I to 15 A / dm ² Io A / dm ² 15 8 «<5 to 5 min

below 35 C 2o to 25 "C Moving on any titmouse, for example with compressed air or by moving the cathodes «;.

Bath with the addition of 2-amino-thiazole

optimal

MMUMMWWKM

Nickel acetate, anhydrous 5o g / l up to

Saturation loo g / l

Nickel chloride, containing water loo g / l up to

Saturation 375 g / l

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BATH

U96974

optimal

5 to 100 mg / 1 Io

1 to 15 A / dm ² lo ^: A / dm ²

2-amino-thiazole current density

Temperature below 35 ° C 2o to 25 ⁰ C

Move in any way, such as with compressed air or through

Moving the cathodes.

Example 5

Bath with the addition of ,, Ifobajlt

Nickel acetate, anhydrous, wrapping chloride, containing water

Cobalt Chloric ^{1 pU}

Current density duration

5o g / 1 to
Saturation loo g / l loo g / l up to saturation 375 g / l if up to I2o g / l ¹ Io.g / l

2 to 6 5 to 5.5 1 to 15A / dm ² Io A / dm ^Z 15 see up to 5 min below 35 ° C 2o to 25 ° C

~ \:; ~ .- ;. en on any Nielse, for example, with compressed air or through

".-; e;: he ;. the xathodes *

909851 / U22 BAD ORIGINAL

With the help of the invention, a glassmaker can , the thickness of the gigantic Niokelschiefot is considerable. be increasedj that allows the use of the method In existing systems with little or no changes

In addition, this results in a simplified application if the electrolysis baths show the application of shiny, huge layers in a layer thickness exceeding a few microns * see below «Io to 2a Mikroiij enable» they can be used in place of the last protective layer of nickel eettsen »instead of wrestling them on this layer on sub«

Examples given as non-limiting examples of the invention are selenium; · ■

a) the sequence of layers, the usual proteins by deposition a copper or brass layer and above that a common one Klckelsclilcht arises »but with the latter the last-mentioned layer is replaced by the deposition of a cracked, dense, shiny layer of nickel or a Nickelellerrlerurrj

'.:.''. - '' iichti '. ·!: * & -U2 a ·: απ ι.ΐ ··.?; ■ -j'.ur.i ^: J * ebn ^ n ·· * - ,. /: * .'... ..-

■ - J

90 98.5 1 / U2: i

BATH ORIGINAL

-13-

- ■ the "Bl« Nickel * »or" Duplex "process eresed» whereby the usual glossy nickel layer is replaced by a dense, shiny, cracked nickel layer "

Diet «Sohichtsequence allows to combine the advantages that due to the duplex Verniokelung and the Verohromung with micro cracks are given | it is not necessary to send out look for a cracking nioktlichioht »which is nobler than the falling nickel layer underneath *

ErfindungsgemäB iIAT behold with bnetleofeer "baths for or HÄlbglertsvernickelung" where do the additives cause a certain Oberfläohenpniiivitat Künne ₉ eil "excellent Haftfettlftlceit the huge expectant NlckelObersugs @r? 6ie! To" if Mn before the alane- or Htl & il & fisifsiekel · coating entpiaiiviert "The J, £ can be carried out in the following way}

- sorgfältigaet flushing the grlftnsenden or Niokelniederechlags _r

Treatment in a "depassivating bath on the basis of alkali metals with the following" as the invention next ttlngehränkenoos example of specified oversight and under the following working conditions:

109851/1 * 22

• ORIGINAL BATHROOM

m-

Xtsrtatron ^{:. ::}

Sodium carbonate _r what, s # r free ^; StrosKlioht ©

g / l
.g / l

Room temperature 5 to ".Xp A / dm ²

Duration of the kattiodiscfoen. Treatment 2o to 3o see «

in front of the Blturätgon'ln. the bath; for the. of the risilg wevüenam Niekeliedersehlags »

a; ifanglich® Nickelscsu.isht stark.p & ssivi «rt is« canoe ain «« envious exposure of about S see duration of the catho precede ·

Although, all BSa®r for biting w @ rd # nöe ¥ trpißlcelungeiß not enjgfinallohet »against impurities ainÄ- as the Ills lichen Hlokelfeädar, one can, in order to keep sl @ in good @ m condition, filter period-iseh or continiierlöh or aach subject to other known cleaning processes like electro-lytic cleaning, like cathodes with low current density, dtr Heutrallsation or the? Filtration Clb © r activated carbon _{9 in} order to "remove *" disruptive organic substances, among other things

loeasi / 1422 '

ORIGINAL BATHROOM

It should be noted * that the cracked even if there is an additional damage, it will tear slowly * Therefore, waiting too long before the deposition of the cracked nickel and de? Chrcunsch looks great because in this case the! «solid © chrome layer leads to the the Hiss © already formed in the nickel, which corresponds to the desired \ Purpose runs counter to *

This waiting time changes depending on the production conditions the structure and the tension <of the lower nickel layer itself. As a clue can apply ».- that spontaneously occurring cracks in the. last nickel slab closes after about a quarter of an hour start over · ■

According to the method according to the invention, kBsisissi Mite © i? Ißae on . . all chrome-plated surfaces can be achieved with the help of conventional chrome-plating baths, which have sulfate, hydrogen fluoride and hydosilicate ions as catalysts.

It must be ensured that the use of. Chrome-plating special · ■■ -T ^ m, .'le only: ".eicriel contain selenium, or the addition of" ■ '. · ■ ■■ · ---: ■ -.r drl · -. ; .--. aer solution for -Me Zvii ^ chent & da \ it unlc ^ IJch. . -.-; ■ -. '■' ■ :. v. ,:> h no special. '/or'.V-.VK : ü.: - iei _r -: ie Aus--

90-9851 / 1 422 *

BATH ORIGINAL

Claims (1)

P. a; t. -e η .t .a H :. β, -ft,: r- tt, c .h .e ι Process for coating the surface of objects with a micro-cracked ear tube suction ; electrolytic: wegj. characterized * Juice "oils articles- before Vw Qhromn a 'elektroXirtisehen treatment' subject who-the" dtt ·. EUR -.Abseheiäung fölner metalllfichen 2wiSehensehieht ,. drives domestic weXeher look RIP t 'bl34enV' oils a Riftblldung in ^one of the? Ohwotmoälcht νψαν & ηα, ά $ & V®röhromungsVor- 2 * procedure naeb. Anspiiieb -1, Äi ^ esis eefcenneeiebn «t * -Ä.-die ..-" metaliisehe- Zwisebenecfoicbt: -ftUf one vorhtr herg4 »et # lit <en Metal looks - cut off @ aenw £ i »4 #" - ν. - 3. Procedure according to claim S _a die laife micro-crack versebaild.metallic intermediate layers generated by applying a cracked nickel layer will" --""""-. . h » Method according to one of claims 1, 2 and 3 _t thereby ge ~ BATH ORIGINAL H96374 «17- characterizes that the potential dee forms the intermediate layer The metal svisehsn that the intermediate layer is supported Metal and that of chrome «Xleger *, · 5. Method according to claim 2 or ^ characterized ₉ that the lower metal layer may be made of copper «■ * ...- .. .-; ■ -. ... ■ ■ '■ ■; /' . .. ';. Method according to claim 2 or 3 »" eedureh ^ ■ marked _tf the lower .HttBllsehiefct durub fesRatasingen will" .."._. . 7 "Seduce nasfe Anapruoh 1 or 4 ₀ by doing the dl" unt®y © Kntalleehioht 4ureh # in "B electrolytically produced and manufactured ₉ which is manufactured by Matfeverni? 3 "ferfahr en naeii k the electrolytic vision ~ ai · "Bi-Kiokel- ¹¹ « »or ■ stand, on thin sole .WB? Ä «» ässii follows Wf. «18 * '■:'. ■ '■ .. 9 »Method according to claim 5» - characterized in that. that smm manufacture the cracked nickel plating an electric. If t is used * which consists on the one hand of NlofetlchSorid, Hiokelsulfapfifc or Mi & kelfluoborat and on the other hand $ uav a single .or-a mixture of at least two of the following compounds? Acetic acid ₈ Hiökelacetatg Sluconic acid _t ~ nickel gluconate, tartaric acid _f nickel tartrate, formic acid ^ nickel formlate, malonic acid ,, Hiokeln & loiiatt Mllehs & ure »Nlckellaetet, -Citio» nensensftiire ₉ 'Nickel citrate ^ succinic acid, hickelsuccess Characterized gekennseiohnet ♦ Vesifahren claim 3§, siugs Hiektlüber-ordered dai ^ for producing the cracked becoming a Elek "trolyt ve'rwendet wlvu _s d @ r essentially of Nicikeiehlorid and AissEioniuBsacetat, -. . 3 s ^l h 9 -andlü _s st "that the sXeltteelftisöiie BaÄ _s" in the üem Swigsheasshisht hergestellt- viird, a gloss & vm Iferläiigejiss "d © s * B © iiaaslJja ^ * ssfiapei has ₈ - deswssd Ifeüge AE® gßwShZt s £ _g ad that he only. loß adf ä'in? öfco £ * s3.a3. wnd the Isi mxBÜbt * 12 «A method according to claim lo _ff characterized in that as the glass former one of the following compounds or a mixture of at least Awei the compounds wirdt used sulfonates, sulfonamides, aromatic sulfonimides * butyn-2-diol-i, 4 _# amine derivatives heterozykliseher compounds such as 2 -Amlno-Thiaaol, cobalt salts. 13 * Verfahi'ert according to any one of claims 7-12, characterized gekennjseicfinet, DAB umm _$ if the lower metal layer is a ölän ^ "· ^ or HälfcglaR Hiekeleeiraiöhfc, this VeraiekeXung dea before depositing the cracked w ^^ ^ u aBwä nickel layer of a depassivation is subject to * BATHROOM ORIGINAL S09851 / U22