GB2158100A - Chromium electroplating bath - Google Patents
Chromium electroplating bath Download PDFInfo
- Publication number
- GB2158100A GB2158100A GB08510979A GB8510979A GB2158100A GB 2158100 A GB2158100 A GB 2158100A GB 08510979 A GB08510979 A GB 08510979A GB 8510979 A GB8510979 A GB 8510979A GB 2158100 A GB2158100 A GB 2158100A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bath composition
- cro3
- bromate
- perchlorate
- kalm2
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 26
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 26
- 239000011651 chromium Substances 0.000 title claims abstract description 26
- 238000009713 electroplating Methods 0.000 title claims abstract description 10
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000203 mixture Substances 0.000 claims abstract description 33
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 claims abstract description 16
- SXDBWCPKPHAZSM-UHFFFAOYSA-M bromate Inorganic materials [O-]Br(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-M 0.000 claims abstract description 14
- SXDBWCPKPHAZSM-UHFFFAOYSA-N bromic acid Chemical compound OBr(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-N 0.000 claims abstract description 14
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims abstract description 13
- ICIWUVCWSCSTAQ-UHFFFAOYSA-M iodate Chemical compound [O-]I(=O)=O ICIWUVCWSCSTAQ-UHFFFAOYSA-M 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 10
- 239000000758 substrate Substances 0.000 claims description 9
- 101000869523 Homo sapiens Phosphatidylinositide phosphatase SAC2 Proteins 0.000 claims description 6
- 102100032287 Phosphatidylinositide phosphatase SAC2 Human genes 0.000 claims description 6
- 150000001768 cations Chemical class 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 5
- 125000002084 dioxo-lambda(5)-bromanyloxy group Chemical group *OBr(=O)=O 0.000 claims description 5
- 229910021653 sulphate ion Inorganic materials 0.000 claims description 5
- 241000272168 Laridae Species 0.000 claims description 3
- 229910052783 alkali metal Inorganic materials 0.000 claims description 3
- -1 alkali metal cations Chemical class 0.000 claims description 3
- 229910001914 chlorine tetroxide Inorganic materials 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 abstract description 4
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 abstract description 4
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 abstract description 4
- 235000011149 sulphuric acid Nutrition 0.000 abstract description 4
- 239000001117 sulphuric acid Substances 0.000 abstract description 3
- 238000007747 plating Methods 0.000 description 12
- 239000000243 solution Substances 0.000 description 11
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 235000019396 potassium bromate Nutrition 0.000 description 4
- 230000001464 adherent effect Effects 0.000 description 3
- AXZAYXJCENRGIM-UHFFFAOYSA-J dipotassium;tetrabromoplatinum(2-) Chemical compound [K+].[K+].[Br-].[Br-].[Br-].[Br-].[Pt+2] AXZAYXJCENRGIM-UHFFFAOYSA-J 0.000 description 3
- 229910001487 potassium perchlorate Inorganic materials 0.000 description 3
- XWNSFEAWWGGSKJ-UHFFFAOYSA-N 4-acetyl-4-methylheptanedinitrile Chemical compound N#CCCC(C)(C(=O)C)CCC#N XWNSFEAWWGGSKJ-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000004153 Potassium bromate Substances 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 230000012010 growth Effects 0.000 description 2
- 229940094037 potassium bromate Drugs 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 206010000496 acne Diseases 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005363 electrowinning Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229940104869 fluorosilicate Drugs 0.000 description 1
- 229910021397 glassy carbon Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- JLKDVMWYMMLWTI-UHFFFAOYSA-M potassium iodate Chemical compound [K+].[O-]I(=O)=O JLKDVMWYMMLWTI-UHFFFAOYSA-M 0.000 description 1
- 239000001230 potassium iodate Substances 0.000 description 1
- 229940093930 potassium iodate Drugs 0.000 description 1
- 235000006666 potassium iodate Nutrition 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/04—Electroplating: Baths therefor from solutions of chromium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Abstract
To a conventional chromium electroplating bath containing chromic acid CrO3 and sulphuric acid H2SO4 are added a perchlorate or bromate or iodate or mixtures thereof. Higher current densities may be used in electrodepositing chromium without impairing the quality.
Description
SPECIFICATION
Chromium electroplating
This invention relates to a bath composition for chromium electroplating and to a method of electrodepositing chromium using such a bath composition.
For electroplating chromium onto a substrate (as opposed to electrowinning chromium), aqueous solutions of chromic acid CrO3 are usually used, together with a catalyyst anion, usually 1% sulphate, although fluoride and fluorosilicate are also used as catalysts. Perhaps the most useful addition is that of the complex fluoride ion, since the current efficiency of the chromium plating process is improved, and therefore the deposition rate is raised. Furthermore, the deposit produced has a higher hardness, and a higher crack density. Operational disadvantages of fluoride-containing baths are that they are particularly sensitive to changes in bath composition and electrolyte contamination (chiefly iron).The aggressive nature of the electrolyte can cause severe corrosion both to the anode and cathode areas where the current density is very low, and to the materials used in the vat construction. Moreover, since the analytical control of the fluoride content is relatively complicated, these solutions tend to be limited in their application, despite their advantages. Nonetheless these additions may be used in conjuction with the present invention.
Current densities at the cathode are usually limited to about 30 A/dm2 (= 3 kA/m2) to avoid 'treeing' at the cathode edges, that is, uncontrolled spiky growths at points of high field gradient.
According to the present invention, a bath composition for chromium electroplating comprises CrO3 in a concentration of from 200 g/l to 600 g/l such as 450 gull, sulphate in a weight ratio S04:CrO3 of from 1:120 to 1 :80, perchlorate in a weight ratio ClO4:CrO3 of from 1:500 to 1:50, preferably 1:200 to 1:80, and metal cations (e.g. alkali metal cations) equivalent to at least substantially half, preferably all, the perchlorate. The bath composition may further comprise bromate or iodate or a mixture thereof in a weight ratio (BrO3/lO3):CrO3 of from 1:20 to 1 :50.
Also according to the present invention, a bath composition for chromium electroplating comprises CrO3 in a concentration of from 200 g/l to 600 g/l such as 450 gull, sulphate in a weight ratio S04:CrO3 of from 1:120 to 1 :80, bromate or iodate in a weight ratio (BrO3 or 103) :CrO3 of from 1:20 to 1:600, preferably from 1:25 to 1:150, and metal cations (e.g. alkali metal cations) equivalent to at least half, preferably substantially all, the bromate or iodate. Bromate and iodate may be mixed within these limits.
Preferably the bath is compounded and then electrolysed before use.
The invention also provides a method of electrodepositing chromium onto a conductive substrate, comprising applying a cathodic potential to the substrate in a bath composition as set forth above, preferably at a current density on the cathode of from 4 to 12 kA/m2 for perchlorate by itself, from 1 1 to 4 kA/m2 for iodate by itself, from 10 to 50 kAlm2 for bromate by itself, and from 15 to 50 kAlm2 for bromate/perchlorate mixtures, preferably at a temperature of from 45"C to 65"C.
Perchlorate and iodate are regarded as non-consumable additives while bromate due to its volatility should be replenished during operation especially if the temperature is allowed to rise.
The invention will now be described by way of example.
A solution was made up containing 450 gll chromic acid CrO3 and 4.5 gll H2S04 sulphuric acid. This is known throughout the specification as SA, and is not according to the invention.
To three samples of a chromic acid/sulphuric acid mixture, solutions of potassium perchlorate KC104 in warm de-ionised water were added to make solutions identical to SA but additionally containing 2 gll, 5 g/l and 10 gIl potassium perchlorate; these solutions were stirred and electrolysed for 1 Ash/1 before use for plating out impurities such as nitrate, as is common practice. These solutions are known respectively as
SAC2, SACS, and SAC10, and are according to the invention.
To two samples of SACS, potassium bromate KBrO3 was added in amounts of 5 9/l and 20 gll, the resulting solutions being known as SAC5B5 and SAC5B20 respectiveiy, and being according to the invention. These, too, were made by dissolving the potassium bromate in warm de-ionised water and adding this to the components for making SACS, making up to the required concentrations as necessary, then stirring and electrolysing before use.
By corresponding techniques, solutions SABS, SAB20, SA15 and SAl20 were made up, containing 450 gll Crow, 4.5 g/l H2S04 and, respectively, 5 gIl KBrO3, 20 g/l KBrO3,5 g/l potassium iodate Kilo3 and 20 gli Kilo3.
All these solutions, when used as chromium electrodepositing baths, were heid at 55"C. The cathode in these experiments was always 18/8 stainless steel and the anode (of twice the cathode area) was of lead. All these solutions would plate successfully also onto other cathodes such as of copper, chromium and vitreous carbon.
EXAMPLE SA
The behaviour of SA is now described as a basis of comparison.
At a current density of 2 kAlm2, a chromium deposit whether grown to 5 microns thickness or to 25 microns thickness was dullgreyish matt with a smooth texture masking any minor surface irregularities on the cathode. Such a deposit is normally regarded as characteristic of too low a current density or too high a bath temperature. Hardness, at 700 to 850 HV, was nonetheless reasonable (800 to 900 being considered adequate for most engineering purposes).
At 5 kAlm2, a chromium deposit grown to 6 orto 25 microns is nodular, bright, mirror-like and smooth to the touch. Pimples may be seen by the naked eye, and are outgrowths from nodules, perhaps 50 microns, with flaky structures. Hardness was 900 to 1050 HV.
At 71/2 kAIm2, the whole surface is covered with these outgrowths and hence (when grown to 6 microns) appears bright-matt and smooth, and when grown to 25 microns visually frosty with a rough surface texture.
At 10 kAlm2, this frosty appearance arises even for 6-micron deposits, and at 20 kA/m2 the appearance is milky-white with a rough surface texture.
The current efficiencies in this range of current densities were as follows for chromium plating to 6 microns and to 25 microns.
(The results at 6 microns are less affected by the nodular outgrowths than are the 25-micron results.)
Current density (kAlm2) 2 4 5 71/2 10
Current efficiency 6(,%) 8 11 11 13 15
25 10 10 10 19 22
EXAMPLE SA C2
The behaviour of bath composition SAC2 (i.e. including 2 g/l of potassium perchlorate) under the same conditions was as follows:
At 2 kA/m2, the results were the same as in Example SA.
At 5kAlm2, and also at 6 kA/m2, a chromium deposit whether grown to 6 or to 25 microns is smooth, bright and shiny, and at 25 microns is nodular with occasional cracks. (Cracks of appropriate size and distribution in chromium plating can be positively beneficial.) There are no large outgrowths from the nodules. Hardness was about 900 HV.
At 71/2 kAlm2, the results are similar to Example SA 5 kA/m2 but rough to the touch.
At 10 kAlm2, the results are similar to Example SA71/2 kA/m2.
Current efficiencies for 6-micron plating were:
Current density (kAlm2j 2 4 71/2 10
Current efficiency (,%) 7 10 12 17
Current efficiencies for 25-micron plating were similar except for being 2% better at the top two current densities.
EXAMPLE SA C5
The behaviour of bath composition SACS under the same conditions are as follows:
At 2 kAlm2, the results were the same as in Example SA.
At 5 kA/m2, at 71/2 kA/m2 and also at 10 kA/m2, a chromium deposit grown to 6 microns is bright, shiny, smooth and crack-free, and grown to 25 microns is bright and mirror-like, and is smooth. At 10 kAlm2, there are some few cracks. Hardness at 5 kA/m2 was about 970 HV and at 10 kA/m2 was 1050 to 1100 HV.
At 121/2 kA/m2, 15 kAlm2 and 20 kA/m2 respectively, the surfaces are pimpled, somewhat flaky and totally flaky; they are all dull-matt and rough.
Current efficiencies for 6-micron plating were:
Current density (kA/m2) 2 5 71/2 10 121/2 15 20
Current efficiency (,%) 6 10 12 13 14 15 16
Current efficiiencies for 25-micron plating were identical except at 15 kAlm2 (23%) and 20 kA/m2 (24%).
EXAMPLE SA Clo The behaviour of bath composition SAC10 under the same conditions was as follows:
At 2 kAlm2, the results were the same as in Example SA.
At 5 kAlm2 and also at 10 kAlm2, a chromium deposit grown to 6 or to 25 microns is visually bright and mirror-like and is smooth to the touch. Hardness at 5 kAlm2 was about 960 HV and at 10 kAXm2 was 1100 to 1200 HV.
At 121/2 kAlm2,the results are unacceptable and somewhat similar to those of SA at 2 kAIm2. At all current densities higher than 121/2 kAlm2, the chromium deposits are at best dull-matt and have rough surface textures.
Current efficiencies for 6-micron plating were:
Current density (kAlm2) 2 5 71/2 10 121/2 15 171/2 20
Current efficiency (,%) 7 10 12 13 13 12 12 12
Cuurrent efficiencies for 25-micron plating were identical within the usable range of current densities.
In Examples SA, SAC2, SACS and SAC10, current efficiencies of 20% are obtainable during 25-micron plating but are always associated with deposits having a totally flake-type structure. Such deposits are obtained as follows:
Bath composition SA SAC2 SACS SAC10
Current density (kAlm2) 5 7l/2 171/2 20
above which flake-type
structure is obtained
Bath composition SA SAC2 SACS SAC10
Current density (kAlm2) 5 6 10 10
up to which smooth bright
25 micron desposit is obtained
EXAMPLES SAC5B5AND SAC5B20 Use of the bath compositions SAC5B5 and SAC5B20 gave visually dull and dark grey deposits with rough surface textures, except for SAC5B20 at 20 kAlm2, which appears silky-grey and is smooth to the touch.
Current efficiencies for 6-micron plating were:
Current density (kAlm2) 2 5 10 15 20
Current efficiency (, %)
SAC5B5 10 21 23 23 24 SAC5B20 4 20 29 35 35 EXAMPLESSAB5, SAB7O, SAI5ANDSAIlO The results from using these bath compositions are summarised as follows:
Current Current
density efficiency (kA/m2) (rì,%) Comments SABS 5 19 black-grey deposit, rough growth.
SAB200 15 33 silky-grey, smooth, adherent
SAB20 20 35 coating, porous without
microcracks, 1400 to 1500 HV.
SA15 2 28 dense grey adherent deposit, SAl20 2 26 400 to 500 HV, a few microcracks.
SA15 5 24 grey deposit, poorly adherent, SAl 20 5 23 600 HV, a few microcracks.
With the SAI solutions, it will be seen that current efficiency actually falls as current density goes from 2 to 5 kA/m2. This effect discourages treeing and stabilises smooth deposits.
Claims (15)
1. A bath composition for chromium electroplating, comprising CrO3 in a concentration of from 200 g/l to 600 gull, sulphate in a weight ratio S04:CrO3 of from 1:120 to to 1:80, perchlorate in a weight ratio ClO4:CrO3 of from 1 :500 to 1:50, and metal cations equivalent to at least half the perchlorate.
2. A bath composition according to Claim 1, further comprising bromate or iodate or both in a weight ratio (BrO3 pius l03):CrO3 of from 1:50 to 1:20.
3. A bath composition for chromium electroplating, comprising CrO3 in a concentration of from 200 g/l to 600 g/l, sulphate in a weight ratio S04:CrO3 of from 1:120 to to 1:80, bromate or iodate or both in a weight ratio (BrO3 plus 103):coo3 of from 1:600 to to 1:20, and metal cations equivalent to at least half the bromate-plusiodate.
4. A bath composition according to Claim 1 or 2, wherein the perchlorate has a weight ratio ClO4:CrO3 of from 1:200 to 1:80.
5. A bath composition according to Claim 3, wherein the bromate-plus-iodate has a weight ratio (BrO3 plus IO3):CrO3 of from 1:150 to 1:25.
6. A bath composition according to any preceding claim, wherein the metal cations are equivalent to substantially all the perchlorate plus bromate plus iodate.
7. A bath composition according to any preceding claim, wherein some or all of the metal cations are alkali metal cations.
8. A bath composition substantially has herein before described with reference to any one of Examples SAC2, SACS, SAC10, SAC5B5, SAC5B20, SABS, SAB20, SA15 and SAl20.
9. A bath composition according to any preceding claim, which has been electrolysed before use for chromium electroplating.
10. A method of electrodepositing chromium onto a substrate, comprising applying a cathodic potential to the substrate in a bath composition according to any preceding claim.
11. A method according to Claim 10, wherein the bath composition contains neither bromate or iodate, and wherein the current density on the substrate is from 4 to 12 kAlm2.
12. A method according to Claim 10, wherein the bath composition contains neither perchlorate nor bromate and wherein the current density on the substrate is from 1 to 4 kAlm2.
13. A method according to Claim 10, wherein the bath composition contains neither perchlorate nor iodate and wherein the current density on the substrate is from 10 to 50 kAlm2.
14. A method according to Claim 10, wherein the bath composition comprises a bromate/perchlorate mixture and wherein the current density on the substrate is from 15 to 50 kAlm2.
15. A method according to any of Claims 10 to 14, wherein the temperature is from 45 to 65 C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08510979A GB2158100B (en) | 1984-05-01 | 1985-04-30 | Chromium electroplating bath |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB848411063A GB8411063D0 (en) | 1984-05-01 | 1984-05-01 | Chromium electroplating |
| GB08510979A GB2158100B (en) | 1984-05-01 | 1985-04-30 | Chromium electroplating bath |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8510979D0 GB8510979D0 (en) | 1985-06-05 |
| GB2158100A true GB2158100A (en) | 1985-11-06 |
| GB2158100B GB2158100B (en) | 1988-02-03 |
Family
ID=26287670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08510979A Expired GB2158100B (en) | 1984-05-01 | 1985-04-30 | Chromium electroplating bath |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2158100B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5243320A (en) * | 1988-02-26 | 1993-09-07 | Gould Inc. | Resistive metal layers and method for making same |
| EP0508758A3 (en) * | 1991-04-09 | 1993-09-08 | Electric Power Research Institute | Prestabilized chromium protective film to reduce radiation buildup |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3654101A (en) * | 1970-01-09 | 1972-04-04 | M & T Chemicals Inc | Novel chromium plating compositions and processes |
| GB1383524A (en) * | 1971-02-19 | 1974-02-12 | Du Pont | Bright chromium plating |
| GB1419613A (en) * | 1974-06-13 | 1975-12-31 | Lea Ronal Inc | Cyanidefree electroplating baths |
| GB1464531A (en) * | 1975-01-10 | 1977-02-16 | ||
| US4234396A (en) * | 1978-03-08 | 1980-11-18 | Mark Perakh | Chromium plating |
| EP0073568A1 (en) * | 1981-08-24 | 1983-03-09 | M & T Chemicals, Inc. | Bright chromium plating baths |
-
1985
- 1985-04-30 GB GB08510979A patent/GB2158100B/en not_active Expired
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3654101A (en) * | 1970-01-09 | 1972-04-04 | M & T Chemicals Inc | Novel chromium plating compositions and processes |
| GB1383524A (en) * | 1971-02-19 | 1974-02-12 | Du Pont | Bright chromium plating |
| GB1419613A (en) * | 1974-06-13 | 1975-12-31 | Lea Ronal Inc | Cyanidefree electroplating baths |
| GB1464531A (en) * | 1975-01-10 | 1977-02-16 | ||
| US4234396A (en) * | 1978-03-08 | 1980-11-18 | Mark Perakh | Chromium plating |
| EP0073568A1 (en) * | 1981-08-24 | 1983-03-09 | M & T Chemicals, Inc. | Bright chromium plating baths |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5243320A (en) * | 1988-02-26 | 1993-09-07 | Gould Inc. | Resistive metal layers and method for making same |
| EP0508758A3 (en) * | 1991-04-09 | 1993-09-08 | Electric Power Research Institute | Prestabilized chromium protective film to reduce radiation buildup |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8510979D0 (en) | 1985-06-05 |
| GB2158100B (en) | 1988-02-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930430 |