CN101126158A - Discoloration resisting method for gold and platinum - Google Patents
Discoloration resisting method for gold and platinum Download PDFInfo
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- CN101126158A CN101126158A CNA2006100301678A CN200610030167A CN101126158A CN 101126158 A CN101126158 A CN 101126158A CN A2006100301678 A CNA2006100301678 A CN A2006100301678A CN 200610030167 A CN200610030167 A CN 200610030167A CN 101126158 A CN101126158 A CN 101126158A
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Abstract
The invention relates to a tarnish-resistant method of gold and platinum, the procedure of the invention includes oil removal, water scrubbing with ultrasonic, polishing, activation, acid cleaning, and chemical passivation, cleaning with hot water and dehydration and drying. All procedures are cleaned with distilled water for more than 20 seconds. The method is characterized in that the tarnish-resistant process on the surface of gold, platinum and the alloy of gold and platinum is completed in chemical passivation liquid; when the gold, the platinum and the alloy of gold and platinum are passivated, the surface is covered with giant molecule of organic substance; as the passivation liquid has no chromate content, the pollution to the environment is reduced; the surface metallic luster and the appearance of the gold and platinum products has no change after the process. The invention has an easy process procedure and convenient operation, thus having great industrial application value.
Description
[technical field]
The present invention relates to the process of surface treatment of a kind of gold and platinum, is a kind of method that makes gold and platinum anti-discolouring.
[background technology]
Gold and platinum are a kind of malleable, mouldable precious metals, and the content in the earth's crust is few, except that as the currency, have also obtained using widely in the artwork manufacturing.But, when gold and platinum and alloy thereof are in atmospheric environment, owing to contain pollution gas such as hydrogen sulfide, sulfurous gas, nitrogen peroxide, hydrogenchloride etc. in the atmosphere, they form corrosion electrolytic solution at gold and platinum surface easily, thereby cause the corrosion of gold and platinum.At this moment, the surface of gold and platinum can generate compound because of corrosion, produces dark-coloured coherent film, and surface obfuscation variable color not only can influence the appearance luster of gold and platinum, and its performance also can reduce, and this is the variable color of gold and platinum.The variable color degree of gold and platinum by itself chemical property and decided by the influence of outside atmosphere medium.The variable color meeting of gold goods has a strong impact on the grade of golden handicraft, therefore, how to prevent the variable color of gold and platinum and alloy thereof effectively, can satisfy the requirement of shelter that golden handicraft " does not change the matrix true qualities " again, is gold and platinum surface-treated key.
At present, the technology that prevents gold and platinum variable color that people propose can be summarized as: method and technologies such as chemical passivation, electrochemical passivation, coating organic materials, multiple layer combination protective film are handled, plating precious metal, they have certain effect to the variable color that prevents gold and platinum.Experiment shows: the surface that anti-gold that coating acroleic acid polyurethane coating, cathode electrophoresis dope, light solidified acrylic acid series cathode electrophoresis dope, acrylic varnish, urethane finishing paint, acroleic acid polyurethane transparent emulsion, fast-drying type acroleic acid polyurethane coating, clear finish, white spirit lacquer, photo-cured coating and various market are on sale and platinum colour-changing agent all can make gold and platinum produces the phenomenon of flavescence, influences the metalluster of gold and platinum.Electroplate not only cost height of precious metal, operation is also complicated, and the feasibility of operating on gold and platinum technology finished product is not strong.Electrolytic passivation may cause the porous of passive film, and easily penetrates various corrosive mediums, and the anti-discolouring effect is also not obvious.Chemical passivation surface protection effect is better, and operating procedure is simple, and still, because passivating solution often adopts chromic salt to make passivator, the cost of wastewater treatment can be higher.
[summary of the invention]
The objective of the invention is to overcome the deficiencies in the prior art, provide a kind of method of surperficial anti-discolouring for solving gold and platinum and the discoloration problem of alloy handicraft in depositing process thereof, this method can be avoided the use of harmful chromic salt, make gold and platinum artwork after present method is handled, anti-tarnishing ability obviously improves, and surface metal gloss and outward appearance do not have visual change.
On the basis of the various schemes of research contrast, the present invention is directed to the production and the application requiring of gold and platinum artwork, adopt the chromate-free chemical passivation, apply the method for macromole protective layer simultaneously, improve surperficial anti-tarnishing ability.Testing sieve is selected the passivating solution of hydrogen peroxide system, adds simultaneously and contains N heterocyclic macromole, and the parent is attached to gold and the platinum surface after the passivation, can obviously improve the discoloration-resisting of gold and platinum.
Technical solution of the present invention is: gold and platinum goods are after pre-treatment such as oil removing, washing, polishing, activation, pickling, carry out passivation and aftertreatment, its process treatment process is: polishing, and------------------chemical passivation---hot water wash---oven dry, the per pass inter process all is no less than 20 seconds with distilled water flushing to acid etching in activation in polishing in ultrasonic washing in oil removing.
Concrete process treatment process is:
(1) polishing: polish step by step to light with No. 800 (#) above silicon carbide (SiC) sand paper wet method;
(2) oil removing: under the room temperature, ultrasonic wave acetone oil removing 15 minutes (min), water flushing, or alkali cleaning, washing lotion composition and technological specification are as follows:
NaOH:30～50 gram (g)/liter (L),
NaCO
3： 20～40g/L，
NaHCO
3： 40～80g/L，
Na
3PO
4： 20～40g/L，
Temperature: 80～90 ℃,
Time: 5～10 minutes (min),
(3) ultrasonic wave washing;
(4) polishing: can adopt mechanical polishing or chemical rightenning, chemical rightenning in the following example:
CrO
3： 80g/L，
NaCl： 18～21g/L，
Time: 5～10 seconds (s),
Temperature: room temperature,
(5) activation:
NH
3·H
2O(30％wt)： 300～700ml/L，
Time: 5～10s,
Temperature: room temperature,
(6) pickling:
H
2SO
4： 30～50g/L，
Time: 10～20 seconds (s),
Temperature: room temperature,
(7) solution composition of chemical passivation treatment process and related process parameter are as follows:
Hydrogen peroxide: 1～45g/L,
Water glass: 2～5g/L,
Contain N larger molecular organics: 0.1～0.5g/L,
Yellow soda ash: 1～4g/L,
Lactic acid: 2～8g/L,
Temperature: 30～50 ℃,
Time: 2～5 minutes (min),
(8) aftertreatment: hot water wash---oven dry
Hot water wash is put into 50 ℃ of water with sample after the passivation, cleans 1 minute (min), dries with distilled water flushing.
Be the best when hydrogen peroxide content is 10～20g/L in the chemical passivation solution.
The silicate, carbonate or their mixture that contain first main group and second main group metal in the chemical passivation solution.The content of silicate, carbonate is 0.5～10g/L, and its optimum content is 1～5g/L.Contain hydroxyl organic acid in the chemical passivation solution, its molecular formula is:
Wherein: R1 is H or CnH2n+1, n=1,2,3
Organic acid is a lactic acid, and oxysuccinic acid, content are 1～40g/L, and its optimum content is 2～8g/L, contains band in the chemical passivation solution and contains N, S heterocyclic larger molecular organics, and wherein molecular formula is for example:
Wherein: R2 is an alkyl, or saturated or unsaturated heterocycle.
N, S organism are quinine and derivative thereof, imidazoles and derivative thereof, and thiophene and derivative thereof, pyridine and derivative thereof, or their mixture, content are 0.01～2g/L, its optimum content is 0.1～1g/L.Gold and platinum surface after treatment, its discoloration-resisting adopts variable color accelerated test and electrochemical test check.
1, the spot test of sulfuration ammonia solution
Examination criteria is Ministry of Light Industry's standard: QJ458-88: gold and platinum coating technology condition.Be specially: with pipette, extract sulfuration ammonia solution 30ml, put into the 100ml volumetric flask, be diluted to scale, shake fair with deionized water; Get top solution 2ml, put into the volumetric flask of 1L, be diluted to scale, shake fair with deionized water; Take out with dropper, drip in test piece, start the watch, is rinsed well then at the time that variable color takes place on gold and platinum sheet surface under the meter simultaneously.
Light discolouration takes place in the surface in test shows, metal gold and platinum surface after the present invention handles 3 minutes (min) afterwards, and undressed gold and platinum test piece within (s) obvious variable color just took place in 20 seconds.
2, TAA test
Testing standard: BS EN ISO 4538:1995, Metallic coatings-Thioacetamidecorrosion test (TAA test) (metal surface corrodes test).Be specially: at 25 ℃, R.H.75%, the thioacetyl ammonia atmosphere is observed gold and platinum appearance over time.Estimate the variable color of gold and platinum sheet according to GB GB12335-90 (metal cladding is the sample grading after the tectum corrosion test of positive polarity to ground), its concrete judgement criteria is listed in table 1:
Table 1, outward appearance grading table
| The outward appearance grading | The variation of specimen surface outward appearance |
| A | No change. |
| B | Slight variable color to moderate. |
| C | Serious discoloration or extremely slight loss of gloss. |
| D | Slight loss of gloss or the extremely slight corrosion product of appearance. |
| E | Serious loss of gloss, or on the sample local surfaces, be furnished with the corrosion product or the spot corrosion of thin layer. |
| F | Corrosion product or spot corrosion are arranged, and one of them is distributed on the whole specimen surface. |
| G | Be furnished with thick corrosion product or spot corrosion on the whole surface, and dark spot corrosion is arranged. |
| H | Be furnished with very thick corrosion product or spot corrosion on the whole surface, and dark spot corrosion is arranged. |
| I | The matrix metal corrosion appears. |
Detect comparing result, see Table 2
Table 2, TAA discoloration test result
| Time (h) | Unprocessed | After the processing |
| 0.5 | B | A |
| 1 | C | A |
| 1.5 | C | A |
| 2 | D | B |
| 4 | E | B |
| 8 | F | C |
| 16 | G | D |
3, electro-chemical test
Na at 5mg/L
2In the S solution, carry out the polarization curve measuring result with the speed of 1mV/s and be shown in Fig. 2.Polarization curve shows, gold and platinum sheet are handled the after-polarization current density at overlay film to be had obviously and reduce, and has improved the negative electrode and the anodic reaction process of gold and platinum variable color simultaneously, has strengthened the anti-tarnishing ability of gold and platinum.
Major advantage of the present invention and benefit are: after passivation technology was handled, gold and platinum surface passivated membrane were even, fine and close, and the sample after Passivation Treatment still keeps all improving a lot aspect gold and the platinum surface luster in the anti-discolouring effect.The novel non-chrome chemical passivation treatment process of development has been avoided the use of harmful chromic salt, reduces the processing cost of waste liquid, and technical process is simple and easy to do, thereby has stronger using value.
[illustrating]
Accompanying drawing 1 is a process flow sheet of the present invention;
Accompanying drawing 2 is a polarization curve of the present invention.
[embodiment]
Provide embodiments of the invention below in conjunction with accompanying drawing.
Get Gold Content and be 99.99%, volume is the gold and the platinum sheet of 20 * 10 * 1 millimeter (mm), this gold and platinum sheet adopt following art breading through pressur rolling forming:
Polishing---oil removing---ultrasonic washing---polishing---activation---acid etching---chemical passivation---hot water wash---oven dry.
1, polishing: polish to light step by step with No. 800 (#) above silicon carbide (SiC) sand paper wet method.
2, oil removing:
Under the room temperature, ultrasonic wave acetone oil removing 15 minutes (min), water flushing, or alkali cleaning, washing lotion composition and technological specification are as follows:
NaOH： 40g/L，
Na
2CO
3： 30g/L，
NaHCO
3： 60g/L，
Na
3PO
4： 30g/L，
Temperature: 85 ℃,
Time: 8 minutes (min),
3, ultrasonic wave washing;
4, polishing:
Can adopt mechanical polishing or chemical rightenning, chemically polishing method is as follows:
CrO
3： 80g/L，
NaCl： 20g/L，
Time: 7 seconds (s),
Temperature: room temperature,
5, activation:
NH
3·H
2O(30％wt)： 500ml/L，
Time: 7 seconds (s),
Temperature: room temperature,
6, pickling:
H
2SO
4： 40g/L，
Time: 15 seconds (s),
Temperature: room temperature,
7, solution composition of chemical passivation treatment process and related process parameter are as follows:
Hydrogen peroxide: 20g/L,
Water glass: 3g/L,
Contain N larger molecular organics: 0.2g/L,
Yellow soda ash: 2.5g/L,
Lactic acid: 4g/L,
Temperature: 35 ℃,
Time: 3 minutes (min),
8, aftertreatment
Hot water wash is put into 50 ℃ of water with sample after the passivation, cleans 1 minute (min).Dry with distilled water flushing.
Comparison example
The anti-tarnishing ability of the present invention and comparison example adopts sulfuration ammonia spot method to compare.
Example one, organic deactivating process for the treatment of
| Composition and processing parameter | Prescription 1 | Prescription 2 | Prescription 3 |
| Benzotriazole (g/L) | 2.5 | 2.5 | 1.5 |
| Potassiumiodide (g/L) | 2 | 1.5 | 1 |
| M-nitrobenzene sodium sulfonate (g/L) | 0.5 | 0.625 | |
| Xitix (g/L) | 1.25 | ||
| Temperature | Room temperature | Room temperature | Room temperature |
| Passivation time (min) | 8 | 4 | 5 |
| The variable color time (min) | 2’45 | 2’30 | 2’10 |
Organism passivation technology anti-discolouring effect is not as the present invention, and because the organic oxidizing agent large usage quantity, cost is higher, so large-scale application has any problem, and cost is too high when single-piece or small serial production.
Example two, electrochemical passivation technology
| Composition and processing parameter | Prescription 1 | Prescription 2 | Prescription 3 |
| Potassium bichromate (g/L) | 45 | 20 | |
| Saltpetre (g/L) | 10 | ||
| Potassiumchromate (g/L) | 8 | ||
| Salt of wormwood (g/L) | 6 | 30 | |
| Potassium hydroxide (g/L) | 20 | ||
| Current density (A/dm 2) | 0.5 | 0.8 | 0.8 |
| Temperature | Room temperature | Room temperature | Room temperature |
| Passivation time (min) | 3 | 4 | 1 |
| The variable color time (min) | 1’20 | 1’40 | 1’30 |
Electrochemical passivation is used chromatedsolution always, though this type of technology owing to the attenuating of chromate content has reduced harm to environment,, its treatment effect is obviously not as the present invention, and after handling, gold and platinum surface can forfeiture metalluster.
Example three, ability cathode electrophoresis deposition oxide technology
| Composition and processing parameter | Prescription 1 | Prescription 2 | Prescription 3 |
| Potassium bichromate (g/L) | 30 | ||
| Gelatin (g/L) | 2.5 | ||
| Aluminium hydroxide (g/L) | 0.8 | ||
| Tin chloride (g/L) | 20 | ||
| Hydrogenchloride (g/L) | 50 | ||
| Beryllium sulfate (g/L) | 3 | ||
| Current density (A/dm 2) | 0.5 | 0.05 | 0.04 |
| PH | 3.5 | 5 | |
| Temperature | Room temperature | Room temperature | Room temperature |
| Passivation time (min) | 1 | 2 | 3 |
| The variable color time (min) | 1’30 | 2’ | 1’40 |
Ability cathode electrophoresis deposition oxide technology adopts the oxide compound of the method for ability cathode electrophoresis at gold and platinum surface deposition one deck light metal usually, and to prevent the variable color of gold and platinum, its anti-discolouring effect is obviously relatively poor.
Claims (10)
1. the anti-color changing method of gold and platinum, it is characterized in that, gold and platinum surface anti-discolouring are handled and are finished in chemical passivation solution, its process treatment process is: polishing---oil removing---and ultrasonic washing---polishing---activation---acid etching---chemical passivation---hot water wash---oven dry, the per pass inter process all is no less than 20 seconds with distilled water flushing;
Its concrete process treatment process is:
(1) polishing: polish step by step to light with No. 800 (#) above silicon carbide (SiC) sand paper wet method;
(2) oil removing:
Under the room temperature, ultrasonic wave acetone oil removing 15 minutes (min), water flushing, or alkali cleaning, washing lotion composition and technological specification are as follows:
NaOH： 30～50g/L，
NaCO
3 20～40g/L，
NaHCO
3 40～80g/L，
Na
3PO
4 20～40g/L，
Temperature: 80～90 ℃,
Time: 5～10 minutes (min),
(3) ultrasonic wave washing;
(4) polishing: can adopt mechanical polishing or chemical rightenning, chemical rightenning in the following example:
CrO
3： 80g/L，
NaCl： 18～21g/L，
Time: 5～10 seconds (s),
Temperature: room temperature,
(5) activation:
NH
3.H
2O(30％wt) 300～700ml/L，
Time: 5～10 seconds (s),
Temperature: room temperature,
(6) pickling:
H
2SO
4 30～50g/L，
Time: 10～20 seconds (s),
Temperature: room temperature,
(7) solution composition of chemical passivation treatment process and related process parameter:
Hydrogen peroxide: 1～45g/L,
Water glass: 2～5g/L,
Contain N larger molecular organics: 0.1～0.5g/L,
Yellow soda ash: 1～4g/L,
Lactic acid: 2～8g/L,
Temperature: 30～50 ℃,
Time: 2～5 minutes (min),
(8) aftertreatment: hot water wash～oven dry,
Hot water wash is put into 50 ℃ of water with sample after the passivation, cleans 1 minute (min).Dry with distilled water flushing.
2. according to the anti-color changing method of described gold of claim 1 and platinum, it is characterized in that hydrogen peroxide content is 10～20g/L in the described chemical passivation solution.
3. according to the anti-color changing method of described gold of claim 1 and platinum, it is characterized in that, contain the silicate of first main group and second main group metal in the described chemical passivation solution, carbonate, borate or their mixture.
4. according to the anti-color changing method of claim 1 or 3 described gold and platinum, it is characterized in that described silicate, carbonate, boratory content are 0.5～10g/L.
5. according to the anti-color changing method of claim 1 or 3 described gold and platinum, it is characterized in that described silicate, carbonate, boratory content are 1～5g/L.
6. according to the anti-color changing method of described gold of claim 1 and platinum, it is characterized in that, contain hydroxyl organic acid in the described chemical passivation solution, its molecular formula for example:
Wherein: R1 is H or CnH
2N+1, n=1,2,3 ...
7. according to the anti-color changing method of claim 1 or 6 described gold and platinum, it is characterized in that described organic acid is a lactic acid, oxysuccinic acid, content are 1～40g/L.
8. according to the anti-color changing method of claim 1 or 6 described gold and platinum, it is characterized in that described organic acid is a lactic acid, oxysuccinic acid, content are 2～8g/L.
9. according to the anti-color changing method of described gold of claim 1 and platinum, it is characterized in that contain band in the described chemical passivation solution and contain N, S heterocyclic larger molecular organics, its molecular formula is:
Wherein: R2 is an alkyl, or saturated or unsaturated heterocycle.
10. according to the anti-color changing method of claim 1 or 9 described gold and platinum, it is characterized in that described N, S organism are quinine and derivative thereof, imidazoles and derivative thereof, thiophene and derivative thereof, pyridine and derivative thereof, or their mixture, content is 0.01～2g/L.
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|---|---|---|---|
| CNA2006100301678A CN101126158A (en) | 2006-08-17 | 2006-08-17 | Discoloration resisting method for gold and platinum |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2006100301678A CN101126158A (en) | 2006-08-17 | 2006-08-17 | Discoloration resisting method for gold and platinum |
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| Publication Number | Publication Date |
|---|---|
| CN101126158A true CN101126158A (en) | 2008-02-20 |
Family
ID=39094289
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104032289A (en) * | 2013-08-23 | 2014-09-10 | 珠海罗西尼表业有限公司 | Method for corrosion resistance and tarnishing resistance treatment of gold and its alloy surface |
-
2006
- 2006-08-17 CN CNA2006100301678A patent/CN101126158A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104032289A (en) * | 2013-08-23 | 2014-09-10 | 珠海罗西尼表业有限公司 | Method for corrosion resistance and tarnishing resistance treatment of gold and its alloy surface |
| CN104032289B (en) * | 2013-08-23 | 2015-02-25 | 珠海罗西尼表业有限公司 | Method for corrosion resistance and tarnishing resistance treatment of gold and its alloy surface |
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Application publication date: 20080220 |