CN107400892A - A kind of processing method of fine silver product surface discoloration - Google Patents

A kind of processing method of fine silver product surface discoloration Download PDF

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Publication number
CN107400892A
CN107400892A CN201710617748.XA CN201710617748A CN107400892A CN 107400892 A CN107400892 A CN 107400892A CN 201710617748 A CN201710617748 A CN 201710617748A CN 107400892 A CN107400892 A CN 107400892A
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CN
China
Prior art keywords
fine silver
silver product
processing method
silver
product surface
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Withdrawn
Application number
CN201710617748.XA
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Chinese (zh)
Inventor
王德雨
张正洁
陈扬
佟永顺
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Jiangsu Yancheng Environmental Protection Science And Technology City Heavy Metal Control Research Center
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Jiangsu Yancheng Environmental Protection Science And Technology City Heavy Metal Control Research Center
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Priority to CN201710617748.XA priority Critical patent/CN107400892A/en
Publication of CN107400892A publication Critical patent/CN107400892A/en
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/10—Other heavy metals

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

The present invention provides a kind of processing method of fine silver product surface discoloration, particular for the recovery of fine silver coin chapter and fine silver handicraft surface color change portion, these goods return and replacement products or old system product is reduced the cost produced again from original appearance is repaired, the method is characterized in that：Cleaning fluid is prepared with thiocarbamide, water and acid, the fine silver product of discoloration is put into cleaning fluid and is dipped to color change portion reinstatement, takes out and is cleaned with deionized water, dried；It is an advantage of the invention that：Technical process is simple, and processing is time-consuming very short；Normal-temperature operation, surface do not produce physical damnification, and silver-colored loss is lacked；Cleaning fluid normal temperature preserves, reusable, and follow-up cleaning is simple, thorough.

Description

A kind of processing method of fine silver product surface discoloration
Technical field
The invention belongs to chemical technology field, and in particular to a kind of processing method of fine silver product surface discoloration.
Background technology
With the raising of living standards of the people and the rise of collecting craze, silverware has become increasingly popular.But it is chronically exposed to sky Silverware such as silver coin in gas（Chapter）, silver-colored goods of furniture for display rather than for use etc., surface easily produces black or yellow spot, gradually covers the whole of silverware Individual surface, influences the aesthetic property and sight of implements, and substantially reduces its reserve value.
The main component of silverware surface black or yellow spotting is silver sulfide, simultaneously containing a small amount of silver chlorate, silver oxide Deng composition.
The method for removing cleaning silverware black stains in the surface or macula lutea generally use has physics polishing processes, chemical reduction method, change Learn etch etc..But currently without it is a kind of easy and effective and do not damage silverware surface method remove silverware surface blackspot or Person's macula lutea.
The physics polishing genealogy of law uses all kinds of abrasive materials such as diatomite, silk, lint, the table for nigrescence silverware of polishing Face.The major defect of this method is that polishing can cause the silver loss in silverware surface, and surface can produce cut, and can not handle The more complicated silverware of surface detail.
Silverware is put into the aqueous solution containing electrolyte by the electronation genealogy of law, keeps the straight of the active metals such as silverware and aluminium foil Contact, silver is reduced into using electrochemical reaction by silver sulfide.The method can thoroughly reduce silver sulfide, the chlorination on silverware surface Silver, silver oxide, and silverware surface is silver to lose.Shortcoming is that silverware surface smoothness decreases after reacting, and influences implements Aesthetic property, reduction reaction cause silver surface activity improve, can cause silverware surface black again jaundice speed accelerate.This is Due to the speed of reduction reaction in traditional reduction reaction, can not be kept slowly and uniformly, when reaction speed is too fast, silver-colored molecule Rearranged on silverware surface, reduce finish and add surface area, cause silverware easily by revulcanization.Simultaneously because The property of copper is more active than silver, when silver-plated bronze, brass or copper ware copper is exposed to surface, i.e., can not be repaired using chemical reduction method.Specially The sharp A of CN 103233236 disclose a kind of medicament and its method for being used to eliminate silverware black stains in the surface or macula lutea, and this method utilizes The medicaments such as sodium acid carbonate are built under a kind of alkalescence condition, with the silver of active metal magnesium-reduced high-valence state.The shortcomings that this method：Medicament Species is too complicated, high expensive；Need magnesium surface processing exposing fresh face and to be brought into close contact silver process product surface, this is in reality It is difficult to accomplish in the operation of border, especially the implements of irregular shape is just more difficult to reach.
The chemical attack genealogy of law uses chemical agent, the vulcanization silver reaction with silverware surface, reaches the purpose for removing silver sulfide. The major defect of this method is to cause the silver loss in silverware surface, is particularly unsuitable for silver-plated implements or is anticipated with commemorating The silverware of justice.Used chemical agent has certain corrosivity, and average family must hig diligence safety using this method.Simultaneously This method does not have effect for removing silver oxide.The A of patent CN 1198783 disclose a kind of composition of cleaning silver or copper, should Method uses copper powder, up to more than ten kinds of organic reagent, wherein also toxic very strong thio-alcohol medicament, not only with certain danger It is dangerous, and be also easy to using copper powder when reduction reaction is carried out, to have the table that small copper powder particle sticks in silverware Face, so that in deuterogenesis's electrochemical corrosion, silverware is caused to change colour again faster.
《The A of CN 103898526 are used for the washing lotion and method for removing silverware surface color spot》The method of middle announcement：Use third Triol, TiO2, aluminium powder also has other many organic reagents, and 24h is irradiated under ultraviolet light to produce photoelectron also The silver sulfide formed on former silverware, complex operation, duration are oversize.《The A of CN 103898537 are used to remove silverware surface color spot Spray coating liquor and method》Drawbacks described above is equally existed, light application time even reaches 48h.《A kind of electrolyte of the A of CN 104328476 and The method that silverware surface color spot is removed with the electrolyte》In not only complex operation, and use highly toxic 2- sulfydryls benzo thiophene The reagents such as azoles, security are poor.《A kind of silverware scavenger speciallies of the A of CN 105506655》Method can only be used for clean silverware Dirt, and removal effect unobvious of the oxide layer to silverware.
The A of application publication number CN 102660747《For silverware and gold-decorated silverware protection Thiourea compounding rust remover and Descaling grease》Middle rust remover contains oxidant ferric sulfate, after the silver rust on silverware surface is removed, Fe3+In acid condition can be after Continuous produced to silverware background is corroded, Fe in solution3+Presence can generate substantial amounts of elemental sulfur, also may proceed to corrode and silverware and cause Follow-up cleaning is difficult；Containing grinding agents such as diatomite in descaling grease, cut can be produced to silver surface, to the requirement of the minute surfaces such as silver coin chapter Very high product is unsuitable.
Further, since fine silver handicraft Surface Quality requires very high, especially finish, but the hardness very little of fine silver, Mohs' hardness only has 2.7.And mostly more or less contain solid particle in chemical agent combination used in above-mentioned patent, locating The physical damnifications such as cut inevitably are produced to fine silver handicraft surface during reason.
The content of the invention
In view of the shortcomings of the prior art, it is an object of the invention to provide a kind of processing side of fine silver product surface discoloration Method, it is characterised in that：Concrete operations comprise the following steps：
（1）, weigh the parts by weight of analysis bright sulfur urea 50 ~ 150, be placed in the beaker for filling 1000mL deionized waters；
（2）, be heated to thiocarbamide under conditions of stirring and be completely dissolved, be cooled to room temperature, insoluble matter filtered out with qualitative filter paper；
（3）, add the mixed acid of 1 ~ 15mL nitric acid, sulfuric acid or the two arbitrary proportion, stir；
（4）, will change colour or the fine silver product of part discoloration is immersed in above-mentioned solution, be dipped to color change portion reinstatement；
（5）, take out fine silver product, cleaned up with deionized water, wipe surface with clean muslin, spontaneously dried under normal temperature Or air-dry.
The beneficial effects of the invention are as follows：Technical process is simple, and processing is time-consuming very short；Normal-temperature operation, surface not generation Reason damage, silver-colored loss are lacked；Cleaning fluid normal temperature preserves, reusable, and follow-up cleaning is simple, thorough.Compared with other method It is cost-effective.
Embodiment
The technical solution adopted by the present invention is：A kind of processing method of fine silver product surface discoloration, including following step Suddenly：
Step（One）：The parts by weight of analysis bright sulfur urea 50 ~ 150 are weighed, are placed in the beaker for filling 1000mL deionized waters；
Step（Two）：Thiocarbamide is heated under conditions of stirring to be completely dissolved, is cooled to room temperature, is filtered out with qualitative filter paper insoluble Thing；
Step（Three）：The mixed acid of 1 ~ 15mL nitric acid, sulfuric acid or the two arbitrary proportion is added, is stirred；
Step（Four）：It will change colour or the fine silver product of part discoloration immersed in above-mentioned solution, be dipped to color change portion reinstatement；
Step（Five）：Take out fine silver product, cleaned up with deionized water, surface is wiped with clean muslin, under normal temperature from So dry or air-dry.
Further, thiocarbamide used is AR, and water is deionized water, and acidic liquid is the pure nitric acid of analysis, analysis The mixed acid of bright sulfur acid or the two arbitrary proportion, the pH of solution is 0.5 ~ 1.
Further, soak time is 1 ~ 40s.
Further, dry is to spontaneously dry or air-dry under normal temperature.
Further, described preparation thiourea concentration is 50 ~ 150g/L, and sour addition is 1 ~ 15mL/L.
Reaction mechanism is as follows：
Although Ag2S solubility product very little, there was only 6.3 × 10 at 25 DEG C-50, but the dissolving of denier is still suffered from aqueous （Because insoluble is all relative, and it is absolute to dissolve）：
Ag2S ⇌ 2Ag++S2-
Represented in formula, this is a reversible reaction, if suitable complexing agent and Ag+Complexing, product concentration reduce, that Chemical reaction equilibrium will be carried out to the right, will be taken off so as to the color change portion of black.
The chemical constitution of thiocarbamide molecule is identified as following resonant：
I.e. it is by the N in molecule+With S atom possessed by free electron pair, with silver ion formed complex ions [Ag ( H2NCSNH2) 3 ] +Into solution, [Ag (TU) is abbreviated as3 ] +, complexing stability constant 13.1, therefore it is right Ag2S, AgCl and metal Ag etc. have very strong dissolving complexing.
Therefore the net reaction of the reaction should be：
Ag2S+TU+H+ → [Ag ( TU) 3 ] ++H2S
The pH value of solution is 0.5 ~ 1.Although sometimes color seems very deep for fine silver surface discolouration part, its quality is simultaneously little, Generally there was only several micrograms, therefore consumption reagent is few, therefore pH is basically unchanged in operation.
Embodiment 1
1st, 120 grams of analysis bright sulfur ureas are weighed to be placed in beaker, add 1000mL deionized waters, heating stirring makes thiocarbamide completely molten Solution；
2nd, remove, be cooled to room temperature, insoluble matter is filtered out with qualitative filter paper；
3rd, add 5mL into thiourea solution again and analyze pure nitric acid, stir；
4th, the fine silver chapter by one piece of discoloration is put into above-mentioned solution, jiggles 10s；
5th, fine silver chapter is taken out, is cleaned up with deionized water, wipes surface with clean muslin, then blown with cool breeze with hair dryer Its surface 3min.
Embodiment 2
1st, 140 grams of analysis bright sulfur ureas are weighed to be placed in beaker, add 1000mL deionized waters, heating stirring makes thiocarbamide completely molten Solution；
2nd, remove, be cooled to room temperature, insoluble matter is filtered out with qualitative filter paper；
3rd, 5mL analytical pure sulfuric acids are added into thiourea solution again, are stirred；
4th, the fine silver piece by one piece of discoloration is put into above-mentioned solution, jiggles 12s；
5th, fine silver piece is taken out, is cleaned up with deionized water, surface is wiped with clean muslin, it is naturally dry to be placed on ventilation It is dry.

Claims (5)

  1. A kind of 1. processing method of fine silver product surface discoloration, it is characterised in that：Comprise the following steps：
    Step（One）：The parts by weight of analysis bright sulfur urea 50 ~ 150 are weighed, are placed in the beaker for filling 1000mL deionized waters；
    Step（Two）：Thiocarbamide is heated under conditions of stirring to be completely dissolved, is cooled to room temperature, is filtered out with qualitative filter paper insoluble Thing；
    Step（Three）：The mixed acid of 1 ~ 15mL nitric acid, sulfuric acid or the two arbitrary proportion is added, is stirred；
    Step（Four）：It will change colour or the fine silver product of part discoloration immersed in above-mentioned solution, be dipped to color change portion reinstatement；
    Step（Five）：Take out fine silver product, cleaned up with deionized water, surface is wiped with clean muslin, under normal temperature from So dry or air-dry.
  2. 2. the processing method of the fine silver product surface discoloration according to right 1, it is characterised in that described thiocarbamide used is point Pure reagent is analysed, water is deionized water, and acidic liquid is the mixed acid for analyzing pure nitric acid, analytical pure sulfuric acid or the two arbitrary proportion, The pH of solution is 0.5 ~ 1.
  3. 3. according to right 1 fine silver product surface discoloration processing method, it is characterised in that described soak time be 1 ~ 40s。
  4. 4. the processing method of the fine silver product surface discoloration according to right 1, it is characterised in that described drying is under normal temperature Spontaneously dry or air-dry.
  5. 5. the processing method of the fine silver product surface discoloration according to right 2, its feature are in described preparation thiourea concentration 50 ~ 150g/L, sour addition are 1 ~ 15mL/L.
CN201710617748.XA 2017-07-26 2017-07-26 A kind of processing method of fine silver product surface discoloration Withdrawn CN107400892A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113430056A (en) * 2021-08-04 2021-09-24 上海淑苑科技有限公司 Jewelry and precious metal cleaning agent and preparation method thereof

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2628199A (en) * 1949-12-21 1953-02-10 Frederick A Lowenheim Tarnish remover
US4561895A (en) * 1982-03-12 1985-12-31 Eriksson Jan Olof Non-abrasive metal cleaning agent
CN1198783A (en) * 1996-06-08 1998-11-11 雷克特和科尔曼产品有限公司 Composition for cleaning silver or copper
CN102660747A (en) * 2012-04-13 2012-09-12 中国文化遗产研究院 Thiourea compound rust remover and rust removal paste for protecting silverware and gilded silverware
CN103923571A (en) * 2014-04-25 2014-07-16 苏州新材料研究所有限公司 Polishing solution as well as preparation method and application of polishing solution
CN104593790A (en) * 2015-01-05 2015-05-06 邯郸学院 Powder for removing surface stains of silverware

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2628199A (en) * 1949-12-21 1953-02-10 Frederick A Lowenheim Tarnish remover
US4561895A (en) * 1982-03-12 1985-12-31 Eriksson Jan Olof Non-abrasive metal cleaning agent
CN1198783A (en) * 1996-06-08 1998-11-11 雷克特和科尔曼产品有限公司 Composition for cleaning silver or copper
CN102660747A (en) * 2012-04-13 2012-09-12 中国文化遗产研究院 Thiourea compound rust remover and rust removal paste for protecting silverware and gilded silverware
CN103923571A (en) * 2014-04-25 2014-07-16 苏州新材料研究所有限公司 Polishing solution as well as preparation method and application of polishing solution
CN104593790A (en) * 2015-01-05 2015-05-06 邯郸学院 Powder for removing surface stains of silverware

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113430056A (en) * 2021-08-04 2021-09-24 上海淑苑科技有限公司 Jewelry and precious metal cleaning agent and preparation method thereof

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Application publication date: 20171128