WO2018218894A1 - 一种铁件表面锌层及铬钝化层电解退镀的方法 - Google Patents

一种铁件表面锌层及铬钝化层电解退镀的方法 Download PDF

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WO2018218894A1
WO2018218894A1 PCT/CN2017/112760 CN2017112760W WO2018218894A1 WO 2018218894 A1 WO2018218894 A1 WO 2018218894A1 CN 2017112760 W CN2017112760 W CN 2017112760W WO 2018218894 A1 WO2018218894 A1 WO 2018218894A1
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deplating
zinc
passivation layer
layer
chromium passivation
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PCT/CN2017/112760
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韩永祥
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韩永祥
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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25FPROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F5/00Electrolytic stripping of metallic layers or coatings

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  • the invention belongs to the field of metal surface treatment and electrolytic deplating, and in particular to a method for electrolytic deplating of a zinc layer on a surface of an iron member and a chromium passivation layer.
  • the invention adopts alkaline electrolysis to remove the zinc layer and the chromium passivation layer, and the surface of the solution is covered with a layer of foam during deplating, and no acid mist or alkali mist escapes, thereby improving the on-site operating environment; the zinc layer does not corrode after being removed. Substrate.
  • the workpiece acts as an anode and does not produce hydrogen embrittlement; zinc ions are deposited at the cathode, and the zinc powder can be directly recovered after being removed, which has certain economic benefits.
  • the object of the present invention is to provide a method for electrolytic deplating of a zinc layer on a surface of a iron member and a chromium passivation layer, which can completely remove the unqualified zinc layer and the chromium passivation layer on the workpiece at one time, and has high removal efficiency. Does not produce acid mist, alkali mist, deplating will not corrode the substrate, will not produce hydrogen embrittlement, and can also recover zinc powder.
  • the technical solution adopted by the invention is: a method for electrolytic deplating of the zinc layer on the surface of the iron piece and the chromium passivation layer, comprising the following steps:
  • the distance between the iron piece to be deplated and the stainless steel plate in the deplating solution is 2-50 cm, and the distance between the preferred iron plate to be deplated and the stainless steel plate in the deplating solution is 5 -20cm.
  • the rectifier output DC voltage is 2-8V.
  • the initial current density of the anode of the electrolytic deplating system is 3-10 A/dm 2 , and the anode current is gradually reduced during the deplating process.
  • the stripping solution comprises the following components by weight:
  • the balance is water
  • the complexing agent is sodium hydroxide or potassium hydroxide.
  • the auxiliary complexing agent is selected from the group consisting of potassium phosphate, trisodium phosphate, potassium pyrophosphate, sodium pyrophosphate, sodium thiosulfate or potassium thiosulfate.
  • the humectant is selected from the group consisting of alkyl glycosides, fatty acid methyl ester ethoxylate sulfonates, fatty alcohol phosphates or fatty alcohol ether phosphates.
  • the function of the humectant is to reduce the interfacial tension between the solution and the workpiece, so that the deplated material and bubbles are easily separated from the surface of the workpiece to be deplated, and on the other hand, a layer of foam is generated on the liquid surface to prevent the alkali mist from escaping.
  • the chromium passivation layer comprises a trivalent chromium or hexavalent chromium passivation layer.
  • the entire electrolytic deplating process is: placing the iron piece to be deplated into the deplating solution, and connecting it to the positive electrode of the rectifier as an anode, and placing the stainless steel plate in the deplating solution to be connected to the negative electrode of the rectifier.
  • the iron and stainless steel plates are separated by 2-50cm in the deplating solution, and the rectifier outputs 2-8V DC to the electrolytic deplating system.
  • the initial anode current density is about 3-10A/dm 2 .
  • the zinc layer begins to dissolve, the zinc layer on the surface of the stainless steel plate is continuously deposited, and the current is continuously decreased. When the current drops to a stable value, the deplating process is completed, and the electroplating process is converted into electrolyzed water, the current value is stable, and the plating layer is completely removed.
  • the whole electroplating process is as follows: the deplating workpiece is an anode, the stainless steel plate is a cathode, and both are placed in the deplating solution. Under the action of direct current, the metal plating on the anode is gradually dissolved from the substrate and enters the solution in the form of ions; Part of the metal ions on the cathode are reduced in powder form.
  • the electroplating process has faster deplating speed than chemical deplating and high efficiency; most metal ions can be directly deposited at the cathode for easy recovery; due to metal ion precipitation, the concentration of metal ions in the electroplating solution can be Maintaining a low level can extend the life of the stripping solution.
  • the invention has the beneficial effects that the method for electrolytic deplating of the zinc layer on the surface of the iron member and the chromium passivation layer of the invention can completely remove the unqualified zinc layer and the chromium passivation layer on the workpiece, and the removal efficiency is high, 8 micrometers.
  • the galvanized layer can be retreated in about 10 minutes; it does not produce acid mist and is environmentally friendly; the deplating does not cause excessive corrosion of the workpiece and does not cause hydrogen embrittlement; the zinc powder deposited by the cathode can be directly recovered; the unqualified zinc layer on the workpiece
  • the chromium passivation layer is removed simultaneously with the deposition of the cathode zinc powder to reduce the process flow.
  • a method for electrolytic deplating of a zinc layer on a surface of an iron part and a chromium passivation layer comprises the following steps:
  • the deplating solution used comprises the following components by weight:
  • a method for electrolytic deplating of a zinc layer on a surface of an iron part and a chromium passivation layer comprises the following steps:
  • the deplating solution used comprises the following components by weight:
  • a method for electrolytic deplating of a zinc layer on a surface of an iron part and a chromium passivation layer comprises the following steps:
  • the deplating solution used comprises the following components by weight:
  • a method for electrolytic deplating of a zinc layer on a surface of an iron part and a chromium passivation layer comprises the following steps:
  • the deplating solution used comprises the following components by weight:

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

本发明公开了一种铁件表面锌层及铬钝化层电解退镀的方法,包括步骤:将待退镀的铁件连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,通过电解退镀,将铁件表面锌层的或铬钝化层溶解,使锌粉沉积在不锈钢板表面。本发明的铁件表面锌层及铬钝化层电解退镀的方法能完全退除工件上的不合格的锌层或铬钝化层,退除效率高;不产生酸雾,对环境友好;退镀不对工件造成过腐蚀,不会产生氢脆;阴极沉积的锌粉或铬层可直接回收;工件上的不合格锌层、铬钝化层退除与阴极锌粉的沉积同时进行,减少工艺流程。

Description

一种铁件表面锌层及铬钝化层电解退镀的方法 技术领域
本发明属于金属表面处理及电解退镀领域,具体地,涉及一种铁件表面锌层及铬钝化层电解退镀的方法。
背景技术
在金属工件的加工过程中,常常会在金属表面上形成各种功能性膜层。在膜层的形成过程中,工件表面会由于各种原因而产生一些不良品,例如不合格的锌层或铬钝化层。目前,铁件上不合格的镀锌层通常需要通过盐酸浸泡退除,退除过程中,工件会剧烈冒泡,造成酸雾逸出,影响生产环境;此外,如果长时间浸泡铁件,氢脆敏感型的工件会加剧氢脆风险。因此需要一种在不腐蚀基材表面的情况下,能完全退除工件上的不合格的锌层或铬钝化层的方法。
本发明采用碱性电解退除锌层及铬钝化层,退镀时溶液表面覆盖一层泡沫,无酸雾、碱雾逸出,改善了现场操作环境;锌层退除完毕后不会腐蚀基材。在电解退除过程中,工件作为阳极,不会产生氢脆;锌离子在阴极沉积,取下后可直接回收锌粉,具有一定经济效益。
发明内容
本发明的目的在于提供一种铁件表面锌层及铬钝化层电解退镀的方法,该方法能一次性完全退除工件上的不合格的锌层及铬钝化层,退除效率高,不产生酸雾、碱雾,退镀不会腐蚀基材,不会产生氢脆,同时还可以回收锌粉。
本发明所采取的技术方案为:一种铁件表面锌层及铬钝化层电解退镀的方法,包括以下步骤:
1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统;
2)打开整流机,输出直流电压至电解退镀系统,开始电解退镀,铁件表面锌层及铬钝化层开始溶解,不锈钢板表面的锌层不断沉积,电解退镀系统电流不断下降;
3)当电解退镀系统的电流下降至稳定值,取出观察,若基材全部露出则表明电解退镀过程完成;
4)将铁件取出,清洗;收集不锈钢板表面锌层。
优选的,在步骤1)中,待退镀的铁件与不锈钢板在退镀液中的距离为2-50cm,优选的待退镀的铁件与不锈钢板在退镀液中的距离为5-20cm。
优选的,在步骤2)中,整流机输出直流电压为2-8V。
优选的,电解退镀系统的阳极初始电流密度为3-10A/dm2,退镀过程,阳极电流逐渐减小。
优选的,所述退镀液包括以下重量百分比的组分:
络合剂          10-30%,
辅助络合剂      0.5-5%,
湿润剂          0.05-0.5%,
余量为水;
其中,所述络合剂为氢氧化钠或氢氧化钾。
优选的,所述辅助络合剂选自磷酸钾、磷酸三钠、焦磷酸钾、焦磷酸钠、硫代硫酸钠或硫代硫酸钾。
优选的,所述湿润剂选自烷基糖苷、脂肪酸甲酯乙氧基化物磺酸盐、脂肪醇磷酸盐或脂肪醇醚磷酸酯。湿润剂的作用是一方面降低溶液与工件间的界面张力,使退镀下来的物质及气泡容易脱离待退镀工件表面,另一方面可在液面产生一层泡沫,防止碱雾逸出。
其中,在本发明中,铬钝化层包含三价铬或六价铬钝化层。
其中,在本发明中整个电解退镀过程为:将待退镀的铁件放入退镀液中,并连接至整流机正极作为阳极,将不锈钢板放入退镀液中连接至整流机负极作为阴极,铁件和不锈钢板在退镀液中相距2-50cm,整流机输出2-8V的直流电至电解退镀系统,初始阳极电流密度约为3-10A/dm2,此时铁件表面锌层开始溶解,不锈钢板表面锌层不断沉积,电流不断下降,当电流下降至稳定值后,即此时退镀过程完成,而转换成了电解水,电流值稳定,镀层被完全退除。
整个电解退镀过程如下:退镀工件为阳极,不锈钢板为阴极,二者同时放入退镀液中,在直流电作用下,阳极上金属镀层从基体上逐渐溶解,并以离子形式进入溶液;阴极上部分金属离子以粉末状还原析出。电解退镀过程与化学退镀相比,退镀速度比化学退镀要快,效率高;多数金属离子可直接在阴极析出,方便回收;由于金属离子析出,电解退镀液中金属离子浓度可维持较低水平,可以延长退镀液的使用寿命。
本发明的有益效果是:本发明的铁件表面锌层及铬钝化层电解退镀的方法能完全退除工件上的不合格的锌层及铬钝化层,退除效率高,8微米镀锌层约10分钟即可退完;不产生酸雾,对环境友好;退镀不对工件造成过腐蚀,不会产生氢脆;阴极沉积的锌粉可直接回收;工件上的不合格锌层、铬钝化层退除与阴极锌粉的沉积同时进行,减少工艺流程。
具体实施方式
实施例1
一种铁件表面锌层及铬钝化层电解退镀的方法,包括以下步骤:
1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统,其中,待退镀的铁件与不锈钢板在退镀液中的距离为5cm;
2)打开整流机,输出3V直流电压至电解退镀系统,开始电解退镀,铁件表面锌层和铬钝化层开始溶解,不锈钢板表面的锌层不断沉积,电解退镀系统电流不断下降;电解退镀系统的初始阳极电流密度为5A/dm2
3)当电解退镀系统的电流下降至稳定值后取出观察,若基材全部露出则表明电解退镀过程完成;
4)将铁件取出,清洗;收集不锈钢板表面锌层。
其中,所使用的退镀液包括以下重量百分比的组分:
Figure PCTCN2017112760-appb-000001
实施例2
一种铁件表面锌层及铬钝化层电解退镀的方法,包括以下步骤:
1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统,其中,待退镀的铁件与不锈钢板在退镀液中的距离为8cm;
2)打开整流机,输出6V直流电压至电解退镀系统,开始电解退镀,铁件表面锌层和铬钝化层开始溶解,不锈钢板表面的锌层不断沉积,电解退镀系统电流不断下降;电解退镀系统的初始阳极电流密度为7A/dm2
3)当电解退镀系统的电流下降至稳定值后取出观察,若基材全部露出则表明电解退镀过程完成;
4)将铁件取出,清洗;收集不锈钢板表面锌层。
其中,所使用的退镀液包括以下重量百分比的组分:
Figure PCTCN2017112760-appb-000002
Figure PCTCN2017112760-appb-000003
实施例3
一种铁件表面锌层及铬钝化层电解退镀的方法,包括以下步骤:
1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统,其中,待退镀的铁件与不锈钢板在退镀液中的距离为15cm;
2)打开整流机,输出7V直流电压至电解退镀系统,开始电解退镀,铁件表面锌层和铬钝化层开始溶解,不锈钢板表面的锌层或铬层不断沉积,电解退镀系统电流不断下降;电解退镀系统的初始阳极电流密度为6A/dm2
3)当电解退镀系统的电流下降至稳定值后取出观察,若基材全部露出则表明电解退镀过程完成;
4)将铁件取出,清洗;收集不锈钢板表面锌层。
其中,所使用的退镀液包括以下重量百分比的组分:
Figure PCTCN2017112760-appb-000004
实施例4
一种铁件表面锌层及铬钝化层电解退镀的方法,包括以下步骤:
1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统,其中,待退镀的铁件与不锈钢板在退镀液中的距离为20cm;
2)打开整流机,输出8V直流电压至电解退镀系统,开始电解退镀,铁件表面锌层的或铬钝化层开始溶解,不锈钢板表面的锌层不断沉积,电解退镀系统电流不断下降;电解退镀系统的初始阳极电流密度为10A/dm2
3)当电解退镀系统的电流下降至稳定值后取出观察,若基材全部露出则表明电解退镀过程完成;
4)将铁件取出,清洗;收集不锈钢板表面锌层或铬层。
其中,所使用的退镀液包括以下重量百分比的组分:
Figure PCTCN2017112760-appb-000005
Figure PCTCN2017112760-appb-000006
经过观察发现,本发明实施例1-4的铁件上的锌层及铬钝化层完全退除干净,退除效率高;基材表面没有受到腐蚀或损伤,也不产生氢脆的现象。其中,实施例1-4退镀过程的参数如表1所示。
表1实施例1-4退镀过程的参数
Figure PCTCN2017112760-appb-000007
由表1可以看出,实施例1-4的退镀过程用时短、效率高,厚度为8-13微米的镀层仅需要9-11分钟即可完全退除干净。

Claims (7)

  1. 一种铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,包括以下步骤:
    1)将待退镀的铁件放入退镀液中并连接至整流机正极作为阳极,将不锈钢板放入退镀液中接整流机负极作为阴极,组成电解退镀系统;
    2)打开整流机,输出直流电压至电解退镀系统,开始电解退镀,铁件表面锌层及铬钝化层开始溶解,不锈钢板表面的锌层不断沉积,电解退镀系统电流不断下降;
    3)当电解退镀系统的电流下降至稳定值后取出观察,若基材全部露出则表明电解退镀过程完成;
    4)将铁件取出,清洗,收集不锈钢板表面锌层。
  2. 根据权利要求1所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,在步骤1)中,待退镀的铁件与不锈钢板在退镀液中的距离为2-50cm。
  3. 根据权利要求1所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,在步骤2)中,整流机输出直流电压为2-8V。
  4. 根据权利要求1所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,电解退镀系统的初始阳极电流密度为3-10A/dm2
  5. 根据权利要求1所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,所述退镀液包括以下重量百分比的组分:
    络合剂          10-30%,
    辅助络合剂      0.5-5%,
    湿润剂          0.05-0.5%,
    余量为水;
    其中,所述络合剂为氢氧化钠或氢氧化钾。
  6. 根据权利要求5所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,所述辅助络合剂选自磷酸钾、磷酸三钠、焦磷酸钾、焦磷酸钠、硫代硫酸钠或硫代硫酸钾。
  7. 根据权利要求5所述的铁件表面锌层及铬钝化层电解退镀的方法,其特征在于,所述湿润剂选自烷基糖苷、脂肪酸甲酯乙氧基化物磺酸盐、脂肪醇磷酸盐或脂肪醇醚磷酸酯。
PCT/CN2017/112760 2017-06-01 2017-11-24 一种铁件表面锌层及铬钝化层电解退镀的方法 WO2018218894A1 (zh)

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