Potassium chloride cyanide-free cadmium plating layer structure

Abstract

The utility model discloses a potassium chloride cyanide-free cadmium plating layer structure which comprises a steel substrate, and a nickel-phosphorus alloy plating layer, a potassium chloride cyanide-free cadmium plating layer and an army green passivation layer which are sequentially prepared on the steel substrate from inside to outside. According to the potassium chloride cyanide-free cadmium plating layer structure disclosed by the utility model, an acetate fog test is carried out for 320 hours according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, no white corrosives are generated on the surface of a plated part, and the plating layer structure has excellent corrosion resistance; according to GB / T 5270-2005 < GB / T 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB /

Description

Technical Field

[0001] The utility model belongs to the technical field of metal surface treatment, and in particular relates to a potassium chloride cyanide-free cadmium plating layer structure. Background Art

[0002] In the prior art, the cyanide-free cadmium plating layer and the hexavalent chromium passivation layer prepared sequentially on the steel substrate have the problem of insufficient corrosion resistance. The standard electrode potential of cadmium is -0.402V, and the standard electrode potential of iron is -0.441V. The standard electrode potential of iron is negative to the standard electrode potential of cadmium. In the atmospheric environment, the cadmium plating layer is a cathodic plating layer relative to the steel substrate and has no electrochemical protection effect on the steel substrate. When the cadmium plating layer has pores or is damaged, galvanic corrosion will occur and destroy the steel substrate.

[0003] Nickel-phosphorus alloy has a series of advantages such as high hardness, good wear resistance, fine crystals, and strong corrosion resistance. It has been widely used in the electroplating industry. [1] The nickel-phosphorus alloy coating is usually used between the bright nickel coating and the surface coating to improve the corrosion resistance of the coating. So far, there is no literature report on the use of nickel-phosphorus alloy coating as a bottom coating.

[0004] The utility model patent "A high corrosion resistance cadmium plating layer for aerospace parts" with the authorization announcement number CN 204918772 U discloses a cyanide-free cadmium plating structure, including a steel substrate, and a cyanide-free cadmium plating layer and a hexavalent chromium low-chromium color passivation layer prepared on the steel substrate from the inside to the outside. At present, aerospace companies generally use this plating structure to prepare a protective layer for steel parts. [2] .

[0005] References: [1] Huang Qingan, Cai Naicai, Zuo Zhengzhong, Study on the cathodic behavior of phosphorous acid in electroplating of phosphorus-nickel alloy [J], Journal of Wuhan University (Natural Science Edition), 1982, No. 4, 55-60. [2] Chen Jianrui, Guo Chongwu, Application of cyanide-free acid cadmium plating on aerospace parts [J], Electroplating and Finishing, 2017, 39(3): 23-24+28. Utility Model Content

[0006] In order to solve the problem that direct cadmium plating on a steel substrate has no electrochemical protection in the atmospheric environment, the utility model provides a potassium chloride cyanide-free cadmium plating layer structure. In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A potassium chloride cyanide-free cadmium plating layer structure comprises a steel substrate, and a nickel-phosphorus alloy plating layer, a potassium chloride cyanide-free cadmium plating layer, and a military green passivation layer sequentially prepared from inside to outside on the steel substrate;

[0008] The thickness of the nickel-phosphorus alloy coating is 4-8 μm.

[0009] Preferably, the thickness of the potassium chloride cyanide-free cadmium plating layer is 8 to 20 μm.

[0010] Preferably, the thickness of the military green passivation layer is 0.4-0.7 μm.

[0011] A potassium chloride cyanide-free cadmium plating layer is prepared on the surface of a nickel-phosphorus alloy coating. The cadmium plating layer is an anodic coating relative to the nickel-phosphorus alloy coating. In this coating structure, the cadmium plating layer has an electrochemical protective effect on the nickel-phosphorus alloy coating.

[0012] Compared with the prior art, the utility model has the following beneficial effects:

[0013] The utility model discloses a potassium chloride cyanide-free cadmium plating layer structure, in which a nickel-phosphorus alloy plating layer is added between a traditional steel substrate and a cadmium plating layer. The cadmium plating layer is an anodic plating layer relative to the nickel-phosphorus alloy plating layer. This plating layer structure can effectively prevent the corrosive medium from corroding the substrate, thereby extending the service life of the plated parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 It is a schematic diagram of the coating structure of Example 1 and Example 2 of the utility model. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The schematic embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0017] A potassium chloride cyanide-free cadmium plating layer structure comprises a steel substrate, and a nickel-phosphorus alloy plating layer, a potassium chloride cyanide-free cadmium plating layer, and a military green passivation layer which are sequentially prepared from inside to outside on the steel substrate.

[0018] According to the current pre-treatment process, the steel workpiece substrate is degreased, derusted and activated.

[0019] After pre-treatment of steel parts, the nickel-phosphorus coating is prepared by the current high-corrosion-resistant nickel-phosphorus alloy plating process.

[0020] Preferably, the thickness of the nickel-phosphorus alloy coating is 4-8 μm.

[0021] Preferably, the nickel-phosphorus alloy coating is prepared by using the PROTEXYER 8713 high corrosion-resistant nickel-phosphorus alloy coating process of Chaobang Chemical:

[0022] PROTEXYER 8713 MU tank opening agent 580~620mL / L, nickel sulfate hexahydrate 280~340g / L, plating solution pH 2.6~2.7, plating tank temperature 60℃~65℃, cathode current density 3~6A / dm 2 , the cathode moves 3 to 5 m / min.

[0023] After the steel parts are plated with nickel-phosphorus alloy, the potassium chloride cyanide-free cadmium plating layer is prepared using the PULIZIER NCC-617 potassium chloride cyanide-free cadmium plating process developed by Chaobang Chemical.

[0024] Preferably, the thickness of the potassium chloride cyanide-free cadmium plating layer is 8 to 20 μm.

[0025] The PULIZIER NCC-617 potassium chloride cyanide-free cadmium plating process is: cadmium chloride 25-35g / L, potassium chloride 100-140g / L, PULIZIER NCC-617 AC complexing agent 100-140g / L, PULIZIER NCC-617 Base auxiliary agent 25-30mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5mL / L, PULIZIER NCC-617 HCD high zone brightener 8-12mL / L, plating tank temperature 20℃-35℃, plating solution pH 7-9, cathode current density 0.5-1.5A / dm 2 , the cathode moves 2 to 4 m / min.

[0026] The existing military green passivation process is used to prepare the military green passivation layer on steel parts after potassium chloride cyanide-free cadmium plating.

[0027] Preferably, the thickness of the military green passivation layer is 0.4-0.7 μm.

[0028] Preferably, the military green passivation layer is prepared using the OVG-31 military green passivation process of Chaobang Chemical:

[0029] OVG-31 military green passivator 80~120mL / L, passivation solution pH value 1.0~1.6, passivation temperature 20℃~30℃, air stirring or swinging the plated parts, passivation time 30~90s.

[0030] After the steel parts are passivated and washed with water, they are dried at 60℃~65℃ for 10~15min. Example

[0031] like Figure 1 As shown, a potassium chloride cyanide-free cadmium plating layer structure includes a steel substrate 1, and a nickel-phosphorus alloy plating layer 2, a potassium chloride cyanide-free cadmium plating layer 3, and a military green passivation layer 4 prepared sequentially from the inside to the outside on the steel substrate 1.

[0032] 1. Pre-treatment:

[0033] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → rust removal → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".

[0034] 2. Nickel-phosphorus alloy plating:

[0035] After pre-treatment of the steel parts, the nickel-phosphorus alloy coating 2 was prepared by using the PROTEXYER 8713 high-corrosion-resistant nickel-phosphorus alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0036] PROTEXYER 8713 MU tank opener 610mL / L, nickel sulfate hexahydrate 330g / L, bath pH 2.6, bath temperature 61°C, cathode current density 4A / dm 2 , cathode moves 4m / min.

[0037] 3. Cadmium plating:

[0038] After the steel parts are plated with nickel-phosphorus alloy, the potassium chloride cyanide-free cadmium plating layer 3 is prepared by the PULIZIER NCC-617 potassium chloride cyanide-free cadmium plating process developed by Chaobang Chemical, and the plating thickness is 12 μm.

[0039] Cadmium chloride 32g / L, potassium chloride 130g / L, PULIZIER NCC-617 AC complexing agent 130g / L, PULIZIERNCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2mL / L, PULIZIER NCC-617 HCD high zone brightener 10mL / L, plating tank temperature 30℃, plating solution pH 7.5, cathode current density 1A / dm 2 , cathode moves 3m / min.

[0040] 4. Passivation:

[0041] After cadmium plating, the steel parts were subjected to the OVG-31 military green passivation process of Chaobang Chemical to prepare the military green passivation layer 4, and the thickness of the passivation layer was 0.6 μm.

[0042] OVG-31 military green passivator 80~120mL / L, passivation solution pH 1.4, passivation temperature 25℃, swing plated parts, passivation time 50s.

[0043] 5. Drying:

[0044] The steel parts were passivated and washed with water and then dried at 64°C for 12 minutes. Example

[0045] like Figure 1 As shown, a potassium chloride cyanide-free cadmium plating layer structure includes a steel substrate 1, and a nickel-phosphorus alloy plating layer 2, a potassium chloride cyanide-free cadmium plating layer 3, and a military green passivation layer 4 prepared sequentially from the inside to the outside on the steel substrate 1.

[0046] 1. Pre-treatment:

[0047] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → rust removal → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".

[0048] 2. Nickel-phosphorus alloy plating:

[0049] After pre-treatment of the steel parts, the nickel-phosphorus alloy coating 2 was prepared by using the PROTEXYER 8713 high-corrosion-resistant nickel-phosphorus alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0050] PROTEXYER 8713 MU tank opener 590mL / L, nickel sulfate hexahydrate 290g / L, bath pH 2.7, bath temperature 63°C, cathode current density 4A / dm 2 , cathode moves 4m / min.

[0051] 3. Cadmium plating:

[0052] After the steel parts are plated with nickel-phosphorus alloy, the potassium chloride cyanide-free cadmium plating layer 3 is prepared by the PULIZIER NCC-617 potassium chloride cyanide-free cadmium plating process developed by Chaobang Chemical, and the plating thickness is 12 μm.

[0053] Cadmium chloride 28g / L, potassium chloride 110g / L, PULIZIER NCC-617 AC complexing agent 120g / L, PULIZIERNCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2mL / L, PULIZIER NCC-617 HCD high zone brightener 10mL / L, plating tank temperature 30℃, plating solution pH 8.5, cathode current density 1A / dm 2 , cathode moves 3m / min.

[0054] 4. Passivation:

[0055] After cadmium plating, the steel parts were subjected to the OVG-31 military green passivation process of Chaobang Chemical to prepare the military green passivation layer 4, and the coating thickness was 0.6 μm.

[0056] OVG-31 military green passivator 110mL / L, passivation solution pH 1.2, passivation temperature 25℃, air stirring, passivation time 40s.

[0057] 5. Drying:

[0058] The steel parts were passivated and washed with water and then dried at 62°C for 14 minutes.

[0059] Test Example 1:

[0060] In this test example, a salt spray test was performed on the potassium chloride cyanide-free cadmium plated samples prepared in Example 1 and Example 2, and an acetic acid salt spray test was performed for 320 hours in accordance with GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test". No white rust was generated on the surface of the plated parts, and the coating structure has good corrosion resistance.

[0061] Test Example 2:

[0062] In this test example, the potassium chloride cyanide-free cadmium plating samples prepared in Example 1 and Example 2 were tested for coating adhesion. The coating adhesion was determined by a thermal shock test method in accordance with GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates". The samples were placed in a heating furnace and heated to 300°C for 30 minutes, then taken out and suddenly cooled in water at room temperature. No bubbling or shedding occurred in the coating, indicating good adhesion.

[0063] The technical solutions provided by the embodiments of the present utility model are described in detail above. The principles and implementation methods of the embodiments of the present utility model are described in detail in this article using specific examples. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present utility model. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present utility model, which all belong to the protection scope of the present utility model.

Claims

1. A potassium chloride cyanide-free cadmium plating layer structure, characterized in that: It comprises a steel substrate, and a nickel-phosphorus alloy plating layer, a potassium chloride cyanide-free cadmium plating layer, and a military green passivation layer which are sequentially prepared from the inside to the outside on the steel substrate; The thickness of the nickel-phosphorus alloy coating is 4-8 μm.

2. The potassium chloride cyanide-free cadmium plating layer structure as claimed in claim 1, characterized in that: The thickness of the potassium chloride cyanide-free cadmium plating layer is 8 to 20 μm.

3. The potassium chloride cyanide-free cadmium plating layer structure as claimed in claim 1, characterized in that: The thickness of the military green passivation layer is 0.4-0.7 μm.

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