JP2015190024A - Thin film plating method improving anticorrosion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that, for example, in multilayer plating using only a DC power supply, a plating layer becomes thicker.SOLUTION: A metallic substrate serving as a cathode is immersed in an electrolyte, electrical plating using a high speed current inversion power supply and electrical plating using a DC power supply, are alternately performed for performing multilayer plating, and plating layers are sequentially formed on minute, uniform, and thin plating layers, thereby the multilayer plating becomes thinner, overall.

Description

  The present invention relates to a thin film plating method in which a metal base is plated as a cathode and a current is reversed at a high speed so as to dissolve a plating surface as an anode, thereby forming a uniform and dense plating layer and improving corrosion resistance.

  Conventionally, in electroplating, a metal base is used as a cathode, a direct current is passed through an electrolytic solution containing metal ions, and metal ions are discharged and deposited on the surface of the metal base to form a plating layer.

  Specifically, a plating layer having a predetermined film thickness is formed on the surface of the metal substrate by filling the electrolytic solution in the electrolytic cell arranged with the metal substrate as a cathode and facing the anode and supplying a direct current. It is general (see, for example, Patent Document 1).

JP 2002-220690 A

  However, in the above prior art, for example, as shown in FIG. 2, bubbles (hydrogen) generated on the surface of the metal substrate are generated more unevenly in the high current portion and less in the low current portion. Due to the tendency, it is difficult to form a dense and uniform plating layer because the high current part is thick and the low current part is thinly plated. As a result, when performing multi-layer plating, the plating layer must be thick. There was a problem that had to be solved.

  In view of the problem that the plating layer becomes thick in the multi-layer plating only with a DC power source based on the above-mentioned conventional technology, the present invention is soaked in an electrolytic solution using a metal substrate as a cathode, Multi-layer plating is performed by alternately performing electroplating with a power source, and by sequentially forming a plating layer on a dense and uniform thin plating layer, it is possible to comprehensively reduce the thickness of the multi-layer plating, Solve the above problems.

  In short, in the present invention, multilayer plating is performed by immersing a metal base in an electrolyte solution as a cathode, and alternately performing electroplating with a high-speed current reversal power source and electroplating with a DC power source. Even if plated, there is little dissolution at the time of reversal, but since the plating is thick at the high current portion but also at the time of reversal, it is possible to form a uniform and dense thin plating layer as a whole. Since electroplating with a direct current power source is applied on the layer, multilayering is achieved by changing the precipitated crystal particles, thereby improving corrosion resistance and saving materials (Ni materials and brighteners) with a thinner plating thickness. Since it is possible to reduce the cost, it is possible to reduce the cost.

It is an enlarged view showing a bubble generation situation in high-speed current reversal electrolysis. It is an enlarged view showing the bubble generation situation in direct current electrolysis. It is an expanded sectional view of the membrane | film | coat formed by electroplating with a high-speed current reversal power supply. It is an expanded sectional view of the membrane | film | coat formed by electroplating with a DC power supply. It is a current waveform figure in a high-speed current reversal power supply. It is a current waveform diagram in a DC power supply. It is the graph which compared the glossiness of the direct current | flow method and the inversion method. It is the graph which compared the uniform electrodeposition property of the direct current | flow method and the inversion method.

  In the surface treatment method according to the present invention, multilayer plating is performed by immersing the metal base in an electrolyte solution as a cathode and alternately performing electroplating with a high-speed current reversing power source described later and electroplating with a DC power source. .

  When electroplating, bubbles are generated from the surface of the metal substrate. When these bubbles are observed by the transmitted light method, the generation of bubbles is detected by a high-speed current reversing power source (Fig. 1) from a DC power source (see Fig. 2). The number of air bubbles is larger, and small air bubbles appear uniformly.

  The high-speed current reversal power supply has faster movement of the active point in the direction of the low current part than the high current part, so that bubbles are made smaller and uniform. Yes (see FIG. 8).

  In the high current portion and the low current portion, the high current portion has a high current density, so that the high current portion has a high current density, so much plating occurs, but there is a lot of dissolution.

  If the plating film is a high-speed current reversal power supply than a conventional DC power supply, uniform and dense plating can be achieved.

  Then, by plating the base with the above method and plating with good leveling with a DC power supply, a plating line with the aim of improving corrosion resistance and reducing costs can be created with a combination of thinner plating films than before. .

  When the cross-sectional structure of the plating layer is observed, the columnar structure (see FIG. 4), which is a direct current characteristic, is different depending on the reversal ratio or the composition of the plating solution in the case of a high-speed current reversal waveform. (See FIG. 3).

  As for the glossiness of the plating, plating with a remarkably higher gloss than the direct current is seen in the low frequency region in the current reversal, and a glossiness of 3 times or more of the direct current is obtained (see FIG. 7).

  For example, in the case of decorative plating Ni-Cr (the transport device is an elevator type), in order to make SBN (semi-bright nickel) and BN (bright nickel) plating thinner than before, SBN is a little (1 rack) with a high-speed current reversal power supply. After plating (see FIG. 3), plating is performed with a DC power source (see FIG. 4), and then BN is plated with a high-speed current reversal power source (see FIG. 3), followed by plating with good leveling with the DC power source (FIG. 3). 4).

  Then, by making the multilayer by changing the precipitated crystal particles, the corrosion resistance is improved and the materials (Ni material and brightener) are saved with a thinner plating thickness than the conventional one.

  FIG. 5 is an example of a current waveform by the reversal current method using a high-speed current reversal power source in the plating method, and FIG. 6 is an example of a current waveform by the direct current method.

  In the case of the 60 Hz area, the current is rectified to a current of the waveform shown in FIG.

In the case of the inversion current waveform shown in FIG. 5 by the high-speed current inversion power source, the inversion ratio of anode: cathode is 15: 3, and the frequency is 15 Hz in the 60 Hz region. Therefore, the inversion ratio 15 of the reference waveform shown in FIG. : 3 is a special waveform in which plus time is five times longer than minus time in one cycle and plus and minus are repeatedly output 15 times per second.
Although the inversion current waveform has an inversion ratio of 15: 3, the inversion ratio can be changed variously.

  In addition, the electrolysis with high-speed current reversal in the above method is also effective for electrolytic degreasing and electrolytic polishing.

For example, if the purpose is to remove rust and scale, electrolysis using an acidic bath such as hydrochloric acid will have a large removal effect, and stubborn oxides such as scales and welds can be easily removed by changing the positive time ratio. Activated, the adhesion of the plating film is good, and the gloss is improved.
In addition, the anodization of aluminum materials has already been widely used in sulfuric acid baths, oxalic acid baths, sulfuric acid / oxalic acid mixed baths, and the like.

Claims (1)

  Thin film plating with improved corrosion resistance, characterized by immersing a metal substrate in the electrolyte as a cathode and performing multi-layer plating by alternately performing electroplating with a high-speed current reversal power supply and electroplating with a DC power supply Method.

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