A method for stripping nickel layer on magnesium alloy surface

Abstract

The invention discloses a method for stripping nickel layer on the surface of magnesium alloy, which comprises the steps of ultrasonic degreasing cleaning, nickel stripping, nitric acid surface conditioning, alkaline polishing and drying. The ultrasonic degreasing cleaning solution is prepared from 10-20g / L potassium hydroxide, 5-10g / L sodium carbonate and 10-30g / L sodium phosphate; the nickel stripping solution is prepared from 300-750g / L hydrofluoric acid, 30-150g / L nitric acid, 100-150g / L phosphoric acid, 10-30g / L mixed complex acid and 5-10g / L hexamethylenetetramine; in the nitric acid surface conditioning, the magnesium alloy workpiece is placed in a dilute nitric acid solution with a concentration of 10-50ml / L for pickling; in the alkaline polishing, the magnesium alloy workpiece is placed in a sodium hydroxide solution with a concentration of 5-10g / L for immersion. The method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can quickly and completely remove the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate, thereby solving the problem of being unable to completely strip or corroding the magnesium alloy substrate in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material surface treatment, and in particular relates to a method for stripping a nickel layer on a magnesium alloy surface. Background Art

[0002] Magnesium alloy has the advantages of light weight, good heat dissipation, strong shock absorption, high electromagnetic shielding efficiency, etc. It is increasingly widely used in the fields of automobiles, electronics, rail transportation, aerospace, military industry, etc. Nickel plating on the surface of magnesium alloy workpieces can make magnesium alloy have high corrosion resistance while maintaining its electrical conductivity and welding performance. Since magnesium alloy itself has high chemical activity, it is difficult to nickel-plate magnesium alloy, and the yield rate of nickel layer on the surface of magnesium alloy is not high. Therefore, it is necessary to strip the unqualified nickel layer and then re-plating the surface of magnesium alloy with nickel.

[0003] The methods for stripping the nickel layer on the surface of magnesium alloy in the prior art are mainly electrolytic method and chemical stripping method. Due to the electric field distribution, the electrolytic method is not ideal for stripping the nickel layer on the corners or inner cavity walls of complex workpieces. The chemical stripping method mainly uses concentrated nitric acid for stripping. Yellow smoke emerges during the stripping process, which brings about environmental pollution problems and often causes corrosion of the magnesium alloy matrix, eventually causing the workpiece to be unusable and scrapped. Moreover, the chemical stripping method in the prior art generally adopts pre-nickel stripping and then secondary deep nickel stripping. The process is cumbersome and easily causes galvanic corrosion between the magnesium alloy and nickel, which easily leads to the scrapping of the workpiece.

[0004] Therefore, developing a method for stripping the nickel layer on the surface of a magnesium alloy so as to quickly remove the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate is a technical problem that urgently needs to be solved in the art. Summary of the invention

[0005] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a method for stripping the nickel layer on the surface of a magnesium alloy, and the method for stripping the nickel layer on the surface of a magnesium alloy comprises the following steps:

[0006] Ultrasonic degreasing cleaning: Put the magnesium alloy workpiece with a nickel layer on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning liquid used for ultrasonic degreasing cleaning is prepared by 10-20g / L potassium hydroxide, 5-10g / L sodium carbonate, and 10-30g / L sodium phosphate. The ultrasonic degreasing cleaning time is controlled to be 2-5min, and the ultrasonic degreasing cleaning temperature is controlled to be >60°C.

[0007] Nickel stripping: Under room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in the nickel stripping liquid, swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, and after 5 to 15 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 300 to 750 g / L of hydrofluoric acid, 30 to 150 g / L of nitric acid, 100 to 150 g / L of phosphoric acid, 10 to 30 g / L of mixed complex acid, and 5 to 10 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for use;

[0008] Nitric acid surface conditioning: At room temperature, place the magnesium alloy workpiece after nickel stripping in a dilute nitric acid solution with a concentration of 10-50 ml / L for pickling. After 5-20 seconds, take out the magnesium alloy workpiece and wash it with deionized water;

[0009] Alkaline bleaching: Place the magnesium alloy workpiece after nitric acid treatment in a sodium hydroxide solution with a concentration of 5-10g / L for immersion, and swing the magnesium alloy workpiece. The immersion time is controlled to be 5-10min, and the immersion temperature is controlled to be 60-90℃;

[0010] Drying: Place the magnesium alloy workpiece after alkaline polishing in a drying furnace with an exhaust device for drying to complete the stripping of the nickel layer on the surface of the magnesium alloy.

[0011] Furthermore, in the above method for stripping the nickel layer on the surface of the magnesium alloy:

[0012] In the ultrasonic degreasing cleaning step, the cleaning solution used for ultrasonic degreasing cleaning is prepared by 10 g / L potassium hydroxide, 5 g / L sodium carbonate, and 10 g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 5 min, and the ultrasonic degreasing cleaning temperature is controlled to be 90° C.

[0013] In the nickel stripping step, the nickel stripping solution is prepared in the following manner: 300 g / L of hydrofluoric acid, 30 g / L of nitric acid, 100 g / L of phosphoric acid, 10 g / L of mixed complex acid, and 5 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use;

[0014] In the nitric acid surface conditioning step, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 10 ml / L for pickling, and the magnesium alloy workpiece is taken out after 20 seconds;

[0015] In the alkaline light emitting step, the magnesium alloy workpiece after the nitric acid surface treatment is placed in a sodium hydroxide solution with a concentration of 5 g / L for immersion, the immersion time is controlled to be 10 minutes, and the immersion temperature is controlled to be 90°C.

[0016] Furthermore, in the above method for stripping the nickel layer on the surface of the magnesium alloy:

[0017] In the ultrasonic degreasing cleaning step, the cleaning solution used for ultrasonic degreasing cleaning is prepared by 20g / L potassium hydroxide, 10g / L sodium carbonate, and 30g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 2min, and the ultrasonic degreasing cleaning temperature is controlled to be 65°C;

[0018] In the nickel stripping step, the nickel stripping solution is prepared in the following manner: 750 g / L of hydrofluoric acid, 150 g / L of nitric acid, 150 g / L of phosphoric acid, 30 g / L of mixed complex acid, and 10 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use;

[0019] In the nitric acid surface conditioning step, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 50 ml / L for pickling, and the magnesium alloy workpiece is taken out after 5 seconds;

[0020] In the alkaline light emitting step, the magnesium alloy workpiece after nitric acid surface conditioning is placed in a sodium hydroxide solution with a concentration of 10 g / L for immersion, and the magnesium alloy workpiece is swung. The immersion time is controlled to be 5 minutes and the immersion temperature is controlled to be 60° C.

[0021] Furthermore, in the above method for stripping the nickel layer on the surface of the magnesium alloy:

[0022] In the ultrasonic degreasing cleaning step, the cleaning solution used for ultrasonic degreasing cleaning is prepared from 14-16 g / L potassium hydroxide, 6-8 g / L sodium carbonate, and 15-25 g / L sodium phosphate, and the ultrasonic degreasing cleaning time is controlled to be 3-4 min;

[0023] In the nickel stripping step, the nickel stripping solution is prepared in the following manner: 500-550 g / L of hydrofluoric acid, 80-100 g / L of nitric acid, 120-130 g / L of phosphoric acid, 15-25 g / L of mixed complex acid, and 8-12 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use;

[0024] In the nitric acid surface conditioning step, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 25 to 35 ml / L for pickling, and the magnesium alloy workpiece is taken out after 10 to 15 seconds;

[0025] In the alkaline light emitting step, the magnesium alloy workpiece after nitric acid surface treatment is placed in a sodium hydroxide solution with a concentration of 6-8 g / L for immersion, the immersion time is controlled to be 6-8 minutes, and the immersion temperature is controlled to be 70-80°C.

[0026] Furthermore, in the above method for stripping the nickel layer on the surface of magnesium alloy: the mixed complex acid is formed by mixing two or more of citric acid, lactic acid, malic acid and tartaric acid.

[0027] The method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can quickly and completely remove the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate, thereby solving the problem of being unable to completely strip or corroding the magnesium alloy substrate in the prior art.

[0028] More specifically, the method for stripping the nickel layer on the surface of a magnesium alloy of the present invention has the following advantages and beneficial effects:

[0029] 1. Compared with the electrolytic nickel stripping method in the prior art, the method for stripping the nickel layer on the surface of magnesium alloy of the present invention can quickly remove the nickel layer on the surface of various complex magnesium alloy parts, solving the problem that the nickel layer on the corners and inner walls of complex workpieces cannot be completely removed.

[0030] 2. Compared with the chemical nickel stripping method in the prior art, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can quickly dissolve the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate, thereby solving the problem of corrosion of the magnesium alloy substrate. Moreover, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention adopts a one-step method to directly strip nickel, without the need for pre-stripping and then secondary deep stripping of nickel in the chemical nickel stripping method of the prior art, thereby simplifying the process and avoiding galvanic corrosion between the magnesium alloy and nickel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings in the following descriptions are only used to further understand the embodiments of the present invention and constitute a part of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0032] Figure 1 It is a flow chart of the method for stripping the nickel layer on the surface of a magnesium alloy of the present invention;

[0033] Figure 2 The present invention is a photograph of a magnesium alloy with nickel plating on its surface before the method for stripping the nickel layer on the surface of the magnesium alloy is implemented, wherein (a) is the front side of the magnesium alloy, and (b) is the back side of the magnesium alloy;

[0034] Figure 3 The present invention is a photograph of a magnesium alloy after the nickel stripping step is completed using the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention, wherein (a) is the front side of the magnesium alloy, and (b) is the back side of the magnesium alloy;

[0035] Figure 4The photographs are of the magnesium alloy after the alkaline light emitting step is completed by the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention, wherein (a) is the front side of the magnesium alloy, and (b) is the back side of the magnesium alloy. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the method for stripping the nickel layer on the surface of a magnesium alloy of the present invention comprises the following steps:

[0038] S1. Ultrasonic degreasing cleaning: Put the magnesium alloy workpiece with a nickel layer on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning liquid used for ultrasonic degreasing cleaning is prepared by 10-20g / L potassium hydroxide, 5-10g / L sodium carbonate, and 10-30g / L sodium phosphate. The ultrasonic degreasing cleaning time is controlled to be 2-5min, and the ultrasonic degreasing cleaning temperature is controlled to be >60°C.

[0039] S2. Nickel stripping: Under room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in the nickel stripping liquid, and swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, observe the nickel layer on the surface of the magnesium alloy workpiece, and after 5 to 15 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 300 to 750 g / L of hydrofluoric acid, 30 to 150 g / L of nitric acid, 100 to 150 g / L of phosphoric acid, 10 to 30 g / L of mixed complex acid, and 5 to 10 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for use;

[0040] S3, nitric acid surface conditioning: at room temperature, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 10 to 50 ml / L for pickling, and the magnesium alloy workpiece is taken out after 5 to 20 seconds and washed with deionized water;

[0041] S4. Alkaline light emitting: Place the magnesium alloy workpiece after nitric acid surface treatment in a sodium hydroxide solution with a concentration of 5-10g / L for immersion, and swing the magnesium alloy workpiece. The immersion time is controlled to be 5-10min, and the immersion temperature is controlled to be 60-90℃;

[0042] S5. Drying: The magnesium alloy workpiece after alkaline polishing is placed in a drying furnace with an exhaust device for drying to complete the stripping of the nickel layer on the surface of the magnesium alloy.

[0043] As a specific embodiment, the mixed complex acid used in the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can be a mixture of two or more of citric acid, lactic acid, malic acid and tartaric acid.

[0044] The method for stripping the nickel layer on the surface of a magnesium alloy of the present invention is described in detail below in conjunction with specific embodiments.

[0045] Example 1

[0046] The method for stripping the nickel layer on the surface of a magnesium alloy according to Example 1 of the present invention comprises the following steps:

[0047] S11, ultrasonic degreasing cleaning: placing the magnesium alloy workpiece with a nickel layer plated on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning solution used for ultrasonic degreasing cleaning is prepared from 10 g / L potassium hydroxide, 5 g / L sodium carbonate, and 10 g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 5 min, and the ultrasonic degreasing cleaning temperature is controlled to be 90°C;

[0048] S12, nickel stripping: at room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in a nickel stripping liquid, and swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, observe the nickel layer on the surface of the magnesium alloy workpiece, and after 15 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 300g / L hydrofluoric acid, 30g / L nitric acid, 100g / L phosphoric acid, 10g / L mixed complex acid, and 5g / L hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for use;

[0049] S13, nitric acid surface conditioning: at room temperature, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 10 ml / L for pickling, and the magnesium alloy workpiece is taken out after 20 seconds and washed with deionized water;

[0050] S14, alkaline light emitting: the magnesium alloy workpiece after nitric acid surface conditioning is placed in a sodium hydroxide solution with a concentration of 5g / L for immersion, and the magnesium alloy workpiece is swung, the immersion time is controlled to be 10min, and the immersion temperature is controlled to be 90°C;

[0051] S15, drying: placing the magnesium alloy workpiece after alkaline polishing in a drying furnace with an exhaust device for drying, so as to complete the stripping of the nickel layer on the surface of the magnesium alloy.

[0052] Example 2

[0053] The method for stripping the nickel layer on the surface of a magnesium alloy according to embodiment 2 of the present invention comprises the following steps:

[0054] S21, ultrasonic degreasing cleaning: placing the magnesium alloy workpiece with a nickel layer plated on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning solution used for ultrasonic degreasing cleaning is prepared from 20 g / L potassium hydroxide, 10 g / L sodium carbonate, and 30 g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 2 min, and the ultrasonic degreasing cleaning temperature is controlled to be 65°C;

[0055] S22, nickel stripping: at room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in a nickel stripping liquid, and swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, observe the nickel layer on the surface of the magnesium alloy workpiece, and after 5 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 750g / L hydrofluoric acid, 150g / L nitric acid, 150g / L phosphoric acid, 30g / L mixed complex acid, and 10g / L hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use;

[0056] S23, nitric acid surface conditioning: at room temperature, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 50 ml / L for pickling, and the magnesium alloy workpiece is taken out after 5 seconds and washed with deionized water;

[0057] S24, alkaline light emitting: the magnesium alloy workpiece after nitric acid surface treatment is placed in a sodium hydroxide solution with a concentration of 10g / L for immersion, and the magnesium alloy workpiece is swung, the immersion time is controlled to be 5min, and the immersion temperature is controlled to be 60°C;

[0058] S25, drying: placing the magnesium alloy workpiece after alkaline polishing in a drying furnace with an exhaust device for drying, so as to complete the stripping of the nickel layer on the surface of the magnesium alloy.

[0059] Example 3

[0060] The method for stripping the nickel layer on the surface of a magnesium alloy according to Example 3 of the present invention comprises the following steps:

[0061] S31, ultrasonic degreasing cleaning: placing the magnesium alloy workpiece with a nickel layer plated on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning liquid used for ultrasonic degreasing cleaning is prepared by 14-16 g / L potassium hydroxide, 6-8 g / L sodium carbonate, and 15-25 g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 3-4 min, and the ultrasonic degreasing cleaning temperature is controlled to be >60°C;

[0062] S32, nickel stripping: at room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in a nickel stripping liquid, and swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, observe the nickel layer on the surface of the magnesium alloy workpiece, and after 8 to 12 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 500 to 550 g / L of hydrofluoric acid, 80 to 100 g / L of nitric acid, 120 to 130 g / L of phosphoric acid, 15 to 25 g / L of mixed complex acid, and 8 to 12 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for use;

[0063] S33, nitric acid surface conditioning: at room temperature, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 25-35 ml / L for pickling, and the magnesium alloy workpiece is taken out after 10-15 seconds and washed with deionized water;

[0064] S34, alkaline light emitting: the magnesium alloy workpiece after nitric acid surface treatment is placed in a sodium hydroxide solution with a concentration of 6-8g / L for immersion, and the magnesium alloy workpiece is swung, the immersion time is controlled to be 6-8min, and the immersion temperature is controlled to be 70-80°C;

[0065] S35, drying: placing the magnesium alloy workpiece after alkaline polishing in a drying furnace with an exhaust device for drying, so as to complete the stripping of the nickel layer on the surface of the magnesium alloy.

[0066] Figures 2 to 4 The comparison of the effects before and after the stripping of the nickel layer on the surface of the magnesium alloy is shown, and it can be intuitively seen that the stripping method of the nickel layer on the surface of the magnesium alloy of the present invention can fully strip all the surface nickel layers on the magnesium alloy, and the magnesium alloy substrate remains intact without any corrosion, thereby ensuring the normal use of the magnesium alloy workpiece.

[0067] In summary, compared with the prior art, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can quickly and completely remove the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate, thereby solving the problem that the prior art cannot completely strip the nickel layer or corrodes the magnesium alloy substrate. More specifically, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention has the following advantages and beneficial effects:

[0068] 1. Compared with the electrolytic nickel stripping method in the prior art, the method for stripping the nickel layer on the surface of magnesium alloy of the present invention can quickly remove the nickel layer on the surface of various complex magnesium alloy parts, solving the problem that the nickel layer on the corners and inner walls of complex workpieces cannot be completely removed.

[0069] 2. Compared with the chemical nickel stripping method in the prior art, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention can quickly dissolve the nickel layer on the surface of the magnesium alloy without damaging the magnesium alloy substrate, thereby solving the problem of corrosion of the magnesium alloy substrate. Moreover, the method for stripping the nickel layer on the surface of the magnesium alloy of the present invention adopts a one-step method to directly strip nickel, without the need for pre-stripping and then secondary deep stripping of nickel in the chemical nickel stripping method of the prior art, thereby simplifying the process and avoiding galvanic corrosion between the magnesium alloy and nickel.

[0070] It should be noted that, in this article, unless otherwise clearly specified and limited, the term "connection" or its synonyms should be understood in a broad sense. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. Moreover, expressions such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. At the same time, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this article are all referenced to the placement state shown in the accompanying drawings.

[0071] It should also be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for stripping a nickel layer on a magnesium alloy surface, characterized in that: The method for stripping the nickel layer on the surface of the magnesium alloy comprises the following steps: Ultrasonic degreasing cleaning: Put the magnesium alloy workpiece with a nickel layer on the surface into an ultrasonic cleaning device for ultrasonic degreasing cleaning, wherein the cleaning liquid used for ultrasonic degreasing cleaning is prepared by 10-20g / L potassium hydroxide, 5-10g / L sodium carbonate, and 10-30g / L sodium phosphate. The ultrasonic degreasing cleaning time is controlled to be 2-5min, and the ultrasonic degreasing cleaning temperature is controlled to be >60°C. Nickel stripping: Under room temperature, immerse the magnesium alloy workpiece after ultrasonic degreasing and cleaning in the nickel stripping liquid, swing the magnesium alloy workpiece to make all parts of the magnesium alloy workpiece fully contact with the nickel stripping liquid, and after 5 to 15 minutes, when the nickel layer on the surface of the magnesium alloy workpiece turns black and dissolves, take out the magnesium alloy workpiece, and wash the residual nickel stripping liquid on the surface with deionized water, wherein the nickel stripping liquid is prepared in the following manner: 300 to 750 g / L of hydrofluoric acid, 30 to 150 g / L of nitric acid, 100 to 150 g / L of phosphoric acid, 10 to 30 g / L of mixed complex acid, and 5 to 10 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for use; Nitric acid surface conditioning: At room temperature, place the magnesium alloy workpiece after nickel stripping in a dilute nitric acid solution with a concentration of 10-50 ml / L for pickling. After 5-20 seconds, take out the magnesium alloy workpiece and wash it with deionized water; Alkaline bleaching: Place the magnesium alloy workpiece after nitric acid treatment in a sodium hydroxide solution with a concentration of 5-10g / L for immersion, and swing the magnesium alloy workpiece. The immersion time is controlled to be 5-10min, and the immersion temperature is controlled to be 60-90℃; Drying: Place the magnesium alloy workpiece after alkaline polishing in a drying furnace with an exhaust device for drying to complete the stripping of the nickel layer on the surface of the magnesium alloy.

2. The method for stripping the nickel layer on the surface of a magnesium alloy as claimed in claim 1, characterized in that: In the ultrasonic degreasing cleaning step, the cleaning solution used for ultrasonic degreasing cleaning is prepared by 10 g / L potassium hydroxide, 5 g / L sodium carbonate, and 10 g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 5 min, and the ultrasonic degreasing cleaning temperature is controlled to be 90° C. In the nickel stripping step, the nickel stripping solution is prepared in the following manner: 300 g / L of hydrofluoric acid, 30 g / L of nitric acid, 100 g / L of phosphoric acid, 10 g / L of mixed complex acid, and 5 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use; In the nitric acid surface conditioning step, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 10 ml / L for pickling, and the magnesium alloy workpiece is taken out after 20 seconds; In the alkaline light emitting step, the magnesium alloy workpiece after the nitric acid surface treatment is placed in a sodium hydroxide solution with a concentration of 5 g / L for immersion, the immersion time is controlled to be 10 minutes, and the immersion temperature is controlled to be 90°C.

3. The method for stripping nickel layer on the surface of magnesium alloy according to claim 1, characterized in that: In the ultrasonic degreasing cleaning step, the cleaning solution used for ultrasonic degreasing cleaning is prepared by 20g / L potassium hydroxide, 10g / L sodium carbonate, and 30g / L sodium phosphate, the ultrasonic degreasing cleaning time is controlled to be 2min, and the ultrasonic degreasing cleaning temperature is controlled to be 65°C; In the nickel stripping step, the nickel stripping solution is prepared in the following manner: 750 g / L of hydrofluoric acid, 150 g / L of nitric acid, 150 g / L of phosphoric acid, 30 g / L of mixed complex acid, and 10 g / L of hexamethylenetetramine are added into an acid-resistant tank with a ventilation device, and stirred evenly for standby use; In the nitric acid surface conditioning step, the magnesium alloy workpiece after nickel stripping is placed in a dilute nitric acid solution with a concentration of 50 ml / L for pickling, and the magnesium alloy workpiece is taken out after 5 seconds; In the alkaline light emitting step, the magnesium alloy workpiece after nitric acid surface conditioning is placed in a sodium hydroxide solution with a concentration of 10 g / L for immersion, and the magnesium alloy workpiece is swung. The immersion time is controlled to be 5 minutes and the immersion temperature is controlled to be 60° C.

4. The method for stripping nickel layer on the surface of magnesium alloy according to any one of claims 1 to 3, characterized in that: The mixed complex acid is formed by mixing two or more of citric acid, lactic acid, malic acid and tartaric acid.

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