Corrosive liquid for detecting ratio of skip plating area of copper-plated welding wire and detection method of corrosive liquid

Abstract

The invention provides corrosive liquid for detecting the proportion of a skip plating area of a copper-plated welding wire and a detection method of the corrosive liquid. The corrosive liquid comprises a hydrochloric acid solution and a lead nitrate solution; the hydrochloric acid solution is prepared by mixing 50-80 ml of analytically pure concentrated hydrochloric acid and 50 ml of water, and the lead nitrate solution is prepared from 5-10 g of analytically pure lead nitrate and 100 g of water; the detection method comprises the steps of sample preparation, chemical corrosion and metallographic microscope observation and analysis. The specific operation comprises the steps that a sample is soaked in the hydrochloric acid solution for 15-30 s, the sample is soaked in the lead nitrate solution for 10-20 s after being washed and blow-dried through alcohol, and after being washed and blow-dried through alcohol, the proportion of the skip plating area is calculated through analysis software of a metallographic microscope according to different proportions of organizational structures. The corrosive liquid and the detection method provided by the invention can completely and clearly display the skip plating area, can quantitatively evaluate the skip plating quality of welding wire copper plating, and have the characteristics of low detection cost, rapidness and simplicity.

Description

Technical Field

[0001] The invention belongs to the technical field of metal coating detection, and particularly relates to a corrosive liquid for detecting plating leakage of a copper-plated welding wire and a detection method thereof. Background Art

[0002] The main purpose of copper plating of welding wire is corrosion prevention. The main component of welding wire is steel, which is easy to rust and corrode when exposed to the atmosphere. Plating a layer of copper on the surface can effectively extend the shelf life and enhance the conductivity. However, due to various reasons, the surface of the welding wire may be leaking. The defects of the copper plating layer of the welding wire make the plating layer very easy to peel off. The peeled copper layer accumulates on the copper conductive nozzle of the welding gun during welding. At the high temperature of welding, the copper powder sinters on the conductive nozzle, making the effective aperture of the conductive nozzle smaller, thus causing poor wire feeding.

[0003] The cross-sectional metallographic method is currently used to detect copper plating leakage in welding wires. This method requires cutting, inlaying, grinding, polishing and other processes, which is time-consuming and inefficient. In addition, the coating is easily damaged during the sample preparation process, resulting in deviations in the test results. In addition, the test surface is limited, and only the coating condition of a single cross-section can be observed, and the overall morphology of the copper plating layer of the entire welding wire cannot be fully observed.

[0004] Based on the above situation, there is an urgent need for a method to efficiently and completely detect the proportion of the copper-plated welding wire leakage area, which can quickly and completely display the overall morphology of the copper plating of the welding wire, thereby providing control direction for production. Summary of the invention

[0005] The purpose of the present invention is to provide a corrosive liquid and a detection method for detecting the proportion of the missed plating area of ​​a copper-plated welding wire, which can obtain a complete and clear overall morphology of the copper plating layer of the welding wire, can completely and clearly display the missed plating area, can quantitatively evaluate the quality of the missed plating of the copper plating of the welding wire, and has the characteristics of low detection cost, fast and simple.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A corrosion solution for detecting the proportion of a copper-plated welding wire leaking area comprises a hydrochloric acid solution and a lead nitrate solution, wherein the hydrochloric acid solution is prepared by mixing 50 ml to 80 ml of analytically pure concentrated hydrochloric acid and 50 ml of water, and the lead nitrate solution is prepared by mixing 5 g to 10 g of analytically pure lead nitrate and 100 g of water.

[0007] A method for detecting the proportion of the missed plating area of ​​a copper-plated welding wire comprises sample preparation, chemical corrosion and metallographic microscope observation and analysis, wherein the corrosion liquid used for the chemical corrosion comprises a hydrochloric acid solution and a lead nitrate solution, the hydrochloric acid solution is prepared by mixing 50ml-80ml of analytically pure concentrated hydrochloric acid and 50ml of water, and the lead nitrate solution is prepared by mixing 5g-10g of analytically pure lead nitrate and 100g of water.

[0008] Furthermore, the specific operation of the chemical corrosion of the present invention is: immersing the sample in the hydrochloric acid solution for 15 to 30 seconds, rinsing with alcohol and blowing dry, then immersing in the lead nitrate solution for 10 to 20 seconds, and then rinsing with alcohol and blowing dry.

[0009] Furthermore, in the chemical etching of the present invention, the temperature of the hydrochloric acid solution is 50-70°C.

[0010] Furthermore, the specific operation of sample preparation described in the present invention is: take the welding wire coil, cut 5 to 10 samples with a length of 20±5 mm with a shearing machine, put the samples into an ultrasonic cleaner for cleaning, rinse with alcohol and blow dry; the surface of the sample after sample preparation should be clean and free of dirt.

[0011] Furthermore, in the metallographic microscope observation and analysis described in the present invention, the sample after chemical corrosion is placed under a metallographic microscope for observation, and the proportion of the leaky plating area is calculated according to the different proportions of the organizational structure through the analysis software provided by the metallographic microscope.

[0012] Furthermore, the metallographic microscope described in the present invention is a ZEISS AXIO Imager metallographic microscope.

[0013] The beneficial effects of adopting the above technical solution are: 1. The etching solution provided by the present invention can clearly display the overall morphology of the copper plating layer's missed plating area.

[0014] 2. The method of the present invention overcomes the defects of the traditional cross-section metallographic method in observing the leakage of copper-plated welding wire, that is, the middle coating is easily damaged, the detection surface is limited, and the overall morphology of the copper-plated layer of the entire welding wire cannot be fully observed.

[0015] 3. The method provided by the present invention can completely and clearly display the overall morphology and the leakage area of ​​the copper plating layer of the welding wire, can quantitatively evaluate the leakage quality of the copper plating of the welding wire, and has the characteristics of low detection cost, fast and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The area percentage analysis diagram of the plating leakage area obtained in Example 1; Figure 2 The area percentage analysis diagram of the plating leakage area obtained in Example 2; Figure 3 The area percentage analysis diagram of the leakage plating area obtained in Example 3; Figure 4 This is the morphology of the leakage plating area obtained by cross-section metallography in comparative example 1. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0018] The copper-plated welding wire wire rod in this embodiment is ER70S-6, and the method for detecting the proportion of the unplated area of ​​the copper-plated welding wire includes sample preparation, chemical corrosion and metallographic microscope observation and analysis, which are as follows: (1) Sample preparation: Take the welding wire rod and cut 5 samples with a length of 25 mm using a shearing machine. Place the samples in a KQ-100DE CNC ultrasonic cleaner and clean them for 16 minutes at 80% power. Rinse with alcohol and blow dry.

[0019] (2) Chemical corrosion: The sample after sample preparation is subjected to chemical corrosion. The specific operation is as follows: immerse the sample in a 50°C hydrochloric acid solution for 30 seconds, rinse with alcohol and blow dry, then immerse it in a lead nitrate solution for 20 seconds, and then rinse with alcohol and blow dry; wherein the hydrochloric acid solution is prepared by mixing 50 ml of analytical pure concentrated hydrochloric acid and 50 ml of tertiary water, and the lead nitrate solution is prepared by mixing 10 g of analytical pure lead nitrate and 100 g of tertiary water.

[0020] (3) Observation and analysis under metallographic microscope: The chemically etched sample was placed under a ZEISS AXIO Imager metallographic microscope for observation. The surface was photographed with a 200x lens under the metallographic microscope. The metallographic photos were binarized and extracted using metallographic analysis software. The area analysis method was then used to calculate the area percentage of the two phases and the proportion of the missed plating layer. The results are shown in Figure 1 .from Figure 1 It can be seen that the copper plating layer obtained in this embodiment has a clear leakage area, and the leakage area accounts for 2.36%. Example 2

[0021] The copper-plated welding wire wire rod in this embodiment is ER50-6, and the method for detecting the proportion of the unplated area of ​​the copper-plated welding wire includes sample preparation, chemical corrosion and metallographic microscope observation and analysis, which are as follows: (1) Sample preparation: Take the welding wire rod and cut 10 samples with a length of 15 mm using a shearing machine. Place the samples in a KQ-100DE CNC ultrasonic cleaner and clean them for 16 min at 80% power. Rinse with alcohol and blow dry.

[0022] (2) Chemical corrosion: The sample after sample preparation is subjected to chemical corrosion. The specific operation is as follows: immerse the sample in a 70°C hydrochloric acid solution for 15 seconds, rinse with alcohol and blow dry, then immerse it in a lead nitrate solution for 10 seconds, and then rinse with alcohol and blow dry; wherein the hydrochloric acid solution is prepared by mixing 80 ml of analytical pure concentrated hydrochloric acid and 50 ml of tertiary water, and the lead nitrate solution is prepared by mixing 5 g of analytical pure lead nitrate and 100 g of tertiary water.

[0023] (3) Observation and analysis under metallographic microscope: The chemically etched sample was placed under a ZEISS AXIO Imager metallographic microscope for observation. The surface was photographed with a 200x lens under the metallographic microscope. The metallographic photos were binarized and extracted using metallographic analysis software. The area analysis method was then used to calculate the area percentage of the two phases and the proportion of the missed plating layer. The results are shown in Figure 2 .from Figure 2 It can be seen that the copper plating layer obtained in this embodiment has a clear leakage area, and the leakage area accounts for 3.41%. Example 3

[0024] The copper-plated welding wire wire rod in this embodiment is of G4Si1 grade. The method for detecting the ratio of the unplated area of ​​the copper-plated welding wire includes sample preparation, chemical corrosion and metallographic microscope observation and analysis, which are as follows: (1) Sample preparation: Take the welding wire rod and cut 10 samples with a length of 20 mm using a shearing machine. Place the samples in a KQ-100DE CNC ultrasonic cleaner and clean them at 80% power for 20 min. Rinse with alcohol and blow dry.

[0025] (2) Chemical corrosion: The sample after sample preparation is subjected to chemical corrosion. The specific operation is as follows: immerse the sample in a 60°C hydrochloric acid solution for 20 seconds, rinse with alcohol and blow dry, then immerse it in a lead nitrate solution for 15 seconds, and then rinse with alcohol and blow dry; wherein the hydrochloric acid solution is prepared by mixing 65 ml of analytical pure concentrated hydrochloric acid and 50 ml of tertiary water, and the lead nitrate solution is prepared by mixing 8 g of analytical pure lead nitrate and 100 g of tertiary water.

[0026] (3) Observation and analysis under metallographic microscope: The chemically etched sample was placed under a ZEISS AXIO Imager metallographic microscope for observation. The surface was photographed with a 200x lens under the metallographic microscope. The metallographic photos were binarized and extracted using metallographic analysis software. The area analysis method was then used to calculate the area percentage of the two phases and the proportion of the missed plating layer. The results are shown in Figure 3 .from Figure 3 It can be seen that the copper plating layer obtained in this embodiment has a clear leakage area, and the leakage area accounts for 2.88%.

[0027] Comparative Example 1

[0028] This comparative example uses the cross-section metallographic method to detect the proportion of the copper-plated welding wire leakage area. The copper-plated welding wire wire rod brand tested is ER70S-6. The detection method includes sample preparation, chemical corrosion, and microscope observation. The specific steps are as follows: (1) Sample preparation: Take the welding wire rod and cut 10 samples with a length of 15 mm using a shearing machine. Place the sample coating surface vertically into the ZXQ-2 mounting machine for mounting.

[0029] (2) Rough grinding: The mounted sample in step (1) was rough ground with the grinding wheel of MPJ-35 metallographic specimen grinding machine, and then smoothed on 280#, 600#, 800#, and 1000# metallographic sandpaper in sequence.

[0030] (3) Polishing: The sample of step (2) was placed on an MP-2 polishing machine for polishing. A 200 mm diameter pressure-sensitive rubber wool polishing cloth was used. A 2.5 μm diamond high-efficiency metallographic polishing agent was evenly sprayed on the sample. The sample was polished at a speed of 1400 rpm for 2 minutes.

[0031] (3) Chemical corrosion: The sample prepared in step (3) was corroded with 4% nitric acid for 10 seconds.

[0032] (4) Observation under a metallographic microscope: After chemical etching, rinse the sample with anhydrous ethanol, dry it with a hair dryer, and observe it under a ZEISS AXIO Imager metallographic microscope at 1000 times magnification. The results are as follows: Figure 4 shown.

[0033] from Figure 4 It can be seen that this method can only obtain the local morphology of the coating, the coating is severely peeled off, and it cannot guarantee the display of the true copper-plated welding wire leakage situation.

Claims

1. A corrosive solution for detecting the percentage of the missed plating area of ​​a copper-plated welding wire, characterized in that: The etching solution comprises a hydrochloric acid solution and a lead nitrate solution; the hydrochloric acid solution is prepared by mixing 50ml-80ml of analytically pure concentrated hydrochloric acid and 50ml of water, and the lead nitrate solution is prepared by mixing 5g-10g of analytically pure lead nitrate and 100g of water.

2. A method for detecting the proportion of the missed plating area of ​​the copper-plated welding wire, characterized in that: The method comprises sample preparation, chemical etching and metallographic microscope observation and analysis, wherein the etching solution used for the chemical etching comprises a hydrochloric acid solution and a lead nitrate solution; the hydrochloric acid solution is prepared by mixing 50 ml to 80 ml of analytically pure concentrated hydrochloric acid and 50 ml of water, and the lead nitrate solution is prepared by mixing 5 g to 10 g of analytically pure lead nitrate and 100 g of water.

3. A method for detecting the proportion of the copper-plated welding wire leakage area according to claim 2, characterized in that: The specific operation of the chemical corrosion is: immersing the sample in the hydrochloric acid solution for 15 to 30 seconds, rinsing with alcohol and blowing dry, then immersing in the lead nitrate solution for 10 to 20 seconds, and then rinsing with alcohol and blowing dry.

4. A method for detecting the proportion of the copper-plated welding wire leakage area according to claim 3, characterized in that: The temperature of the hydrochloric acid solution is 50-70°C.

5. A method for detecting the proportion of the copper-plated welding wire leakage area according to claim 2, characterized in that: The specific operation of the sample preparation is: take the welding wire coil, cut 5 to 10 samples with a length of 20±5 mm with a shearing machine, put the samples into an ultrasonic cleaner for cleaning, rinse with alcohol and blow dry.

6. A method for detecting the proportion of the copper-plated welding wire leakage area according to claim 2, characterized in that: The metallographic microscope observation and analysis is to place the chemically corroded sample under a metallographic microscope for observation, and calculate the proportion of the missed plating area according to the different proportions of the organizational structure through the analysis software provided by the metallographic microscope.

7. The method for detecting the percentage of the copper-plated welding wire leakage area according to claim 2, characterized in that: The metallographic microscope is a ZEISS AXIO Imager metallographic microscope.

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