ã€China Aluminum Network】 Many friends think that the main problem of aluminum alloy plating is the problem of coating adhesion. In particular, the variety of aluminum alloy plating parts processed and produced is complex and the problem is reflected in the aluminum casting parts. Cavities, recesses, backs, blind holes, and screw holes, etc.
In summary, there are mainly the following causes of aluminum alloy plating pre-treatment adhesion problems:
(1) The bore diameter of the inner cavity of the aluminum alloy electroplating part is too small and too deep, so that the plating solution and the cleaning liquid flow in the workpiece and the circulation amount is small, so that the pre-processing work of the inner pore slot of the product is not very thorough. In this way, the bond strength of the plating layer is poor or there is no binding force; and the product has an interfacial tension between the angle and the right angle of the root, which can not be cleaned. At this time, the obtained coating has no way to ensure a good binding force.
(2) In the pre-treatment process, due to the etching effect of the acid-alkali solution, especially the surface of the rough surface porous oil is not easy to clean thoroughly, and the solution in the gap between the gap and the surface of the micropore hole during the electroplating process will be discharged later. Affects the quality of deep deposits.
2 improved scheme for the pre-processing part of targeted aluminum alloy electroplating
According to the repeated trials of the aluminum alloy electroplating process, it was found that the angles of the electroplated surface and the crevices in the acid-base solution can be effectively treated, but why the problem has repeatedly occurred? This is mainly due to the pretreatment of the aluminum alloy electroplating process. When the water is cleaned, the rough surface of the electroplating parts, the included angle, and the dirt of the gaps are not thoroughly cleaned.
In order to solve the problems existing in the conventional pretreatment cleaning of aluminum alloy electroplating, we have repeatedly tested a variety of water cleaning methods. It is concluded later that, under conditions that ensure the quality of coating and economical efficiency, we rely on zinc and the first Add an ultrasonic oscillating water cleaning before sub-zinc immersion, and further into the aluminum alloy plating process:
Alkali erosion A water wash, a pickling, a water wash, an ultrasonic cleaning, a zinc immersion, a pickling, a water wash, an ultrasonic cleaning, and a second zincation.
3 process improvement
3.1 Improvement of Water Cleaning in Aluminum Alloy Plating
3.2 The introduction of ultrasonic cleaning for aluminum alloy plating processing production applications.
We know that because of the strong penetrating ability of ultrasonic waves, it has a good cleaning effect on complex shapes, cavities, and pores, which is unmatched by other cleaning methods.
(1) Ultrasonic cleaning principle is used in aluminum alloy plating.
The basic principle of ultrasonic cleaning is the "cavitation" effect. In the course of the “cavitation†effect of ultrasonic waves, an instantaneous high-pressure shock wave of more than 100 MPa is formed, resulting in intense stirring of the media solution. The "cavitation" effect continues near the surface of the workpiece and the interface of the cleaning fluid and impinges on the dirt attached to the surface of the workpiece.
(2) Ultrasonic equipment selection and parameter design in electroplating production of aluminum alloys.
1 ultrasonic equipment. In recent years, domestic enterprises specializing in the production of ultrasonic equipment have emerged, and a variety of ultrasonic cleaners have been used in the field of surface treatment. My company is in the existing aluminum alloy automatic silver plating line for technological transformation, one or two zinc bath in front of an additional ultrasonic cleaning tank, the tank size is 1500mm × 1000mm × 1000mm, the tank body is PP material. According to the structure of silver-plated wire trough, vibration box type ultrasonic wave is adopted, and ultrasonic vibration box material is adopted
Made of 316I stainless steel plate, stainless steel plate argon arc welding. The ultrasonic vibration box is installed on the side of the cleaning tank and the 316L stainless steel is lined in the tank body, which can effectively reduce the ultrasonic energy absorbed by the PP material. Ultrasonic box emission surface is treated with hard chromium plating, which can enhance the service life of the ultrasonic vibration box.
2 ultrasonic power. The higher the ultrasonic power, the stronger the cavitation effect, the better the cleaning effect and the faster the speed. However, for workpieces with high processing precision, low surface roughness and loose workpiece materials, such as long-time strong washing can cause surface state damage or even scrap, so the size of the cleaning power should be based on the workpiece geometry, dimensional accuracy requirements and the workpiece material is reasonable select. Most of our company's workpieces are aluminum forging blanks with low surface roughness. At the same time, there are some aluminum alloy castings and the workpiece material is loose. While ensuring the cleaning quality, after calculation and analysis, for a cleaning tank with a length of 1500×a width of 1000×a height of 1000mm, there are 12 ultrasonic vibrators per tank, and the total power of the vibrator is 1296w.
3 ultrasonic frequency. The lower the ultrasonic frequency is, the more cavitation is, the stronger the effect is. However, due to the longer wavelength, the direction of the impact force is weakened, and the cleaning effect of the part covered by the workpiece will be affected, but the depth of the workpiece gap or small depth The dirt can be removed, so when selecting the ultrasonic frequency range, it must be differentiated according to the shape and structure of the workpiece. Generally, small parts should use higher frequencies, and large parts should adopt lower frequencies. In the pre-plating process, the commonly used frequency is between 15 and 40 kHz. According to the structural characteristics of the company's workpiece and the workpiece material state, the ultrasonic frequency is fixed at 28Khz.
4Aluminum alloy plating pretreatment improved effect verification
Before the process of aluminum electroplating was improved, we used the pH test paper to test the inner groove of the workpiece before the zinc plating, and the slits, etc. were clearly red. This is because the acid at the corners of the workpiece processing surface was not cleaned. To explain the pre-treatment is not thorough. After adding the ultrasonic cleaning to the aluminum alloy electroplating process, the PH test paper is used to test the surface of the workpiece without changing the color at all the included angles. This intuitive reflection shows that the effect of cleaning has been greatly improved.
5 aluminum alloy electroplating processing production before the summary
Our long-term practice in electroplating process production has proved that aluminum alloy electroplating quality problems are more common than hardware, but as long as we seize the key to the various problems in the production process, we carefully observe and diligently process electroplating operations. In thinking, summing up, and then combining these findings with effective improvements, we can successfully support the quality and stability of aluminum alloy electroplating products.
Floor Lamp,Floor light, Standing Lamp,Led Floor Lamp
JINGYING , https://www.jingyinglight.com