Current status of metal powder preparation technology: From the production point of view, in the preparation process of many metal powders, the atomization method is the main preparation method of solder powder. According to different atomization methods, there are mainly three kinds of gas atomization, rotary disk centrifugal atomization and ultrasonic vibration atomization.
1, gas atomization
Gas atomization is to use a high-speed gas stream to crush the molten liquid flowing through the nozzle, atomize it into fine droplets, and cool and solidify in the sedimentation to form powder particles. The product has the advantages of high milling efficiency and large output, but the obtained products are mostly ellipsoidal and the surface is rough with fine powder adhesion, the oxygen content is high, the powder particle size distribution is wide, the proportion of fine powder is high, and the subsequent processing is difficult. . In addition, nitrogen consumption is large and the cost is high.
2, rotating disk centrifugal atomization method
Rotary disk centrifugal atomization Zui was originally developed by the American Prattz & Whitney Aircraft Manufacturing Company. Due to its unique powder size, controllability and cleanliness of the shape and low cost, it has been paid more and more attention, and has become an important method for preparing metal or alloy powder. Compared with gas atomization, the preparation of solder powder by centrifugal atomization method is relatively easy to control the atmosphere, the product has good sphericity, small oxidation degree, easy particle size control, high yield and high output. The disadvantage is high equipment speed, high heat resistance and wear resistance of the motor. In addition, the use of vacuum exhaust devices and high speed motors has increased the cost of the equipment.
3. Ultrasonic atomization method
Ultrasonic atomization is a new type of milling method developed in recent years. The molten metal is atomized into a powder by ultrasonic atomization equipment. Compared with the above two atomization processes, the solder powder prepared by the ultrasonic atomization process has a good sphericity, a narrow particle size distribution, and a low oxygen content, but the yield is small.