Research Of Ultrasonic-based Wet Mechanical Plating

Mechanical Plating is an environment-friendly surface treatment technology.It becomes a more and more widely used process in industry application for the advantages of non-toxic raw material,low energy consumption,no pollution to the environment and the good properties of the coating.But the tumbling barrel of Mechanical Plating equipment is relatively closed with only one feeding hole,it can only be used for small size parts while some platy and long axis structure or larger parts can not use Mechanical Plating process to get anticorrosive coatings.The types of processing parts were restricted.In order to solve the problem mentioned above and get Mechanical Plating coatings for larger parts to enlarge the application scope of Mechanical Plating technology,the main work and contribution of this paper are as follows:By combining the principle of Mechanical Plating and Ultrasonic Peening,a novel method named Ultrasonic-based Wet Mechanical Plating was present in the text.Using ultrasonic vibrations to provide motives for impact media to drive glass beads vibrated with high frequency.So the glass beads can impact the metal powder which had been activated by activator onto the workpiece surface at a high speed to get zinc coatings on metallic surfaces.In the paper,the equipment of Ultrasonic-based Wet Mechanical Plating was designed.The equipment was mainly made of ultrasonic generator,ultrasonic transducer,vibrating container and supporting structure,et al.The frequency of ultrasonic generator is 28 kHz,the power can be adjusted between 0 to 2500W.The frequency of ultrasonic transducer is 28 kHz and the power is 100W.The process of Ultrasonic-based Wet Mechanical Plating was worked out,the formula was analyzed and optimized.The species and best ratio of activator,corrosion inhibitor,dispersing agent,deposit modifier and sustainable activator were developed.Experimental investigations were conduct and the zinc coatings were made under the new process.The surface morphology,cross-section morphology and layer components were test using the instruments of scanning electron microscope,Metallurgical Microscopy and EDS.The bonding strength,porosity and anti-corrosion properties of the Ultrasonic-based Wet Mechanical Plating coatings were evaluated using scribing test,filter paper method and neutral salt spray test.The results show that the color of zinc-coating gained by new process was silver gray,and the finish was fine and uniform.The coating was made of zinc powders,pore and driving metal.There was no crystallization product or alloy phase in the coating.The zinc content was more than 94%,the iron content was 3.28%and the tin content was 1.88%.Zinc powders in the coating were randomly arrangement and had no obvious regularity.The deformation of zinc powder particles in internal coating layer was smaller but the deformation was obvious in the superficial layer,some zinc powder particles turn into ellipsoid or flat structure.The coating was complete after the scribing test,the pore rate was low and the corrosion resistance was better than traditional mechanical zinc coating which had the same thickness.The influences of zinc powder,impact media,strengthen time,alloying element and driving metal to the performance of zinc coatings were analyzed respectively.The results show that with the decrease in size of zinc powder particles,the density of the coating improved and corrosion resistance of the coating became well.With the decrease in size of glass beads,the finish of the layer surface became good and the density of the coating was improved.With the increase of strengthen time,the quality of zinc coating became well.By adding a certain amount of alloying element,the corrosion resistance of the coating became well.The driving metal in the coating exist between zinc powders,it can connect zinc powders and the substrate of parts and contribute to enhance the bonding strength.