| Colored stainless steels have superb decorative,hard-wearing,corrosion preventive and good processable properties,so they have great application prospect.Acid-chemical coloring and electrochemical coloring are the main two methods to prepare colored stainless steels,but the two means still have their key technological problems in common like the colored films are nonuniform and their properties are not ideal,so restrict the extension and application of colored stainless steel seriously.To solve these problems above,the following contents were studied in this paper:(1)To improve the uniformity of colored film,a new approach of ultrasonic chemical coloring was presented for the first time,and the effects of frequency,power,temperature to acid-chemical coloring on stainless steel were discussed:the influence law of chemical coloring curves at different ultrasonic wave conditions such as frequency,power was investigated with coloring potential;the macroscopic and microscopic uniformity of colored films were characterized with the help of scanning electron microscopy(SEM)and polarizing microscope;the corrosion prevention of film was tested by NSS and Tafel polarization;and the surface composition of films were determined by XPS and EDS;and theother film properties such as abrasive resistance,thermostability,resistance of soiling,ultraviolet aging resistance,impact resistance and machining property at different ultrasonic wave conditions were investigated too.(2)A new method,trielectrode control system,was set up to control the color of electrochemical coloring film based on the traditional electrochemical coloring device,used Pt electrode as measuring electrode,stainless steel for working and lead plate as the counter electrode,then joined the three electrodes into the potential measurement device.The relationship between potential and film color was investigated,so film color can be controlled by the changes of potential on stainless steel.(3)Based on the trielectrode control method,the process conditions of electrochemical coloring were studied,and the effects of ultrasonic wave on color and uniformity were studied as well.The results show that:(1)Ultrasonic wave has significant effects on chemical coloring of stainless steel:Firstly,ultrasonic wave can remarkably increase the colored film's uniformity,the film layer schows a excellent uniformity in both macro and micro.Secondly,ultrasonic wave can accelerate the chemical coloring and notably decrease the temperature of chemical coloring,after the ultrasonic waveappended,the lowest colored temperature decrease from 55? to less than 40?,so the energy consumption during coloring is reduced greatly.Thirdly,ultrasonic wave,similar to ordinary chemical coloring,has no influence on the elements and composition of the film,the main elements are O,Fe,Cr and Ni;the main compositions are the mixture of FeO,Fe2O3,Cr2O3 and a little Ni(OH)2;Fourthly,ultrasonic wave can improve the film's wear-resistance and adhesive force,but has no effects on other performance,such as corrosion prevention,ultraviolet aging resistance,resistance of soiling,thermostability,machining property and so on.(2)The trielectrode control method proposed in this paper above is feasible in electrochemical coloring controlling,the color of film can be got by this method under a certain current density,and improve the film reproducibility.(3)Ultrasonic wave also has a great influence on electrochemical coloring,and the uniformity of colored film can be improved significantly,but the colored time prolong.In short,the key technological problems such as inferior film uniformity on production of colored stainless steel can be solved by ultrasonic chemical coloring,the energy consumption was reduced greatly,and the other film properties of colored stainless steel are enhanced remarkably,and have industrialized application prospect. |
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