The Research Of Mold Steel Chemical Polishing Based On Liquid Of Sulfuric Acid-Phosphoric Acid

Chemical Polishing is a kind of very important process on surface treatment of die steel and its alloys. Chemical Polishing can make the surface smoothand bright, increase light and thermo reflection ability, enhance corrosion resistance, etc. Traditional Chemical Polishing is' etching die steel products inintermixture of phosphoric acid, sulfuric acid and nitric acid. But in this processthere was oxynitride gas give off, like yellow fume. It caused serious airpollution, damage to human's health. So, purge the "yellow fume" is necessary.After inquired lots of documentation and analysisd, we decide to exploit anew technique of Chemical Polishing which can increase surface lightness andavoid pitting corrosion. The new technique based on miscible liquids ofphosphoric acid and sulfuric acid. To guaranteed polishing quality, some matters such as oxidant, organic macromolecule, surfactant, and heavy metallic salt must add in. These matters are very important of Chemical Polishing, they can enhance smoothness and brightness, avoid pitting corrosion. In fact, it's very difficult to decide which added matters were useful, we must do a great manyof experiments.In this subject, we use orthogonal experimental to study the action of theseadded matters and there synergism. Finally, we confirmed which added matterswere most useful and without sideeffect. Because some technological conditionsare also contribute to polish quality, so we still studied the optimized conditionssuch as polish time and temperature.In our research we still analysis the process by SEM and mechanism by electrochemical method of this Chemical Polishing technique; this is the firsttime who use SEM to study Chemical Polishing process without yellow fume.After researched we considered that planing and brighting were occurd at thesame time, mucouse coat theory and passivation theory can give explanation of polishing mechanism. In addition, to obtain the aluminum surface smooth andbright organic macromolecule adsorpted on the surface is bottleneckThis new polishing technique had overcome two chief deficiencies of someChemical Polishing methods without yellow fume, favorable of environment protection, and some manufactory were used this technique already. We think itcan widely used in the future.