Study On Micro - Etching Mechanism Of Micro - Etching System Of Manganese Dioxide

The general method of ABS (acrylonitrile-butadiene-styrene) resin surface etching included the chromic acid (H2CrO4) and sulfuric acid (H2SO4) solution, however, the carcinogen chrominum (VI) ions would pose a serious environmental threat. A more environmental friendly etching system has been proposed and the search for a replacement to the conventional H2CrO4 etching solutions has gained to reduce the pollution to environment.After a great deal of experimental researches, excellent etching systems including binary system (MnO2-H2SO4) and ternary system (MnO2-H2SO4-H3PO4) were obtained. Recently, the MnO2-H2SO4 etching solution for the ABS surface etching was prepared by 12.3 mol/L H2SO4 and 30 g/L MnO2, and then stirring at 70℃ for 20 min. Meanwhile, a MnO2-H2SO4-H3PO4 etching system including 10.7 mol/L H2SO4,60 g/L MnO2 and 4.2 mol/L H3PO4 for the ABS surface etching was investigated, and then the etching solution was carried out at 60℃ for 10 min. Compared with MnO2-H2SO4 etching system, the adhesion strength of the ABS in MnO2-H2SO4-H3PO4 etching solution was enhanced in a short etching time and at lower temperature.For MnO2-H2SO4 binary system, the crystal [Mn(SO4)2(H2O)2]·2H2O was obtained, using the method of saturated solution slowly cooling. So for the first time, the Mn(IV) complex was got in strong acid solution. The crystal structure of the complex was determined by single crystal X-ray diffraction analysis, and the results indicated that the Mn(IV) adopted an octahedral geometry, and was coordinated by two oxygen atoms of water molecules and four oxygen (O) atoms of deprotonated sulfuric acid. Two Mn(IV) were linked by one sulfate ion via two oxygen atoms, forming 1D structure. The layers were further linked by hydrogen bond via water molecules, forming three-dimensional net structure. Through the structural analysis of the complex [Mn(SO4)2(H2O)2]·2H2O, it cleared the soluble Mn(IV) in the MnO2-H2SO4 etching system, explaining the etching mechanism reasonably. To further clarify the characteristic of [Mn(SO4)2(H2O)2]·2H2O complex, the complex was also analyzed by TG, IR, UV and CV.Meanwhile, another new Mn(H)-complex Mns(HPO4)4(μ-OH)2(H2O)2 complex was synthesized, and the crystal structure was determined by single crystal diffraction. The result indicated that Mn(II) adopted an octahedral geometry, and every molecule included five Mn(II), dividing into three types. Mnl was coordinated by O atoms of four HPO42-, one -OH- and one H2O; Mn2 was coordinated by O atoms of five HPO42-, one -OH-; Mn3 was coordinated by O atoms of six HPO42-. Moreover, the complex was characterized by TG, IR analyses.For MnO2-H2SO4-H3PO4 system, the etching mechanism was also studied by UV and CV. This result implied that Mn(IV) ion could be coordinated by phosphoric acid (H3PO4) in the H2SO4 system to form the Mn(IV)-H3PO4 complex, and the coordination ability of H3PO4 for Mn(FV) was stronger than H2SO4. Hence, the soluble Mn(IV) ion concentration in MnO2-H2SO4-H3PO4 system could be enhanced.