Investigation On Corrosive Behavior And Product Of ZnO-B₂O₃-SiO₂Glass Doped With Rare Earth Oxides

Y2O3、Gd2O3doped zinc-borosilicate glasses were prepared by melt quenchingmethod. Rare earth doping effect on the properties of corrosion and weathering, and theirproducts, are explored with help of SEM, EDS, ICP-AES, XRD, LSCM and pH meter.Results showed that:Chemical stability of borosilicate glass in etching medium get weaken in the order ofartificial seawater, deionized water and alkali.The pH value of the original deionized water was7.97, and the pH of all solutionsafter corrosion was higher than that, and it can be speculated from corrosion mechanismthat the product of water corrosion should be highly fragmented SiO2-H2O system.(Zn,Al)3(Si,Al)2O5(OH)4is found on both of the long-term soaked surface and theshort-term soaked surface, in addition, H2Si14O29·xH2O and Zn(OH)2are found on thelong-term soaked surface. Those products do not contain sodium and boron element.From the surface morphology of alkali corroded glass, co-doped rare earth can reduceunicom shaped corrosion. Na6[AlSiO4]6·4H2O suspended solid is found in alkali solutionsoaking ZB, and suspended solids in solutions soaking other samples are amorphous state.The pH value of seawater after soaking glass become lower than artificial seawater,and corrosion mechanism of glass in seawater is great different with that in water. Theideal doping amounts are1.00mol%Y2O3(ZBY4) and0.25mol%Gd2O3(ZBG1)respectively. Y2O3and Gd2O3co-doped samples are all improved on seawater resistance,and the optimal doping amount is0.5mol%Y2O3+0.5mol%Gd2O3.Mg4Al2(OH)12(CO3)·3H2O is formed on the corrosion surface of basic sample, and nocrystal is found on corrosion surface of ZBY4、ZBG1.After35d,85℃,95%RH artificial simulation of weathering,1.00mol%Y2O3(ZBY4),0.25mol%Gd2O3(ZBG1) and0.5mol%Y2O3+0.5mol%Gd2O3showed muchbetter weathering resistance property, which is consistant with results of natural weathering in Yichang Hubei.0.5mol%Y2O3+0.5mol%Gd2O3co-doped rare earth played a stronginhibitory effect on the leaching of sodium and zinc. Weathering degree in Yichang Hubeiregion is higher than that in Jining Shandong. According to element types in the productarea, it can be speculated that products of artificial weathering may be Na2CO3, NaHCO3or sodium aluminate, Sodium metaaluminate. CaSO4·2H2O is formed on naturalweathering surface of glass in Hubei Yichang, and the white product is amorphous on thethe weathering surface of glass in Jining Shandong.Phase separations of samples composited with1mol%Y2O3、0.25mol%Gd2O3、0.5mol%Y2O3+0.5mol%Gd2O3、0.25mol%Y2O3+0.75mol%Gd2O3、0.75mol%Y2O3+0.25mol%Gd2O3getsuppressed compared with the basic glass.