A Study On Synthesizing Cordierite From Rectorite

Cordierite is a low expansion coefficient material of a wide range of application ,and this is the main purpose of this study. The study successfully synthesized a high-quality cordierite using a special ore material-rectoritex as the main clay raw material ,which was produced at Zhongxiang, Hubei province ,and talc powder and industrical Al2O3 as the additives.First.this study proceeded the theories analysis by referring to a large quantity of interrelated data ,both domestic and international;then made a array of analysis towards the chemical and physical performances of the samples by testing the water absorption,open porosity, bulk density, banding strength and thermal expansion coefficient ,etc;after these the study analysted the microstructure of the samples using XRD and SEM, finally the author established the synthesizing process of the cordierite. During the study we tried to lower the thermal expansion coefficient of cordierite by adding additives. On the basis of the data referred to, the additives as Nd2O3 , Al2TiO5 , Li2SiO3 ,ZiSiO3 , CeO are used in the study,while adding Li2SiO3 in MgO-Al2O3- SiO2 -ZrO2 system and GeO in MgO - Al2O3 - SiO2. As a result ,many performances of cordierite were improved by adding these compound additives.After the study towards the way that the additives be added in the materials ,we finally fixed that directly adding additions in the raw materials not only saved some synthesizing process, but also a best way to improve the properties . The chemical and physical properties, phase fabricates and microstructure of the samples that added additions were tested by the testing methods above. The results showed that the cordierite can be synthesized at a lower temperature (1280 ,2h) while using the rectorite as the main clay raw material, and the thermal expansion coefficient is 2.73×10-6 /℃, the water absorption is 8.17%, the porosity is 18.17%, the bulk density is 2.07 g/cm3,and the banding strength is 65.46Mpa; after adding additives, the thermal expansion coefficient ofcordierite had a large lowed range, that the lowest value is 2.59×10-6 / ℃ while adding Nd2O3 15%, 2.60×10-6/℃ while adding Al2TiO5 15%,2.63× 10-6 /℃ while adding Li2SiO3 6%, 2.51×10-6/℃ while adding ZiSiO3 18%, 2.61×10-6 /℃ while adding CeO 0.8%,2.55 ×10-6 /℃ when adding GeO2 1.5mol in MgO·Al2O3·xGeO·(5-x)SiO2 system,and the chemical and physical properties of the samples have homologously improved, as well as the water absorption, porosity, bulk density and banding strength. Then we can make a conclusion that adding additives is a good way to improve properties.