Study On The Preparation And Properties Of Cordierite Glass-ceramics Via Thermoelectric Coupling

Glass-ceramic is a special inorganic non-metallic material that combines the glass phase and crystal phase formed by the crystallization process of the basic glass under the action of appropriate heat,electricity,and magnetism.In this paper,cordierite glass-ceramics are prepared by a combination of thermal field and electric field.The electric field is controlled to control the precipitation of crystal nuclei,and then the number and size of crystal grains are controlled to improve its thermal expansion coefficient,dielectric constant,etc.Performance,so that it can be fully used in practical applications.In this study,the Mg O-Al₂O₃-Si O₂base glass was prepared by the melting method,and the cordierite(Mg₂Al₄Si₅O₁₈)obtained by heat treatment and thermal field-electric field treatment was used as the research object,using differential scanning calorimetry（DSC）and X-ray diffraction analysis（XRD）,Scanning Electron Microscope（SEM）,Fourier Infrared Spectroscopy（FTIR）,X-ray Photoelectron Spectroscopy（XPS）and other test methods to carry out related research.The heat treatment system was determined,and the thermal expansion coefficient and dielectric constant of the glass were preliminarily tested.The evolution mechanism of crystal grains under thermoelectric coupling is analyzed.The results are as follows:By adopting the traditional"two-step"heat treatment system,the temperature and time of nucleation and crystallization during the entire crystallization process are clarified,and crystal grains with complete appearance are obtained.During this process,it was discovered that titanium dioxide was added to the raw materials as a nucleating agent,so that a single cordierite phase was precipitated during the crystallizing process of the glass.Compared with the base glass,its thermal expansion coefficient and dielectric constant have changed.Through the performance analysis of the glass-ceramics,it is found that the introduction of the electric field changes the amount of crystal nucleus precipitation in the magnesium-aluminum-silicon system,which in turn affects the number and size of crystal grains inside the glass,and promotes the crystallization of the glass..With the increase of the electric field intensity,the dielectric constant of the glass sample gradually increased,reaching the highest at 1200V,which was 3.2.The thermal expansion coefficient of glass-ceramics has also changed.With the increase of the electric field intensity,the number of crystal grains gradually increases and reaches saturation at 1200V.The thermal expansion coefficient reaches the lowest value of3.171×10^-6/K.The introduction of electric field has brought us new research ideas,which breaks the traditional method of preparing glass-ceramics,provides a new method for future research.Under the effect of thermoelectric coupling,it is found that the number of crystal grains in the magnesium-aluminum-silicon glass-ceramics will gradually increase with the increase of the electric field voltage,and then reach saturation at 1200V.Due to the introduction of the electric field,it produces good miscibility with the glass melt and participates in the rupture of the Ti-O-Si bond in the four-coordinate[Ti O₄]of the silicon-oxygen network structure,and the titanium will change from the titanium oxide tetrahedron[Ti O₄]to titanium Oxygen octahedron[Ti O₆].Titanium separates from the silicon-oxygen network framework to form crystal nuclei and promote crystal growth.This study provides useful insights for describing the growth law between electric field voltage and glass-ceramic nucleation.