Study On The Structural Characteristics,evolvement(Aging)rules Of Ancient Blue-and-White Porcelain Glazes And Their Functions On Scientific Identification

The dating and identification of ancient ceramics is an interdisciplinary study developed with the application of modern instruments in archaeology.At present,methods such as thermoluminescence and X-ray fluorescence spectroscopy have been widely used.For the blue-and-white porcelain,although a relatively complete standard database according to its elemental composition has been built as the basis for identification,the researches on structural features are still lacking,which limit the application on identification of blue-and-white porcelain.In this paper,the three aspects of ancient blue-and-white porcelain: blue-and-white spot,secondary pollutant and transparent glass phase were studied by optical microscopy(OM),scanning electron microscopy(SEM)and Fourier transform infrared absorption spectroscopy(FTIR).From the perspective of material science research,the research on its structural characteristics and structural evolution(aging)is carried out,which lays a foundation for its application in scientific identification.(1)Through the analysis of the spots on the blue-and-white porcelain samples in the middle and late Ming Dynasty,combined with the previous research on the early Ming Dynasty spots and on the composition of cobalt,it was found that the blue-and-white porcelain crystal spots before Ming Xuande were dominated by dendritic magnetite crystals;which were mainly clusters of needle-shaped clusters of anorthite crystals after Ming Xuande,the structure is distinctive and can be used as an important basis for the dynasties.(2)Through the analysis of the Qing Dynasty blue and white porcelain samples,it is found that there are yellow-brown secondary pollutants in the glazed cracks and bubbles.The secondary pollutants in glaze cracks are the deposition of external materials,including iron ions,acid ions,humus and a small amount of clay colloids in soil environment.thier structure are beach-like,grain-free,and well bonded to the glaze,which cannot be formed by artificially simulated soil minerals;The secondary pollutants in bubbles are oxidation product of iron in the glaze,the color of which are from light yellow to dark brown.Secondary pollutants formed by artificial heat treatment are all black.The difference of secondary pollutants under artificial aging and natural aging can be used as an important basis for scientific identification of glazes.(3)Through the hydrothermal and annealing treatment of the imitation blue-and-white porcelain samples,the changes of the microstructure and molecular structure of the glaze surface during the aging process were investigated,and compared with the ancient blue-and-white porcelain,the aging states of the ancient porcelain were infered.It is found that during the storage of blue-and-white porcelain for hundreds of years,the most obvious change molecular structure of the glaze is water corrosion.Ion-exchange between glaze and water occurred and form a hydration layer of a polyhydroxy group on glaze.In contrast,the structural changes caused by the spontaneous relaxation of the glaze are negligible.The relationship between the peak position of the infrared spectrum and the degree of water corrosion can be used to determine the approximate age of blue and white porcelain.