Regulating The Microstructure Of Dolomite Porcelain And Its Effect On Properties

In recent years,pottery production has been increasing year by year,and waste potteries are also increasing.Because high-temperature fired potteries are chemically stable and difficult to degrade in the natural world after being discarded,thus their large accumulation will cause certain environmental problems.Dolomite porcelain is a kind of energy-saving and environmental-friendly pottery that can be degraded in soil.However,it has disadvantages such as slow degradation rate and low bending strength,which can no longer meet people's requirements for pottery products.Therefore,it is necessary to improve the mechanical and degradation properties of dolomite porcelain,and expand its scope of use so as to further reduce the environmental pollution of waste potteries.In this thesis,the chemical composition and microstructure of the glass phase in dolomite porcelain were firstly regulated by introducing tricalcium phosphate,the structure and properties of the samples were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,raman spectroscopy,fourier transform infrared spectroscopy?FT-IR?and³¹P magic angle spinning-nuclear magnetic resonance spectroscopy?MAS-NMR?.It's found that the content of glass phase in the P-containing sample significantly increased,and the Si?Al?—O—P—O—Ca?Mg?structure has formed in the glass phase,which makes the pottery connected more closely and its mechanical properties increase.When 10 wt%of tricalcium phosphate was incorporated in dolomite porcelain,the sample's bending strength is increased from 24.99 MPa to 38.73 MPa.Under acidic conditions,the P—O bonds in the glass phase are easily hydrolyzed,which greatly improves the degradability of dolomite porcelain.As a result,the degradation performance of the sample with 15 wt%tricalcium phosphate is almost doubled that of dolomite porcelain.In addition,according to the chemical and crystalline phase composition of traditional dolomite porcelain to prepare strengthened dolomite porcelain,by adjusting the quartz content,additives type and temperature to regulate strengthened dolomite porcelain crystal phase composition.The study shows that when the content of quartz is reduced from 31 wt%to 0,the mechanical properties of strengthened dolomite porcelain with a quartz content of 0 and 5wt%are better,which are 30.34 MPa and 30.68 MPa,respectively.On this basis,additives?modified kaolin,tricalcium phosphate,firing additives,and mixed additives of these three additives?were introduced,which found that the mechanical and degradation properties of samples significantly increased after the addition of additives,and the comprehensive performance of the three additives mixed in vitro with quartz content of 5%is the best.Due to the incomplete transformation of the crystalline forms of anorthite and mullite at 980°C?the firing temperature of traditional dolomite porcelain?,the calcination temperature of the strengthened dolomite porcelain was increased to 1040°C to fully transform the crystalline form.At this temperature,the content of anorthite in the strengthened dolomite porcelain greatly increased,and the content of quartz decreased.Moreover,when doping tricalcium phosphate and the three additives in the strengthened dolomite porcelain,the sample's P exists with the form of Q⁰ and Q¹ in the glass phase,making the strengthened dolomite porcelain's bending strength up to 58.93 MPa,which is 2.36 times that of traditional dolomite porcelain.At the same time,it has excellent degradation performance.