Xudong Luo

Effect of Adding Cr2O3/Fe2O3 on Aluminum Titanate Properties

The effect of adding Cr2O3/Fe2O3 and sintering temperature on the crystal structure, decomposition, and sintering capacity of aluminum titanate prepared from ferroalloy plant alumina-titania slag and rutile is considered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used in order to determine the crystal phase and microstructure of each series of specimens, X’pert Plus software is used for calculating aluminum titanate crystal lattice parameters, and the Archimedes method is used to determine apparent density and open porosity. Research results show that aluminum titanate may be synthesized from alumina-titania slag and rutile by solid phase reaction. Structural defects, formed as a result of the action of adding Cr2O3/Fe2O3, accelerate ion diffusion in aluminum titanate. Thermal defects, caused by action of high temperature, also facilitate aluminum titanate formation. The rate of aluminum titanate decomposition is reduced due to a solid solution within which Cr3+ and Fe3+ in the Cr2O3/Fe2O3 additive substitute for Ti4+ and Al3+.

Study on the Sintering Mechanism of Y2O3 on CaZrO3 Ceramic

In order to research the sintering mechanism of Y2O3 on CaZrO3, CaZrO3 was synthesized by solid reaction using analytical ZrO2 and CaCO3 as raw materials and Y2O3 as additive. The liner change rate, the relative density, XRD and the microstructure of the CaZrO3 samples were determined, and the effect of Y2O3 on sintering of CaZrO3 was researched. The results show that the sintering property of CaZrO3 is enhanced by adding Y2O3. When the content of Y2O3 is lower than 2 % (mass-%), the lattice volume of CaZrO3 increases to 0.262 nm3, which is attributed to Zr4+ being replaced by Y3+ in the CaZrO3 crystal. However, the content of Y2O3 is up to 4 %, and the lattice volume decreases due to Ca2+ being replaced by Y3+. The liner change rate of the samples increases with increasing Y2O3 additive. When Y2O3 is 4 %, the liner change rate of CaZrO3 reaches maximum (26.9 %). The relative density of the samples increases from 63.99 to 84.45 % with increasing addition of Y2O3, and the average grain size of CaZrO3 increases from 1.64 to 2.65 μm when the additive increases from 0 to 4 %.

Effect of Blowing-Agent Addition on the Structure and Properties of Magnesia Porous Material

Magnesia porous material was slip casted from magnesite flotation tailings, fused magnesia, and additives of sodium hexametaphosphate, sodium citrate, and α-Al2O3 powder. The suspension of magnesia porous material was prepared with foaming sodium dodecyl sulfate (SDS) and foam-stabilizing dextrin. The cured material was dried and sintered. The effects of adding blowing agent on the properties of the suspension and the physical properties and microstructure of the sintered specimens were studied. The results showed that the tested suspension was a pseudoplastic fluid. The apparent porosity of sintered specimens increased whereas the thermal conductivity decreased as the blowing-agent content increased. The number and size of local agglomerates decreased. The pore size increased. The grain-size and pore-size distributions became more uniform.

Effect of Al2O3 + 4SiO2 Additives on Sintering Behavior and Thermal Shock Resistance of MgO-Based Ceramics

In order to improve the sinterability and thermal shock resistance of ceramic based on MgO magnesium oxide of micron grain size composition is used as the main starting raw material with additions of nano-Al2O3 and nano-SiO2. Ceramic based on MgO is prepared by adding different amounts of Al2O3 and SiO2 to MgO in a molar ratio 1:4. The mixture is molded and sintered in an air atmosphere. Ceramic phase composition and microstructure are studied in an x-ray diffractometer and a scanning electron microscope. The effect of adding different amounts of Al2O3 + 4SiO2 on sinterability and thermal shock resistance of MgO base ceramic is studied. Addition of Al2O3 + 4SiO2 has a favorable effect on test ceramic sinterability and thermal shock resistance. During reaction of solid substances there is formation of magnesia-alumina-spinel and forsterite that leads to retardation of periclase phase grain migration. The degree of specimen compaction is improved and this has a favorable effect on sinterability of ceramic based on MgO. The degree of compaction increases as there is an increase in sintering temperature in the range 1400 to 1500°C. In addition, specimen thermal shock resistance is improved due to connection between microcracks. As a result of adding Al2O3 in an amount up to 30 wt.% + SiO2 in an amount up to 45 wt.% MgO sinterability and thermal shock resistance are improved.