Papers by Author: Jian Er Zhou

Abstract: Membrane modification is an important technology to improve the membrane performance. Ceramic membranes modified with nanometal oxide coating are prepared by homogeneous precipitation or in-situ hydrolysis method. TEM images show that the nanocoating distributes in the surface of the membrane pores. The nanocoating has no the separation function but just changes the surface characters of ceramic membrane. The permeate flux of the modified membrane increase above 20% than the unmodified membrane while treating the stable o/w emulsion with the concentration of 4g/L.

Abstract: Due to low water absorption, high bending strength and abrasion resistance, and excellent chemical and frost resistance, porcelain building ceramic tiles are the highest increase in production and sales over all other kind of building ceramic tiles materials. In this paper, porcelain building ceramic tiles was prepared by a fast firing process of rare earth tailings as the main raw material, low fused sand and Zhuji porcelain sand et al mixture. Effects of firing temperature and forming pressure on the sintering behavior and mechanical property of porcelain building ceramic tiles were studied. The sintering behavior of the fired samples was evaluated by linear shrinkage and water absorption. The fired samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and bending strength measurements. The sample is pressured at 15 MPa and sintered at 1180 °C and endowed with 0.04% of the water absorption and 51 MPa of the bending strength, due to denser microstructure. The obtained results would contribute to save natural resources and protect environment.

Abstract: To meet the requirement of ceramic pigment for ink jet printing, CoAl₂O₄ pigment was prepared by nitrate-glycine method. The effect of nitrate/glycine ratio, calcination temperature and organic sacrificial agent on the particle size and chroma of the blue pigment were considered. The results show that the particle size of the pigment increases with the increase of glycine in the ratio and the decrease of the calcination temperature. However, the increase of the calcination temperature results in the broadening of the particle size distribution of the pigment. The addition of the organic sacrificial agent contributes to decrease the particle size of the pigment, which is about 2.0 μm. The chroma of the pigment is L*=47.62、a*=9.49、b*=-51.41. The blue pigment can be used in ink jet printing.

Abstract: Alumina microfiltration membrane was prepared with solid particle sintering method by changing the content of TiO2. The membrane flux, rejection to PEG10000 and rupture strength were tested. The results showed that: when the firing temperature is 1400°C, PVA is 2%, TiO2 is 1%, alumina microfiltration membrane flux reached 1.93m3/m2·h, PEG10000 retention rate is 13.5%, and the flexural strength is 74.38MPa.

Abstract: C/SiC composite and TC4 alloy were successfully brazed using 70Ag28Cu2Ti (wt. %) as filler metal at 820 °C~920 °C for 5 min ~30 min. The effects of brazing parameters on the microstructures, phase composition, shear strength of the brazed joints were investigated by SEM, XRD. The mechanical performances of the brazed joints were measured by a universal mechanical testing machine. The results show that successful joining of C/SiC composite and TC4 alloy owes to interfacial reactions between the brazing alloy and the parent materials, and resultantly produce TiC, Ti5Si3 and Ti-Cu serial compounds at the interfaces; the interfacial structure of the brazed joint is C/SiC composite / TiC / Ti5Si3 /Ag (s.s) +Cu (s.s) / TiCu2 / Ti3Cu4 / TiCu / Ti2Cu / TC4 from C/SiC composite side to TC4 alloy side; the maximum shear strength of the brazed joint is 53.3 MPa at 860°C for 10min.

Abstract: The high sintering temperature of Al₂O₃ is the main reason of the high cost of the common ceramic membrane supports. To decrease the sintering temperature, kaolin and talc were chosen as sintering aid because the reaction between kaolin, talc and Al2O3 generates cordierite. The Al₂O₃-cordierite porous ceramic samples were sintered in the range of 1450~1510°C. The microstructure and the bending strength of the samples were characterized. The results show that the content of kaolin is no more than 8%, the bending strength of the porous ceramic sintered at 1460°C and 1510°C are 77MPa and 153MPa, respectively. The further increases of the kaolin content result in the decrease of the bending strength and the porosity. The needle-like cordierite locates in the neck of Al₂O₃ grains. The reaction between kaolin and Al₂O₃ contributes to increasing the sintering velocity. The ceramic support using cordierite as sintering aid has the acid/alkali corrosion resistance in some degree.

Abstract: Acicular mullite porous ceramics were synthesis by high-temperature sintering technique. In the present work, Kaolin and industrial aluminum hydroxide were selected as raw materials, AlF₃ used as catalyst. XRD and SEM were used to detect the crystal type and microstructure of prepared mullite ceramics, respectively. The influences of sintering temperature on the growth of crystal, the apparent porosity and compressive strength of the resulting porous ceramics were investigated. The results indicate when sintering temperature ranges from 1250 ~ 1400°C, much acicular mullite crystal appeared in the resulting ceramics. The apparent porosity, the compressive strength and the morphology of the mullite whisker changed obviously with the sintering temperature. When sintering temperature is 1400°C, the porous ceramics showed the maximum compressive strength of ~28 MPa and the maximum apparent porosity of ~63%.

Abstract: Highly permeable porous alumina (Al₂O₃) hollow fiber membranes have been developed by a combined phase inversion and sintering technique. Ethanol substituting for water was used as the external coagulant in order to prepare Al₂O₃ hollow fiber membranes with low trans-membrane resistance. The prepared Al₂O₃ membranes show a special asymmetric structure with an outer skin layer, highly porous inner surface and sub-layer composed of long and large finger-like pores. The influences of sintering temperature on the average pore size, N₂ permeability and bending strength were investigated. Results show that Al₂O₃ hollow fiber membranes with higher permeability can be prepared using ethanol as the external coagulant. The prepared Al₂O₃ hollow fiber membranes show a N₂ permeability of 871.5 m³·m^-2·h^-1·bar^-1 and a bending strength of 91.4 MPa when sintered at 1550°C for 5h.

Abstract: Mesoporous alumina is usually used as adsorption material, catalyst carrier or separation media due to its high adsorption and good thermal stability. However, the nanosized powder trends to aggregation except that its size is in sub-micron scale. The best choice is that the sub-micron alumina particles with mesoporous structure are prepared. In the present work, the mesoporous alumina spheres were prepared by micro emulsion method using aluminium isopropoxide as raw material and water/dimethylbenzene emulsion as reaction media. The obtained powder was characterized by XRD, TEM and BET. The results show that the particles are global. The particles size is in the range of 100 ~ 200 nm to several micrometers. The particle owns the worm-like structure with the pore size of 5 nm. The BET surface area of the mesoporous alumina is 81.8 m²/g. The obtained powder is suit to be used as the packing material in chromatograph.

Abstract: Ca0.6Mg0.4Zr4(PO4)6 coating was used as environmental barrier coatings (EBC) to improve the alkali corrosion resistance of SiC ceramic at high temperature. A new sol-gel based process has been developed for preparing high quality and thick C0.6M0.4ZP coating on SiC ceramic with once deposition. The prepared C0.6M0.4ZP coating on SiC ceramic is homogeneous and dense, and shows a thickness of about 200 μm when sintered at 1400 °C for 3h. The effectiveness of C0.6M0.4ZP coating in improving the alkali corrosion resistance of SiC ceramic was evaluated based on the SEM microstructural analysis, mass change and flexural strength measurements after being subjected to alkali Na-salt attack at 1000 °C for 96 h. Significantly improved alkali corrosion resistance was confirmed for SiC ceramic using C0.6M0.4ZP coating as EBC.