Papers by Author: Shi Quan Liu

Abstract: Porous silica ceramic substrates were coated with silica sols via dip coating to obtain waterproof performance. Silica sols were prepared through acid-catalyzed hydrolysis and condensation of tetraethyl orthosilicate. The gelation temperature, ratio of ethanol/TEOS, times of coating, and sintering temperature have been studied. The sample with the best waterproof effect was prepared by 5 times of repeated coating using a sol prepared at 25 ^oC with an ethanol/TEOS ratio of 7 and sintering at 550 °C.

Abstract: The mechanic properties mainly the room temperature bending strength and the creep of the Al₂O₃ ceramic specimens which were prepared by cold isostatic pressing and had undergone different thermal histories have been measured and compared. The results suggest that the bending strength of the ceramic increases after high temperature soaking. The ceramic can withstand cyclic rapid cooling with an initial temperature of 200 °C. The sample has shown a very good dimensional stability after a long service time (50h) at 1550 °C.

Abstract: Thermal fatigue is a common problem when ceramics are used at high temperature. Typically, the mechanic properties of ceramics decrease after either long service times at high temperatures or cycles of temperature changes. The thermal fatigue process, the factors influencing the thermal fatigue and the prediction of the thermal fatigue life of ceramics are concerned topics. The thermal fatigue of ceramics is mainly explained by the critical stress fracture and thermal shock damage theories. The thermal fatigue tests include the traditional strength method, the quench-indentation method and the non-destructive detection such as the acoustic emission technique. Based on the thermal fatigue theories, the thermal fatigue life can be predicted using built models. The establishment of the standards for the testing of ceramic thermal fatigue will enhance the comparability of experimental data and further promote the development of analysis theory of thermal fatigue, benefiting the design of engineering ceramics.

Abstract: The industrial solid wastes mainly include mining tailings and industrial slags. Their typical applications in glass-ceramics are reviewed. The compositional design of the glass-ceramics based on the compositional features of wastes and the routes to increase the percentage of wastes in the glass batches are emphasized. To increase the addition of industrial solid wastes in the glass preparation is one of the key factors influencing the utilization of the wastes. One way to achieve this is to apply different wastes with compositional complementarity in glass batches. A few successful examples are summarized in this paper to provide good references for the further related research.

Abstract: Different amounts of SiO2 were used to substitute P2O5 to prepare lithium-iron-phosphate glass melts. It was found that glass can only formed after annealing the melt cast sample if the sample contains SiO2 not more than 5 mol%. The addition of 5 mol% SiO2 into the lithium-iron-phosphate glass strengthens the phosphate glass network. The density, chemical durability, both the transition and crystallization temperatures increase with the addition of SiO2. In addition, the addition of SiO2 results in the decrease in the activation energy of lithium-iron-phosphate glass, making the glass easier to crystallize. However, both the lithium-iron-phosphate glass and the glass with SiO2 show surface crystallization with LiFeP2O7 as the crystalline phase.

Abstract: Mesoporous silica hollow microspheres were quickly synthesized with a simple reaction medium which only contains tetraethylorthosilicate (TEOS) as silica source, octylamine (OA) as template and water. It is proposed that a dispersion of TEOS-in-water is formed when water is added into the mixture of TOS and OA. Water becomes basic due to dissolution of OA. Fast hydrolysis and condensation of TEOS then occurs at the interface of droplets lead to the formation of silica shells. Hollows are formed due to the volume contraction caused by the large difference in the densities of condensed silica and liquid TEOS. In addition, OA assembles with silica, templating the nanopores in the silica shells.