A novel technique for making open-cell Al_2O_3-ZrO_2 ceramic foam with plant seed template

The aim of the present research is to provide a technique for preparing open-cell Al2O3-ZrO2 ceramic foams with uniform cell size.This technique used plant seeds to array templates and centrifugal slip casting to obtain cell struts with high packing density.Aqueous Al2O3-ZrO2 slurries with up to 50 vol.% solid contents were prepared and the rheological characteristic of the slurries was investigated.Consolidation was performed at an acceleration of 2,860 g for 60 min.The effect of the characteristic of plant seeds on the drying behavior of Al2O3-ZrO2 green compact was analyzed.The effects of the solid contents of slurries on segregation phenomena of Al2O3 and ZrO2 particles and green compact uniformity were investigated.The compressive stress-strain curve and deformation behavior of Al2O3-ZrO2 ceramic foams prepared using plant seed template were analyzed.The results showed segregation phenomenon is negligible for highly stable slurry with 50 vol.% solid loading.The prepared cell struts of Al2O3-ZrO2 foams have high green density (61.9% TD), sintered density (99.1% TD) and homogeneous microstructure.When sintered at 1,550 ℃ for 2 h, the cell size of Al2O3-ZrO2 foam is approximately uniform and the diameter is about 1.1 mm.The porosity and compressive strength of sintered products is 66.2% and 5.86 MPa, respectively.

Predicting model on ultimate compressive strength of Al_2O_3-ZrO_2 ceramic foam filter based on BP neural network

In present study, BP neural network model was proposed for the prediction of ultimate compressive strength of Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting. The inputs of the BP neural network model were the applied load on the epispastic polystyrene template （F）, centrifugal acceleration （v） and sintering temperature （T）, while the only output was the ultimate compressive strength （（7）. According to the registered BP model, the effects of F, v, T on 0 were analyzed. The predicted results agree with the actual data within reasonable experimental error, indicating that the BP model is practically a very useful tool in property prediction and process parameter design of the Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting.

Study on Mg PSZ Ceramics Doped with Y_2O_3 and CeO_2

Mg PSZ ceramics doped with Y 2O 3 and CeO 2 was prepared using traditional processing method. The fine grain PSZ ceramics( d c10 μm) sintered at low temperature(1550 ℃) was obtained by means of composition design. The effects of co stabilization of Y 2O 3, CeO 2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y 2O 3 and CeO 2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t ZrO 2 precipitates in c ZrO 2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress induced transformation toughening and microcrack toughening.

添加剂对SiC-Al_2O_3陶瓷过滤器性能的影响

采用有机泡沫浸渍工艺制备泡沫陶瓷过滤器,研究添加剂SiO2微粉和CeO2对碳化硅-氧化铝基泡沫陶瓷过滤器的影响。采用正交实验并对陶瓷进行性能检测,结果表明,SiO2微粉和CeO2的加入量与烧成温度之间存在最佳配比。采用最佳配方在1380℃下制得的碳化硅-氧化铝基泡沫陶瓷过滤器常温抗压强度为2.10Mpa,热震稳定性为20次。

Effect of Al powder and silica sol on the structure and mechanical properties of Al_2O_3-ZrO_2 foams

Polymeric sponge replication method is one of the common ways for ceramic foam production. The existence of central triangular voids in the struts results in a decrease of mechanical properties limiting their applications. To remove this defect, some additives consisting of Al powder particles and silica sol are added to ceramic slurries consisting of Al2O3 and ZrO2 （partially stabilized zirconia）. With increasing temperature for pyrolyzing and sintering of raw materials, first the Al powder and then the glass phase which consisted of melted Al2O3, ZrO2 and SiO2 was soaked into hollow struts. SEM investigations showed that the center of foam struts were free of hollows. XRD considerations depicted that a ZrO2 phase with tetragonal crystallographic structure is present in the produced foam which could be the reason of improved toughness and mechanical properties. Compressive strength of foams increased significantly due to the decrease of closed porosity. The Weibull statistical study showed remarkable increasing of the Weibull module and its value for foams with 10, 20 and 30 ppi was 5.91, 6.06 and 6.53 respectively.

Study on analysis of crystal structure in CeO_2 doped with Er_2O_3 or Gd_2O_3

To simulate the effects of burnable poison doping in nuclear fuel UO2,Er2O3(or Gd2O3)-doped CeO2 pellets were prepared. Changes in lattice constant and atomic disordering for CeO2 due to the Er2O3 and Gd2O3 doping were measured by means of XRD and XAFS. By the Er2O3 doping,the lattice constant decreased,and a disordering of lattice structure was induced in the samples. The doping with Er2O3 also induced the disordering of atomic arrangement around Er atoms,which was observed through the change in XAFS spectra. In contrast,the effect of Gd2O3 doping was smaller than that of Er2O3 doping. The result was discussed in terms of ionic size of dopants in CeO2 crystal.

磷酸三钠对高钛高炉渣制备微晶泡沫玻璃的影响

以高钛型高炉渣和废玻璃粉为主要原料,碳酸钙为发泡剂,硼砂为助熔剂,采用"一步法"烧结在900℃低温下制备了微晶泡沫玻璃。借助DSC、XRD、SEM等分析测试手段,研究了磷酸三钠(Na_(3)PO_(4)·12H_(2)O)添加量对制备微晶泡沫玻璃的影响。结果表明,在不同的磷酸三钠添加量(0%~10%,质量分数)下,微晶泡沫玻璃的主要物相变化不显著,均为透辉石Ca(Mg,Al)(Si,Al)_(2)O_(6),富铁普通辉石Ca(Mg,Fe)(Si,Fe)_(2)O_(6)以及普通辉石CaMgSi_(2)O_(6);随着Na_(3)PO_(4)·12H2O含量增加,微晶泡沫玻璃抗压强度和导热系数减小,体积密度和吸水率先减小后增大。当磷酸三钠添加量为6%时,微晶泡沫玻璃具有最优的综合性能。