Danyu JIANG
,
Chen ZHANG
,
Jianlin SHI
,
Tingrong LAI and Dongsheng YAN(Shanghai Institute of Ceramics
,
Chinese Academy of Sciences
,
Shanghai 200050
,
China)
材料科学技术（英文）
The composite of Dy-α-sialon/10 wt pct nano-size SiC particles has been prepared from precursor powders of Si3N4, AIN, Al2O3, Dy2O3 and nano-size β-SiC. The hardness, toughness and bending strength of the composite at ambient temperature are a little higher than those of Dy-α-sialon.while the bending strength is maintained up to 1000℃ and about 2 times more than that of Dy-α-sialon at the same temperature. The fracture surfaces show that the grain size of the composite is smaller than that of Dy-α-sialon, and both Of them have predominately transgranular mode of fracture. It is believed that the decrease of the bending strength of Dy-α-sialon at elevated temperature is caused by the viscous flow of the grain boundary phase, while the addition of nanosize SiC particles effectively increases the viscosity of the grain boundary phase and therefore prevents the strength loss of Dy-α-sialon/nano-size SiC composites at elevated temperature
关键词:
Wenbo FEI
材料科学技术（英文）
This paper shows that it is easier to form intelligent ceramics than other materials. Self-adaptive factors and relevant function mechanisms, which determine the formation of intelligent ceramics, are studied and data from the design of the PLZT with complex functions are presented.
关键词:
Zhijun LIN
,
Meishuan LI
,
Yanchun ZHOU
,
null
,
null
材料科学技术（英文）
Layered ternary ceramics represent a new class of solids that combine the merits of both metals and ceramics. These unique properties are strongly related to their layered crystal structures and microstructures. The combination of atomic-resolution Z-contrast scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM), selected area electron diffraction (SAED), convergent beam electron diffraction (CBED) represents a powerful method to link microstructures of materials to macroscopic properties, allowing layered ternary ceramics to be investigated in an unprecedented detail. Microstructural information obtained using TEM is useful in understanding the formation mechanism, layered stacking characteristics, and defect structures for layered ternary ceramics down to atomic-scale level; and thus provides insight into understanding the ``Processing-Structure-Property" relationship of layered ternary ceramics. Transmission electron microscopic characterizations of layered ternary ceramics in Ti-Si-C, Ti-Al-C, Cr-Al-C, Zr-Al-C, Ta-Al-C and Ti-Al-N systems are reviewed.
关键词:
Layered ternary ceramics
,
ternary
,
ceramics
,
MAX
,
phase
,
TEM
,
S
Applied Physics Letters
The effect of high-energy ball milling on the structure of nanometer sized amorphous ceramics, a-Si3N4 and a-Si-N-C, respectively, has been investigated. At high milling intensity, a-Si3N4 may rapidly crystallize into a mixture of alpha-Si3N4 and beta-Si3N4 after the initial 4 s of milling whereas no structural changes were observed at low milling intensity. For a-Si-N-C, mechanical milling does not cause structural changes at both low and high intensity. It was found that extension of mechanical milling of these hard ceramics can introduce large volume fractions of contamination fragments from the milling media. We conclude that the observed structural changes occurring in a-Si3N4 may be due to mechanical effect, rather than local heating and/or impurity effect. (C) 1996 American Institute of Physics.
关键词:
ni-zr;alloys;powders;metals
Materials Science and Technology
In order to meet increasing requirement for the evaluation and design of damage tolerance of brittle materials, a simple expression was proposed to estimate the damage tolerance quantitatively using basic material parameters, based on the features of damage tolerance and fracture mechanics. The calculated results from this equation indicated that the damage tolerance of nanolayer grained ceramics was over 10 times higher than that of some brittle ceramics, while glass has the lowest damage tolerance. Therefore, the damage tolerance of various ceramics can be estimated directly using their basic properties data without the necessity of additional tests. SEM examination and finite element simulation showed that the high damage tolerance of the layer grained ceramics was attributed to delamination in grains, interlocking microstructures and crack deflection.
关键词:
damage tolerance;brittle material;nanolayer grained ceramics;reliability;liquid reaction synthesis;ti3sic2;ti3alc2;microstructure;indentations;glass
Transactions of Nonferrous Metals Society of China
The influence of some additives on bulk density, phase composition, mechanical strength and thermal shock resistance of aluminium titanate (AT) ceramics was investigated. AT ceramics with different additives of MgO, SiO(2) and Fe(2)O(3) were prepared by reaction sintering. Properties of AT ceramics were tested by using Archimedes, three-point bending and thermal cycling tests. It was found that additives of MgO, SiO(2) and Fe(2)O(3) or their compound additives are favorable to reduce the porosities of AT, enhance mechanical strength and thermal shock resistance. The role of additives can be rationalized in terms of promotion of sintering process, formation of new phases and influence on lattice constant c of AT ceramics.
关键词:
aluminium titanate ceramics;additive;bulk density;mechanical;properties;thermal-stability;mullite;composites;sol
材料导报
多相材料是材料研究发展的必然结果。提出多相材料的研究，目的是要拓宽材料研究的视野，主张模糊各类材料的界限，运用纳米材料制备技术，博采各类材料制备工艺之所长，以使用上的要求为材料研究的准则，制作出低成本和高性能稳定性的材料。还强调在考虑材料研究中的问题时，始终以满足使用要求为目标，并不一味地追求材料的高性能，务求创新。提倡用逆向思维来考虑多相材料的研完，研究对象则针对于信息、能源、生物和环保领域的应用。多相材料材料研究About the Research of Multi-phase MaterialsGuo Jingkun (Shanghai Institute of Ceramics,Chinese Academy of Sciences ,Shanghai 200050, China)
关键词:
