The paper contains the results of a preliminary study of SiCw-reinforced Al2TiO5 matrix composites. With the increase in the SiC whisker content, the bending strength of composites also increased. For the 7 wt.% SiCw composition, the strength had increased by 170% from the value for Al2TiO5ceramic without notable alteration of thermal expansion coefficient.

Mechanical properties of in-situ toughened Al2O3/Fe3Al nano-/micro-composites were measured. Effects ofFe3Al content, sintering temperature and holding time on properties and microstructure of the composites wereinvestigated. The addition of Fe3Al nano-particles decreased the aspect ratio and grain size of Al2O3, and changedthe fracture mode of composites. The maximum bending strength and fracture toughness were 832 MPa and 7.96 MPa m1/2, which were obtained in Al2O3/5 wt.% Fe3Al sintered at 1530 8C and Al2O3/10 wt.% Fe3Al sintered at 1600 8C, respectively. Compared to monolithic alumina, the strength increased by 132% and the toughness increased by 73%. The improvement in the mechanical properties of the composites was attributed to the change in fracture mode from intergranular fracture to transgranular fracture, the "'in-situ reinforced effect" arising from the platelet grains of Al2O3 matrix, refined microstructure by dispersoids, as well as crack deflection and bridging of intergranular and intragranular Fe3Al.

On the basis of analyzing the formation mechanism of thermal stress in coatings, according to practical thermal conditions and mechanical principle, the calculating model that can estimate thermal stress of coatings during fabricating process is established. Through observing the microstructure of coatings by SEM, the thermal mechanical behavior and its effect on the properties of coatings are studied. The results show that, in graded coatings, parameters of thermal mechanical behavior and fabrication stress change with the compositions. The largest stress exists in the bottom layer and the thermal stress decrease from the substrate to the surface. In graded coatings, the highest stress and the average stress are both lower in coatings. The gradient distribution of coatings' composition can effectively reduce thermal stress during fabrication process.

Fe3Al nano-particles and commercial purity Al2O3 powders were used as raw materials to fabricate in situ reinforced Al2O3/Fe3Al nano/micro-composites. Densification and microstructure were studied. The Al2O3 matrix grains were characterized by platelet grains. The Fe3Al particles inhibited the grain growth of Al2O3 grains and limited the densification of the composites. In Al2O3/Fe3Al composites, the Fe3Al particles were uniformly dispersed in the Al2O3 matrix. The major Fe3Al micro-particles, about 1 mm in average size, existed at Al2O3 grain boundaries, and the Fe3Al nano-particles were found embedded in the matrix grains. The grain size of the intragranular particles ranged from several to several hundred nanometers. The grain size and aspect ratio of Al2O3 platelet grains and distribution of intragranular Fe3Al could be optimized by controlling the Fe3Al contents and sintering process. The in situ formed Al2O3 platelet grains, as well as Fe3Al dispersoids, were beneficial to the increase of the mechanical properties of alumina.

Pure and 2 mol% yttria-doped zirconia nano-powders were synthesized via the precipitation method, using ZrOCl2