Impacts of precursor solution recipe, processing parameters, and pellet thickness on the lithium ionic conductivity of the ceramic materials with perovskite structure of Li0.3La0.57TiO3 were investigated and new method was proposed to synthesize Li0.3La0.57TiO3 solid state electrolyte. The results showed that ionic conductivity of Li0.3La0.57TiO3 membrane which was synthesized by firstly forming colloidal TiO2 (i.e., TiO2 sol) and then Li+ and La+ were added to the colloidal TiO2 was on the order of 10-5 S/cm. It also showed that the temperatures corresponding to a full decomposition for L0.3La0.57TiO3 is about 750°C and materials start forming perovskite structure when temperature reaches about 900°C and the lithium ionic conductivity gains about 21% increase when the pellet thickness is reduced to about ¼
In this study, to investigate effects of rhenium addition on the microstructures and mechanical properties, 15Cr-1Mo ODS ferritic steels with rhenium additions were fabricated by the mechanical alloying, hot isostatic pressing, and hot rolling processes. Unremarkable differences on grain morphologies and nano-oxide distributions were estimated in the microstructure observations. However, the ODS ferritic steels with 0.5 wt.% rhenium showed higher tensile and creep strengths at elevated temperature than that without rhenium. It was found that rhenium is very effective to improve the mechanical properties.
Thermal/cold spray deposition were used for additive manufacture of oxide dispersion strengthened (ODS) steel layers. Mechanically alloyed F/M ODS steel powders (Fe(bal.)-10Cr-1Mo-0.25Ti-0.35Y2O3 in wt.%) were sprayed by a high velocity oxygen fuel (HVOF) and cold spray methods. HVOF, as a thermal method, was used for manufacturing a 1 mm-thick ODS steel layer with a ~95% density. The source to objective distance (SOD) and feeding rate were controlled to achieve sound manufacturing. Y2 Ti2 O7 nano-particles were preserved in the HVOF sprayed layer; however, unexpected Cr2 O3 phases were frequently observed at the boundary area of the powders. A cold spray was used for manufacturing the Cr2 O3 -free layer and showed great feasibility. The density and yield of the cold spray were roughly 80% and 45%, respectively. The softening of ODS powders before the cold spray was conducted using a tube furnace of up to 1200°C. Microstructural characteristics of the cold sprayed layer were investigated by electron back-scattered diffraction (EBSD), the uniformity of deformation amount inside powders was observed.
In this study, ODS ferritic stainless steels were fabricated using a commercial alloy powder, and their microstructures and mechanical properties were studied to develop the advanced structural materials for high temperature service applications. Mechanical alloying and uniaxial hot pressing processes were employed to produce the ODS ferritic stainless steels. It was revealed that oxide particles in the ODS stainless steels were composed of Y-Si-O, Y-Ti-Si-O, and Y-Hf-Si-O complex oxides were observed depending on minor alloying elements, Ti and Hf. The ODS ferritic stainless steel with a Hf addition presented ultra-fine grains with uniform distributions of fine complex oxide particles which located in grains and on the grain boundaries. These favorable microstructures led to superior tensile properties than commercial stainless steel and ODS ferritic steel with Ti addition at elevated temperature.
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