An electrochemical microactuator based on highly textured LiCoO2

In this paper we demonstrate a novel electrochemical actuator based on an array of micro-pillars of intercalation compound LiCoO2 with induced crystallographic texture (Lotgering factor f = 0.96) to enhance actuation strain. The highly textured LiCoO2 posts were fabricated by hot-press sintering and subsequent dicing, and the contrived texture facilitated both electrochemical lithiation and resulting actuation strain in the longitudinal direction. Compared with traditional actuator materials, such as piezoceramics, the micro-pillar array of LiCoO2 showed an almost one order higher actuation strain (1.2%) at a low applied voltage (<5 V). The conceptual demonstration outlined in this paper provides a foundation for the design and application of intercalation compounds as novel smart materials

Fabrication and electrical properties of bulk textured LiCoO2

Fabrication and electrical properties of bulk textured LiCoO

Development of novel melt spinning based processing route for oxide dispersion strengthened steels

Melt spinning of an Fe-5Y and Fe-1Y-1Ti (wt%) alloys produced a relatively uniform spatial distribution of Y and Ti in solid solution and ribbons with consistent yield (> 60% by weight), fast processing time ( 100 g feedstock material) and repeatability. Heat treatment in the presence of Fe2O3 as an oxygen source (Rhines pack method) at 973 K validated the potential of forming < 20 nm Yrich oxides in the 1 Fe-5Y ribbons. Pulverized Fe-1Y-1Y ribbons were consolidated to bulk using the field assisted sintering technique (FAST) incorporating nano-sized Fe3O4 powder as the oxygen source. After FAST at 1273 K, 50 MPa and 30 min a comparatively high number density of sub-micron Y and/or Ti-rich oxides were developed. Further formation of fine-scale oxides took place during post-FAST annealing, resulting in an approximate 20% increase in hardness at temperatures below 573 K, but with a reduced hardening effect above 673 K due to a small fraction of persistent porosity and mechanically weak prior ribbon boundaries that were decorated with Ti-rich oxide

Microstructural and mechanical characterisation of Fe-14Cr-0.22Hf alloy fabricated by spark plasma sintering

Fe-14Cr pre-alloyed powder and pure Hf powder were mechanically alloyed to produce powder with nominal composition Fe-14Cr-0.22Hf (wt. %) that was consolidated by the spark plasma sintering (SPS) technique in order to investigate the ability of Hf to produce a nanometric dispersion of oxide particles in a ferritic matrix. Comprehensive microstructural and mechanical characterisation of the as-milled powder and the consolidated material was performed using electron microscopy, X-ray diffraction, atom probe tomography and indentation techniques. It was shown that Hf additions can effectively produce, by internal oxidation, a fine scale dispersion of Hf-O nanoparticles in the consolidated material. A uniform grain structure was produced in the alloy. Although the nanoparticle dispersion was not homogeneous at the finest scale, the resulting dispersion strengthening contributed significantly to the hardness. According to these results, internal oxidation of reactive elements rather than direct addition of oxides may offer additional opportunities in the design and development of oxide dispersion strengthened steels