TiO2 Whiskers Research Articles

Towards Fluoride-Based Oxygen Gas Sensors Operating at Room Temperature: Effects of the Whisker Materials Incorporated in the Sensing Electrode on Response Time.

This study is concerned with improvement of the response time of the amperometric oxygen sensors of the type, Ag_??_Ag6I4WO4_??_PbSnF4_??_sensing electrode, O2, of which sensing electrode was a mixture of iron(II)phthalocyanine, PbSnF4 and a whisker material (one of 9Al2O3•2B2O3 and TiO2 whiskers different in length, aspect ratio and conductivity). A good linear relation was found between the short-circuit-current and the square root of oxygen partial pressure for all the sensing electrode mixtures. The response time was strongly influenced by the length and conductivity of the incorporated whisker materials. Incorporation of an whisker material with appropriate length (-20μm), conductivity (-10-1S cm-1) and aspect ratio (20) was found to allow fast response (20s) at room temperature. The fast response results from formation of uniform reduction sites on the conductive whisker network in the sensing electrode.

腐食防食 粉末冶金法により作製したウィスカー強化アルミニウム基複合材料の機械的性質と局部腐食挙動

The high strength and stiffness, lightness and low coefficient of thermal expansion make metal matrix compositions attractive materials for a diverse range of applications including aerospace, automotive, medical and sports equipment. In this study, the mechanical properties and corrosion behavior of whisker reinforced pure aluminum matrix composites produced by powder metallurgy technique were investigated by measurement of tensile and electrochemical properties in conjunction with their microstructures. The tensile strength and elongation of the composites reinforced with Al borate and TiO2 whiskers were nearly equal to those of SiC whisker reinforced composite. The reactivities of Al borate and SiC whiskers with pure Al were lower than that of TiO2 whiskers. The interfacial reactants act as anchors to enhance the cohesive force between matrix and fillers. The oxides whisker reinforced composites had more noble pitting potential compared to SiC whisker. Especially, TiO2 indicated the most noble pitting potential. On the corroded surface of TiO2 whisker reinforced composite, some precipitation products were found in the vicinity of whiskers. This is explained by the fact that the reactivity of whiskers with pure aluminum is different for the each combination. Therefore, the susceptibility of pitting corrosion depends on the formation ability of galvanic couple.

特集 粉末の成形・加工 酸化チタンウィスカー強化Ａｌ基複合材料の疲労特性

Titanium oxide whisker reinforced aluminum matrix composites were fabricated by a powder metallurgical method. Our previous study on tensile properties of TiO2(N)/A1 composite indicated that the interfacial reaction occured considerably on the fabrication process, however, their tensile properties were nearly equal with those of SiC(W)/ Al composite.In this study, fatigue strength was examined by rotating bending test, and the whisker /matrix interface structure was investigated by scanning electron microscope and X-ray diffraction method. For the TiO2(w)/A1 composite, TiO2 whisker changed to Ti2O3 after hot pressing and A1, Ti and A12O3 were produced after hot extrusion at the interfaces. Fatigue limit for the TiO2(R)/A1 composite increased about 50% compared with that of monolithic aluminum. Fatigue crack growth direction was diflected by the whisker and propagated in the matrix along the interface. This fact means that the resistance to crack initiation and propagation increased because the adhesion force between whisker and matrix was improved by the existence of reactants at the interface.