Biaxial Low Cycle Fatigue for Notched, Cracked, and Smooth Specimens at High Temperatures

Push-pull and reversed torsion tests were carried out for notched, precracked, and smooth hollow cylindrical specimens of type 304 stainless steel at 923K in air. This paper describes the crack direction in the three types of specimens and the parameter that correlates the biaxial low cycle fatigue failure data. All types of specimens, except the smooth specimen in the reversed torsion test, failed by mode I cracking. Failure life of the specimens was discussed in connection with the crack mode. The equivalent stress based on COD could correlate the biaxial fatigue data whereas the Mises’ equivalent stress and the maximum principal stress could not.</jats:p

Fabrication and Performance of Photocatalytic GaN Powders

Group-III nitrides are expected to be used in future photocatalytic materials. InGaN is expected to be used for photocatalytic applications in the visible light region. Photocatalytic materials are used primarily in coatings and powders, and powdered photocatalysts are expected to be formed from group-III nitride powders. In this study, we produced GaN powders by nitriding Ga precursors at high temperatures under an atmosphere of NH3. The photocatalytic characteristics of the GaN powder were dependent on nitrization temperature. In addition, the crystallinity of the GaN powders and the photocatalysis were rapidly improved at nitrization temperatures over 1000°C.</jats:p