The heat treatment in carbon powder is a safe and effective strategy to enhance the photocatalytic activity of titanium dioxide (TiO 2 ) coatings. Firstly, Ti coatings were prepared by mechanical coating operation with Ti powder on alumina balls. Secondly, the target TiO 2 coatings were prepared using the prepared Ti coatings by the multi-heat treatment (pretreatment in carbon powder, oxidation in air and reduction in carbon powder). During the pretreatment, thin films of Ti 2 CO and micro-cracks form in the surface of the Ti coatings. The formed thin films and micro-cracks are helpful for forming a nano-fiber morphology of rutile TiO 2 , during the subsequent oxidation. During the reduction, oxygen vacancies generated in the lattice of rutile TiO 2 are in favor of narrowing the band gap. The target TiO 2 coatings with a nano-fiber morphology and the narrowed band gap, effectively enhances the photocatalytic activity by more than 3 times, compared with the pristine TiO 2 coatings.

Results are reported from an ongoing experimental investigation of the effects of thermo-oxidative aging on the mechanical behavior of an epoxy shape memory polymer (SMP). Chemo-rheological degradation due to macromolecular scission and cross-linking is one of the main factors contributing to the chemical aging of thermo-responsive SMPs. This aging may manifest as residual strain or irreversible material property changes, which can affect the performance and limit the useful life of a SMP. A relatively new epoxy SMP based on the diglycidyl ether of bisphenol A is synthesized, and specimens are tested under uni-axial tension using a dynamic mechanical analyzer. Fundamental viscoelastic behavior and thermal expansion coefficients are first characterized, showing a glass transition near 60 °C. Shape memory cycle experiments are performed at shape fixing temperatures of 80, 125, 150 and 175 °C, and the effect of fixing time at each temperature is examined upon subsequent strain recovery at 80 °C. Performance parameters such as recovery ratio, speed of recovery and residual strain are quantified as a function of shape fixing time and temperature. No effect of chemical aging was seen at a fixing temperature of 80 °C, although the recovery ratio decreases initially with increasing fixing time and stabilizes near 92 %. Only minor effects of chemical aging are seen in the mechanical responses for fixing temperatures of 125 and 150 °C, but specimens exhibit progressively more noticeable color changes that indicate oxidation. Significant effects are observed at the highest fixing temperature of 175 °C, where chemical aging at longer fixing times results in a reduction in recovery rate across the rubber-glass transition temperature, progressively larger residual strains, lack of complete strain recovery at 80 °C, and higher temperatures to achieve 90 % strain recovery.

Advanced fiber reinforced ceramic composite having self-healing function (shFRC) has been developed. The composite includes the silicon carbide interlayer as healing agent at the interface between alumina fiber and alumina matrix. The healing agent interlayer caused the preferential fracture of the fiber/matrix interface and the interface fracture gave rise to the slip of the interface during crack propagation. Thereby the shFRC could exhibit a large deformation at the fracture and large fracture energy. Moreover, the high temperature oxidation of the healing agent made the interface delimitation rebounded by the formed oxide and the reaction heat. As a result, the maximum strength and the stiffness degraded by the interface delimitation could be recovered by the healing. Consequently, it was found that the shFRC containing the interlayer of the healing agent can survive the repeated crack propagation or initiation due to the large impact damage.

An electrochemical polymerization method has been developed newly to fabricate a single layer polypyrrole (PPy) film and some single layer carbon-nanofiber (CNF)/PPy films with several different weight ratios of CNF such as 3%, 5%, 7%, and 10%. The CNF/PPy composite material was newly fabricated first time for this research. PPy was fabricated by oxidation of pyrrole monomer in a mixed solution of propylene carbonate and LiTFSI (Bis(trifluoromethane)sulfonamide lithium salt). Ni sheets were used as working and counter electrodes during polymerization. SEM images were taken on surfaces and cross-sections of the CNF/PPy composite samples. Conductivity is shown to be improved much from 77.93S/cm to 124.3S/cm due to the high conductivity of CNF. Experimental results show that conductivity increases approximately linearly. Actuation strain was measured. The strain of a PPy film was 12.6% and for a 10% CNF/PPy film, the strain was 8.6%. It was noticed from experiments as the strain of samples was reduced as CNF weight ratio increased. Bending motions were observed for both PPy and CNF/PPy films when subjected to electric currents. The tip deflections of the films varied from 0.5mm to 2mm. Mechanical properties such as Young’s modulus and strength were tested and it was shown that the CNF enhanced the strength of the composite samples greatly. The CNF/PPy films show a great potential to be a good candidate for good sensor and actuator material.

This paper deals with the study of different structuring methods for high temperature nickel alloys, which are used for compressor and turbine blades in aeroengines. The ideal structured surface combines high oxidation resistance with low drag in a hot gas flow. The effect of drag reduction due to riblet structured surfaces was originally inspired by the shark scales, which have a drag reducing riblet structure. Riblets were successfully produced on a NiCoCrAlY coating by picosecond laser treatment. This method is suitable for larger structures within the range of some tens of micrometers. Furthermore, experiments were performed by depositing different materials through polymer and metal masks via electrodeposition and physical vapor deposition. All fabricated structures were oxidized at 900–1100°C for up to 100 h to simulate the temperature conditions in an aeroengine. The resulting shape of the riblets was characterized using scanning electron microscopy. The most accurate structures were obtained by using photolithography with a subsequent electrodeposition of nickel. This method is suited for single digit micrometer structures. The reduction of the wall shear stress was measured in an oil channel. The riblet structures prior to oxidation showed a reduction of the wall shear stress of up to 4.9%.

Self-healing is the most valuable phenomenon to overcome the integrity decreases which are caused by the damages in service. Thus, self-healing should be automatically occurred as soon as the damages occur, and the healed zone should have high integrity before damaging. In the case the structural ceramics, the severest flaw is surface cracks which are possible to be introduced by crash, fatigue, thermal shock and corrosion during service. Thus, the self-healing of surface cracks in the structural ceramics is an important issue to ensure the structural integrity of the ceramic components. The present author and coworkers succeeded to endow the excellent self-healing ability to structural ceramics by using the high temperature oxidation of the dispersed silicon carbide particle. In the present paper, the healing mechanism, behavior and advantages will be introduced. Moreover, our latest self-healing ceramics will be also reported.