In this study, the effect of the surface treatment on mechanical response of LaNi_5 thin film actuator deposited on polyimide substrates was investigated. Since this actuator could be reversibly driven by hydrogen pressure control, this actuator is expected as a sensor and/or controller of hydrogen gas flux in various hydrogen related devices. In the experiments, initiating time of the actuation after hydrogen gas exposure is tremendously reduced by surface treatment. This significantly modified mechanical response is attributed to switching of the reaction rate determining steps. Dissociation of hydrogen gas molecules on the sample surface is considered to be changed to permeation/diffusion of hydrogen atoms in the film by the surface treatment treatment. Furthermore, we concluded that the high responsiveness, induced by the treatment, was caused by not only hydrogen migration rate, but also hydrogen solubility limit at room temperature.

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Closed Cellular materials containing heat resistant polymer for smart systems has been developed. Heat resistant polymer particles coated with a nickel-phosphorus alloy layer using electroless plating were sintered by spark plasma sintering method. The compressive and damping tests were carried out to measure the mechanical and damping properties of this material, respectively. The results showed that the stress-strain curve had a liner region, long plateau region and wavy region, and the sintering temperatures of the specimens affected the compressive strength of each specimen. The damping capacity of this material were shown to be very large. These results indicate that this metallic closed cellular material can be utilized as a material for energy-absorbing and passive-damping systems.

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This paper describes the possibility of Me-DLN films as temperature sensor. DLC is used as coating material for the cutting tools up to now. The problem is low adherence between film and substrates. In order to solve it DLN was proposed. In this study Metal-containing DLN was deposited onto ceramics substrate by DC and RF discharged of siloxane vapor. During deposition metal phase was fabricated by magnetron sputtering of metal target. Temperature-conductivity dependence was measured by standard 4-terminal method in the temperature range of 80-400 K in vacuum. Dimensionless temperature sensitivity of investigated films are calculated as a evaluation of temperature sensors. All films are demonstrated weak temperature dependence of conductivity and calculation of dimensionless temperature sensitivity show that Me-DLN has a possibility to be used as wide range temperature sensors. And Me-DLN temperature sensors are hoped to have not only the properties of coating materials but also sensing function.

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This report asked for the hardness of the screw thread section of the bolt which was not able to be measured with the conventional hardness examination machine directly by nano indentation, and the nano indentation hardness of a screw thread section is examined about the bolt made from pure Ti. Following conclusions were obtained. (1)The martens hardness of the screw thread section of the pure Ti bolt tends to increase from a screw thread tip gradually up to the position of 1000/μm. (2)The martens hardness of the screw thread section of the pure Ti bolt shows a low value from a screw thread tip in the position of 3500μm.

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Commercially pure (CP) titanium is widely used for biomaterials because of its good biocompatibility. Actually used biomaterials for a stent, for example, are subjected to inelastic deformation. However the inelastic deformation of CP titanium has not been clarified yet. In this paper, inelastic deformation, especially, viscoplastic deformation such as strain rate effect, creep, stress relaxation and uniaxial ratchetting are investigated by a series of tests using CP titanium at room temperature. Microscopic observation is also conducted by uniaxial loading tests using a rectangular specimen. The test results show that the CP titanium has large viscoplastic deformation, and especially large creep deformation and stress relaxation cause a problem to use CP titanium for a biomaterial.

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In this paper, a series of tests are conducted to clarify viscoplastic deformation of Ti-6Al-4V Pure tensile tests with several strain rates, creep tests, stress relaxation tests and uniaxial ratchetting tests are chosen for the purpose. Moreover, cyclic tension-compression loading is also performed. The test results show that Ti-6Al-4V has viscoplastic deformation, and large creep, stress relaxation and ratchetting strain occur in spite of the small stress rate effect of the pure tension. Particularly, the large creep strain and ratchetting strain occur though the stress levels for creep tests and maximum stresses for ratchetting tests are lower than the yield stress.

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Uniaxial tension fatigue tests were carried out in air and in high vacuum environments using test pieces made of Ti-6Al-4V with small artificial defects. We examined environmental effects of high vacuum on S-N properties and fatigue crack growth limit. As a result, the following were obtained, (i) Regardless of defect sizes, fatigue lives in high vacuum were much longer than those in air. The slope of S-N curve showed different tendencies between in air and in high vacuum corresponding to defect sizes, (ii) The downward trend of ΔK_<th> with decreasing crack size existed not only in air but also in high vacuum, and the tendency was stronger in high vacuum than in air.

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Rotaing bending and axial fatigue tests have been performed using solution treated and aged materials in two beta titanium alloys, Ti-15Mo-5Zr-3Al and Ti-22V-4Al alloy. Subsurface crack initiation was found to be a microstrructure and a stress ratio related phenomenon. In the former alloy, cracks were initiated internally only in a material that was solution treated above the beta transus and at a certain stress ratio in relatively short life regime. The effects of grain size and mean stress were not characterized entirely by the Hall-Petch relationship and the Goodman relationship, respectively, which was attributed to different crack initiation mechanisms. In the latter alloy, subsurface crack initiation was also seen in the long life regime around or above 10^7 cycles, resulting in a step-wise S-N curve. A smooth facet invariably existed at the crack initiation site. The occurrence of this mode of failure is discussed based on microstructural and mechanical considerations.

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This study examines the Martensite transformation of Ni-Ti Shape Memory Alloy. Fast, transformation temperature of Ni-Ti Shape Memory Alloy is measured by using Differential Scanning Calorimetry and Dynamic Mechanical Analysis. Since the result by DMA coinsides with that by DSC Measurement, the heat treatment temperature which influences with Martensite transformation temperature is investigated by DMA. Next, crystal structure is investigated by X-ray diffraction mater. Usually it is considered that the crystal structure of Martensite state is as B19 structure, While, the B2 is found in that state.

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Spark plasma sintering (SPS) process has paid to attention because of lower sintering temperature and shorter sintering time compared with conventional sintering method. In this research, The Ti-6Al-4V matrix composites (TMC) reinforced with SCS-6 have been fabricated by using SPS. The Ti-6Al-4V powders and SCS-6 mats were alternately fill into the dies and sintered by SPS. TMC was sintered at temperature of 800, 900, or lOOO℃ and at pressure of 30, 60MPa. The effect of sintering temperature and sintering pressure on tensile properties of TMC by SPS were evaluated. Tensile test of the sintered TMC by SPS was carried out. In addition tensile properties of TMC were experimentally evaluated with 10 to 30% volume fraction of SCS-6. The fatigue strength of TMC will be discussed.

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A new process was developed to form high performance photocatalyst film of titanium dioxide by oxidizing titanium metals in the burning flame of acetylene gases. The oxide film by this process has much superior resistance to scratch, wear and chemical reactions to a conventional titanium dioxide spray coating film. Further, this film shows superior performances in the visible-light photo-catalysis; ten times or more of photo-current density and wide absorption wave range up to 490nm comparing with the conventional spray coating film up to 410nm.

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Pure titanium and titanium alloy are generally used as orthopaedic implants like total hip arthroplasty because of its high strength and high biocompatibility. Stability of bone-implant interfacial bonding is a critical factor for successful total hip arthroplasty. Because of the problems of loosening and dissolution of harmful ion with cemented techniques, alternative cement-less fixation of the total hip arthroplasty has been developed. Plasma spray coating of bone-like apatite is an example to add strong bonding capability with bone to metallic materials. However, this physical coating treatment shows weak base-coating bonding strength and difficult to apply on irregular surface. Chemical treatments do not have such drawbacks. The alkali-heat treatment method, developed by Kokubo et al, is a kind of chemical treatment to enhance the bone-bonding strength of pure titanium. This technique involves soaking the implant in an alkali solution and subsequent heating, resulting in a strong bone-bonding ability and a high bone affinity. This study transplants alkali heat treated titanium alloy on the rabbit femoral bone and examined in vivo interfacial bonding strength.

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