Norio Muto

Preparation of semiconducting carbon fibre by pyrolysis of polyacrylonitrile precursor

Semiconducting carbon fibres were prepared from polyacrylonitrile precursor by pyrolysis in an inert atmosphere in temperature range 550–800 °C. The obtained fibres have an electrical resistivity between 104 and 10−2 Ω cm−1 and showed negative temperature coefficients. Electrical resistivity was mainly governed by the pyrolysis temperature and both electrical resistivity, ρ, and thermistor constant,B, decreased with increasing pyrolysis temperature and duration. A linear relation between log ρ and thermistor constantB was observed. Chemical analysis and infrared spectra indicated that the concentration of nitrogen and hydrogen decreased and basal plane structure developed accompanying an increase in carbon content as the pyrolysis temperature increased.

Materials design of CFGFRP-reinforced concretes with diagnosing function for preventing fatal fracture

When concretes reinforced by CFGFRP (carbon fiber-glass fiber reinforced plastics) composites containing three types of carbon fiber bundles with different ultimate elongation values are subject to two-point loading tests, the electrical resistance increases linearly with the increase of load, strain and deflection of CFGFRP-reinforced concretes during loading and unloading but when the maximum value of the previous load is exceeded, the increase of electrical resistance becomes non-linear. This behavior is an effective way of knowing the magnitude of the maximum load during loading and unloading. The change in electrical resistance of CFGFRP reinforced concretes during loading increases largely when the carbon fiber bundle is fractured and is maintained thereafter against the increase of external load due to the presence of glass fibers. This behavior can also be used to prevent fatal fracture. Change in electrical resistance can supply better information for damage in concrete structures than strain or ...

Coiled carbon fibers from PAN precursors

Abstract Acrylic (PAN) fibers with a novel coiled morphology as precursors for semiconducting carbon IR detection elements were prepared using a “hybrid” spinning technique combining principles from standard wet and dry spinning methods. Fiber structure and morphology were found to depend on furnace temperature and coagulation conditions. The highest-density fibers were formed at a furnace temperature of 180°C and a coagulation bath composition of H 2 O:DMF = 3:1 at 19°C. Fibers with diameters of 100–200 μm were obtained, which when fired had resistivities in the range ≈ 3–70 Ω cm, and thermistor constants of B ≈ 1300–2500 K. Their application as IR detection elements is reported.

Infrared detection by semiconducting fibre

On examine la resistivite electrique et les proprietes de detection IR de deux types de fibres de carbone a base de brai et de rayonne, et on les compare a celles de fibres SiC et Si-Ti-C-O

Intelligent materials for civil engineering: proposal of ken materials

Advanced technology has become too much complicated for general public to understand. Very limited expert can understand and treat this sort of complicated technology. Advanced technology is losing close contact to most people. The present speaker characterize this phenomenon as technomonopoly. Unless people accept and support technology, environmental issues cannot be solved. Intelligent materials have to be developed to simplify technology in order to recover friendship to general public. When general public understand technology, feel satisfied with technology and think technology of their own, technodemocracy is thus achieved.

Detection of Damage by Measurement of Electrical Resistance in CFGFRP Composites.

CFGFRP (carbon fiber-glass fiber-reinforced plastics) composites are materials with a self-diagnostic function for detecting latent damage. Three type of carbon fiber bundles with different ultimate elongations and one type of glass fiber bundle with a large ultimate elongation were tested as conductive fibers and insulating fibers, respectively. Electrical resistance increased with increasing strain, and a tremendous change was seen at the transition point where the carbon fiber bundles fractured. Data obtained by the acoustic emission method were measured simultaneously, and these changes showed results similar to changes in the electrical resistance. Permanent, residual strain and residual electrical resistance were observed even after the removal of load, and these changes were dependent on the maximum strain applied in the past. Latent damage of CFGFRP composites can be detected by a method based on the measurement of their changes in residual electrical resistance after unloading. The method based on measuring changes in the electrical resistance of the CFGFRP composites during and after loading is simple in terms of technique and manageable in terms of cost for detecting latent damage and preventing fatal fracture.

Design of Intelligent Structures Containing CFGFRP Composites with Self-Diagnosing Function for Fracture

CFGFRP (carbon fiber-glass fiber reinforced plastic) composites are intelligent materials with self-diagnosing function for fracture. Electrical resistance and residual electrical resistance of CFGFRP increased with increasing strain, and these changes were dependent on the maximum strain applied in the past trials. When the carbon fibers fractured, the electrical resistance increased largely, and afterwards CFGFRP were able to resist the load due to the presence of the glass fibers. Large change of the electrical resistance is an effective phenomenon for preventing fatal fracture. This check point could be controlled through suitable selection of the type of carbon fibers according to its value of ultimate elongation. In the application of this method, the electrical resistance of CFGFRP-reinforced concretes was measured, and these changes showed results similar to those of CFGFRP composites. CFGFRP used as reinforced materials of the concretes are intelligent materials with a self-diagnosing function for latent damage of the concretes