Pulse laser processing point by point method is applied for heat resistant Fiber Bragg Grating structure. In order to fabricate fine FBG, a close packaged picosecond laser system is used with a CCD camera microscopy. An optical fiber is mounted on a precision translation stage. The stage speed is controlled by the current position and the corrector output. In order to contact the FBG on a metal surface, nano-size colloidal silver adhesive is used under temperature monitoring. Heat expansion of SUS plate can be successfully monitored by strain gauge of the heat resistant FBG. It can be available for monitoring the structural integrity of high temperature industrial plant. Complex coolant piping systems of liquid sodium and molten salt are facing the risk of coolant leakage, which is the most promising usage.
The relationship between machinability, addition of inoculants and solidification structure has been investigated by measurement of cooling curves, observation of microstructures and cutting tests for FC250 flake graphite cast irons which have different morphology of graphite and matrix structure fabricated by Fe-Si and C-series inoculants. The D-type graphite has been observed in the Base (inoculant-free) alloy, and A-type graphite appeared in alloys which have included higher contents of inoculants. The width of flank wear of each alloy was decreased with increasing of cutting force, while the cutting temperature was increased with increasing of cutting force. The width of flank wear of each alloy has been also increased with increasing of area fractions of graphite and ferrite, although the width of flank wear has been decreased with increasing of area fractions of perlite. The surface of flank of Al2O3 coated tool has been observed by scanning electron microscope (SEM), and some compounds including Si was confirmed on that surface. Those compounds probably are formed during cutting, and wear of cutting tool has been accelerated, even in the case of low cutting force.
A flame combustion method enables the synthesis of diamond using acetylene-oxygen gas in ambient atmosphere. It has various advantages over other methods. We previously synthesized diamond films on a Mo substrate surface by the flame combustion method. In this method, most diamond films delaminate as a result of thermal stress during cooling. To prevent diamond film delamination for the synthesis of good diamond films, a three-step synthesis method was proposed. However, the surface roughness of synthesized diamond films by this method became large. In previous study, to reduce the surface roughness by flame combustion and to achieve good adhesion on the Mo substrate, the flow ratio of oxygen flow rate to acetylene flow rate and synthesis time of the three-step synthesis method were varied during the synthesis of diamond. In result, the surface roughness of synthesized diamond films was reduced by this method. However, the surface roughness was not yet enough, and it is more necessary to reduce the surface roughness. In this study, to reduce further the surface roughness, the diamond seed particles as generation nuclei for the diamond synthesis were changed to small. To investigate the surface morphology and the surface roughness of synthesized diamond films, synthesized films were observed. The diamond seed particles size and the flow ratio and synthesis time of the three-step synthesis method affected the surface morphology and the surface roughness of synthesized diamond films. The surface roughness of the synthesized film was reduced further by this study. The surface roughness in the Case 3 condition was the smallest in this experiment. Furthermore, to confirm influence factors of the surface roughness of synthesized diamond films, diamond seed particles on the substrate surface after the seeding treatment and generation nuclei on the substrate in the synthetic initial stage were observed.
An insulator contains silica aerogel as a main material is expected to be used in a high temperature range because of its high heatresisting property. However, it is so important for securing heat insulating performance to inhibit radiant heat generated when such insulator is used at about 150 ℃ because the main material silica has high directional emittance. In this study, it is clarify the content of the various types of particles contributing to the radiation heat transfer reduction that can lower the effective thermal conductivity of the insulator. In addition, it is analyzed the influence of the thermal conductivity and the emittance of the particles on the effective thermal conductivity of the insulator. And it is verified the differences in effects of the particle at several temperatures.