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In both 2009 and 2010, massive Chattonella blooms occurred in Tachibana Bay. Observation results show that high cell densities of Chattonella were distributed in the central area of Tachibana Bay with low salinity water. Model results indicate that the low salinity water originated from the Ariake Sea and intruded into Tachibana Bay during the northerly or weak winds. It is suggested that low salinity water was mainly discharged from the northern area of the Ariake Sea. Northerly wind enhanced the horizontal advection of the low salinity water intruding into Tachibana Bay originating from the northern area of the Ariake Sea.

In 2010, a massive bloom of the raphidophycean flagellate Chattonella occurred in the Ariake Sea and Tachibana Bay. Bloom dynamics and hydrographical conditions were examined by field survey. The development and decline of the bloom occurred three times in Tachibana Bay. First and third bloom developments synchronized with precipitation, and the second bloom developed in synchronization with a salinity decrease which occurred in relation to an increase of river discharge from the Chikugo River which takes several days to flow from the Ariake Sea. These results imply that the bloom was transported with the low salinity water from the Ariake Sea to Tachibana Bay. During blooms along the northern coast of Shimabara Peninsula, the predominant phytoplankton species changed from Chattonella to Skeletonema. Low salinity water intrusion induced an interregional difference of the Chattonella and Skeletonema bloom spatially-differentiated by the salinity in the Ariake Sea and Tachibana Bay.

This study discusses the fusion of chlorophyll-a (Chl.a) estimates around Tachibana Bay (Nagasaki Prefecture, Japan) obtained from MODIS and GOCI satellite data. First, the equation of GOCI LCI was theoretically calculated on the basis of the linear combination index (LCI) method proposed by Frouin et al. (2006). Next, assuming a linear relationship between them, the MODIS LCI and GOCI LCI methods were compared by using the Rayleigh reflectance product dataset of GOCI and MODIS, collected on July 8, July 25, and July 31, 2012. The results were found to be correlated significantly. GOCI Chl.a estimates of the finally proposed method favorably agreed with the in-situ Chl.a data in Tachibana Bay.

We studied the expanding and reducing of cracks in thermal cycling such as heating and cooling for the ZrO2+8%Y2O3 layer built up from plasma spray on stainless steel and carbon steel, with the following Results1) The ZrO2+8%Y2O3 layer showed self-repair in thermal cycling such as heating and cooling.2) The ZrO2+8%Y2O3 layer sprayed on carbon steel had better self-repair than that sprayed on stainless steel, indicating that ZrO2+8%Y2O3 layer self-repair was influenced by a substrate's expansion coefficient.3) Self-repair of the ZrO2+8%Y2O3 layer is the characteristic property of ZrO2+8%Y2O3 layer built up by spraying particles.

In thermal spraying, molten particles strike a solid surface, where they are flattened and quenched within a very short time. Considerable in-plane tensile stress on the order of 100 MPa can develop within each splat during quenching after solidification because thermal contraction of the particle is constrained by the underlying solid. Ni-20Cr alloy and alumina powders have been plasma sprayed in air onto steel substrates that were maintained at about 473 K. The influence of spraying conditions such as spray distance on the magnitude of the quenching stress have been studied by measuring the curvature of the substrate during spraying. Mechanical properties such as Young’s modulus and bend strength of the deposited coatings have also been measured. A strong correlation was found between the quenching stress and the strength of Ni-20Cr coatings, which suggests that the strength of interlamellar bonding limits the quenching stress at such temperature.

Methods to measure the surface temperature and the velocity of thermally sprayed particles were developed and applied to plasma-sprayed Mo, Ni-Cr alloy, and alumina particles in the air.In the temperature measurement, radiation from particles within a cylindrical measurement volume is measured and its spectrum is analyzed by a monochromator. Then the spectrum is compared with the spectra of blackbody radiation to determine the surface temperature of the particles through the least squares method.Spatial filtering technique using a mask with four thin parallel slits was adopted in the velocity measurement. When a single particle travels in front of the plates, radiation passing through the spacings between the plates is detected by a photo-multiplier, which gives a signal with four peaks. Then the velocity v of the particle is given by υ=d/t, where d is the distance between the neighboring slits and t the period between the peaks. It was also found that the mean velocity of a high-density particle stream can be determined by analyzing the power spectrum of the signal by a method such as FFT.As the results of those measurements, the change in the temperature and the velocity of sprayed particles with the distance from the exit of a plasma-torch was obtained. Where as the metal powders exhibited similar history of cooling and deceleration with the distance, alumina particles were found to be accelerated to a much higher velocity close to 300 m/s but decelerated at a much faster rate. The temperature of alumina particles could be measured for only a limited region due to the weak radiation. Also the effects of particle size on the distribution of both the temperature and the velocity of sprayed Mo particles were examined.

Stresses generated within plasma-sprayed coatings were evaluated dynamically by measuring the curvature of a strip-shaped substrate throughout the process of deposition. Four kinds of powder, Mo, Ni, Al and 80Ni-20Cr alloy, were plasma-sprayed in the air on five kinds of substrate, Mo, Ni, Al, 80Ni-20Cr alloy and mild steel. It was found that the stress due to deposit build-up is always tensile, whose magnitude mainly depends on powder material, not on substrate material: ranging approximately from 10 to 100 MPa in the order of Al ≽ Mo alloy.. By the curvature change at the onset of spraying, upon which surface treatment of substrate showed significant influence, existence of a higher tensile stress within a boundary layer between a coating and the underlying substrate was suggested.

TiC and Mo powders were sprayed by the plasma twin-torch process to form an FGM layer over a substrate to be used as an emitter in a thermoionic energy converter. The sprayed TiC coatings showed high absorptance for solar radiation. As compared to TiC monolayer coating and TiC/Mo two-layer coating formed on Mo substrate, FGM coatings performed better in a thermal cycling test.

The adhesive mechanism of plasma jet-sprayed nickel, chromium, molybdenum, tantalum, and tungsten coatings on aluminum and mild steel substrates was investigated. The compositions of the boundary layers between the coatings and the substrates were studied using x-ray diffraction. Experiments on the bonding behavior between substrates and nickel drops heated by the levitation melting process were also performed. The results of the experiments show that: (i) the substrate surface is melted by the sprayed particles, and a boundary layer which consists of an intermetallic compound consisting of the elements of the coating and substrate materials is formed between the coating and the substrate; (ii) this layer is necessary to improve the adhesion between the sprayed coating and the substrate; (iii) the adhesive mechanism between the sprayed coating and the substrate surface and the composition of the boundary layer were confirmed by a liquid nickel-drop experiment.

A method for the simultaneous and in situ measurement of both coating thickness and deposition stress during thermal spraying was developed. A strip-shaped substrate was fixed on a pair of knife edges and the displacements of the front and the rear surfaces of the sample during thermal spraying were measured using a pair of displacement meters. Then the coating thickness could be monitored as the increase in the difference between the two displacement signals, whereas the stress was detected as the curvature of the strip. Molybdenum, 80at.%Ni-20at.%Cr alloy, aluminium and Al 2 O 3 powders were plasma sprayed onto mild steel substrates in air. As the result, three stages of stress generation were clearly identified as those due to (1) the formation of the coating-substrate boundary, (2) deposit build-up and (3) cooling after deposition. It was found for the materials tested that the stresses within the coatings due to the first two causes were tensile whereas that due to cooling was either tensile or compressive.

An optical diplacement meter was developed to measure and control the thickness of coatings deposited by thermal spraying. The displacement of the surface of a workpiece was monitored continuously during the spraying process by detecting the position of a bright spot made on the surface by laser illumination using a linear image sensor. A cylindrical lens was used to reduce the error due to speckle and a differential method was employed to discriminate the coating thickness from the displacement due to thermal deformation. By stopping deposition when the meter output reached a predetermined value, the thickness of plasma sprayed alumina coating could be controlled with a standard deviation of 24 μm.

The gas velocity by the fluid dynamic method (shown in Fig.6 and the expression 2), the temperature distribution (shown in Fig. 14) and the mixing rate of air (as measured by the Orsat apparatus) (shown in Fig. 11) into the jet along the jet axis at various distances from the nozzle under the ordinary operating conditions for spraying process are experimented and some considerations of the results are made. Moreover, the flying velocities of the spraying powders (Al2O3, Mo and Nickelbase alloy) in the jet are measured by using the turning disc (shown in Fig. 1).The results can be summarized as follows.Under the conditions of the flow rate of operating gas 30l/min and the operating currents 450 and 550 A.(1) At the 50 mm' distance from the nozzle(i) Flying velocity of spraying powderAl2O3: 150-160 m/secMo: 100-105 m/secNickel-base alloy: 70 m/sec(ii) Gas velocity: 120-140 m/sec(iii) Temperatureunder current 550 A: 2, 200°Cunder current 450 A: 1.700°C(iv) Mixing rate of air: 55-65%(2) At the 100 mm' distance from the nozzle(i) Flying velocity of spraying powderA12O3: 140-150 m/secMo: 95-100 m/secNickel-base alloy: 60-70 m/sec(ii) Gas velocity: 40-50 m/sec(iii) Temperature (under current 450, 550 A): 800-900°C(iv) Mixing rate of air: about 90%

The mechanism of adhesion of the plasma jet-sprayed Ni, Cr, Mo, Ta and W coatings to the Al and mild steel substrates is in vestigated. The compositions of the boundary layer between the coating and the substrate are made clear by application of the X-ray diffraction analysis.Moreover, in order to appreciate in detail the adhesive mechanism and the composition of the boundary layer, an experiment on the behavior of bonding between the substrate and Ni drop heated by the levitation melting process is also carried out.Main results of the experiment are summarized as follows:(1) The substrate surface is melted by the spraying particles, and a boundary layer is formed between the coating and the substrate.(2) The layer consists of an intermetallic compound formed by each element of the coating and the substrate.(3) The layer is important for the sprayed coating to improve the adhesion to the substrate.(4) The mechanism of adhesion of the sprayed coating deposited to the substrate surface and the composition of the boundary layer are made clear from the results of the experiment by the levitation melting process.

The press-sintering process of the sprayed coating to improve the denseness and the bonding of the deposited coating has been developed. This new process is superior to the conventional fusing process in which the structural change and the thermal strain of the substrate take place during the treatment. Then, the press-sintering process is applied to a Nickel base self-fluxing alloy coating deposited by oxy-acetylene flame spraying process. Some properties of the press-sintered coating are also investigated.In conclusion, it is clear that the coating, sintered under suitable pressing, has almost the same denseness and bonding as the fused coating, and a higher wear resistance than the fused one.

Superconducting properties and microstructures of the Bi-Pb-Sr-Ca-Cu oxide films prepared by plasma spraying have been studied. Films with a thickness of about 150 µm have been prepared from Bi1.52Pb0.48Sr1.66Ca1.18Cu2.31O x powders. The as-sprayed films, deposited on nickel substrate, are amorphous and not superconductive. After annealing in air at 840°C the films exhibit a zero-resistance temperature of 107 K (zero field) with a transition width of about 11 K.