Masami Futamata

Improvement of Solution Type Plasma Spraying Process

To fabricate thermal spraying coatings with good reproducibility, it is necessary to improve the process of the equalization of both thermal history and impacting behavior of the particles. In this study, the characteristics of the solution type plasma spraying using the hollow-cathode type torch are investigated. The physical and mechanical properties that are different from usual thermal spraying coatings are described. By using solutions including metal ingredients in a state of ion, colloid or sol, thinner coating that cannot be made by conventional plasma spraying methods is formed on various substrates. The coatings are uniform in appearance.

Application of atomic absorption spectrometry to laser plume analysis

Abstract In order to investigate the formation and properties of the plume induced by Nd–YAG laser, the absorption spectra of the elements contained in pure aluminum, aluminum alloy such as aluminum, magnesium, zinc, silicon, and titanium were analyzed by using atomic absorption spectrometry. The results have indicated that the elements having low melting and atomizing points were detected at first followed by the atomization of other elements with increasing laser power. Further, a basic discussion on the influence of compression field caused by the reaction of plume vaporizing was also done.

Characteristics of Plume Sound in Nd:YAG Laser Drilling.

In order to obtain the fundamental characteristics of the plume sound induced during Nd : YAG laser drilling, the relationship between the sound pressure level and laser oscillating method, laser processing conditions were investigated and the frequency spectrum analysis was also done. The sound pressure waveform and frequency spectrum relate to the oscillating method, that is to say, the frequency spectrum, which is induced by Q-switch laser, consists of continuous spectrum such as white sound and n×fQ (n: 1, 2, 3, …, fQ : Oscillating frequency of Q-switch laser), the one induced by CW laser, contains only the continuous spectrum. The sound pressure level was influenced by laser processing conditions. Further, it could be estimated that the relationship between the sound power (W) and the reaction force (FPl) could be expressed as W∝FPl2. Based on the results above, it can be expected that the useful informations about process monitoring can be obtained from the plume sound.

Friction Characteristics of Thermal Sprayed Coatings and its Application on High-strength Bolted Joints.

The sliding friction between solids is a problem related to the material surface and its neighborhood. It is very important to control and adjust it in engineering. In this research, the characteristics of sliding friction between thermal sprayed surfaces have been studied. Materials sprayed were aluminum (Al), zinc-5% aluminum alloy (Zn-A1), and alumina (Al2O3) and sliding pairs were either of the same material or of different materials. Further, it also has been studied from the standpoint of applying thermal spraying to the surface treatment for high-strength bolted joints. In the experiments, frictional force was recorded as a function of sliding distance. It was found that force-distance curves of as-coated specimens could be classified into two types; one is periodical oscillation with the stick-slip such as for the sliding pair of Zn-Al/Zn-Al and the other is with random fluctuation for the sliding pairs of Al/Al and Al2O3/Al2O3. The coefficient of friction was biggest for sliding pair of Al/Al, which is about 2 times as high as that of the shot-blasted surface of mild steel substrate (for Al/Al and Zn-Al/Zn-Al). It has been confirmed also that Amontons law is applicable in any of the sprayed sliding pairs tested. Especially, it has be shown that aluminum-sprayed coating and zinc-sprayed coating will be expected to apply to high-strength bolted joints, because of having big coefficient of friction and strong corrosion resistivity.

Development of Measuring Apparatus for Laser Plume Force and its Applications.

This study presents new measuring apparatus which can be applied to in-process measurement of plume reaction force in laser materials processing. The principle of measuring apparatus is based on the load-cell device of parallel beams structure type which has a high stability and high detection sensitivity.In this paper, an effectiveness of new measuring apparatus, the relationship between plume reaction force and irradiation conditions of pulsed Nd-glass laser and target materials were investigated. As the results, it was found that the measuring apparatus developed by us appears to be useful for the analysis of plume reaction force. The plume reaction force increased with increasing output power, decreased with increasing pulse duration. Furthermore the force depended on the value of focal length, focal condition and the kinds of target material.

Effect of post‐weld heat treatment on properties of commercially pure titanium/pure aluminium friction welds. Study of friction welding of titanium/aluminium (1st report)

Summary This paper describes a fundamental investigation of the friction welding conditions for commercially pure titanium/pure aluminium joints and the effect of post‐weld heat treatment (PWHT) on the mechanical and metallurgical properties of friction welds. The investigation also clarifies the range of friction welding conditions able to ensure production of fracture‐free welded joints having more than 100% joint efficiency in tensile tests and excellent bending ductility in the as‐welded condition. PWHT temperatures up to 873 K (600 °C) x 36 ksec (10 h) have no effect on joint mechanical properties, especially in terms of joint tensile and bending ductility. However, they sharply decrease during PWHT at 873 K (600 °C) for more than 72 ksec (20 h). X‐ray diffraction analysis and SEM observations confirm that these reductions are due to the formation of large contents of Al3Ti intermetallic compounds at the pure aluminium/pure titanium interface. The critical width of the Al3Ti phase (during PWHT at 873...

Measurement of plasma jet force - By trial measuring apparatus using the load-cell of structure of parallel beams.

The new measuring apparatus of plasma jet force using the load-cell on the parallel beams structure has been developed and applied to the measurement of argon gas plasma jet force.The load-cell of parallel beams structure is easily manufactured and has excellent sensitivity of measurement. The experimental results of the plasma jet force measurement are described and discussed.It has been indicated that the plasma jet force depends on arc current, arc voltage, working gas flow rate, gas supplying method, and stand-off condition. The plasma jet force is closely related with the input power and is proportion to the square root of input power.