Takashi Ide

Evaluation of elastic emission machined surfaces by scanning tunneling microscopy

Elastic emission machining (EEM) developed by the authors is one of the atomic size machining methods. Roughness of the finished surface is as small as atomic size. It is also found that finished surfaces attain the perfection in the sense of physical properties to the extent of better than or comparable to chemically etched surfaces. EEM can be considered as a machining method utilizing chemical activities of ultrafine powder particle surfaces, instead of an etchant as in the conventional chemical etching. In this paper, the authors have developed a scanning tunneling microscope(STM) in order to evaluate the surfaces finished by EEM with the resolution of atomic size. STM measurements are carried out for the surfaces finished by EEM and by chemical etching. The result shows the existence of the micro pits with the diameter of 1 nm and the depth of 1 nm on the chemically etched surface. In contrast, neither pits nor projections are detected on the surface finished by EEM and an atomically smoothed surface...

A New Measurement and Evaluation of Wettability between Solid and Liquid Metals in Ultra-High Vacuum. (2nd Report). Experimental Examination of Wettability and Atomic Diffusion.

This paper presents experimental results of the wettability and atomic diffusibility of liquid metals on clean solid surfaces. Six types of liquid metals; Au, Ag, Cu, Al, Fe, Ti, and three types of substrates; tungsten, glass-like carbon, highly oriented pyrolytic graphite (HOPG), are used as the specimens. Contact angles of liquid metals are measured with good reproducibility using a continuous Ar sputter cleaning process as is introduced in the previous paper. Interaction energies of these systems are obtained. As liquid Fe has different diffusibility for two carbon substrates, glass-like carbon and HOPG substrates, atomic concentrations of the substrate surfaces are investigated using scanning Auger electron spectroscopy. Consequently, it is found that liquid Fe has atomic diffusibility with a glass-like carbon surface but not with HOPG (001) surface.

An explanation of the wetting and the mutual diffusion mechanisms of liquid metals using ab-initio atomic orbital calculation

In this report, in order to clarify fundamentally the wetting phenomenon between pure material surfaces, we propose a new method for the experimental evaluation and consider quantitatively the wetting mechanism from the microscopic standpoint of the chemical reaction between interfacial atoms. Ab-initio molecular orbital calculation was performed to explain the wetting and the mutual diffusion mechanisms. It was found that the calculated binding energies were in good agreement with the interaction energies estimated from measured contact angles, and it was also cleared that the hybridization of the interfacial d-orbitals was one of the most important elements of the mutual diffusion.

Atomic force between diamond and metal surfaces.

This paper describes the atomic force based on chemical bonds between diamond and metal (Cu, Fe or Al) surfaces. This atomic force affects the limit of ultra precision machining, therefore, the coefficient of friction on the tool rake face at the time of cutting was measured in vacuum. The measured coefficients of friction of Cu, Fe and Al were 0.18, 0.30 and 0.36, respectively. Also, the interaction force based on atomic force was measured in comparison with the coefficient of friction. The interaction force required to separate the elastic contact between the diamond tip and the flat metal plane was measured with a microelectro-balance in an ultra high vacuum. The interaction energy (interfacial energy) calculated by measured interaction force of Cu, Fe and Al were 1.87, 2.49 and 3.77 J/m2, respectively. Thus, the coefficient of friction was strongly correlated with the interaction force, or Cu<Fe<Al. This suggested that the friction of metal cutting was caused by the atomic force based on the chemical bond at the interface. In order to estimate the atomic force theoretically, the electron energy of interface was calculated by the local density of electron states. The local density of states of diamond surfaces adsorbed by metals were calculated by using the recursion method based on semi-empirical tight binding theory. The results of calculation predicted that the values of atomic force were Cu<Fe<Al.

Studies on Powder Particle Beam Machining by Electrostatic Acceleration. 5th Report. Adhesive Impact-Deposition of Tungsten Microparticle.

The possibility of a film formation based on impact adhesion of solid particles was investigated by making tungsten submicron-sized particle beam vertically irradiate at the velocities of several hundreds m/s onto silicon substrate. The deposition phenomena of impact particle were examined by evaluating geometrical parameters of each deposit, and it became clear that relatively small particles are selectively deposited and accompanied by severe plastic self-flow and slight penetration into substrate, and the deformation degree depends on the impact velocity. As for the interfacial characteristics of film-deposited silicon, the tensile adhesive strength superior to the fracture strength of silicon and nearly ohmic current-voltage characteristics are observed which are similar to thermally joined junction, with both of pull testing and point-contact diode measurement. These suggest metallurgical change at interfacial layer of silicon.