Papers by Author: Takeshi Tanaka

Abstract: A fundamental study on finishing aided by an ultraviolet ray (generally mashining:referred to as U-RAM^R) was conducted to evaluate its applicability to the polishing of aluminum alloy. Qualitative analysis with X-ray photoelectron spectroscopy (XPS) was used to estimate the chemical reaction induced on Al surfaces that were immersed in some solutions. Inductively coupled plasma spectroscopy (ICPS) was employed to quantitatively analyze the amount of oxidized/dissolved Al, Mg and Fe. The following conclusions were obtained by investigation of the aluminum alloy polishing process. Aluminum does not dissolve in TiO₂-solution, whereas a small amount of Al dissolves into cathilon dye solution. Although only a small amount of Al dissolves in TiO₂-cathilon dye solution in the absence of UV irradiation, the amount of Al dissolved increases slightly under UV irradiation with the formation of oxide, nitrogen oxide and nitride on the Al surface. In addition, a small amount of an aluminum chloride dissolves into TiO₂-cathilon dye solution. An Al alloy (A5052) surface was made flat by polishing with TiO₂-cathilon dye slurry under UV irradiation.

Abstract: Our main purposes were to establish ultraviolet-ray aided machining (here after reffered to as U-RAM) and clarify the chemical and mechanical polishing mechanism. The inner/outer surfaces of small cup-type nickel tube is strongly required to polish, simultaneously. The present study deals with the new development of simultaneous polishing technology and the verify of polishing phenomena that uses a photocatalyst and a cathilon (a luminous dye: Cathilon Brilliant Flavine; hereafter referred to as cathilon) excited by an ultraviolet ray (hereafter referred to as UV). Measurements and observations clarified that TiO₂ of 0.18-μm grain size polished chemically/mechanically the outer surface using cathilon, and cathilon chemically polished the inner surface of small cup-type nickel tube, simultaneously. Further measurements indicated that the chemical erosion roughened the inner surface, when cathilon increased from 2.5, 5 to 20wt%. An increase of TiO₂ to 20wt% at 20wt% of cathilon did not result the flatter surface. Aluminum oxide does not provide the polishing ability due to the poor photocatalyst effect compared with TiO₂.

Abstract: The main purposes of this study were to lessen the deformities in the machined surface, to make the crystal grains on the machined surface appear, and to apply this machining at the micrometer level instead of at the nanometer level. The present study targets the development of a polishing technique that uses a photocatalyst and a luminous dye (Cathilon Brilliant Flavine; hereafter referred to as cathilon) excited by an ultraviolet ray. Nickel (hereafter referred to as Ni) was polished chemically and mechanically at the sub-micrometer level under an ultraviolet-ray irradiation. Measurements clarified that TiO₂ of 0.1 μm grain size mechanically polished the Ni, and cathilon chemically polished Ni. A flat surface was attained on the Ni by chemical and mechanical polishing using both the TiO₂ and cathilon, when they were irradiated by an ultraviolet ray. Further measurements indicated that the corrosion of Ni surface became large under an ultraviolet-ray excitation. The eroded trace was large when cathilon is rich. Though much TiO₂ tends to roughen Ni surface, the flat surface was obtained in the case of much TiO₂ and much cathilon due to both equivalent influences.

Abstract: This study targets the development of a polishing technique that uses a photocatalyst and a fluorescent substance excited by an ultraviolet ray. Nickel (hereafter referred to as Ni) was polished chemically and mechanically at the micrometer level under ultraviolet-ray irradiation. Measurements clarified that TiO2 of 0.1-μm grain size, at which size the excitation by the ultraviolet ray was less influential, mechanically polished the Ni. Cathilon (a luminous dye) chemically polishes Ni. The corrosion of the Ni surface became large under ultraviolet-ray excitation. A flat surface was attained on the Ni by chemical and mechanical polishing using both the TiO2 and cathilon, when was irradiated by an ultraviolet ray.

Abstract: In this study, we proposed an electro-rheological fluid-aided polisher (ERAP) using one-sided, patterned electrodes. The characteristics of ER fluid and ER fluid containing abrasive grit were investigated. The polishing performances of ER fluids with and without abrasive grit employing ERAP were verified and the following conclusions were obtained. Decreases in viscosity and in the ER effect were observed when highly polymerized liquid crystal (hereafter referred to as HPLC) was diluted with silicon oil. However, the mixing of abrasive grit increases the ER effect, but the ER effect of ER fluid containing abrasive grit decreased when mixed with abrasive grit. The viscosity decreased with increases in aliphatic saturated cyclic hydrocarbon oil (hereafter referred to as NCDM) mixed in highly polymerized compound (one kind of HPLC). The larger the positive dielectric anisotropy, the larger the ER effect in low-polymerized liquid crystal (hereafter referred to as LPLC). The smaller the grit size, the weaker the ER effect. When polished with HPLC, the polished surface was rough due to the large viscosity of an HPLC:silicon oil ratio of 4:14 mixed with #2000WA. However, the smallest surface roughness was attained at 0.5kV/mm for an HPLC:silicon oil ratio of 1:17 mixed with #2000WA. The surface quality was improved at an HPLC: silicon oil ratio of 1:17 mixed with #3000WA. When polished with LPLC, the surface roughness was improved by the increased ER effect when LPLC having a positive dielectric anisotropy was used. However, the surface roughness showed no change when LPLC with a negative dielectric anisotropy was used, due to its small ER effect.

Abstract: The purpose of this study is to fabricate a wheel using fullerenes with nano-scaled particles, and to investigate the polishing performance of fullerene wheel. A super smooth surface was formed on a silicon wafer by polishing the wafer with metal-bonded diamond wheels using a diamond abrasive grit of 0-0.125 μm and fullerenes with a diameter of 0.7 nm. We used two kinds of metal-bonded diamond wheels for pre-polishing and a metal-bonded fullerene wheel for the finishing process. Though the surface roughness after polishing with the fullerene wheel was almost equal to that obtained by polishing with the metal-bonded diamond wheel using diamond abrasive grit of 0-0.125 μm, the chemical-mechanical polishing process was clarified by AFM (atomic force microscope) observation when we used a metal-bonded fullerene wheel with 5wt% KOH (potassium hydroxide) solution. The greater number of smoothed portions on the surface of the silicon wafer indicated that the fullerenes provided the same polishing ability as that of the abrasive grit.

Abstract: In this study, we proposed ER fluid-aided polisher (ERAP) using one-sided, patterned electrodes. The characteristics of ER fluid and ER fluid containing abrasive grit were investigated. The polishing performances of ER fluid containing abrasive grit were verified using an ERAP. The following conclusions were obtained. Thick clusters formed between both electrodes with increased voltage. Abrasive grit was condensed on the thick clusters of ER fluid-particles that formed around the electrodes with further increases in voltage. The ER effect is a hardening of ER fluid under loading by an electric field. The ER effect of ER fluid containing abrasive grit decreased because the grit clusters bound weakly to each other. The ER effect decreased with a decrease of grit size. The surface roughness showed little change when a Shower curtain (a nylon cloth) was used for a pad. An electric field was generated around the cutting zone when a Toraysee (a washable lens cloth) was used as a pad. This leads to large efficiency and high precision in polishing. The surface roughness decreased with increased voltage up to 1.0kV/mm, because the abrasive grit was tightly fixed by the ER effect. A minimum surface roughness was attained at approximately 1.0 kV/mm when using WA and SD grits. The surface roughness increased due to a hardening of the ER fluid, causing deep scratching of the workpiece at 2.0kV/mm.

Abstract: When a light-excitation substance such as a high polymer absorbs the light energy of an ultraviolet ray, it will be excited. If this substance reacts with the processing material in an atomic order under the excited conditions, it may be available for use in fine processing. Thus, it appears that the processing in a sub-nanometer order may be realized by a phenomenon called luminescence. The following merits can be considered: 1) little reaction heat, 2) little heat influence on the processed material, 3) easy reaction control in comparison with chemical processing. In this research, the processing principle was verified by dipping the processing material for a fixed time in pure water mixed the fluorescent substance exposed to an ultraviolet ray. The surface of copper that had been precisely lapped was used in the experiment. The abrasion of its surface was observed by AFM. Based on the results of these basic experiments, an ultraviolet-ray irradiation type polisher was manufactured for use in the polishing experiment of copper. This paper describes the polishing characteristics of copper exposed to an ultraviolet ray.

Abstract: We observed that the lubrication effect is greater than the cooling effect for decreasing the friction heat in face grinding. It was clarified that cool-air grinding is difficult to apply to face grinding under the present grinding conditions. We could obtain the minimum ground surface roughness (hereafter noted as surface roughness) at a mist suppｌy volume of 15 to 30ml/h in mist grinding. The largest stock removal rate (hereafter noted as grinding efficiency) is obtained in mist grinding. However, grinding efficient was small in cool-air mist grinding, by which a large cooling effect of cool air was expected. Though mist and cool-air mist grinding perform similar to wet grinding in few grinding passes, wet grinding is properly applied by large chip removal action in many grinding passes.