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Cutting tools are often coated with titanium nitride (TiN) for its good wear resistance. The method of coating by physical vapor deposition (PVD) has many superior features over other methods of deposition. Among the parameters affecting the wear resistance of PVD TiN coatings, the most crucial ones are the deposition temperature and the coating thickness. This paper presents an experimental investigation of the wear characteristics of PVD TiN coatings produced at two deposition temperatures (around 220 [degrees] C and 371 [degrees] C) and for a range of coating thicknesses (0.48 [[micro]meter] to 3.25 [[micro]meter]). A ball-on-flat configuration was used in the study. The fiat specimen, made of M2 tool steel coated with TiN, was slid against a 52100 chromium steel (Cr-steel) or a tungsten carbide (WC) ball, dry. These two counterbody materials were chosen because of their different properties. The wear volume was measured and wear scar examined with a 3-D optical profilometer. The worn surfaces and debris were analyzed with scanning Auger microscopy (SAM) and an electron probe microanalyzer (EPMA). Quantitative data were obtained for the wear volume and coefficient of friction (COF) as functions of the sliding cycles. In the case of TiN versus Cr-steel, the presence of transferred wear debris on the flattened ball surface and iron oxide in the wear tracks of the coating surface was a major factor controlling the wear behavior. In the case of TiN versus WC, no transferred layers were observed; instead, the presence of flake type debris from the coating in the wear tracks appeared to be the controlling factor. It was concluded that deposition temperature, coating thickness, and counterface influenced wear behavior. For the lower deposition temperature, wear was significantly reduced by thinner coatings. However, for the higher deposition temperature, wear reduction was only obtained with the Cr-steel counterface.

As various small electronics components are being rapidly moved along an assembly line, their leads must be cut and clinched into holes of a circuit board for the next soldering operation. This process must be achieved economically both in time, and in combating wear by preserving the cutting tools' sharpness. The present study investigates the shearing action and subsequent fracture in cutting. Plastic analysis for both cutting and forming (clinching) is presented with the support of measured data obtained on a prototype machine employed in the research. Wear analysis of the cutting surfaces leads to a recognition of the role played by various geometric parameters such as lead shape, cutter and anvil angles, cutter and anvil distance, etc.

Vanadium (V)-doped WO3/TiO2 microporous film on a titanium (Ti) plate was prepared by using the micro-arc oxidation process. Incorporating V and tungsten (W) species into the TiO2 lattice in one step yields band gap narrowing and strong visible-light (Vis) photoactivity, dominated mostly by incorporation of WO3 and V2O5 oxides, and possibly W xTi1− xO2. Photoactivity under ultraviolet light (UV) irradiation was likely attributable to its WO3-loaded microporous structure, which favored cationic molecule adsorption on its active sites. Although post annealing enhanced film crystallinity, photocatalytic ability was decreased largely because of changes in doping levels. This suggests that the as-oxidized microporous film is feasible for photocatalytic cationic dye degradation under UV and Vis irradiation. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the photoelectrocatalytic (PEC) property of microporous WO3-loaded TiO2/Ti layer, prepared via micro-arc oxidation (MAO) of Ti plate, followed by sputtering deposition of a thin Pt layer as a Pt-TiO2/Ti electrode. The WO3-loaded TiO2 layer which is associated with a more acidic surface forms many local electrochemical cells on its micro-pores immersed in cationic dye solution. The electrocatalytic (EC) reactions can take place in the local cells by the applied electrons. A low resistivity that is accomplished by MAO technique and by platinization offers an easy path for the electron motions in the Pt-TiO2/Ti electrode. All these features make the EC oxidation of aqueous dye pollutants practically feasible without using counter electrodes and supporting electrolytes. Our experiments demonstrate that, under PEC condition, the Pt-TiO2/Ti shows the highest degradation rate constant of 0.83h−1 at an applied bias of 1.0V and exhibits significantly high PEC and EC oxidation activities at a low applied bias of 0.25V. This is attributable to high anodic currents generated in the Pt-TiO2/Ti even at low bias. The modified microporous electrodes conclusively reveal a very interesting EC property as a two double-sided device that functions the PEC and EC oxidation simultaneously without a need of supporting electrolyte and expensive Pt cathode. [Copyright &y& Elsevier]

Abstract: This study reports the preparation of microporous TiO2-WO3/TiO2 films with a high surface area using a two-step approach. A porous WO3/TiO2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO2 (N,C-TiO2) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO2 lattice using direct current magnetron sputtering. The resulting microporous TiO2-WO3/TiO2 film with a 0.38-μm-thick N,C-TiO2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO2-WO3/TiO2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO3/TiO2 can be used as a template of hybrid electrode because it enables rapid fabrication. [Copyright &y& Elsevier]

Abstract: Titanium dioxide (TiO2) films are deposited by codoping nitrogen and carbon on indium tin oxide-coated substrates as visible light (Vis)-enabled catalysts. The X-ray diffraction peak intensity of the preferential orientation in (211) plane declines when the topmost 1.0μm layer of the film is ground off. The decrease in the crystallite size and the crystallinity of anatase TiO2 film is also evidenced by a shift towards the high wave number and broadening of the Raman spectra. Low doping concentrations of N (1.3%) and C (1.8%) are estimated by X-ray photoelectron spectroscopy (XPS) which displays an N 1s peak at 396.8eV and a C 1s peak at 282.1eV, respectively. This is attributed to the substitution of the oxygen sites with nitrogen and carbon, which is believed to be responsible for the Vis photocatalytic activity into a wavelength of >500nm. The cross-sectional transmission electron microscopy images show larger pores at the grain boundaries and in larger columnar crystals than in the undoped TiO2 film. All of these results indicate that porosity, crystallinity and shift in the preferential orientation are more pronounced close to the surface than close to the bottom of the sample. Wettability upon measurement of the water contact angle, methylene blue degradation and radical formation tests under both ultraviolet and Vis irradiation demonstrate that the topmost surface renders not only a larger reactive surface area but also a better carrier transport route than the rest of the film, improving its photocatalytic activity. These results show that surface porosity of the film is dominant than the tailoring of the photocatalytic activities of N,C-codoped TiO2 catalysts. [Copyright &y& Elsevier]

Abstract: This study elucidates how indium tin oxide (ITO) thin film affects the microstructural and photocatalytic properties of layered TiO2/ITO films prepared by DC magnetron sputtering. Two ITO substrates, as-received ITO (aITO) and in situ sputtered ITO (sITO), are adopted herein. Photocatalytic measurements of methylene blue and dimethyl sulfoxide indicate that the layered TiO2/sITO film has greater photocatalytic oxidation than the TiO2/aITO catalyst. According to photoelectrochemical tests, the latter exhibits a completely opposite activity to that of the former. Secondary ion mass spectrometry elemental depth profiles reveal that tin atoms in the sITO film really permeate into the growing TiO2 film and promote the formation of the crystalline Ti1−x Sn x O2 layer. Additionally, cross-sectional transmission electron microscopy images and the selective area diffraction patterns show the difference between the diffusion of tin in the two catalysts. The photocatalytic oxidation capability is further enhanced in the layered TiO2/sITO film because of an increase in the bandgap energy and a positive shift in the Fermi level energy of the Ti1−x Sn x O2 layer. Conversely, tin diffusion is limited in the aITO substrate under controlled conditions, in such a manner that a Schottky barrier can form at the TiO2/aITO interface. Therefore, photogenerated electrons can be efficiently transferred from the overlaid TiO2 film to the aITO substrate, producing a remarkable photocurrent density under UV illumination. Microstructural measurements reveal that the growth of the reactive {001} facets and columnar porous structure are favored by the synergetic effect of ITO substrate and an extended period of deposition. Accordingly, the photocatalytic capabilities are further raised. [Copyright &y& Elsevier]

Abstract: Graded TiO2 films were deposited on unheated glass substrates by using a twin dc magnetron sputtering system. The graded TiO2 films showed a highly polycrystalline structure of anatase with a little rutile phases revealed by X-ray diffraction spectra. The surface energy of the fresh and UV irradiated films were evaluated by water contact angle measurement. The results indicated that the water contact angle of the fresh graded TiO2 films was found within 100–112°. The films then became a highly hydrophilic surface with the water contact angle of almost zero under 60min UV irradiation. The XPS spectrum of Ti 2p revealed that the graded TiO2 films became a stoichiometric titanium oxide layer near the surface, proving that titanium was fully oxidized. It was found that the surface OH group density depended on the substrates employed for given sputtering conditions. In addition, AFM images revealed a considerably rough surface of the graded films with RMS roughness of 12.6–14.5nm. One can conclude that the unique properties of highly hydrophobicity and photo-induced hydrophilicity can be attributed to fully oxidized chemical composition and higher roughness on the film surface. [Copyright &y& Elsevier]

Abstract: A twin DC magnetron sputtering system was used to prepare graded TiO2 and layered TiO2/ITO films on the unheated substrates. XRD analysis showed that the annealed TiO2 films contained more intensity of anatase phases and mixed with a little of rutile as compared with the as-deposited counterparts. The film morphologies, i.e., microstructure and surface roughness, were investigated by scanning electron microscopy and atomic force microscopy. The preferred orientation of the films along with surface morphology strongly depended upon the substrate materials and the post-heat treatment employed. X-ray photoelectron spectroscopy revealed that the films were heavily oxidized, regardless of post-heat treatment. The nanoindentation measurements on the films exhibited a comparatively higher hardness, Young''s modulus and adhesive strength. One can conclude that the TiO2 samples with a highly homogenous and polycrystalline structure and with a controllable surface roughness can be produced by this sputtering technique and the post-heat treatment. [Copyright &y& Elsevier]