Abstract: The present study is undertaken to investigate the influence of annealing and normalizing heat treatment on the bimetallic interface microstructures of 304 stainless steel and gray cast iron. The current work is aim to control the bimetal interface microstructures by different types of heat treatment processes to improve performance of the bimetallic castings performance. For low temperature annealing, specimens are heated to 760 0C for 60 min in an electrical heating furnace. For high temperature annealing and normalizing, specimens are heated to 920 0C for 120 and 240 min. A different interface structures are obained for all heat treated samples. Annealing and normalizing induce a significant effect on the diffusion of C and Cr elements and slightly effect on the diffusion of Ni element. Thickness of interface layer 1 (austenite + carbide) increases by increasingthe annealing temperature.
Abstract: Lithium vanadate doped tungsten trioxide films were coated on conducting fluorine doped tin oxide substrate by the sol-gel and dip coating methods using lithium vanadate and peroxotungstic acid sol. The concentration of lithium vanadatewas varied and the effects of lithium vanadate on morphology, microstructure and electrochromic properties of WO3 film were investigated. The synthesized tungsten trioxide with 10 wt.% lithium vanadate can be identified as amorphous structure. It observed that the crystallinity of the films are increase and more smooth when Li concentration increased and exhibits excellent properties in electrochromic performance in terms of diffusion coefficient is about as 2.6×10-9 cm2s-1 with the potential scan from -1.0 to +1.0 V as a scan rate of 100 mVs-1 in 0.5 M H2SO4 solution.
Abstract: Magnesium phosphate glasses co-doped with Er3+/Nd3+ concentration were prepared using melt quenching technique and thermal annealing process was proposed to control any defects found in the glass samples. The physical and optical properties of the samples were investigated. The amorphous nature of the samples were confirmed using X-ray diffraction pattern. It shows that all samples are in amorphous state. The optical band gaps and Urbach energies were obtained from the optical absorption spectra. The studyshows that the optical band gap energy,Eopt isincreasingas the Nd2O3 content increased. Meanwhile, Urbach energies, ΔE decreased due to increase of Nd2O3 content. The results obtained from this study shows that the optical band gap, Eopt and the Urbach energy, ΔE are intherange of 3.95 –3.98 eV and 0.367 –0.437 eV respectively.
Abstract: Porosity has many effects on performance of ceramic knife including sharpness, durability, etc, the metallographic detection for porosity of food contact ceramic knife was established in this study. Bycompared the relation ofsharpness, durabilityand porosity, Calculated quantitative metallographicofporosity, andestablishedthestandardatlasofmetallographicsample, the porosity was detected. The results showed that not only the <0.5% porosity could be detected, and the opening, the closing porositywould be detected quickly and accuratelyat the same time. It could be used in optimizing process and monitoring quality and safety of food contact ceramic knife.
Abstract: The temperature uniformity of most carbon fiber is degraded on the entire area. Therefore, understanding the thermal characteristics based on surface density and electrode shape becomes necessary. In this paper, the samples were fabricated according to the area density of carbon fiber and polyethylene terephthalate (8.8 g/m2, 20.2 g/m2, 42.1 g/m2). Different voltages (2V, 4V, 6V) were applied on them and the image was taken using thermal camera. Initially, the samples were investigated for morphology and element characterization by SEM-EDAX of surface heating elements and found that increased area density resulted in increase in the number of carbon atoms and decrease in number of oxygen atoms. It was also found from sheet resistance test that area density has inverse proportional relation with sheet resistance. In addition to that, regardless of the shape of the electrode, the increase in area density leads to a rise in temperature. It also increased the range of the temperature variation. Therefore, the uniformity and temperature stability can be satisfied by securing the electrode part as wide as possible through uniform electrode shape. In case of homogeneous electrode type, the saturation time of maximum temperature was 270 seconds, and the loading time was longer than 70 seconds of the concentrated electrode type. Therefore, in order to satisfy the reference temperature (30°C~ 50°C), the required surface heating product should be manufactured with the area density of 20.2 g/m2 at a voltage applied around 6V or less.
Abstract: Lithium molybdate doped tungsten trioxide electrochromic films were prepared from tungsten trioxide precursor and lithium molybdate powder by sol-gel and dip coating methods on fluorine doped tin oxide glass. The films, which synthesized were flat and amorphous structure, which confirmed by x-ray diffraction patterns. From UV-vis transmittance spectra within the wavelength from 400 to 800 nm. and cyclic voltammogram at the applying a potential of 1.0 V (bleached state) to -1.0 V (colored state) in sulfuric acid 0.5 M solution. The doping lithium molybdate 10 mol% films showed good result in terms of transmittance modulation, high diffusion coefficient and optimal surface area. Therefore, doping lithium molybdate 10 mol% has better outcome when compared to undoped lithium molybdate.
Abstract: Roll forming process, due to increased product performance, higher quality, and lower cost with other advantages, has been made suitable process to form any shapes in the sheets. In this paper stress, strain and thickness distribution in the steel galvanized hot coil commercial (SGHC) sheet with Round shape ribs formed by roll forming process was investigated by a Finite Element code, ABAQUS software. The stress and strain distributions are considered during forming. Since in round shape ribs the flow of material is easier than quadrilateral one, the Stress distribution was more uniformand thinning strain was concentrated in the ribs with maximum value of 14.5% while this value in quadrilateral shape rib forming is 15.5%. The results show that this method is applicable in reducing the thickness strain.
Abstract: These days sheet metal forming is a widely used in different industrial fields with large production volumes. Formability of metal sheets is limited by localized necking and plastic instability. In sheet metal forming processes like drawing and stamping the main challenge is thinning of the metal sheet in some regions. To reduce thinning of the sheet product, roll forming has been suggested instead of stamping process. Thinning strain can cause necking, tearing or wrinkling which are failure of the metal sheet. In this study a new engineering technique is proposed in order to prevent thinning of the steel galvanized hot coil commercial (SGHC) in roll forming process. An explicit finite element code, ABAQUS software, was used to simulate the roll forming process. The results show that the proposed technique has an important effect on thinning of the sheet and can reduce it significantly. Investigation on the second and third and fourth rollers show the effect of modified roller dimension as on reducing the thickness. These reductions in second, third and fourth rollers are from 4 percent to 0.5 percent, 2.8 to 1.4 percent and from 1.4 to 0.7 percent respectively. The reasons of the new techniques effect were also discussed.
Abstract: A machining method of large-sized spiral bevel gears in cyclo-palloid system has been developed using a computer numerical control (CNC) machining center. As a result of trial machining, the tooth surfaces were rough and leprous tool mark occurred. Therefore, the tooth surfaces were polished using a poly-vinyl alcohol (PVA) elastic grindstone after machining in order to improve the surface roughness and the occurrence of leprous tool mark. However, the wear and clogging of the elastic grindstone occurred after polishing. In this paper, the tooth surfaces of the large-sized spiral bevel gears are polished using a radial bristle brush instead of a PVA elastic grindstone. The swarf cutting that was machined by the side of a tool was carried out in polishing in order to make the life of the radial bristle brush. After polishing, the tooth surface was observed and the surface roughness was measured. Afterwards, the surface roughness and the occurrence of leprous tool mark before and after polishing were compared. As a result, the surface roughness and the occurrence of leprous tool mark were improved.