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In this study, static and vibration analyses of functionally graded gears (FGGs) have been performed using the FE-based numerical method. The gear body is divided into uniform thickness homogeneous sub-domains conforming to the gear tooth profile. Material properties vary in the radial direction according to power-law gradation with metal at the innermost and ceramic at the outermost surface. Three FG gear cases are studied, assuming the gradation for the entire body, radially outer half, and the outer quarter of the gear. Parameters like root stress, weight reduction, tooth stiffness, and natural frequencies of FG and bi-material gears are studied and presented with steel gear as a reference. For FGGs, root stress increases and the weight of the gear reduces with an increase in gradient index. It has been observed that the maximum difference in the fundamental frequencies of FGGs and steel gears is 12% compared to 25% for bi-metal gears. [ABSTRACT FROM AUTHOR]

In the present work, an alumina-titania (13%) coating has been deposited by the air plasma spray process on a mild steel substrate by preheating the substrate to different temperatures. Coating thickness was measured by a scanning electron microscope, the hardness of coatings was measured, and morphology was also checked. The crack compliance technique has been used to determine the residual stress, as it is a very simple method, and also, it is compatible with conventional machining equipment and wire electric discharge machining equipment. Specimens were cut by the diamond cutter up to certain depth in microns, and the strain relieved was recorded. For finding out the residual stress, these recorded values of strain have been used by doing a finite element analysis (FEA) using the ANSYS 15.0 (Ansys, Inc., Canonsburg, PA) software. For validation of the model, uniaxial tension was applied on a sample by using the INSTRON universal testing machine (Instron Inc., Norwood, MA), and strain values at both the coating side and the substrate side were recorded and matched with the model under the same value of the load. After verifying the model, an equation has been developed using the Minitab software (Minitab Inc, Bengaluru, India), and the strains previously recorded were used as an input to the equation obtained, and the value of residual stress was calculated. The maximum value of residual stress was found at the coating-substrate interface, and the values of residual stress for sample preheated at 250°C, 200°C, and 150°C were found to be compressive, with the magnitude of -176.28 MPa, -243.54 MPa, and -255.42 MPa, respectively. [ABSTRACT FROM AUTHOR]

Low cost sol-gel drop cast method has been successfully employed for preparation of nanocrystalline tungsten oxide (WO) thin films. The effect of processing temperature on the structure, morphology, electrical conductivity, thermoelectric power and band gap was studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscope (FESEM), Transmission electron microscopy (TEM), Atomic force microscopy (AFM), two probe technique and UV-visible spectroscopy. XRD analysis showed that WO films are crystallized in the orthorhombic phase and present a random orientation. XPS confirms formation of WO. FESEM analysis revealed that surface morphology of the tungsten oxide film consists nanocrystalline grains with uniform coverage of the substrate surface. TEM of WO film showed nanocrystals having diameter ranging from 60 to 80 nm. AFM analysis showed surface morphology of WO film is not smooth. The DC electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 7.264 × 10 to 1.606 × 10 (Ω cm) as processing temperature increased from 400 to 700 °C. Thermo electric power measurement confirms n-type conduction. The band gap energy of WO film decreased from 3.264 to 2.531 eV as processing temperature increased from 400 to 700 °C. [ABSTRACT FROM AUTHOR]

Novel chemical synthesis method has been successfully employed for the preparation of n type α-FeO nanoparticles. Thin films of annealed FeO powders processed on glass substrates using spin coating technique. The effects of process temperature on the structural, morphological, electrical transport and optical properties were studied. X-ray diffraction study revealed formation of single phase nanocrystalline hexagonal α-FeO. Microstructural analysis confirms nanostructured morphology. Dc electrical conductivity measurement reveled the semiconducting nature with room temperature electrical conductivity increased from 10 to 10 (Ω cm) as process temperature of FeO increased from 400 to 700 °C respectively. The n-type electrical conductivity is confirmed from thermo-emf measurement with no appreciable change in thermoelectric power after increasing processing temperature. The decrease in the band gap energy from 3.88 to 2.62 eV was observed after increasing process temperature. [ABSTRACT FROM AUTHOR]