Sharda Pratap Shrivas; G. K. Agrawal; Shubhrata Nagpal
Abstract
Friction stir welding (FSW) broadly used in the same grade as aluminium alloy but for aluminium alloy material it requires high speed rotation of FSW tool which develops high temperature on tool. In this paper process parameter of FSW are studied based on the strength of welding joint and predict FSW ...
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Friction stir welding (FSW) broadly used in the same grade as aluminium alloy but for aluminium alloy material it requires high speed rotation of FSW tool which develops high temperature on tool. In this paper process parameter of FSW are studied based on the strength of welding joint and predict FSW tool speed as low as possible according to the past literature. Constant machining parameters are tool rotation of FSW is 800 rpm and welding speed 15 mm/min. In this work analysing the strength variation of welding joint under two mode of pre-heating temperature on the work-piece then variation of cooling medium apply after preheating to change the grain structure of work-piece. In this work the FSW process is passed over two pieces of aluminum at once and the effect of tool rotation and temperature of the tool is discussed by preparing the sample for testing according to the ASTM dimension.
Zuhair Al-Jaberi; John J. Myers; K. Chandrashekhara
Abstract
The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability ...
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The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability by considering exposure to harsh environmental conditions and testing the specimens after exposure, rather than testing bond performance during exposure. The influence of directly applying temperature on bond behavior represents an open topic that needs to be investigated in more detail. This study is one of the first studies to investigate the bond behavior when the composite is subjected to tension force simultaneously with applying temperature. The temperatures considered in this study were at freezing, ambient, and high temperature, which are more representative of structural elements under field conditions. A total of 16 specimens were strengthened and tested under single-lap direct shear. The key parameters investigated include (a) the type of fiber [laminate carbon vs. wet layup glass] (b) the level of temperature applied on specimen, including ambient condition 21°C (70 °F), freeze condition -18 °C (0 °F) and hot weather 49 °C (120 °F), and (c) the exposure regime (direct exposure during loading process vs. loading after exposure). Most of the specimens were subjected to tension force simultaneously with applying temperature, and the other specimens were later tested after exposure to the heating and cooling cycles. These cycles are proposed to simulate 20 years of the typical in-situ weather conditions in the Central United States. The results showed that overall the EB strengthening systems exhibited good performance when subjected to cycles of heating and cooling prior to testing. High reduction of FRP-epoxy bond properties was up to 59% when exposed to high service temperatures. Different modes of failure were observed such as debonding at fiber-matrix interface and debonding due to shearing in laminate.
Lin Li; Shibing Tian; Ruhao Pan; Chao Wang; Chi Sun; Junjie Li; Changzhi Gu
Abstract
The uniformity in temperature-field of the hot filament chemical vapor deposition (HFCVD) system is of great importance since it is a critical parameter that determines the quality of the deposited films. In fact, the temperature-field is mainly filament distribution dependent. In conventional analysis ...
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The uniformity in temperature-field of the hot filament chemical vapor deposition (HFCVD) system is of great importance since it is a critical parameter that determines the quality of the deposited films. In fact, the temperature-field is mainly filament distribution dependent. In conventional analysis method, the filament array usually has an equal-space distribution, which leads to a remarkable edge effect and consequently unable to obtain large area uniformity in temperature-field in HFCVD for high-quality thin film deposition. Here, we proposed theoretically an asymmetrical filament distribution to reduce the edge-effect of temperature field. The adjacent filament distance was optimized by using numerical simulation based on heat-transfer theory. Based the optimized condition, temperature difference as low as 13 K between the center and edge region of the filament arrays can be achieved in 100-mm substrate, which is only one tenth of the temperature difference of that in the case that the filaments were evenly distributed. Thus unequal-space distribution can be employed to enhance the uniformity in temperature field of the HFVCD system in favor of the growth of high quality thin films in large area.
R. Tholkappiyan; Fathalla Hamed; K. Vishista
Abstract
Lanthanum (La3+) ion doped zinc ferrite nanoparticles were synthesized by combustion method using glycine as fuel. The as-synthesized ZnFe1.96La0.04O4 nanoparticles were subjected to annealing temperature of 900 oC for time intervals of 2 h, 6 h, 12 h, 24 h and 48 h. The as-synthesized and annealed ZnFe1.96La0.04O4 nanoparticles ...
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Lanthanum (La3+) ion doped zinc ferrite nanoparticles were synthesized by combustion method using glycine as fuel. The as-synthesized ZnFe1.96La0.04O4 nanoparticles were subjected to annealing temperature of 900 oC for time intervals of 2 h, 6 h, 12 h, 24 h and 48 h. The as-synthesized and annealed ZnFe1.96La0.04O4 nanoparticles were characterized as a single phase with normal spinel structure. The surface morphology of these nanoparticles were found to be non–uniform and agglomerated with fine pores/voids. The induced strain and dislocation density were reduced with increasing annealing time which enhanced crystallinity and increased grain size. The values of optical band gap calculated from UV/Vis/NIR spectra of the as-synthesized and annealed ZnFe1.96La0.04O4 nanoparticles were found to decrease with increasing annealing time. They range from 2.48 to 2.19 eV from the simple method and 2.42–2.12 eV for direct and 1.87–1.71 eV for indirect from Kubelka–Munk function method. The optical band gap in ZnFe1.96La0.04O4 nanoparticles can be tuned as function of varying annealing time and it seems to correlate with induced strains in the nano-crystallites. Therefore, the tuning of optical band gap with just changing the heating treatment of ZnFe1.96La0.04O4 nanoparticles may make them suitable photocatalysis.
Alaba O. Araoyinbo; Azmi Rahmat; Mohd Nazree Derman; Khairel Rafezi Ahmad
Abstract
The basic concept of Gibbs standard state free energy predicts a favorable condition for both room and high temperature fabrication of nanoporous alumina in phosphoric acid electrolyte. The anodization of aluminum foil in acidic electrolytes is made possible by the well known process parameters that ...
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The basic concept of Gibbs standard state free energy predicts a favorable condition for both room and high temperature fabrication of nanoporous alumina in phosphoric acid electrolyte. The anodization of aluminum foil in acidic electrolytes is made possible by the well known process parameters that have been studied over the years. These parameters i.e. voltage, current density, type of electrolyte etc have been very effective when anodizing aluminum at freezing temperatures. When the operating temperature is raised above the freezing temperature, additional process parameters would be required to make the pore formation possible. The fabrication of the aluminum foil was carried out using phosphoric acid as the electrolyte source. The electrolyte pH was adjusted to 1, 3 and 5 in order to simulate different anodizing conditions. A potential of 50 V from a dc power supply was applied across the electrochemical cell, while a power regulating device with different power rating was attached to the electrochemical cell to provide the operating system with additional parameters that could influence the surface structure of the alumina. The micrographs obtained show that the propagation and growth of the pores at both room and high temperatures was made possible by the power regulating device attached to the cell.
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