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LED technology improved its efficacy through its innovative structures and development. General lighting and automobile industries are rapidly shifting from halogen lamps to LED lamps. LED is popular due to its high lumen output and efficiency which is considered a significant advantage. LED produces localized heat at its junction which directly affects its maximum lumen output range and even leads to failure. The conventional method for LED thermal management involves passive cooling using heat sinks and coolant fluid. The present work emphasizes active cooling of LED array considering various real- time parameters such as junction temperature, ambient and heat sink temperature. The LED experiences active cooling with the help of the feedback system loop controlling the junction temperature by varying the fan speed based on the heat sink temperature sensor output.

The objective of the study is to investigate the effect of current pulsation frequency on the weld bead microstructure, segregation and hardness of Hastelloy C-2000 weldments. Bead on Plate (BoP) welds were made by using Pulsed Current Gas Tungsten Arc Welding method (PCGTAW) at eleven different frequencies. The weld bead width and depth of penetration was measured with the help of Dinolite macro analyzer. The microstructure of weldments are further examined through optical microscope and Scanning Electron Microscopy (SEM) to identify the type of grain, grain coarsening and extent of the Heat Affected Zone (HAZ). The grain structure turn into finer and equiaxed in all cases and there was an optimum frequency range over which the significant grain refinement was observed. Microsegregation of alloying elements were computed with the aid of Energy Dispersive X-ray Spectroscopy (EDS). Vickers Hardness Tester was used to measure the hardness of the weld samples at ambient conditions.

This research is an attempt to investigate the possibility of enhancing wear and corrosion behaviour of aluminium alloy and composites for high-temperature applications. The 319 alloys with minor additions of Ni, Ti and Fe elements using the liquid metallurgy technique, Al-Si-Cu-Mg matrix alloy (Al alloy) was obtained and it was used as a base alloy and it is reinforced with Silicon carbide (SiC), Magnesium oxide (MgO) under the following composites, namely Al alloy/3wt % MgO (AA-SRM), Al alloy/ 3wt % SiC (AA-SRS) and Al alloy/3wt %SiC-3wt % MgO (AAHRSM) using a stir casting route. The wear test was investigated under the following factors, namely constant sliding velocity 3.21 m/s, sliding distance up to 10000 m under different loadings (4.9, 9.8, 14.7, 19.62, and 24.5 N) using wear test by a pin on the disc test rig. The wear rate was calculated using the tested samples under different loadings, sliding distance, and weight concentration conditions.

This study examines the influence of cryogenic treatment on the microstructure and on the physical properties of the rapid prototype SLS material. The wear properties of the rapid prototype SLS material both before and after cryogenic treatment are studied in three phases. Phase I deals with the sample preparation through the SLS technique; Phase II involves the preliminary tests like roughness test, hardness test, SEM and wear test. Phase III is the cryogenic treatment of the sample in the setup designed. The cryogenic coolant used is Nitrogen, having a boiling point of 77 K, and the whole treatment process takes about 2 to 3 days. Phase IV deals with the testing of the cryogenically treated samples in which similar tests to that in Phase I are carried out. These results are tabulated and graphs are plotted. Furthermore, the percentage change in the hardness and wear properties of the samples are found.

The current research work scrutinized the influence of plasma arc in the metallurgical and mechanical behavior of Nimonic 80A weldment. Defect free weld bead of 6 mm thickness was achieved in a single pass through plasma arc welding. The microstructure of weldment is decorated with cellular dendritic structure at the center and at the weld interface region columnar dendritic structure was observed. Metallurgical analysis showed the Cr and Ti secondary precipitates in the interdendritic region of the WZ. The existence of M23C6 and Cr2Ti were observed through the X-ray diffraction analysis. Both tensile test and microhardness test were conducted to study the mechanical properties of weldment. The result concluded that both the strength and ductility inferior than base metal and the hardness of the weld bead is similar to that of BMl.

In these work AZ91 magnesium matrix composites reinforced with two weight fractions (5 and 10 wt. %) of TiB2 particulates were fabricated by cold chamber die casting process technique. The microstructure, density, hardness, mechanical properties of the specimens was investigated. Microstructure studies showed that fairly uniform distribution of reinforcements was achieved up to the weight fraction studied. As compared to base alloy AZ91, the hardness and tensile strength considerably increased with increasing reinforcement content. The presence of TiB2 particles improved the hardness around 24.4 %, compressive strength around 67.2% and the yield strength around 20%. The enormous amount of increment in the compressive strength due to the dislocation density created by the difference in thermal properties of matrix and composites and also due to the micro-pores presence in the composite.

Duplex stainless steel (DSS) 2205 grade is welded with austenitic filler wires (ERNiCrMo-3 and ERNiCrMo-4) using gas tungsten arc welding (GTAW) process to operate at marine environments. Microstructure using optical (OM) and scanning electron microscopes (SEM) with energy dispersive spectroscope (EDS) are utilized to examine the metallurgical characterization of DSS 2205 weldments. Microhardness, impact, and tensile tests are employed to obtain the mechanical properties of weldments. Secondary precipitates such as Mo23C6 and Cr23C6 are formed in the ERNiCrMo-3 weldment which reduced the mechanical properties. In this study, ERNiCrMo-4 filler wire is provided enhanced mechanical properties for welding DSS 2205.