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The present experimental work is carried out on SAE 420 steel to optimize process parameters of low-power laser hardening to improve surface micro-hardness and wear resistance for dry sliding for bio-medical applications. Laser power is the most significant factor for micro-hardening and wear resistance. Rank two for scanning speed and three for standoff distance, respectively. The experiments show that the surface micro-hardness of treated samples varies from 711 to 833 Vickers Pyramid Number by optimized process parameters such as laser beam power of 300 W, laser scan speed of 1.0 mm/s, and standoff distance of 225 mm. In comparison, the base material micro-hardness is 208 Vickers Pyramid Number as the predictive equation generated for finding micro-hardness value for the above three laser hardening process parameters. The dry sliding wear test is conducted on all laser-treated samples and a comparison is made with the untreated sample. A significant improvement in wear resistance was observed for treated as compared to untreated samples. The wear of laser hardened sample of SAE 420 steel was 3.67 x10-9 g/cm compared to untreated base metal wear rate of 139.00 x 10-9 g/cm at an applied load of 30 N and sliding speed of 300 revolutions per minute. The scanning electron microscopy analysis of wear samples (untreated, treated maximum, and minimum hardness) is observed for investigating material removal patterns.

In the present research work, the influence of heat input rates on microstructures, hot tensile properties, and weld surface hardness number of Super Duplex Stainless Steel 2507 super duplex steels and austenitic steels 316L plates were investigated. Pulsed current and constant current modes were used in Tungsten Inert Gas (TIG) welding to join the dissimilar metals using ER2205 as filler. Microstructural studies were revealed at different zones of pulsed and constant current TIG weldments using optical microscopy. The tensile test was conducted at two different temperature conditions (i.e., 27 and 350°C) to investigate the strength of dissimilar weldments. Hardness measurements were made on the weld surface along the transverse direction using Vicker’s hardness tester. The microstructures revealed the formation of inter-granular austenite at the fusion zone with grain boundaries with austenite structures. Due to the constant heat input, a significant microstructural development with high austenite fractions was observed in constant current (CC)-TIG weldment. In comparison to CC-TIG weldments (UTS at 27°C = 600 MPa UTS at 350°C = 456 MPa), higher tensile characteristics were noted in Pulsed Current (PC)-TIG weldments (UTS at 27°C = 695 MPa UTS at 350°C = 475 MPa). The UTS of PC-TIG weldment is improved by 15.8% when compared to CC-TIG weldment due to the controlled heat input rates. PC-TIG weldments exhibited improved hardness numbers in various zones with smaller HAZ widths than CC-TIG weldments.

The durability of geopolymer concrete containing Ground Granulated Blast Furnace Slag (GGBS) and Rice Husk Ash (RHA), along with Lightweight Expanded Clay Aggregate (LECA), was investigated. Six different LWGPC mixtures were made with NaOH molarities of 8, 10, and 12M. For each molarity, two combinations of source materials were selected: 100% GGBS (G) and 80% GGBS with 20% RHA (RG). In all the mixtures, coarse aggregate was substituted with 35% LECA. LWGPC mixtures were exposed to 3% HCl, 5% MgSO4, and 3.5% NaCl for studying the durability properties. The test results demonstrate that 100% GGBS with 12M NaOH (12G) outperformed all other mixtures. The residual compressive strength of 12G mix LWGPC specimens after six months of exposure was found to be 86.4% in an acid environment, 90.6% in a sulfate environment, and 91.4% in a salt environment. The elemental composition analyzed using EDAX reveals that silica, alumina, calcium, and sodium are the predominant elements that form a dense microstructure with N-A-S-H, C-A-S-H, and C-S-H. Further, the inner properties of the specimens exposed to chemicals were examined using MATLAB R2023b and ImageJ 1.54f based on SEM images. The SEM image showed that the porosity of LWGPC specimens ranged from 0.5194 to 0.6748 µm, signifying an enhanced durability performance. The experimental results and microstructural analysis show that the LWGPC incorporating RHA and GGBS with LECA offers a superior performance, making it a promising solution for sustainable and durable construction. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis and characterization of hybrid zinc oxide/silver ion (ZnO/Ag+) nanocomposites tailored for PV cell applications. The nanocomposites are synthesized through a cost-effective method, leveraging the unique properties of both ZnO and Ag. Characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) are employed to analyze the structural, morphological and optical properties of the nanocomposites. Moreover, the electrical properties and photoelectric performance of the PV solar cells are evaluated and compared with conventional PV devices. The results demonstrate the potential of ZnO/Ag+ nanocomposites in enhancing the overall performance of PV solar cells. [ABSTRACT FROM AUTHOR]

This offers a thorough examination of sustainable practises within the domains of design and production. This seminal study explores the pivotal convergence of environmental awareness and inventive thinking, offering a strategic guide towards a more ecologically responsible and enduring trajectory. In the current epoch characterised by pressing global environmental issues, this book presents a pertinent and indispensable resource for individuals in professional, scholarly, and educational domains who aspire to effect constructive change. By utilising a diverse range of case studies, expert perspectives, and current research, “Blueprints for Green Horizons” offers a comprehensive framework for achieving sustainable design and production. The manuscript illustrates the seamless integration of sustainability into design and production processes, emphasising the importance of environmental responsibility across the entire lifecycle, from initial concept to end customer. It examines the significance of responsible consumer behaviour in promoting sustainable production, urging readers to make well-informed decisions that contribute to the advancement of a more sustainable global environment. This manuscript advocates for the integration of diverse academic fields, such as design, engineering, economics, and environmental science, to foster successful collaboration in addressing intricate sustainability issues.

Given the increasing magnitude of environmental concerns, it has become crucial to prioritise the transition towards a sustainable and environmentally conscious future. Remanufacturing is a vital strategy in the forefront of the ecological revolution, as it possesses the ability to significantly mitigate waste, preserve resources, and diminish the carbon footprint associated with contemporary enterprises. This abstract examines the concept of remanufacturing as a potential driver for a more environmentally sustainable future. It highlights the innovative progress, economic advantages, and environmental benefits that can be achieved through its extensive implementation. Remanufacturing represents a significant shift in manufacturing practises, going beyond traditional recycling efforts. Remanufacturing is a process that involves the restoration and refurbishment of previously used products to their original specifications, so effectively prolonging the lifespan of consumer goods, machinery, and electronics. This practise has the dual purpose of limiting the disposal of significant quantities of trash and diminishing the need for new, untapped resources, thereby alleviating concerns related to resource depletion and environmental deterioration. In addition to its economic benefits, remanufacturing plays a significant role in mitigating greenhouse gas emissions. The energy consumption associated with the process of remanufacturing is frequently significantly lower compared to the energy requirements for manufacturing wholly new things. This leads to a significant decrease in carbon emissions, which is a crucial measure in addressing the issue of climate change.

An attempt was made in the present work to study the compressive strength and microstructure of geopolymer containing high calcium fly ash (HCFA) and silica fume. Concentration of sodium hydroxide solution 8M, 10M, 12M & 14M, liquid to binder ratio 0.5 and sodium hydroxide to sodium silicate ratio 2.5 were selected for the mixes. Geopolymer mortar test results indicated that the mix with 40% silica fume by the weight of HCFA yielded higher compressive strength under ambient curing. The XRD pattern typically shows the major portion of amorphous phase of geopolymer. The existence of C-A-S-H gel, N-A-S-H gel and hydroxysodalite gel products were observed through SEM which developed dense microstructure and thus enhanced strength of HCFA and silica fume geopolymer.

Nanocomposites comprising semiconductor materials hold immense potential for advancing photovoltaic technologies due to their unique optoelectronic properties. This research focuses on the synthesis and characterization of a ZnO-CdO (zinc oxide and cadmium oxide) nanocomposite using the sol-gel method for potential application in photovoltaic devices. The sol-gel approach provides a versatile platform for tailoring material properties to enhance photovoltaic performance. The structural, morphological, and optical characteristics of the ZnO-CdO nanocomposite were extensively analyzed using techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible spectroscopy. The XRD analysis confirmed the crystalline nature of the nanoparticles and assessed potential changes in their crystal structure upon nanocomposite formation. SEM and TEM images provided insights into particle size, shape, and distribution, corroborating successful nanocomposite fabrication. This study underscores the significance of sol-gel synthesis in tailoring semiconductor nanocomposites for photovoltaic applications. The characterized structural, optical, and photovoltaic properties provide a foundation for further optimization and integration into advanced photovoltaic devices. [ABSTRACT FROM AUTHOR]

The present study examines some durability aspects of ambient cured bottom ash geopolymer concrete (BA GPC) due to accelerated corrosion, sorptivity, and water absorption. The bottom ash geopolymer concrete was prepared with sodium based alkaline activators under ambient curing temperatures. The sodium hydroxide used concentration was 8M. The performance of BA GPC was compared with conventional concrete. The test results indicate that BA GPC developes a strong passive layer against chloride ion diffusion and provides better protection against corrosion. Both the initial and final rates of water absorption of BA GPC were about two times less than those of conventional concrete. The BA GPC significantly enhanced performance over equivalent grade conventional concrete (CC).