Materials Science Forum Vol. 1132

Abstract: Aluminum Bronze bushing sleeves or sleeve bearings are used in the various parts of vehicles like camshaft bushing, suspensions, shock absorber, gears and strut bushes for anti-wear, anti-friction and for bearings high tensile loads. This research presents a comprehensive study on the development of Aluminum bronze bushing sleeves using horizontal centrifugal casting method. The effect of centrifugal casting parameters i.e. molds rotation speed, melt temperature, alloy composition and heat treatment optimizes mechanical properties and also microstructure of developed bushing sleeves. These bushing sleeves with desired composition have been developed by using induction furnace to reduce its import and to save foreign exchange. Different samples were casted by using horizontal centrifugal casting machine by varying parameters like rotation speed of mold and pouring temperature of melt in order to get good quality bushing sleeve. The addition of trace elements like Manganese, Iron, nickel and Zinc optimize the mechanical properties of bushing sleeves for particular application in elevating and depressing mechanism of heavy vehicles. The developed material was characterized by using different characterization techniques like Spectroscopy (OES), wet analysis, mechanical testing, optical microscope and Scanning Electron Microscope (SEM).

Abstract: In many different industries, cavitation-induced erosion and damage to engineering parts have been a major problem. This is especially true when it comes to fluid systems. Modern materials and welding methods are always being researched to improve the components' resistance to cavitation damage as a way to address this problem. This study examines the cavitation resistance of friction stir welded joints made of high-purity copper alloy Cu99, which has promising mechanical qualities. The project entails the creation of friction stir welded joints made of Cu99 copper, followed by extensive testing to see how well they resist erosion caused by cavitation. A cavitation testing device is used for the testing, simulating the circumstances that can cause cavitation damage to fluid systems in the actual world. The cavitation intensity, exposure time, and temperature changes are the relevant parameters. The performance and longevity of the friction stir welded joints under cavitation conditions are assessed using the experimental results. Investigations are conducted into the effect of post-weld heat treatment, grain boundary features, and microstructural changes in improving cavitation resistance. The goal of the study is to offer important new information on friction stir welding's potential as a method for raising the cavitation resistance of Cu99 copper components.

Abstract: Aluminum alloys are known for their wide application in the automotive, river and marine boat constructions, but also in hydraulic systems (radiators/oil coolers). Their use is made by manufacturing parts directly from the semi-finished state, with or without certain volumetric heat treatments and surface hardening, depending on the functional role and the physical-mechanical characteristics pursued. Some of these parts work in hydrodynamic conditions, where cavitation manifests itself through erosion, such as: propellers of boats and barges, pump rotors in water cooling systems of automobiles. Visual analyzes performed on sailboat and powerboat propellers, after identical durations and operating conditions, showed cavitation erosion damage, different depending on the type of aluminum alloy. As a result, the paper presents and analyzes the behavior and resistance to erosion by vibratory cavitation of 4 types of aluminum alloys in the state of rolled semi-finished products. To highlight the differences in the destruction of structures under the cyclic stresses of cavitational microjets, macro and microscopic images of the eroded structure are used, as well as the curves with the values of the parameters specific to cavitation, recommended by the ASTM G32 -2016 norms and used in the research laboratory's custom. The analysis of the results shows that the resistance of the structure to cavitation erosion is dependent on the type of alloy, the degree of brittle intermetallic compounds and the mechanical properties specific to toughness.

Abstract: High entropy alloys possess excellent properties and a great deal of research is being carried out on them. AlCrCo_(1-x)Fe_(1+x)Ni₂ (x= 0, 0.5, 1) alloys were arc melted and suction cast in strip form in a controlled atmosphere. The alloys were characterized for crystal structure, phases and Vickers hardness. A two phase vermicular structure was observed for alloys with x = 0 – 0.5 consisting of Ni rich BCC and Cr rich FCC phases while a widmanstatten structure formed in alloy with x = 1 (without Co). An increase in the amount of BCC phase and hardness was noted with the replacement of Co with Fe caused mainly due to increase in Al and decrease of Cr in composition obtained through EDS. Vickers hardness of 251 H_V was measured in alloy without Co.

Abstract: This study is carried out to investigate the ductile to brittle fracture behavior of special high strength low alloy steel (HSLA), which is used in aerospace applications. As aerospace materials are subjected to temperature variations during their actual use therefore it is very important to know their fracture behavior with change of temperature. Alloy having 0.3 %C, 0.88 % Mn and 1.0% Si was heat treated to obtain tempered martensite and ferrite and tempered martensite structures. Impact toughness tests were carried out at temperature range from – 60 °C - 200 °C in as received, fully quenched, and tempered and quenched and tempered in two phase (a+ γ) state. Then the effect of different heat treatments on impact transition temperature was studied.

Abstract: Welding of dissimilar alloys, specifically that of titanium (Ti) and nickel (Ni), poses numerous challenges due to their significant differences in properties. This review paper aims to provide a comprehensive overview of the challenges associated with the welding of Ti alloys to Ni alloys and explore welding techniques, especially Tungsten Inert Gas (TIG) welding, Metal Inert Gas (MIG) welding, Laser beam welding, Laser-Arc hybrid welding and friction stir welding processes employed in this context. The challenges primarily involve the formation of brittle intermetallic phases, which can compromise joint quality. Additionally, issues such as thermal distortion, oxidation, and corrosion resistance further complicate the welding process. The paper also highlights recent advancements and innovations in dissimilar welding, such as the use of hybrid welding processes and advanced filler materials, to address the challenges and enhance joint performance. The knowledge shared in this review can guide future research and developmental efforts aimed at improving welding techniques, joint quality, and overall performance of Ti to Ni alloys welds.

Abstract: Solid-state diffusion bonding (DB) of Copper-Copper (Cu/Cu) was carried out under varying bonding parameters (time and temperature) in argon shielding gas environment. Initially, the bonding was performed at bonding temperatures of 800, 850, and 900 °C for 60 minutes. Secondly, the bonding was carried out at holding times of 90, 120, and 150 minutes at 900 °C. The microstructural and mechanical properties of the bonding interface were evaluated via lap shear and micro hardness tests, X-ray diffraction, and Optical microscopy. It was found that the optimal bonding parameters for the joint interface was 950 °C for 150 minutes, resulting in maximum shear strength of 133 MPa. The X-ray diffraction also shows the formation of solid solution of Cu without the formation of any intermetallic compounds (IMC). The micro hardness test revealed a maximum hardness of 89 HV at the joint interface. Optical microscopy shows the formation of voids at the joint interface take place due to the Kirkendall effect, which increased with higher temperatures for longer time, and cause a wide diffusion-affected zone (DAZ).

Abstract: Self-assembled hierarchical Bi₂WO₆ microsphere was synthesized via a facile hydrothermal method. The fabricated Bi₂WO₆ exhibited up to 85.3% Cr(VI) reduction efficacy which was much greater than that of commercially available P25 TiO₂ nanoparticles. Furthermore, Bi₂WO₆ microsphere also produced about 1.5-fold greater H₂ quantity in water splitting compared to P25 TiO₂. The photocatalytic enhancement of Bi₂WO₆ microsphere was ascribed to its unique hierarchical porous architecture and large surface area which can improve the charge carrier quantities for redox reactions. The present study could be useful for fabricating Bi₂WO₆ photocatalyst with improved performance in environmental remediation and renewable energy applications.

Abstract: This study focuses on synthesizing and characterizing a semi-Interpenetrating Network (semi-IPN) elastomeric hydrogel comprising natural rubber (NR) and polyethylene glycol methacrylate (PEGMA) for efficient removal of Methylene Blue (MB) dye from aqueous solutions. The impact of varying PEGMA/NR ratios (100/0 to 0/100) was investigated. SEM images displayed a porous and uniform structure with interconnected pores of different sizes. FTIR analysis confirmed the formation of a semi-IPN structure, showcasing functional groups in both NR and PEGMA. Adsorption studies revealed the hydrogel's efficacy in MB dye removal, achieving a maximum adsorption capacity of 6536 mg/g at a PEGMA/NR ratio of 90/10. UV-vis spectroscopy validated the reduction in MB concentration post-exposure to the hydrogel. These findings highlight the cationic ionic nature of the PEGMA/NR semi-IPN elastomeric hydrogel as a promising adsorbent for MB dye removal in wastewater applications, particularly in industrial wastewater treatment.