Narrow Results

This study investigates the mechanical, fatigue, water absorption, and flammability properties of polyethylene terephthalate (PET) core-pineapple fiber sandwich composites reinforced with silane-treated neem fruit husk (NFH) biosilica additives. The novel approach includes modifying the fiber’s surface and incorporating biosilica to enhance environmental resistance. The composites were prepared using a hand layup method, followed by silane treatment of the biosilica, pineapple fiber, PET core and vinyl ester resin. Subsequently, to evaluate environmental impacts on composite’s performance, sandwich composites were subjected to temperature aging at 40^∘C and 60^∘C in a hot oven for 30 days and warm water aging at the same temperatures in tap water with pH 7.4. According to the results, adding 1%, 3%, and 5 vol.% silane-treated biosilica significantly improved the mechanical properties. The composite with 3% biosilica (L2) showed a tensile strength of 120.8MPa, flexural strength of 194.4MPa, compression strength of 182.4MPa, rail shear strength of 20.21MPa, ILSS of 23.14MPa, hardness of 85 Shore-D, and Izod impact strength of 6.56 J. Even under temperature and water aging conditions, the composites showed only minimal reductions in properties, highlighting the efficacy of the silane treatment. The temperature-aged L2 composite had a tensile strength of 104MPa, flexural strength of 172.8 MPa, compression strength of 164MPa, and ILSS of 22.5MPa, while the water-aged L2 composite exhibited a tensile strength of 96MPa, flexural strength of 152.8MPa, compression strength of 146.4MPa, and ILSS of 21.4MPa. Scanning electron microscope (SEM) analysis confirmed uniform dispersion of biosilica particles, critical for improved performance, though higher concentrations led to agglomeration and stress points. The composites also demonstrated excellent flame retardancy, maintaining a UL-94 V-0 rating with decreased flame propagation speeds, specifically 9.05mm/min for L2. These findings underscore the potential of silane-treated biosilica as a reinforcing additive to enhance the durability and performance of composites in adverse conditions.

The effect of thermal heat treatment on the mechanical and electrical properties of Cu–Ag alloys was investigated. The homogenization heat treatment leads to an increase in tensile strength and a decrease in electrical conductivity due to dissolution of Ag into copper matrix. Also, it is shown that electrical conductivity of as-cast Cu–Ag alloys decreases with increasing Ag content. In contrast, the aging heat treatment gives rise to increase both the tensile strength and electrical conductivity because the Ag solute diffuses out from copper matrix during aging heat treatment. Therefore, it can be mentioned that the electrical conductivity of Cu–Ag alloys depends on Ag solute in copper matrix. Also, aging treatment is favorable to acquire high strength and high electrical conductivity.

This paper investigates the impact of heat input and post-weld aging behavior at different temperatures on the laser paper welded maraging steel grade 250. Three different levels of heat inputs were chosen and CO₂ laser welding was performed. Aging was done at six different temperatures: 360${}^{\circ }$C, 400${}^{\circ }$C, 440${}^{\circ }$C, 480${}^{\circ }$C, 520${}^{\circ }$C and 560${}^{\circ }$C. The macrostructure and microstructure of the fusion zone were obtained using optical microscope. The microhardness test was performed on the weld zone. Tensile tests and impact tests were carried out for the weld samples and different age-treated weld samples. Fracture surfaces were investigated by scanning electron microscopy (SEM). Microhardness values of the fusion zone increased with increasing aging temperature, while the base metal microhardness value decreased. Tensile properties increased with aging temperature up to 480${}^{\circ }$C and reduced for 520${}^{\circ }$C and 560${}^{\circ }$C. This was mainly due to the formation of reverted austenite beyond 500${}^{\circ }$C. XRD analysis confirmed the formation of reverted austenite.

Wide bandgap II–VI semiconductor quantum dots embedded in glass matrix have shown great potential for opto-electronic device applications. The current problem is to achieve low size dispersion, high volume fraction, and better control over the size of the quantum dots in glass matrix. In this work, a modified growth method has been proposed to achieve a greater control over the size of quantum dots, to reduce their size dispersion and to increase their volume fraction. A theoretical model has been developed to quantitatively estimate the various parameters of the quantum dots. The effects of aging on various parameters of quantum dots in Semiconductor-Doped Glass (SDG) samples have also been discussed in the present work.

The aging property of radiation vulcanized natural rubber was studied using various kinds of antioxidants. Aging test was done at 100°C for various lengths of time. It was found that some antioxidants are excellent in preventing the oxidative degradation of the irradiated rubber. DAH (2,5-di-tert-amylhydroquinone) + CBP (2,2′-dihydroxy-3,3′-di(-methyl-cyclohexyl)-5,5′-dimethyl diphenyl methane) + P16 (tris(2,4-di-tert-butylphenyl)phosphate) in a proportion of (1:0.5:0.5) was found to be the best combination to achieve 100% retention of tensile strength.