Advances in Science and Technology Vol. 175

Abstract: Natural fibers are considered as alternative reinforcements in composites due to their accessibility, affordability, renewability and potential positive effects on some properties. Sources of these fibers include bast, leaf, seed and grass. In this paper, untreated tiger grass fiber, which is typically used as material in soft brooms, has been reinforced in epoxy resin with varying loading of 0 %, 5 %, 10 %, 15 % and 20 % by mass of matrix. For the composite manufacturing, the samples were prepared with the use of silicone molds and were subjected to tensile and water absorption tests. Based from the results, the tiger grass fiber reinforcement has provided significant improvements on tensile strength. The sample with 20 % fiber content achieved the maximum strength of 42 MPa which correspond to about 91 % enhancement as compared to the plain sample. This could be associated with the stress transfer between the unidirectional fibers and the epoxy matrix. As for water absorption, all composites only attained minimal mean values that ranges from 0.035 % to 0.063 %. This could be linked to the water-resistant characteristic of the matrix that protected the reinforcing fibers from being exposed directly to water.

Abstract: The incorporation of natural fillers like eggshells in polymers has gain attention due to their potential capability to enhance some properties while providing possible cost savings. In this paper, quail eggshells were used as bio-based filler in silicone rubber and their effects on the mechanical properties were investigated. For the composite manufacturing, samples containing 4.8 wt.% (5 phr), 9.1 wt.% (10 phr) and 13 wt.% (15 phr) of crushed quail eggshells were manually prepared. The mechanical characterization tests considered are compression, tensile and hardness. Based from the results, the sample with 4.8 wt.% filler achieved the highest compressive strength of 2.79 MPa and hardness of 53.3 which correspond to improvements of about 11 % and 6 % as compared to the plain rubber, respectively. These enhancements can be associated with the good dispersion of the filler at lower loading. However, higher filler contents resulted to a decrease in mechanical properties which could be linked to the possible agglomeration of crushed eggshells and weak filler to matrix interaction caused by lack of surface treatment. Nevertheless, the improvements attained by adding quail eggshells at lower percentage in rubber can still make it an alternative filler to consider.

Abstract: This study investigates the effect of introducing an intermediate solution treatment after cold drawing and before artificial aging on the mechanical and electrical properties of the 6201 aluminum alloy. The solution heat treatment was performed at 510 °C for one hour. Aging treatments were conducted at temperatures ranging from 150 °C to 200 °C for durations between 2 h and 30 h. This heat treatment route yielded comparatively softer materials, with a maximum ultimate tensile strength (UTS) of approximately 325 MPa. Electrical conductivity (EC) measurements demonstrated that the T6-temper method consistently produced higher EC values reaching values of around 63 %IACS compared to the conventional process, deomstrating inverse relationship between strength and conductivity. It was found that T6-155-30 condition produces the best combination of strength, ductility and EC of 325 MPa, 11.5% and 58.6 %IACS, respectively.

Abstract: Post-weld heat treatment (PWHT) was investigated to evaluate its effects on dissimilar friction stir welded (FSWed) T-joints of AA6061 and low carbon steel. The non-PWHT joint was compared with four PWHT conditions involving solution treatment, quenching, natural aging, and subsequent artificial aging at 0-12 hours. Microstructural characterization revealed a largely continuous Al/steel interface in the non-PWHT joint, while PWHT promoted interfacial cracking and modified precipitation behavior in the stir zone and heat-affected zone of AA6061. Hardness increased monotonically with aging time, reaching ~95–100 HV after PWHT artificial aging at 12 hours. Tensile strength peaked at 212MPa after 4 hours of artificial aging, while maximum strain decreased from ~9% to ~5.3% after 12 h artificial aging, indicating ductility loss under prolonged aging. Fracture location after PWHT consistently occurred at SZ, highlighting a critical failure region governed by joint geometry and microstructural heterogeneity.

Abstract: This study investigates the development and application of Ni-W alloy gradient coatings fabricated via electrodeposition as a direct strategy for industrial energy efficiency optimization. An eight-layer graded coating architecture was successfully synthesized on low-carbon steel substrates through a programmed current density sequence (2–16 A/dm²). This approach produced a progressive increase in tungsten content from ~11.3 at.% at the substrate interface to ~21.9 at.% at the surface, achieving a maximum microhardness of 875 HV via combined solid solution strengthening and grain refinement (3.8–12.5 nm). Crucially, the compositional gradient effectively mitigated internal stresses, enabling the deposition of thick (100 µm), crack-free coatings, in contrast to the cracking observed in homogeneous high-W coatings beyond 40 µm. The enhanced durability and surface properties directly address key industrial energy loss mechanisms. Preliminary assessments indicate that the extended component service life can reduce embodied energy consumption for replacements by up to 65%, while the superior surface hardness and lubricity contribute to operational energy savings of 8–15% in transmission systems through friction reduction. These results demonstrate a clear pathway for leveraging advanced surface engineering to achieve significant, quantifiable energy savings in manufacturing operations..

Abstract: The performance and reliability of sliding bearings are strongly influenced by the tribological properties of the materials employed. In the present study, the wear behavior of a bronze alloy was investigated under lubricated conditions using SAE 20W-40 engine oil as the working fluid. To enhance performance, a bronze–Cr–Ag alloy system was developed and its tribological response was evaluated against AISI 52100 bearing steel under controlled laboratory conditions. The study focused on key parameters such as the coefficient of friction, wear rate, and material loss, which are critical in determining the operational life of bearings. Furthermore, the role of lubricants in mitigating tribocorrosion was examined, highlighting how SAE 20W-40 oil interacts with the alloy surface to form protective films, thereby minimizing direct metal-to-metal contact. The findings demonstrate that bronze-based alloys, when modified with chromium and silver, exhibit superior tribological performance in lubricated environments, making them promising candidates for sliding bearing applications.

Abstract: In corrosive geothermal environment corrosion fatigue lowers the lifetime expectancy of high alloyed steels. The load type is directly affecting corrosive and mechanical failure mechanism. Therefore, main objective is to gain general understanding upon the formation of the passivation layer and corrosion fatigue failure of duplex stainless steel AISI 2205 specimen tested under pure axial push/pull load and rotation bending load in a specifically designed corrosion chamber surrounded by the Northern German Basin electrolyte at 369 K. The thickness of the passive layer directly depends on flow direction and velocity of the corrosive media and under rotation bending additionally of the rotation speed of the specimen. Crack initiation and failure are associated with corrosive degradation of the passive layer and pit formation while mechanical degradation is secondary.

Abstract: This study investigates the assessment of stresses in a Thermoplastic Polyurethane (TPU) disk under diametral compression relying on full-field strain measurements by Localized Spectrum Analysis (LSA). A checkerboard pattern was first laser-engraved on the disk surface. The LSA processing of the checkerboard images captured in the undeformed (reference state) and deformed (at –8 kN) configurations allowed the determination of the two in-plane principal stretch ratios and the corresponding principal directions. An incompressible behavior was assumed to derive the out-of-plane stretch ratio. Using a neo-Hookean constitutive model, the maps of the Cauchy stress tensors and the First Piola-Kirchhoff stress tensors were deduced. This study demonstrates the potential of the LSA strain measurement technique for deriving stress maps in soft materials, which will be used in future work to feed into the Virtual Fields Method (VFM) for identifying interparticle contact forces in soft granular systems.

Abstract: This study presents a 250 kHz ultrasonic pulse velocity-based two-stage prediction model and a standardized field manual for diagnosing early frost damage in cementitious materials. The first stage predicts compressive strength from UPV and curing age, while the second stage estimates early frost damage depth using the predicted strength. Among several regression algorithms, ensemble models showed the highest predictive accuracy. Based on these results, a site-applicable standard operating procedure was developed, defining sampling rules, repeatability criteria, k-correction for indirect paths, and judgment protocols. The proposed model-to-manual framework enables fast, consistent, and reproducible on-site assessment of early frost damage during winter construction.

Abstract: This study presents an experimental comparison study of a newly developed Torque-shear Nut (TSN) under transverse cyclic loading for field application. For comparison, conventional high-strength bolt (HT) and Torque-shear bolt (TSB) were used to examine Loosening Speed, Stabilization cycle and residual clamping force. In this study, customized load cells were adopted to measure real-time axial forces. Two types of bolt size M16 and M20 were tested under four different displacements range of 0.5, 1.0, 1.5 and 2.0mm. Test results showed that the residual clamping force ratio of TSN ranged from 75% to 99% after 1000 cyclic loads, the loosening rate increased with greater displacement amplitude leading to a lower final residual clamping force ratio, and the stabilization cycle ranged from 32 to 306 cycles. These results showed values very similar to those of HT and TSB.