Key Engineering Materials Vol. 985

Abstract: The main purpose of this investigation was to study the effect of strain hardening on wear properties of 316 austenitic stainless steel (ASS). Cold deformation was performed by using a universal tensile machine for 20% CW and 40% CW followed by heat treatment to relieve internal stresses. A secondary cold working process was performed for the heat-treated samples followed by a secondary heat treatment. Wear test measurements and microscopic examinations were preformed for all samples. It was observed that by increasing the strain hardening percentage the hard brittle martensite phase increases. Also, by increasing both the SiC grit of the emery papers (which was used in the wear test) and the time of the wear test, the weight lost per unit area was decreased. The wear resistance was increased by using single and double 20% strain hardening but by exceeding the cold working to more than 40% the wear resistance decreased.

Abstract: This paper deals with the martensitic transformation and functional properties in the quenched single crystals of the Co₃₅Ni₃₅Al₂₈Fe₂ medium-entropy alloy, oriented along the [001]_B2-direction. The microstructure and chemical composition of the single crystals have been studied in detail using transmission and scanning electron microscopy. The {111}_L10 martensite twins up to 10-20 nm width and γ/γ′-phase precipitations larger than 100 μm are detected. The thermoelastic B2-L1₀ martensitic transformation upon stress-free cooling/heating in single crystals of Co₃₅Ni₃₅Al₂₈Fe₂ alloy is characterized by the accumulation of elastic energy, which is the driving force of the reverse martensitic transformation, and the low dissipation energy. The reverse transformation starts at lower temperatures than the forward transformation M_s>A_s. The regularities of the stress-induced B2-L1₀ martensitic transformation change due to an increase in the contribution of the dissipated energy and M_s^σ<A_s^σ. There is shape memory effect with the reversible strain (3.2±0.3)% and high temperature superelasticity with the reversible strain (3.3±0.3)% in the temperature range from 323 K to ≥548 K in the [001]_B2-oriented single crystals. These crystals withstand stress up to 1200 MPa in compression without destruction.

Abstract: Gray iron, a widely used engineering material, is favored for its desirable properties such as good damping capacity, thermal conductivity, and corrosion resistance. However, when exposed to elevated temperatures over time, issues like oxidation and graphite depletion can impact its durability. High-silicon gray iron, with elevated silicon content exceeding 3.0%, is known for its ability to withstand heat and oxidation, making it suitable for many applications, including cookware. This study investigates the impact of varying silicon levels (2.00-4.56%Si) on the solidification behavior, microstructure, and oxidation resistance of gray iron. Three heats with different silicon concentrations were produced and analyzed. Results indicated that higher silicon content increases the eutectoid temperature, stabilizes the ferritic structure, and introduces Type-D graphite in the microstructure. Graphite depletion was observed only in samples with 2.00%Si. The oxidation resistance improved with higher silicon content, as evidenced by a decrease in weight gain after exposure to 800 °C for 4 hours. This suggests the potential of using lower silicon levels in gray iron for cookware applications, balancing material cost with good impact resistance.

Abstract: AMS 6260 alloy is a nickel-chromium-molybdenum steel containing Ni, Cr, Mo, with Fe as the main component, and is one of AMS (aerospace materials specifications) in the United States. This material has high hardenability and high toughness. For this reason, it is used as a material for parts that require high toughness, such as gears in aircraft engines. However, while AMS 6260 alloy after heat-treatment has high hardness, it significantly reduced machinability. Therefore, it is extremely difficult to achieve high efficiency and high accuracy in the cutting process of AMS 6260 after heat-treatment. In this paper, the experimental milling of the hardened AMS 6260 alloy after heat-treatment is conducted under some cutting conditions using a coated cemented carbide radius end mill, and the effect of cutting conditions on the flank wear and surface roughness is investigated. As a result, optimal cutting conditions on the tool wear and surface roughness were clarified.

Abstract: To preserve the environment and its resources for future generations, research must focus on alternate methods of producing materials that begin with an environmentally friendly and sustainable source. In view of this, nanosize reinforcing fillers were obtained from date palm agricultural waste without use of any toxic chemicals. Date nanofillers (DNF) with typical filler sizes ranging from 30-110 nm in width and 1-10 mm in length were obtained using rotary mechanical ball milling methods. This filler was then dry blended with the polypropylene (PP) to make a biocomposites thin film to study processability characteristics of this fillers. The loading of this filler was kept in the range of 1-5wt. % and film were melted cast through a slit height of 0.6mm. The resulting PP/DNF biocomposites films were subsequently analyzed by various analytical techniques to established structure property relationship. The change in thermal properties with loading of this filler was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA study showed that the thermal stability of film samples improved up to 20 °C when compared to the neat PP, representing an 8% enhancement. While the DSC measurement indicated that the crystallinity of the highest filler loading sample reduced from 52.89% to 41.79% in comparison to the PP sample. The surface morphology of some samples shows the compact and smooth feature, indicating the incorporation of fiber fillers could improve the structure of polymer. Therefore, study gave some insight into the processing behavior of such composites, which may be useful in some packaging applications.

Abstract: Large quantities of date palm frond waste generated from the pruning process are accumulated or burned in burn barrels, harming the environment and having very little economic value. However, because of the lack of data revealing the characteristic magnetic properties of biochar derived from date palm fronds, further research on low-cost and sustainable strategies could offer a new composite material and serve to extend the way for novel applications. In this study, we prepared biochar derived from palm fronds via pyrolysis under a limited-oxygen atmosphere at a lower temperature of 300 °C for 2 h. We introduced a facile strategy for the production of magnetic biochar with various doses of annealed steel sludge material via ball milling. Various amounts of annealed steel sludge material (5%, 15%, and 25% w) were added to date palm frond biochar, and the obtained product was fabricated by ball milling. The physicochemical characteristics of the magnetic biochar composite were subsequently analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and UV-vis spectroscopy. Our findings showed that the ball milling method is a successful step for producing date palm fronds with magnetic biochar material possessing rough and packed pores, as shown by SEM. XRD patterns assumed the existence of magnetic phases of iron oxide (magnetite (Fe₃O₄), hematite (α-Fe₂O₃), and maghemite (γ-Fe₂O₃) at different generated peaks. FTIR outputs exhibited the abundant presence of various oxygen-containing functional groups (- COOH and -OH) on the surface of magnetic biochar material, which help to create chemically reactive sites to adsorb potential surrounding species. The UV spectra showed a noticeable enhancement of the optical properties of the magnetic biochar with an increase in the sludge dose for light absorption in the visible region from wavelengths of 400 – 700 nm . This result signifies the synthetic optimization and potential application of magnetic biochar materials for composites that could be employed in targeted uses including soil amendment, water remediation and energy applications.

Abstract: A vast amount of agricultural waste, such as dried leaves, stems, pits, seeds, etc., are produced by date palm trees in Saudi Arabia each year. This waste is an excellent source of degradable biomass suitable for many uses. Crystalline nanocellulose (CNC) is one of the most important nanomaterials that can be used in various applications. Due to its unique properties, which include biorenewability, optical transparency, high mechanical strengths, and sustainability, nanocrystalline cellulose has become a significant nanomaterial in recent years. In this study, CNC was isolated from the waste date palm leaves and used for the production of PA-modified membranes for water treatment by reverse osmosis membrane technology. The membranes were prepared by surface polymerization with the polyamide as a selective layer on the polysulfone support film. Three membranes were produced, two with 0.01% and 0.02% (w/v) CNC and the third with PA-free CNC for comparison. Each membrane produced was tested using different characterization techniques. The polyamide membrane with 0.01% w/v CNC had a higher water permeability of 43.25 L/m² h bar than the membranes with 0% w/v CNC (36.25 L/m² h) and 0.02% w/v CNC (42.85 L/m² h bar). Under the same conditions, salt retention was also found to be above 98% for both NaCl and MgSO4 for the two modified membranes. The contact angle was found to be 68.04±3.7, 72.83±0.8, and 63.76±5.5 for PA(0%CNC), PA-CNC (0.01% w/v), and PA-CNC (0.02% w/v), respectively. The 0.01% PA-CNC membrane exhibited a higher water contact angle, greater hydrophobicity and lower surface roughness. As a result, the isolated CNC might be appropriate for use as a modifier agent for membrane fabrication and water treatment.

Abstract: Nanocarbon synthesis from diverse sources has garnered significant attention, with a particular focus on materials derived from biomass. Carbon dots (CDs), due to their water solubility, low toxicity, and biocompatibility, have emerged as promising candidates for a wide range of applications. In recent years, CDs have found utility in several applications such as bioimaging, drug delivery, and biosensors. In this study, we present an eco-friendly, straightforward, and cost-effective technique for the synthesis of carbon dots through a hydrothermal reaction, utilizing peeled date palm midribs as the source material. High-resolution transmission electron microscopy, X-ray diffraction, UV-visible absorption spectroscopy, photoluminescence analysis, Fourier-transform infrared spectroscopy, and zeta potential measurements services to investigate the synthesized carbon dots' morphology, crystal and structure, and optical properties. The results show that the carbon dots had a size distribution ranging from 2.5 to 6 nm, and a crystallographic interplanar distance of 0.23 nm corresponding to the graphitic structure. When excited at a wavelength of 340 nm, the synthesized dots exhibited a prominent bluish emission at 420 nm, highlighting their potential for use in optical and biological applications. This work underscores the feasibility of harnessing sustainable biomass sources, such as date palm midribs, for the green synthesis of carbon dots with desirable properties, opening up new avenues for their utilization in cutting-edge technologies.

Abstract: Degenerative disc disease is an increasing problematic complication following lumbar fusion surgeries. Posterior lumbar interbody fusion (PLIF) is a well-established surgical method for spine stability following intervertebral disc removal. The position and number of titanium cages in PLIF are remain contingent on individual surgeon experience. Thus, a systemic investigation of the efficacy of titanium single mega cage versus two cages in treating degenerative lumbar spinal diseases is imperative. A biomechanical study was aimed to compare the stability achieved in PLIF through interbody reconstruction using a single mega cage (32 mm) Vs. a dual cage (22 mm). Normal intact finite element model of L3–L4 was developed based on computed tomography images from a healthy 27-year-old male volunteer. The study tested the intact model (Model A) and its surgically operated counterparts using four PLIF implantation methods: single transverse cage (Model B), single transverse cage with bone graft (Model C), dual transverse cage (Model D), and dual transverse cage with bone graft (Model E). Combined loads simulating physiological motions—flexion, extension, axial rotation, and lateral bending —were applied across all loading directions. The assessment includes all model range of motion (ROM), micromotion between the cage and endplate, and stress on the cage and internal fixation system (screw and rod). The ROM between Models B, C, D and E were consistently reduced by over 71% compared to intact Model A under all motion scenarios. Model D exhibited the highest peak stress of 115 MPa on the cage during flexion, surpassing Model C and E (Flexion) by fourfold. Model E demonstrated the lowest cage stress (20 MPa) during extension, outperforming the other models. Notably, Model E exhibited minimal endplate stress (2 MPa), cage stress (21 MPa), micromotion (13 µm) during extension, and screw-rod stress (56 MPa) during flexion, making it superior to other implantation methods. In the context of PLIF, Model E showed enhanced biomechanical stability, reducing ROM, stress on the endplates, cage, screw-rod system and micromotion. Alternatively, Model C may be a viable alternative in standard PLIF, especially in cases with limited intervertebral space, providing efficient clinical outcomes with shorter operative times and reduced costs and ease of implantation. Also, this computational study provides valuable understandings into optimizing cage implantation strategies for improved outcomes during PLIF.