Journal of Materials Engineering and Performance最新文献

To address boundary lubrication failure and surface fatigue wear in guide bushings under complex operating conditions, this study proposes a synergistic strategy combining topology-optimized bionic surface textures and MAX phase-reinforced PTFE coatings, leveraging multi-scale structural and material design to enhance interfacial tribological performance. Inspired by the micro-protrusion architecture of mosquito compound eyes, bionic textures were designed via topology optimization and fabricated on Cr12MoV steel surfaces using pulsed laser machining, while curing the PTFE-Mo₂Ga₂C composite coating on the surface. Reciprocating friction tests demonstrated that increasing the optimized aperture size of textures reduced the average friction coefficient by 13.5% and wear rate by 39.1%. Transient structural simulations validated the stress redistribution capability of topology-optimized textures on curved bushing surfaces, showing a 41% reduction in peak contact stress compared to non-optimized designs. Mechanistic analysis revealed a dual lubrication mechanism, PTFE extruded at texture edges forms lubricating films retained within grooves for cyclic replenishment, and MAX phase microparticle released from micro-pores dynamically reduce friction through lamellar shear. This synergy enhances lubricant retention, promotes uniform stress distribution, and delays coating wear.

The mechanical properties of pipeline steel significantly influence the operational safety and service life of underground gas storage (UGS). This study follows results of tensile tests on the base metal (L450-BM) and welds (L450-WM) of L450 pipeline steel, evaluating their strength and ductility alongside analyzing their microstructure and fracture morphology. Using finite element software and based on experimentally measured mechanical properties, fatigue simulation models for the base metal and weld specimens were established to capture the evolution of fatigue life under different loading conditions. Results indicate that the ductility of L450-WM is significantly lower than that of L450-BM, with elongation at fracture being 17.2% for L450-BM and 14.6% for L450-WM. The fracture types are characterized as quasi-cleavage fracture and cleavage fracture, respectively. Both L450-BM and L450-WM exhibit reduced fatigue life with increasing average tensile force and load spectrum amplitude. Under a tensile force of 6.5 kN with an amplitude greater than 0.1, the fatigue cycles of L450-WM decreased by nearly two orders of magnitude, reaching only 1.8% of the L450-BM. These findings provide valuable data and theoretical support for material selection and pipeline failure prevention in UGS.

3D bioprinting is a promptly developing biomedical alternative of 3D printing technology. It acts as a robotic device, which prints any tissue, organs, and blood vessels layer by layer according to our designed model on CAD System; further, it was cultured in a bioreactor. This procedure is not a replica of the generation of vascular structure in in vivo condition. The objective of the proposed design is to provide precise control on bioreactor-based 3D printer for blood vessel generation followed by the angiogenesis process. This proposed 3D printer design used extrusion-based coaxial nozzle for printing the entire structure layer by layer and simultaneously cultured layer by layer using a modified rotatory bioreactor. Control of each component is done by programmable logic controller PLC), and simulation of the electronics circuit was done by LabVIEW. In the proposed design of the 3D bioprinter, decision-based logic circuits were used to improve the utilization of media. The simulation result of the PLC shows that there is strong control on each parameter such as pH control, oxygen control, waste product control, rotational speed control, media stem rod, nozzle temperature, and pressure used for printing. Results indicated successful control of parameters pH (7.2-7.4), oxygen (~6%), and CO₂ (~10%) which contributed to improved cell viability and angiogenesis throughout the culture process. Automation of waste media management was implemented using decision-based logic circuits, resulting in enhanced media utilization efficiency. The analysis conducted using Computational Fluid Dynamics (CFD) demonstrated a consistent flow distribution and effective shear stress management. Additionally, the uncertainty analysis confirmed the stability of the system, revealing minimal fluctuations in pressure (±7.90 mmHg) and shear stress (±179.36 N/m²). LabVIEW results verify that all electronic circuits work properly. The uncertainty analysis provided a strong framework for data reliability, measuring the variability in pressure, velocity, and strain rate on shear stress caused by sensor inaccuracies and system fluctuations. Overall, the proposed design provides a better environment for the printing of vascular structures by extrusion-based coaxial nozzle printing technology and modified rotatory bioreactor used for vascular cell culture.

Due to the regulations restricting the use of lead, the implementation of lead-free solders became a legal requirement more than 15 years ago. In addition to the well-known SAC305 solder, new alloys containing various concentrations of Bi, together with other additives improving the soldering process and reliability of joints, have appeared. The paper focuses on comparative study of wetting properties of SAC305 and commercially available third-generation lead-free solder alloys containing Bi: REL61, REL22, and HRL-1. The improved sessile drop method, was applied to measure the contact angle (θ) of the selected solders on a copper substrate. The highest contact angle value (36°) was observe for HRL-1 and the lowest (27°) for REL22. Initially the spreading phenomenon was very fast, below the resolution of the measurement method. In some cases of the wetting disturbance by the external factors, wetting has been inhibited and the intermetallic phases developed at the solder/substrate. The formation of a halo area at the substrate around the drop was also observed, most likely formed due to the surface diffusion of solder atoms. This phenomenon led to a further reduction of the contact angle, but the spreading of the drop was much slower. Comprehensive microstructure and chemical composition examination of the drop/substrate interfaces after wetting tests evidenced the presence of Cu₆Sn₅ phase for all samples. Moreover, it was proved that the alloy additives (e.g., Ag and Bi) influenced the achieved contact angle and reduced unfavorable intermetallic phases formation such as Cu₃Sn (e.g., Ni, Sb, and Ti).

Wear and corrosion are the main causes of structural failure of mechanical parts, using thermal spraying to fabricate raw materials into coating, which is a common method of protection of mechanical parts. In this work, FeCrCoMoCB amorphous coating was fabricated on the 45# steel substrate using supersonic plasma spraying (SPS). The microstructure, phase composition, mechanical, corrosion, and wear properties of FeCrCoMoCB amorphous coating were systematically investigated. The results show that FeCrCoMoCB amorphous coating had a relatively flat surface, low porosity with a dense structure, high hardness, and had an amorphous rate of more than 90%. The coating displays a passive region of about 500 mV, corrosion potential of − 1.01 V, and current density of 1.89 × 10^-5 A/cm². The wear mechanism of FeCrCoMoCB amorphous coating is dominated by oxidation wear, and with the increase of load, the abrasive wear transforms into delamination wear.

For developing the suitable heat treatment for binder jetting additive manufactured (BJAM) 17-4PH stainless steel (17-4PH SS) to improve the mechanical properties, the evolutions of microstructure and strengthening behavior of sintered samples were specifically studied after solution and solution-aging heat treatments. The obtained results indicated that the grain boundary distribution proportion and grain size presented unobvious differences among samples. While, the δ-Fe content decreased in samples after both solution and solution-aging heat treatments, and the activation of {110} < 110 > slip system increased after heat treatments, resulting in the increase in toughness, the elongation rates reached 14.1% and 14.4%, respectively, whereas the original sample exhibited an elongation of 13.4% under identical testing conditions. Relying on the hybrid strengthening mechanism composed of precipitation strengthening from Cu-rich precipitates and the dislocation strengthening, sample after solution-aging heat treatment presented the highest tensile strength. A significant strength enhancement to 1100 MPa was achieved, marking a ~ 39% improvement over the baseline(791 MPa), achieving toughening and strengthening synchronously.

The present research investigates the performance of mild steel (MS), copper (Cu), and tungsten copper (WCu) form tools in fabricating large-area micro-textured surfaces, alongside the optimization of EDM parameters for surface texturing. The WCu tool electrode achieved the highest form accuracy, producing uniform, sharp-edged micro-pillars, followed by Cu and MS electrodes. The lower form accuracy of the MS tool leads to a higher overcut in the MS-textured surface and reduced interspacing, resulting in increased textured density. The overcut in the cavities is (sim) 50 ± 15, (sim) 75 ± 20, and (sim) 110 ± 20 µm for WCu, Cu, and MS tools, respectively. MS-textured surfaces exhibited the roughest morphology, with uneven recast material deposition with high frequency, micro-cracks, pockmarks, and voids, further reducing the patterned surfaces' hydrophobicity. XRD analysis indicates tensile residual stress, microstrain, crystallite size reduction, stable oxide layer, and carbide formation on patterned surfaces. The MS-textured surface exhibited the highest corrosion resistance, with a corrosion rate (CR) of 0.00918 mm/year, compared to the Cu- and WCu-textured surfaces, which showed CR values of 0.01994 and 0.02773 mm/year, respectively. Additionally, the MS-textured surface demonstrated the lowest wear rate and coefficient of friction (COF), recording a wear rate of 0.001138 mm³/m and a COF of 0.433.

In this study, ultrasonic surface rolling (USR) was introduced to reduce the coefficient of friction (COF) and wear volume of 17Cr2Ni2MoVNb carburized gear steel. Residual stress distribution, microstructure, microhardness, and fretting wear behaviors with different USR rolling loads (600 N, 800 N 1000 N, and 1200 N) based on the gas carburizing treatment were examined. Results showed that dislocation and grain refinement were formed after USR treatment, and the residual compressive stresses (−527 MPa) and microhardness (908 HV_0.2) at the top surface were increased by 57.78 % and 14.21 % of the samples treated with 1200 N. In addition, fretting wear behavior tests verified that the reduced COF and wear volume were due to the formation of a compressive stress field and gradient ultrafine grain. Moreover, carburized samples exhibited adhesion and three-body abrasion wear mechanisms, and the USR-treated samples showed oxidative wear and lamination.