Journal of Materials Engineering and Performance最新文献

The metallization of 3D printed plastic structures has sparked widespread interest and intrigue among researchers and industry professionals alike. However, the compatibility issue arises between metal and plastic additive manufacturing technologies due to their substantial discrepancy in process temperatures. This paper explores refining fused deposition modeling by investigating the impact of copper electroless plating on 3D printed acrylonitrile butadiene styrene (ABS) parts. Electroless plating, a form of chemical metal deposition unlike conventional methods deposits metal without an electrical current. The 3D printed structure undergoes direct immersion in a copper (Cu) electroless plating bath, ensuring strong uniform adhesion. The research addresses challenges associated with ABS porosity and roughness, with a particular emphasis on surface preparation, adhesion, and dimensional stability. The proposed plastic 3D printing technology, combined with electroless plating, eliminates the need for etching or roughening of the ABS structure. Assessment criteria include ASTM standard surface finish and mechanical behavior (tensile, flexural, and hardness). Scanning electron microscopy reveals uniform copper plating, and results indicate superior mechanical properties and surface roughness in copper plated ABS specimens compared to non-plated ones. The research article highlights a remarkable improvement in mechanical properties post-electroless plating, with increases in tensile strength by approximately 81%, compression strength by 37%, Shore D hardness by 39%, and impact resistance by 81%, alongside a notable reduction in surface roughness by approximately 92.5%, affirming the efficacy of the plating process in enhancing material performance and surface quality. The findings offer crucial insights for ASTM-compliant FDM 3D printing advancements.

Friction is the most important phenomenon that emerges in the movement of two adjacent surfaces. The resulting wear and release of thermal energy causes failures of engines. It leads to a decrease in the performance of the mechanical system and energy loss. Among the effective ways to control these problems, lubrication is particularly important. Nowadays, adding nano-additives such as pure metals, metal oxides, metal sulfides, and carbon allotropes improves the tribological properties of lubricants. In fact, due to their potential for emission reduction and improving fuel economy, they are widely used as lubricant additives. Among nano-additives, molybdenum disulfide (MoS₂) is extensively applied as a lubricant additive due to its unique properties. But what is very important is the high dispersibility of the nano-additive in the base oil, which directly affects the tribological properties of oils. Therefore, more favorable results can be expected by overcoming the tendency to accumulate MoS₂. So, we synthesized carbon-based nanocomposites (NCs) of MoS₂ to spread on a suitable substrate, thus preventing their accumulation and using the synergistic effect of carbon materials in lubrication. MoS₂ was synthesized through two different methods, providing non-identical morphologies for MoS₂. Using the one-step hydrothermal method, we grew nanoflowers-like MoS₂ (NFLs-MoS₂) on a carbon substrate. MoS₂ with nanosheet morphology (NSs-MoS₂) was synthesized using the hydrothermal method and then spreads on carbon substrate by calcination. The tribological properties of synthesized NCs are much better than pure MoS₂ and carbon bases.

Mechanical response during bending experiments of Ni-Mn-Ga-Co-Cu melt-spun ribbons with the L2₁ austenite structure was studied. This material exhibited anisotropy in mechanical properties depending on the side to which the applied bending force was directed. When force was applied to the “free side,” a substantial load drop was observed in the initial stage of bending. On the other hand, no load drop anomalies were observed when force was applied to the “wheel side.” Additionally, mechanical training effects were assessed by applying up to 10 bending cycles. It was demonstrated that with an increase in the number of bending cycles, there was no significant decrease in bending force, and the load–displacement curve remained unaltered. The temperature dependence of annealing of the ribbons' mechanical properties was also examined. The Ni-Mn-Ga-Co-Cu melt-spun ribbons were annealed at 373 K, 573 K, 773 K, 973 K, and 1173 K for 30 min, followed by subsequent bending tests. Annealing influenced bending response through two major phenomena detected. The first was associated with crystal structure ordering and recovery; while, the second was attributed to grain growth. Changes in mechanical properties influenced by different annealing temperatures were correlated with alterations in the microstructure of the studied ribbons.

Substantial in situ TiC precipitation in high-titanium steel can significantly enhance its wear resistance. This improvement is attributed to the high hardness, low density, large precipitation volume, and stable chemical properties of TiC, which has attracted increasing attention. This paper firstly summarizes the recent research progress on the solute redistribution model, kinetics, and thermodynamic calculations of TiC precipitation, as well as the relevant experimental research on high-titanium steel prepared by the melting cast method. It provides a detailed analysis of the microstructure, mechanical properties including hardness, tensile strength, yield strength, elongation and impact toughness, and other properties of high-titanium steel, highlighting the influencing factors. Additionally, the wear resistance and wear mechanisms of high-titanium steel with different Ti content under different wear conditions are compared, including two-body wear, three-body wear, lubrication wear, and impact wear. At last, the future potential research directions for high-titanium steel are proposed, aiming to provide support for further development and application.

Stainless-steel feedstocks achieve increasing importance as sustainable and cost-efficient alternative regarding thermal spraying. However, the wear resistance is often insufficient for demanding applications. Therefore, an additional surface hardening step by thermochemical processes, in particular by gas nitriding, is promising for enhancing surface functionality. The characteristic porosity of thermally sprayed coatings facilitates deep nitrogen diffusion increasing hardness and wear resistance, due to the formation of precipitates. Because nitrides are thermally stable, applications at elevated temperatures are enabled. The process combination was examined for the ferritic stainless-steel AISI 431 applied on mild steel by high-velocity oxygen fuel spraying (HVOF), followed by subsequent gas nitriding. The influence of the thermochemical treatment with respect to a variation in the nitriding potential has been determined in terms of microstructure, phase formation, hardness distribution as well as reciprocating wear resistance at room and elevated temperature. The increase in hardness over 900 HV0.01 and wear resistance with wear rates consistently lower than 1.3 × 10^-4 mm³ Nm⁻¹ can be attributed to the successful enrichment of nitrogen and the formation of mainly Fe₄N precipitates at the coating’s surface. Even at 350 °C, the nitride surface layer provides better wear protection compared to the as-sprayed condition.

Graphical Abstract

The motivation for this research was the need for a reliable prediction of the distribution of microstructural parameters in steels during thermomechanical processing. The stochastic model describing the evolution of dislocation populations and grain size, which considers the random phenomena occurring during the hot forming of metallic alloys, was extended by including phase transformations during cooling. Accounting for a stochastic character of the nucleation of the new phase is the main feature of the model. Steel was selected as an example of the metallic alloy and equations describing the nucleation probability were proposed for ferrite, pearlite and bainite. The accuracy and reliability of the model depends on the correctness of the determination of the coefficients corresponding to the specific material. In the present paper these coefficients were identified using the inverse analysis for the experimental data. Experiments composed constant cooling rate tests for cooling rates in the range 0.1-20 °C/s. The inverse approach to a nonlinear model is ill-conditioned and must be transferred into an optimization problem, which requires formulating the appropriate objective function. Since the model is stochastic, it was a crucial, yet demanding task. The objective function based on a metric of the distance between measured and calculated histograms was proposed to achieve this goal. The original stochastic approach to identifying the phase transformation model for steels was tested, and an appropriate optimization strategy was proposed.

Poisonous wastes, including lead slag, mattes, acidic sludge, particulates, and emissions of airborne gases, are primary industrial wastes related to the lead-acid battery industry. Herein, the phase conversion technique for PbO₂/PbSO₄ components and impurity contents of spent lead paste were studied. The reductive sulfur fixation technique was employed for the extraction of pure lead product from spent lead paste and immobilizing sulfur, which was relatively improved as compared to the release of sulfur oxides and lead particulates when traditional recycling techniques were used. Furthermore, a bench-scale experiment was carried out for the revival of chemical reagents and removal of impurities from the spent lead paste to understand the reliability and efficiency of this novel method from the perspective of a chemical-free process. The results reveal that the products were achieved in three distinct layers, i.e., impurities-free P-paste, sulfated residue (PbSO₄), desulfurized residue (PbCO₃) and the final product (α-PbO). In this work, the recovery efficiency of spent lead-acid batteries is higher than 99.9%. Moreover, the metal impurities such as Fe, Sb, Zn, Cu, and Mg were efficiently removed, and 99.89/99.999/99.94% of the reduction/sulfation/carbonization efficiency were achieved. This chemical-free research paves novel and appropriate extraction of lead for engineering and industrial sectors.

The microstructure and mechanical properties of Al/Ti dissimilar refill friction stir spot welding joints at different rotational speeds were studied. The grain size of each zone of the joint increases with increasing rotational speed. An interfacial layer with thickness less than 50 nm was formed at the interface. Combined with the numerical simulation results, the multiple effects of thermal and mechanical action on microstructure are explained. The microhardness of the aluminum alloy joint presents a ‘W’ shape distribution. The tensile strength increases firstly and then decreases with the increase in rotational speed. The joint strength of 6353 N is the highest at 1300 rpm. The sleeve stir zone fracture occurs at the interface, and the fracture mode is brittle fracture. The pin stir zone fracture occurs at the aluminum alloy, and the fracture mode is ductile mixed fracture.

Recently, the automotive industry has increasingly focused on additive manufacturing as a new technology for reducing the weights of automobiles. In this study, fatigue tests were conducted on additively manufactured high-entropy alloys with different defect characteristics to clarify the relationships between their defect characteristics and fatigue strengths and to elucidate their fatigue fracture mechanisms. In addition, the effect of shot peening as an effective fatigue strength improvement method for an additively manufactured component was investigated. As a result, when defects formed by additive manufacturing were smaller than crystal grains, the numbers and sizes of defects affect fatigue crack growth behavior and barely affect fatigue life. Shot peening reduces the crack growth rate and is effective in extending the fatigue life. However, improvement in the fatigue limit is not achieved because the crack initiation site is a facet. From the above results, for defects smaller than the grain size, shot peening is a more effective method for improving fatigue life than reducing the numbers and sizes of defects.