Mechanical Attrition Research Articles

Decisive role of preparation technique on the structural, electrical and magnetic properties of vanadium doped ZnO nanoparticles

1% vanadium doped ZnO powders have been successfully synthesized via two different preparation techniques viz., glycine assisted combustion method and mechanical attrition method to understand their impact on the structure-property relation. X-ray Diffraction study validates the Wurtzite phase formation of ZnO with hexagonal structure. X-ray diffraction peak discloses the marked role of size and strain component. Evidently, the shift of lattice strain with the preparation techniques from compressive to tensile nature show the importance of structure property relations in the ZnO compounds. SEM micrographs depict the formation of densely populated nanograins with networking like structures which is characteristics of combustion synthesized product whereas as top down approach exhibits the presence of coarse grains amidst the broken sea of fine particles. Selected area electron diffraction (SAED) images display ring and bright circular spot pattern with changes in method of preparation, which further clarifies the distinct nature of investigated ZnO:V particles. Vibrational spectral study gives clear evidence on the structural disorder as deduced from the changes associated with longitudinal optical mode phonon scattering. Interestingly, the UV spectral study divulges the increment in optical band gap as well as a strong visible light absorption (about 30 %) for milled ZnO:V over their chemically prepared counterparts. Photoluminescence spectra of milled V doped ZnO upheld the structural disorder taken place with the suppression of Near Band Edge (NBE) transition and the shifting of broad asymmetric defect emission band towards the lower wavelength regime. Impedance study enlightens the crucial role of synthesis method with 5 times enhanced grain boundary resistance along with suppression of grain contribution in the milled samples. Magnetic study highlights the remarkable distinction of preparation route which alters the ferromagnetic ordering in the combustion synthesized samples to conventional diamagnetic signature of the host ZnO in the milled samples.

Unveiling Mechanobiology: A Compact Device for Uniaxial Mechanical Stimulation on Nanofiber Substrates and Its Impact on Cellular Behavior and Nanoparticle Distribution.

Biotechnology and its allied sectors, such as tissue culture, regenerative medicine, and personalized medicine, primarily rely upon extensive studies on cellular behavior and their molecular pathways for generating essential knowledge and innovative strategies for human survival. Most such studies are performed on flat, adherent, plastic-based surfaces and use nanofiber and hydrogel-like soft matrices from the past few decades. However, such static culture conditions cannot mimic the immediate cellular microenvironment, where they perceive or generate a myriad of different mechanical forces that substantially affect their downstream molecular pathways. Including such mechanical forces, still limited to specialized laboratories, using a few commercially available or noncommercial technologies are gathering increasing attention worldwide. However, large-scale consideration and adaptation by developing nations have yet to be achieved due to the lack of a cost-effective, reliable, and accessible solution. Moreover, investigations on cellular response upon uniaxial mechanical stretch cycles under more in vivo mimetic conditions are yet to be studied comprehensively. In order to tackle these obstacles, we have prepared a compact, 3D-printed device using a microcontroller, batteries, sensors, and a stepper motor assembly that operates wirelessly and provides cyclic mechanical attrition to any thin substrate. We have fabricated water-stable and stretchable nanofiber substrates with different fiber orientations by using the electrospinning technique to investigate the impact of mechanical stretch cycles on the morphology and orientation of C2C12 myoblast-like cells. Additionally, we have examined the uptake and distribution properties of BSA-epirubicin nanoparticles within cells under mechanical stimulation, which could act as fluorescently active drug-delivery agents for future therapeutic applications. Consequently, our research offers a comprehensive analysis of cellular behavior when cells are subjected to uniaxial stretching on various nanofiber mat architectures. Furthermore, we present a cost-effective alternative solution that addresses the long-standing requirement for a compact, user-friendly, and tunable device, enabling more insightful outcomes in mechanobiology.

A Recent Review on Nanocrystal Manufacturing Techniques with Pharmaceutical Application

Abstract: This review article constitutes an introductory report on nanotechnology focusing on the various manufacturing approaches of nanocrystals. Nanocrystals are a solid form to tackle the issue identified with poor fluid solvency. Hence, it is a useful technique in improving the bioa-vailability of various poorly soluble drugs. On a broader way, nanocrystal technology is mainly classified as top-down technology, bottom-up technology and a combination of top-down and bottom-up technology. Top-down technology is based on the principle of breaking down a com-plex into small crystals. This process is executed by using high-pressure homogenization, laser ablation, media mills, ultrasound technology, vacuum dissolution, gas condensation and mechani-cal attrition. Bottom-up technology is based on the principle of preparation by gathering at-oms/molecules together. It is achieved by using precipitation, supercritical fluid, gel-gel technol-ogy, spray drying, hydrolysis, and condensation. Due to the diverse characteristics and properties of drugs, a combination of top-down and bottom-up techniques is best for manufacturing nano-crystals. Some of the promising technique includes nano-edge technology and smart-crystal tech-nology. These techniques are discussed in this review.

Enhancing wear resistance of aluminum alloy by fabricating a Ti-Al modified layer via surface mechanical attrition treatment

The limited wear resistance of aluminum alloys hinders their application in lightweight equipment. Herein, we present the successful fabrication of a Ti-Al modified layer on the surface of aluminum alloy 2024 via surface mechanical attrition treatment (SMAT-Ti). Tribological assessments indicate an improvement in tribological performance. Specifically, the average friction coefficient and wear rate of the SMAT-Ti treated sample decreased by 49.1% and 81.9%, respectively, compared to untreated sample. Analysis of wear surfaces and molecular dynamics simulations demonstrate that the improvements observed can be attributed to the wear-resistant tribofilm formation. Furthermore, the integration of Ti particles beneath the subsurface facilitates the formation of HCP bands and dislocation locks. These microstructural changes obstruct frictional shear deformation and crack propagation, effectively reducing wear.

Enhancing Flame Retardancy: Enrichment of Huntite for Paint Industry Applications

Huntite, a naturally occurring carbonate mineral, originates through the alteration processes of dolomite and magnesite. While its structural characteristics align with typical carbonate minerals, its distinction arises from its polyhedral conjunctiveness. The versatile utility of huntite spans several industries, including paint, flame retardant, plastic, polymer, and pharmaceutical sectors. Noteworthy among its diverse applications is its utilization as a flame-retardant additive in raw materials. In this investigation, three samples received from the Denizli region of Turkey were subjected to detailed analysis followed by an enrichment process involving mechanical attrition and sieving of 38 microns where undersize products were obtained, exhibiting 86.9% huntite for the H-1 sample and 91.9% huntite for the H-2–3 sample. The huntite concentrates were then incorporated into paint formulations with the objective of enhancing flame retardancy. A series of testing protocols were implemented to assess the quality of the resulting paints, ultimately yielding a fire-resistant paint formulation through utilizing the H-1 sample.

Phase field study on phase stability at high temperatures in nanograined Fe–Ni alloy prepared by plastic deformation

The phase stability at high temperatures in nanograined Fe–Ni alloy prepared by surface mechanical attrition treatment (SMAT) and ball milling (BM) modes are drastically different. For example, the onset temperature (As) of reverse martensitic transformation (RMT) of nanocrystal prepared by SMAT is higher than that of coarse crystal, while BM exhibits the opposite result. The elastoplastic phase field model for RMT was first proposed to investigate the correlation between RMT and its forward martensitic transformation (FMT), in turn, the above experimental phenomena were revealed in this paper. The prepared nanocrystals with the same diameter (15 nm) by SMAT and BM mode were taken as representative examples. The simulation results indicated that the strain energy is relaxed by the applied strain during FMT in nanocrystalline prepared by smaller plastic deformation mode (e.g. SMAT), but it is enhanced by larger plastic deformation mode (e.g. BM). The stored strain energy in BM mode is much larger than that in SMAT mode, and hence the driving force provided for subsequent RMT is also larger in BM mode. Therefore, the phase stability of the martensitic nanocrystals prepared by BM mode at high temperatures is much lower than the counterpart by SMAT mode, which agrees well with the experimental measurements.

New method for position and energy controlled surface mechanical attrition treatment and its effects in 304 stainless steel

New method for position and energy controlled surface mechanical attrition treatment and its effects in 304 stainless steel

Nickel-based superalloy architectures with surface mechanical attrition treatment: Compressive properties and collapse behaviour

Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices, making them simultaneously strong and tough. Herein, we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy (IN625) microlattices after surface mechanical attrition treatment (SMAT). Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71% and also triggered a transition in their mechanical behaviour. Two primary failure modes were distinguished: weak global deformation, and layer-by-layer collapse, with the latter enhanced by SMAT. The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT, which effectively leveraged the material and structural effects. These results were further validated by finite element analysis. This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.

Strength and ductility improvement in a heterostructured Mg-Gd-Y alloy with inversely-gradient hardness distribution

The Mg-8.75Gd-2.85Y (wt%) alloy processed by surface mechanical attrition treatment (SMAT) was annealed at 350 °C followed by peak-ageing. Recrystallization occurred in the surface layer of the specimen induced by the annealing treatment. The obtained heterostructure contained a fine-grained (FG) layer with thickness of about 350 μm on the top and a coarse-grained (CG) layer at the bottom. The sample exhibited a reversely-gradient distribution in hardness, in which the FG layer showed lower values than the CG layer. It was related to the different behaviors of recrystallization and precipitation. Compared with the homogeneous CG alloy, the heterostructured sample exhibited enhancement in both strength and ductility. The increase of yield strength was mainly ascribed to grain boundary strengthening and dislocation strengthening. The random texture of the FG layer and the synergetic effect of the heterostructure were beneficial to the improvement of ductility. This work provides valuable insights for developing gradient-structured Mg-RE alloys for high performance in engineering applications such as automotive, aerospace and defense industries.

The response of 316 L steel manufactured by selective laser melting route to high-temperature oxidation behaviour: The role of microstructure modification

The current work examines the effect of 316 L steel's microstructure, which is modified through varying scanning angles with the sample surface (HNS (0°), INS (45°), and VNS (90°)) in the selective laser melting (SLM) method and through surface mechanical attrition treatment (SMAT), on its high-temperature oxidation behaviour (at 600–800 °C) is investigated. We have obtained a deeper understanding of the steel's oxidation behaviour by applying various characterisation techniques. The SMATed steel has a ∼ 1000 μm thick deformed layer containing a gradient microstructure, and its topmost layer contains fine twins and nanograins (∼30 nm). The hardness of this surface is ∼1.65 times the non-treated steel's hardness. All samples follow a parabolic rate law during oxidation. The VNS sample unveils the slowest oxidation rate amid the non-treated samples. SMAT increases the activation energy of oxidation. The distribution of elements across the oxidised samples' cross-section shows discontinuous Cr spreading within the oxide layer on the non-treated samples; however, the deformed samples show uniform distribution. Unlike non-SMATed samples, a minute decline in Cr and Mn content is observed underneath the oxide layer on the SMATed samples, confirming their enhanced outward diffusion. The oxide layer on SMATed samples has more Cr- and Mn-rich oxides. These oxides occupy the grain boundaries of the oxidised non-SMATed surfaces, where the micro-pores and cracks are present. Conversely, oxidised SMATed surfaces display uniform, defect-free Cr- and Mn-rich oxides with finer grains. Moreover, the SMATed layer remains reasonably stable during high-temperature oxidation (hardness drop ranges between ∼9 and ∼ 30%).

Effects of SMAT Temperature and Stacking Fault Energy on the Mechanical Properties and Microstructure Evolution of Cu-Al-Zn Alloys

Alloys with a gradient structure (GS) exhibit a superior combination of strength and ductility. However, the effects of treatment temperature and stacking fault energy on the tensile behavior and microstructure evolution of GS alloys have not been systematically investigated. In this study, GS Cu-Al-Zn alloys with different stacking fault energy (SFE, 40/7 mJ/m2) were prepared using surface mechanical attrition treatment (SMAT) at cryogenic and room temperature, respectively. The microstructure results indicate that more stacking faults and deformation twins were activated in the SFE-7 alloys at cryogenic temperature, which led to higher strength compared to that of the alloys SMAT-ed at room temperature. In addition, it was found that the yield strength and hetero-deformation-induced (HDI) stress of the SFE-7 alloy were significantly higher than those of the SFE-40 alloy, resulting in a good combination of strength and ductility. Furthermore, more dispersed strain bands were observed in the SFE-7 sample during whole tensile deformation, which contributes to higher ductility.

Influence of Mechanical Attrition on Protective Properties of Anomalous Electrodeposited Ni-Co Alloys

Influence of Mechanical Attrition on Protective Properties of Anomalous Electrodeposited Ni-Co Alloys

Low-ECD Inverted Emulsion Fluid Shows Superior Performance

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211539, “New Low-ECD Organophilic Clay-Free Inverted Emulsion Fluid Weighted With Manganese Tetroxide Showed Superior Performance in Different Fields: Success Story of Drilling With OCIEF in High-Overbalance Environment Without Downhole Problems, Stuck-Pipe Events, and Nonproductive Time,” by Vikrant Wagle, SPE, Abdullah Yami, SPE, and Abdullah Al Moajil, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ The complete paper describes the success of using a new low-equivalent-circulating-density (ECD) organophilic clay-free inverted emulsion fluid (OCIEF) in gas reservoirs at elevated temperatures and with differential pressures up to 4,500 psi. The objective of the paper is to highlight the superior performance of OCIEF over barite-based conventional invert-emulsion drilling fluids and formate-based, water-based drilling fluids in the study. The fluid overcame challenges in such an environment without compromising performance. Introduction The new low-ECD OCIEF, using manganese tetroxide as the weighting agent, was developed with an aim to offer improved drilling performance in maturing fields. Its nondamaging nature, the result of the presence of the acid-soluble and micronized manganese tetroxide, would help to complete the well with an openhole design. In an OCIEF, the organophilic clay and organophilic lignite are replaced by a polymeric viscosifier and a polymeric filtration-control agent, respectively. A unique gel structure is provided by the use of the polymeric viscosifier in the oil-based drilling fluid. Also, it not only increases cuttings-carrying capacity but also helps to increase barite sag resistance in the fluid. In the absence of low-gravity solids in terms of organoclay and organolignite, an OCIEF shows low plastic viscosity and a higher rate of penetration compared with conventional organoclay-based oil-based muds. In the OCIEF described in the paper, the solids content has been further reduced by replacing the barite (4.2 SG) with manganese tetroxide (4.8 SG). The acid solubility of manganese tetroxide would make the drilling fluid nondamaging, especially for reservoir zones. Formulation of Low-ECD OCIEF. The OCIEF was designed for long lateral sections where low rates of penetration (ROPs) can be observed in a slimhole drilling environment with a bottomhole temperature (BHT) of approximately 300°F. The OCIEF was tested for drilling in high-static overbalance conditions (3,000–4,500 psi) and had to be resistant to potential contaminants. The OCIEF was formulated with the acid-soluble manganese tetroxide with a water-phase salinity of 200,000–250,000 ppm. Two 95-lbm/ft3 OCIEFs were formulated. The 95-lbm/ft3 OCIEF 1 was developed with an engineered bridging package of variously sized ground marbles. This formulation was specifically for short laterals and lower differential pressures. The acid solubility of the ground-marble-based package was an additional benefit of the OCIEF 1 fluid formulation. An alternate, OCIEF 2, was developed for longer intervals with higher overbalance conditions. OCIEF 2 was formulated with a bridging package that included sized resilient graphite, fibers, and sized ground marble. The bridging package was designed for longer laterals because it was expected that the bridging solids would undergo increased mechanical attrition. A single polymeric filtration-control additive was used in both formulations.

Loss of Grem1-lineage chondrogenic progenitor cells causes osteoarthritis

Osteoarthritis (OA) is characterised by an irreversible degeneration of articular cartilage. Here we show that the BMP-antagonist Gremlin 1 (Grem1) marks a bipotent chondrogenic and osteogenic progenitor cell population within the articular surface. Notably, these progenitors are depleted by injury-induced OA and increasing age. OA is also caused by ablation of Grem1 cells in mice. Transcriptomic and functional analysis in mice found that articular surface Grem1-lineage cells are dependent on Foxo1 and ablation of Foxo1 in Grem1-lineage cells caused OA. FGFR3 signalling was confirmed as a promising therapeutic pathway by administration of pathway activator, FGF18, resulting in Grem1-lineage chondrocyte progenitor cell proliferation, increased cartilage thickness and reduced OA. These findings suggest that OA, in part, is caused by mechanical, developmental or age-related attrition of Grem1 expressing articular cartilage progenitor cells. These cells, and the FGFR3 signalling pathway that sustains them, may be effective future targets for biological management of OA.

Influence of Surface Mechanical Attrition Treatment Parameters on Microstructure and Residual Stress of Mg5Zn0.2Ca Alloy

Influence of Surface Mechanical Attrition Treatment Parameters on Microstructure and Residual Stress of Mg5Zn0.2Ca Alloy

Micro-mechanisms underlying enhanced fatigue life of additively manufactured 316L stainless steel with a gradient heterogeneous microstructure

The fatigue life of additively manufactured 316L stainless steel (SS) in an aqueous corrosive medium is shown to improve markedly when the surfaces were processed by surface mechanical attrition treatment (SMAT). SMAT induced surface nano-crystallization owing to severe plastic deformation and yielded a gradient microstructure beneath the surface of additively manufactured SS 316L, which increases the resistance to fatigue crack initiation and propagation. During cyclic deformation, dislocations are generated and accumulated in the cell boundary, resulting in the evolution of persistent slip bands (PSBs) at the surface of the as-manufactured specimen. Continuous intrusions and extrusions of PSBs provide crack initiation sites due to strain localization at the surface of the as-manufactured specimen, whereas the crack initiation region moved from the surface to the sub-surface layer after SMAT. Mainly, the mutual crossing of shear bands or twin boundaries accommodates most of the plastic deformation and provides crack nucleation sites at subsurface regions in this case. To elucidate the fatigue failure mechanism associated with fatigue loading (interactions of stacking faults, slip bands, and deformation twins), electron back-scattered diffraction and transmission electron microscopy analysis of the fatigue-failed alloy after SMAT was performed at different distances adjacent to the fatigue-failed tip. The interfaces between dislocation forest and twin-twin boundaries hinder dislocation motion and disrupt stress concentration. In addition, amorphous bands were formed at the interfaces between twin and shear bands which co-deform with the matrix during dynamic loading and act as a natural sink for dislocations, delaying decohesion and commencement of fracture. The changes in the crack initiation site and fatigue micro-mechanism cause considerable changes in fatigue life. This work provides insight into the failure mechanisms of additively manufactured SS for designing surface modification techniques to enhance the fatigue life of the parts post-printing.

Mechanical behavior and microstructure-property correlation of a metastable interstitial high entropy alloy with hierarchical gradient structures

Metastable high entropy alloys (MHEAs) are attractive materials due to their exceptional mechanical properties, particularly in addressing the challenge of the strength-ductility trade-off. However, one of the major hurdles of MHEAs is that their yield stresses are still relatively low compared to the engineering requirements, even with carbon-doped treatment and grain refinement. To further improve the strength of MHEAs, surface mechanical attrition treatment (SMAT) was applied to an interstitial MHEA (iHEA) with Fe49.5Mn30Co10Cr10C0.5 (at.%) compositions. Mechanical tests demonstrated that the yield stress of the iHEA had been improved by 32.6% after only 15 min of treatment without sacrificing ductility, and a 60-min treatment made the ultimate tensile strength approach 1 GPa. In-depth quantitative analysis indicated that hierarchical gradient microstructures were generated by SMAT, including grains, dislocations, twins, and dual phases. The theoretical analysis confirmed the synergetic extra-strengthening caused by the gradient distributions of various microstructures. Furthermore, the microstructural heterogeneity resulted in the hetero-deformation induced (HDI) hardening, contributing to strain hardening and maintaining sufficient ductility. The microstructure-property correlation revealed by this study provides guidance for the mechanical property design of MHEAs via gradient structure.

The role of microstructure modifications on electrochemical and plasma-nitriding behaviour of 316L steel produced by laser powder bed fusion

ABSTRACT The study investigates the impact of microstructure modifications on the corrosion, passivation, and plasma-nitriding behaviour of 316L steel. Microstructure modifications are achieved through the laser powder bed fusion (L-PBF) process and surface mechanical attrition treatment (SMAT). Three scanning strategies (concerning the orientation of the sample surface with scanning directions) are used in the L-PBF process, and the corresponding samples are labelled as HNS (0°), INS (45°), and VNS (90°). The scanning strategies have altered the average grain size (maximum for HNS and minimum for VNS) and porosity (HNS has the highest). Porosity disappears after SMAT. The surface of the SMATed specimen (VS) has equiaxed austenite nanograins (∼32 nm) with a fine distribution of α’-martensite, nanotwins, and high dislocation density. Microstructure affects the passivation, corrosion, and nitriding behaviour of the steel. The VNS has the lowest corrosion rate, decreasing further after SMAT. The SMATed sample exhibits the lowest nitrided layer thickness (∼65 μm). SMAT followed by nitriding causes a gradient-structured layer (with improved hardness) consisting of a nitrided layer, SMATed layer, and core. The nitrided HNS sample (∼78 μm thick nitrided layer) is dominated by γ’-Fe4N, while the nitrided VNS and VS samples have a relatively higher proportion of expanded austenite.

Surface Severe Plastic Deformation for Improved Mechanical/Corrosion Properties and Further Applications in the Bio-Medical and Hydrogen Sectors

Various techniques enabling surface severe plastic deformation (SSPD) have been developed or optimised over the past years. This manuscript presents a broad overview of recent developments in the field of SSPD and its application that take advantages of having a deformed gradient surface with both (i) higher strength and (ii) an improved "reactivity". First, the principle and technological advantages/disadvantages of several SSPD technologies, involving either guided or non-directional mechanical impacts, are recalled. Then, after a short recall on the nature of the structure the modified surface formed under SSPD, the effects of the processing parameters and temperature of deformation on the surface roughness and subsurface microstructure modifications are illustrated with a particular emphasis on the surface mechanical attrition treatment (SMAT) and ultrasonic shot peening (USP) techniques deriving from the traditional pre-strain shot peening. The effect of these surface and sub-surface modifications on the mechanical properties, and in particular the fatigue response, are recalled with a special emphasis on the surface integrity and potential over shot peening. Then, the manuscript concentrates on the effect of the surface enhanced diffusion of chemical species induced by the presence of structural defects to modify the corrosion behaviour and enhance the potential assisted SSPD + thermo-chemically “duplex” treatments. In these cases, in addition to induce grain refinement and dislocations, the importance of controlling some potential surface contamination is stressed. Finally, the manuscript terminates by illustrating some new research studies on potential applications for the challenges in the hydrogen sector for its solid-state storage and the protection of mechanical infrastructures as well as for bio-medical applications with biocompatible Ti-based alloys and biodegradable Mg-based ones.

Gradient Microstructure and Properties of Surface Mechanical Attrition–Treated AZ91D Alloy: An Effect of Colliding Balls Velocity

The surface properties of the AZ91D alloy are altered using surface mechanical attrition treatment (SMAT), a promising method of severe surface deformation, where the role of process parameters is crucial. In this study, specimens are SMATed using ≈3 and ≈10 m s−1 ball velocities (maintaining a constant percentage coverage). The SMATed specimens show higher twin density near the surface, which is reduced gradually, and twin thickness is increased with increasing depth. Further, high‐velocity balls cause more twin density and better grain refinement (≈32 nm grain size at the surface). The higher ball velocity helps form a considerably thicker gradient layer (≈3500 μm) with higher hardness (≈1.98 GPa) and compressive residual stress (≈281 MPa) within a shorter SMAT duration (≈10 min). Ball velocity also influences nanomechanical properties such as nanohardness, creep resistance, strain rate sensitivity (SRS), etc. The non‐SMATed alloy's SRS is about 0.037–0.040. The gradient microstructure affects SRS. The SRS value near the SMATed surface (where the reduced grain size plays a dominating role) is about 0.018–0.027; however, it drops suddenly to ≈0.01 (with a slight increase in depth), and subsequently, it rises with an increased distance in the SMATed layer (where twins play a dominating role).