Grinding Treatment Research Articles

Influence of Thermal and Chemical Treatment on Biosorbent from Rice Husk and Its Application in Removal of Resorcinol from Industrial Wastewater

The removal of phenolic compounds is of great importance because of their toxic nature and potentially harmful effects on the environment and human health. This study examines the use of rice husk as a biosorbent for eliminating phenolic compounds, particularly resorcinol, from industrial wastewater. Three types of rice husk, namely raw rice husk (RRH), chemically treated rice husk (CTRH), and thermally treated rice husk (TTRH), are utilized after grinding and methanol treatment. Characterization techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and optical microscopy are used to analyze the rice husk-based adsorbents. The microscopic analysis reveals the presence of nano-pores in TTRH and the existence of carbonyl and hydroxyl groups in all sorbent samples. XRD analysis confirms the presence of silica in biosorbents. This study also examines the influence of dosage and initial concentration on resorcinol sorption. Optimized dosages of 0.5 g (RRH), 0.5 g (CTRH), and 1.5 g (TTRH) result in sorption capacities of 14 mg/g (RRH), 11 mg/g (CTRH), and 5 mg/g (TTRH). Isotherm analysis indicates that the Langmuir isotherm best describes the sorption behavior of TTRH, while the Freundlich isotherm is observed for CTRH, and both RRH and CTRH follow the Temkin isotherm.

Enhancing the ultrasonic plastic welding strength of Al/CFRTP joint via coated metal surface and structured composite surface

Ultrasonic plastic welding (UPW) is a promising technology for joining metal to carbon fiber reinforced thermoplastic composite (CFRTP) but shows poor joint strength in the existing studies. This work conducts UPW of AA6061 aluminum alloy to carbon fiber reinforced PA66 (CF/PA66) by employing a polymer coating as an interlayer. Simple metal surface grinding and silane coupling agent (SCA) treatment are used to strengthen the bonding of the metal/coating interface. Structured CF/PA66 surface fabricated by ultrasonic embossing acts as energy directors to improve the bonding strength of the coating/plastic interface. The results show that relatively high tensile-shear strength (about 31.0 MPa) can be obtained. Micro-mechanical interlocking and chemical bonding (Al-O-C and Al-O-Si bonds) are considered as the bonding mechanism of the metal/coating interface.

Effect of physical treatments on the functional and structural features of soluble dietary fiber from soybean dregs.

In this research, the effects caused by ultrafine grinding (U), high-temperature cooking (HTC), microwave (M) and combined treatment (U-HTC, U-M) were evaluated on the functional properties and structural characteristics of soluble dietary fiber (SDF) obtained from soybean dregs. Physical treatments could increase the extraction yield of SDF and improve the functional properties of SDF. The highest extraction yield (277.15 ± 5.87 g kg-1 based on the weight of soybean dregs) and purity (863.37 ± 5.15 g kg-1 based on the extract weight) of SDF was found in the sample by U-M treatment. U-HTC and U-M combined treatments significantly improved the water solubility and oil holding capacity of SDF. U-M treatment significantly increased the ability of SDF to adsorb cholesterol and perform cationic exchange; compared to the control, these abilities were increased by 138.46% and 10.38%, respectively. At pH 2.0, the nitrite ion adsorption capacity (NIAC) of SDF obtained by U-M combined treatment was 184.55 μg g-1 , which was significantly higher by 32.10% compared with that of the control. The results obtained by X-ray diffraction and scanning electron microscopy showed that the structure of SDF generated from soybean dregs became coarser and more porous, and the crystallinity decreased after physical treatments. Combined physical treatment is an effective way to improve the extracted yield and functional properties of SDF from soybean dregs. © 2023 Society of Chemical Industry.

Surface nano-crystallisation and mechanical properties of Ti[sbnd]Ta composite materials after surface mechanical grinding treatment

Surface mechanical milling generates gradient nano-structure surfacial layers that enhance the mechanical properties of titanium (Ti)–tantalum(Ta) composites for medical implants. Herein, the effect of surface mechanical grinding treatment (SMGT) on the surface nano-crystallisation of TiTa laminated composites was investigated in terms of micro-structure and Coherent Scattering Regions (CSRs) size using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A strengthening effect was verified using a micro-hardness tester and tensile testing machine, and the fracture mechanism was analysed through fracture observation. The experimental results showed that gradient nano-structures were formed on the surface of the TiTa laminated composites after SMGT, with the smallest CSRs size of the outer surface layer of approximately 13.3 ± 0.4 nm. The plastic deformation mechanism of the TiTa laminated composites during SMGT was a dislocation cutting mechanism. The micro-hardness and tensile strength of the TiTa laminated composites increased after SMGT up to 440 HV and 1097.528 MPa, respectively. The fracture mechanism of the TiTa laminated composites after SMGT was a combination of ductile fracture and quasi-cleavage fracture mechanisms. After SMGT, the TiTa laminated composite performed well and exhibited excellent potential for use in biomaterials.

ОПРЕДЕЛЕНИЕ ДИАПАЗОНА ЭФФЕКТИВНЫХ РЕЖИМОВ ШЛИФОВАНИЯ И МАТЕРИАЛОВ ШЛИФОВАЛЬНОГО КРУГА ДЛЯ ОБРАБОТКИ СТАЛИ 95Х18

The development of a mathematical model for the grinding treatment of steel 95X18 with recommended grinding wheels, namely a wheel of silicon carbide green, el’bor wheel, diamond wheel is discussed. When studying the influence of grinding modes and grinding wheel materials during the processing of 95X18 steel on the roughness of the treated surface, a multifactorial experiment was carried out. The roughness of the treated surface was evaluated according to the Ra parameter, using a portable profilometer of the MarSurf PS1 model. Based on the data obtained, it is possible to choose the optimal cutting mode based on the required roughness of the treated surface. It has been established that in order to achieve a stable quality of the treated surface Ra 0.63, it is necessary to use a diamond wheel at cutting speeds from 10 to 25 m / s and low feed rates. The obtained regression equations showed that an increase in the cutting speed or a decrease in the feed led to a decrease in the roughness of the treated surfaces. The main provisions of the metal cutting technology and the mechanical engineering technology were used.

Assessing the environmental impact of gold production from double refractory ore in a large-scale facility

Despite the strict environmental management regulations, there is still a considerable adverse impact on the ecosystem and human health when it comes to large-scale gold mining operations. Gold mining is an energy-intensive process that can discharge substantial quantities of chemicals combined with gaseous emissions into the environment. Considering gold mining's significant role in Nevada's economy and the growing concern about climate change, it's necessary to investigate the environmental burdens of this sector. To provide a comprehensive environmental perspective on the large-scale gold mining operations in Nevada, this study used a life cycle assessment (LCA) approach to evaluate the environmental burdens of gold production from double refractory ores in the roasting process. The Tool for Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) method was used to evaluate the categories of acidification, ozone depletion, global warming, smog, carcinogenics, non-carcinogenics, respiratory effects, and fossil fuel depletion. Results showed that major contributors to greenhouse gas (GHG) emissions were grinding and off-gas treatment stages being responsible for 34.80 % and 56.10 % of the total global warming, respectively. The carbon footprint for producing one kg of gold was 12,200 kg CO2-eq. Sensitivity analysis was also employed on electricity to observe the influence of electricity on key contributor stages. A 10 % change in electricity reduced the GHG emissions in crushing and grinding by 12.2 % and 7.10 %, respectively, while delivering an insignificant effect on the off-gas treatment. Significantly, this study stands as the first initiative to apply LCA in the North American mining industry, with a unique focus on the off-gas treatment post-roasting and its associated emissions. Our findings can serve as a foundational database, aiding stakeholders in making informed decisions and enhancing sustainable practices in the gold mining industry.

Silver decoration of Cr2O3 nanoparticles: Facile preparation of Cr2O3 nanoparticles and Ag–Cr2O3 nanocomposites and characterization of their antibacterial activity and ability to photocatalytically degrade organic wastes under visible light

An eco-friendly, single-step process was adopted for the preparation of Cr2O3 nanoparticles (CR-NPs), and different concentrations of Ag were doped into the CR-NPs through liquid impregnation to synthesize a series of Ag-CRNPs composites. In order to prevent agglomeration, chemical transformation, and weak adhesion of Ag to CR-NPs, a mechanical process of circular-motion grinding and high-temperature treatment in a sealed condition were used. Well-defined heterojunctions were successfully formed between Ag and CR-NPs. In comparison to the CR-NPs, the Ag-doped CR-NP composites exhibited excellent performance in photocatalytic and antibacterial applications. Under visible light (VL), the best-performing composite (2 %-Ag decorated CR-NPs) showed 96 %, 79 %, and 57 % decomposition of methylene blue, Congo red, and tetracycline, respectively, in 100 min, which was attributed to a synergetic effect in the composites. The rate constant of the photocatalytic reaction is 14 times higher than that of the reaction without a photocatalyst. The enhanced efficiency was attributed to a reduced bandgap, prolonged retention of photogenerated electron–hole pairs, an increased amount of active spots, and increased absorption of VL. Similarly, the best-performing composite exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with zones of inhibition of 15.4 and 15.1 mm, respectively. The 2 %-Ag decorated CR-NPs were the most efficient and exhibited robust recyclability until the fifth cycle (≥90 %). The photocatalytic activity was primarily driven by reactive oxygen species, holes and hydroxyl radicals.

Surface grain refinement of casting A380 aluminum alloy by ultrasonic-assisted surface mechanical grinding treatment

A novel surface processing technique, ultrasonic-assisted surface mechnical grinding treatment (U-SMGT), was proposed and applied to modify the surface micriostructure of the casting aluminum alloy (A380). Comprehensive post-process chracterization techniques including 3D profilometry, optical microscope, scanning electric microscopy (SEM), and electron backscatter diffraction (EBSD) were carried out to investigate the surface morphology and microstructure of the processed region (PR). It was found that a surface layer of grain refinement with a thickness of about 50 µm was formed. In the as-received base material (BM), large clusters of dendritic eutectic phase with a size of approximately 20 µm were isolated by α-Al matrix. Nano-indentation tests showed that hardness of the eutectic and α-Al in the as-received BM was 2.15 GPa and 1.2 GPa respectively. After U-SMGT, the large dendritic eutectic phase was broken down into much fine particles with an average size of 0.57 µm. These fine particles were uniformly distributed into the α-Al matrix. Nano-indentation measurement exhibited a hardness of 2.27 GPa within the processed region. The overall high hardness in the processed region is a result of the pinning effect of uniformly distributed fine dendrites and grain refinement of Al-matrix.

Layer ablation and surface textured of Carbon fiber reinforced plastics by infrared pulsed laser

AbstractFor high‐quality composite bonded repairs, the research utilized a 1064 nm infrared pulsed laser to obtain geometry and texturing surface. The impact of grinding and laser treatment (0.4, 0.7, and 1.5 J/cm2) on the surface features of composite material was investigated, along with the tensile strength and failure modes. Findings demonstrated that laser treatment could significantly enhance surface roughness parameters and wetting properties compared to grinding. Additionally, an optimal laser energy density of 0.7 J/cm2 achieves complete resin removal without fiber damage while creating a laser‐induced periodic surface structure (LIPSS) based on a fiber weaving texture. The research revealed the synergistic bonding mechanism of “submicron mechanical locking” and “micron anchoring.” Laser treatment enhances the tensile strength of repaired specimens to 445 MPa, which was 90% of the original specimens, and substrate fracture was the associated failure mode.Highlights This paper applies laser technology to simultaneously achieve 3D geometry and surface texture on composites bonded repairs. A laser‐induced periodic surface structure was achieved while the resin was completely removed without carbon fiber damage. The tensile recovery rate of the laser‐treated sample was satisfied with the requirements of aircraft maintenance.

Comparative analysis of dietary fibers from grapefruit peel prepared by ultrafine grinding: Structural properties, adsorption capacities, in vitro prebiotic activities

Ultrafine grinding treatment was used to treat grapefruit peel from Shatianyou, Majiayou, Dabumiyou and Jinggangmiyou, subsequently structural properties and adsorption capacities of extracted soluble dietary fibers (SDFs) were comparatively analyzed, moreover SDF from untreated Dabumiyou (D-SDF) and SDF from Dabumiyou treated with ultrafine grinding (UD-SDF) were selected for in vitro prebiotic activity determination. The structural analysis exhibited that all SDFs manifested spectral characteristics of typical polysaccharides and showed a typical cellulose I-type structure, ultrafine grinding treatment broke chemical bonds between molecules, leading to a decrease in crystallinity, further reduced thermal stability of SDFs. The pectin content of SDFs were enhanced after modification, which may influence functional properties of SDFs. Moreover, SDFs from Dabumiyou showed better adsorption capacities for water molecule, oil molecule and cholesterol molecule. Compared to D-SDF, UD-SDF could effectively promote bacteria proliferation and stimulate probiotic strains to produce more short-chain fatty acids. This study was beneficial to better understanding physicochemical properties of SDFs extracted from different grapefruit peel by ultrafine grinding treatment and encouraged the use of grapefruit peel SDF in products with prebiotic properties.

Stress corrosion cracking behavior of AISI 316L stainless steel treated by surface mechanical grinding

The effects of surface mechanical grinding treatment (SMGT) on stress corrosion cracking (SCC) behavior of machined 316L stainless steel surface were investigated by comparing to those of turned and milled surfaces. The surface stress state, roughness, microstructure, and microhardness induced by the different surface machining processes were tested and analyzed. The SCC tests on the turned, milled and SMGT samples were conducted in boiling MgCl2 solution at 155 ℃, and the crack morphologies were analyzed in detail to establish the relationship between the surface integrities and the resulting SCC behavior. The findings indicated that the SMGT altered the SCC initiation behavior and improved SCC resistance of the turned and milled surfaces of 316L stainless steel, and the surface stress state, microstructure refinement and surface strengthening induced by SMGT contributed to the improvement of the SCC resistance.

Facile fabrication of aluminium alloys with gradient nanostructures incorporating α-Al2O3 particles for enhanced tribological properties

Aluminium alloys are crucial in lightweighting equipment. However, their limited wear resistance hinders their further utilization. Herein, a gradient nanostructure layer incorporating α-Al2O3 particles is successfully fabricated on aluminium alloy 2024 using a novel method called strengthening grinding treatment (SGT). The tribological properties were investigated by a ball-on-disc tribometer. The results show that SGT effectively enhances the anti-wear performance. Compared to the untreated sample, the average friction coefficient and the wear rate of the SGT-treated sample decreased by 34.7 % and 90.1 %, respectively. The wear surface analysis demonstrates that the presence of α-Al2O3 in the gradient nanostructure effectively restricts shear deformation and crack generation. Additionally, the formation of a wear-resistant tribofilm composed of 'glaze' during friction contributes to further wear reduction.

Physicochemical properties of superfine grinding-microwave modified artichoke soluble dietary fiber and their alleviation of alcoholic fatty liver in mice.

The effects of superfine grinding (SG) and microwave treatment (MT) on the structure and physicochemical properties of artichoke soluble dietary fiber (ASDF) and its protective effects on mice with alcoholic fatty liver (AFL) were studied. We compared the changes in structural characteristics and physicochemical properties of ASDF, SG-ASDF (ASDF treated by SG), MT-ASDF (ASDF treated by MT), and CM-ASDF (ASDF treated by SG and MT). Moreover, we evaluated the effects of the obtained ASDF on the growth characteristics, blood lipid levels, and liver of mice with AFL. Our results of the study showed that CM-ASDF had a more concentrated and uniform particle size, a higher extraction rate of ASDF and significantly improved water-holding capacity (WHC), oil-holding capacity (OHC) and water swelling capacity (WSC) of ASDF (p < 0.05). After the ASDF intervention, mice with AFL exhibited a significant improvement in body lipid levels and reduce liver inflammation. Specifically, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malonaldehyde (MDA), Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were significantly increased (p < 0.05). And the hematoxylin-eosin (HE) staining results showed significant improvement of hepatic steatosis in mice with AFL. In summary, our study found that both SG and MT could improve the structure and physicochemical properties of ASDF, with CM-ASDF being the most effective. Additionally, CM-ASDF was selected to continue the investigation and demonstrated an excellent protective effect on mice with AFL, with the high dose group (H-ASDF) showing the greatest benefit. These findings provided some new insights for future comprehensive utilization of ASDF and drug development for the treatment of AFL.

Prediction of Surface Microstructure, Grain Size, Martensite Content, and Microhardness of 316L Austenitic Stainless Steel in Surface Mechanical Grinding Treatment Process

Prediction of Surface Microstructure, Grain Size, Martensite Content, and Microhardness of 316L Austenitic Stainless Steel in Surface Mechanical Grinding Treatment Process

AC-MFL testing method for surface crack on reground billets using flexible parallel-cable-based probe

Square billet is an important industrial raw material. Due to the large amount of oxidation skin on the surface after continuous casting process, it needs surface grinding treatment. Meanwhile, the billet surface is prone to stress concentrations and cracks in the crystallization zone, so it is easy to break and cause accidents in the subsequent process. However, the poor surface condition of the reground billet, such as the large roughness and fluctuations in the shape, makes it difficult to be tested by traditional methods. In this paper, the relationship between the excitation frequency of alternative current magnetic flux leakage (AC-MFL) and the fluctuation of magnetic field generated by uneven surface is studied, and the high-frequency AC leakage field formation is restated. Furthermore, a flexible probe integrating parallel cables (PC) magnetizer and receiving coils is proposed, which can realize the profiling testing and reduce the influence of the undulating surface. Finally, the wavelet transform is used to reconstruct signals, which increases the average signal-to noise ratio (SNR) from 7.25 dB to 11.89 dB.

The Application of Portable X-ray Fluorescence (pXRF) for Elemental Analysis of Sediment Samples in the Laboratory and Its Influencing Factors

Several techniques, such as chemical methods and inductively coupled plasma mass spectrometry (ICP-MS), are available to accurately determine element content. However, they are time-consuming, labor-intensive, or expensive. Portable X-ray fluorescence spectrometry (pXRF) can be applied in various scenarios, with significantly higher efficiency and cost-effectiveness than laboratory methods. However, it also has limitations such as lower detection capability, relatively high detection limits, and lower accuracy than laboratory methods. In this study, we focused on applying pXRF to determine the elemental content of sediment samples and investigate its use in mineral exploration. A variety of factors influencing the results of pXRF analysis were analyzed. Our results showed that pXRF could detect more than 30 elements in stream sediments. The reliability of pXRF’s measurements was affected by factors such as the kind of element, sediment particle size, sample grinding treatment, count time, averaged element content, standard deviation of content, and range of content variation. The combination of pXRF analysis and laboratory analysis of partial samples is adequate for establishing a multi-element content inference equation. With this equation, it is possible to effectively infer the content gradient of elements, which will provide valuable support for mineral resource exploration.

Stabilizing nanograined austenitic stainless steel with grain boundary relaxation

Grain boundary (GB) relaxation can be triggered by interaction of GB with partial dislocations during plastic deformation, which is effective to stabilize nanograined structures in a number of face-centered cubic (FCC) metals and alloys. But this mechanism is interfered by deformation-induced martensitic transformation in 304 stainless steels with a metastable FCC structure. In this work, gradient FCC nanograined structures were prepared in a 304 stainless steel by using warm surface mechanical grinding treatment. GB relaxation was triggered in the samples with grains below 60 nm in size, in which partial dislocation dominates the plastic deformation. With the GB relaxation, thermal stability increases with decreasing grain sizes, contradictory to the conventional “smaller less stable” trend. The onset temperature for coarsening of nanograins of ∼30 nm in size is as high as ∼896 °C (0.7 Tm), about 250 °C above the reported value of the steel. The GB relaxation was not detected in martensitic nanograins of the same composition, of which the instability temperatures is around 650 °C (0.54 Tm), independent of grain size from 26 nm to the submicron scale, as it is controlled by the reverse martensitic transformation.

Effects of gradient nanostructures on the tribological properties and projectile abrasion during high-speed penetration in AerMet100 steel

To reduce the mass abrasion of AerMet100 ultra-high strength steel projectiles at increasing velocities, surface mechanical grinding treatment (SMGT) was employed to prepare a gradient nanostructure (GNS) on the AerMet100 surface. The microstructure of the GNS were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and nanoindentation. It was found that the gradient nano-crystal structure was successfully prepared, and the martensite plate width was reduced to about 30 nm. As the distance from the surface depth increased, the plate size gradually increased, with the depth of the grain refinement layer measuring approximately 300 μm. The microhardness of the GNS AerMet100 was 870 Hv0.025, which was approximately 40% higher than that of the AerMet100 substrate. Additionally, the hardness was observed to decrease with increasing GNS depth. The friction and wear behavior of coarse grained (CG) AerMet100 and GNS AerMet100 were investigated. The results showed that their friction coefficients were similar, but wear volumes of GNS AerMet100 were smaller than those of CG AerMet100, the wear mechanisms of two surfaces were predominantly abrasive and adhesive wear. Furthermore, the projectiles penetration test showed that the mass loss of GNS AerMet100 was significantly lower than that of CG AerMet100 under similar velocity condition. Within the velocity range of 1200–1750 m/s, the degree of erosion and wear loss of the CG AerMet100 and GNS AerMet100 projectile noses increased with increasing penetration velocity, and the wear mechanism was mainly abrasive wear.

A Brief Review of Micro-Particle Slurry Rheological Behavior in Grinding and Flotation for Enhancing Fine Mineral Processing Efficiency

Recent years have witnessed growing research interest in applying rheology in grinding and flotation treatment of finely disseminated ores. Slurry rheology has long been identified as the comprehensive effect of inter-particle interactions, including their aggregation and dispersion states in slurry, which are more impactive under the fine-particle effect. In this regard, rheology has the potential to play a significant role in interpreting the flowing and deforming phenomena of inter-particle aggregates, particle-bubble aggregates, and flotation froth. Though much attention has been paid to the rheological effect in industrial suspension, this has not been the case for mineral grinding and flotation for fine particles. The influential mechanism of rheology on the sub-processes of mineral processing has not been systemically determined nor revealed thoroughly, thus the underpinning mechanism for enhancing the processing efficiency has been difficult to discover. This paper reviews the current application and importance of rheology in fine mineral processing, and the potential research direction in the field is proposed.

Facile synthesis of hybrid WO3/MoOx electrochromic films for application in complementary electrochromic devices

In this study, WO3 nanoparticles and MoO3 nanoribbons were prepared using a microwave-assisted hydrothermal method. Following a grinding treatment, a stable WO3/MoO3 suspension having a nanoheterojunction structure was obtained. Moreover, oxygen vacancies were introduced in the MoO3 nanoribbons (MoOx) during the grinding process. Consequently, the ground WO3/MoOx composite film exhibited an enhanced electrochromic (EC) performance compared to the ground WO3 and MoO3 films not only due to its favorable morphology for ion transport but also the enhanced intervalence electron transfer. To further evaluate the potential of ground WO3/MoOx electrodes for practical applications, a complementary electrochromic device (ECD) was constructed using ground WO3/MoOx and polyaniline:poly(4-styrenesulfonate) (PANI:PSS) as cathodic and anodic coloring materials, respectively. This complementary ECD yielded a transmittance modulation of 55.4% at 650 nm with rapid switching times of 7.4 s (bleaching) and 3.6 s (coloring). The ECD also exhibited a high coloration efficiency of 154 cm2/C and a high cycling stability with an 80.6% transmittance retention after 2000 cycles. These results demonstrate that ground WO3/MoOx composites are attractive materials for fabricating high-performance ECDs.