Surface Modification Of Powders Research Articles

Enhancing permeability and mechanical properties of rubber cement-based materials through surface modification of waste tire rubber powder

In this study, the authors present a detailed investigation into the surface mineralization of recycled rubber powder (RP) to enhance its performance in cement mortars. A modified rubber, referred to as RTC, is produced by employing a straightforward and efficient method involving the deposition of tannic acid (TA) and calcium carbonate (CaCO3, <5 μm) on the surface of RP. The main objective of this research is to elucidate the impact of RTC on the impermeability, mechanical properties, and pore structure of rubberized mortar. Through a comprehensive set of characterizations and tests, we demonstrate the successful deposition of TA and CaCO3 on the RP surface, resulting in RTC with excellent chemical activity and hydrophilicity, while also providing nucleation sites for hydration products. This modification process facilitated improved interfacial affinity with cement paste, enhancing bonding between rubber and cement paste. Remarkably, the incorporation of rubber into mortars with markedly enhanced resistance to permeation, with RTC mortars demonstrating particularly noticeable improvement. The marginal decrease in density in comparison to conventional mortars arises from the rubber's lightweight properties. Moreover, rubber exerts a minor adverse influence on hydration kinetics, yet this detrimental impact is alleviated in mortars incorporating RTC. Notably, the study elucidates the nuanced changes in porosity induced by rubber incorporation, underscoring its influence on the mechanical performance of rubberized cement mortars. The RTC5 mortar with a 5% content demonstrates the most remarkable enhancement compared to RP5 mortar. Overall, this study highlights the potential of surface mineralization of RP as a promising approach for improving the performance of rubberized cement mortars.

A Brief Review of Surface Modification of Carbonyl Iron Powders (CIPs) for Magnetorheological Fluid Applications

Magnetorheological fluids (MRFs) is a smart fluid system that exhibits swift and reversible alterations in their rheological characteristics when exposed to an external magnetic field. MRFs are used for applications in various areas, including automotive systems, robotics, aerospace, and civil engineering. The performance of MRFs depends on the behavior of the dispersed magnetic particles, necessitating thoughtful consideration of particle traits to optimize fluid performance. Carbonyl Iron Powders (CIPs), high purity iron (&gt;98%) reduced from penta carbonyl iron, are widely employed in MRFs due to their exceptional magnetic characteristics. Nevertheless, the innate surfaces of CIPs tend to conglomerate, leading to compromises in fluid stability and rheological performance. To overcome the challenges, an intensive research has been devoted to advancing surface modification techniques that augment the dispersion, stability, and overall functionality of MRFs based on CIPs. This review describes the comprehensive approach to surface modification of CIPs for highly stable MRFs. We discuss the various surface modification methodologies that have been explored to optimize the behavior of carbonyl iron-based MRFs. Coating techniques, surfactant functionalization, magnetic coatings, and emerging approaches such as nanocoatings and electrochemical modification are also summarized. Moreover, insights into potential applications and future prospects of these modified MRFs are provided.

Effect of surface modification of metal powders (by aluminum stearate) on the properties of metal injection molding feedstock

Metal injection molding (MIM) is a net-forming technology for manufacturing miniature metal parts, which can improve the manufacturing accuracy of complex-shaped parts. In this study, aluminum stearate was used to modify the 17-4PH stainless steel powder, the binder was composed of (PMMA) and (PEG) with the volume ratio of 7:3. The effects of aluminum stearate surfactant amount on the feedstock viscosity, water debinding rate and thermal debinding shape were studied. The results showed that the coating of aluminum stearate breaks the agglomeration between the powders and decreases the viscosity of the feedstock. When the addition of aluminum stearate was 0.6wt% of the powder mass, the melt index, density and flexural modulus of the feedstock were 81.5 g/10 min, 5.44 g/cm3, and 1643Mpa, respectively, and the thermal debinding shape retention was the best of all debinded parts. However, too much aluminum stearate makes the feedstocks thicker and the green part weaker.

Effect of low-pressure plasma treatment on the thermal behaviour of organo-modified montmorillonite nanoclay

The thermal behaviour of nanoclay can be considered an important factor in obtaining high-performance polymer nanocomposite. Thus, the current study aims to investigate the effect of plasma treatment on the thermal stability of two organically modified nanoclays, Cloisite 30B (C30B) and Nanomer I.34TCN (I.34TCN), compared with pristine NaMMT.The nanoclays were studied and characterised using Thermogravimetric Analysis (TGA). TGA was used to measure the weight loss of the plasma-treated and untreated nanoclays (C30B, I.34TCN, and NaMMT nanoclays) over a 30-630 C temperature range.Based on TGA results, the decomposition of all plasma-treated nano clays (C30B, I.34TCN and pristine NaMMT) was shifted to a lower temperature than in the untreated ones at all those stages. Thus, plasma treatment was successfully used as a convenient method to alter the chemical structure and surface morphology of MMT nanoclays for better thermal behaviour and filling distribution.This hypothesis can be corroborated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) for a better understanding of the structural and surface changes that occurred due to the plasma action, which can provide an interpretation of the changes in the thermal behaviour of nanoclays.The plasma treatment, therefore, can improve the thermal stabilisation of the nanocomposite powders for the LS fabricated parts and even for the surrounding powder for the recovery process. Plasma-treated nano clay, therefore, can be used to reinforce polymers with an expectation of increasing the thermal stability of the resultant composites. Thus, the plasma-treated composite can be fabricated for laser sintering applications in fields that require high thermal stability.The surface modification of nanoclay powders via plasma treatment can be used as a convenient method to alter the chemical structure and surface morphology for better thermal behaviour and filling distribution.

The photocatalytic ability of visible-light-responsive interfacial charge transfer complex between TiO2 and Tiron

The surface modification of commercial TiO2 powder with catecholate-type ligand Tiron (TIR) leads to the formation of the interfacial charge transfer complex (ICT) absorbing in the visible spectral range. The estimated band gap energy of the ICT complex (Eg = 2.2 eV) by density functional theory (DFT) calculations agrees with experimental measurements. The surface-modified TiO2 with TIR has enhanced sorption capacity towards Pb2+ ions compared to the pristine one due to the presence of free sulfonate groups. Our attempt to reduce Pb2+ ions to metallic form failed. The TiO2-based ICT complex with TIR can serve as an efficient sorbent to remove Pb2+ ions from the solution without the ability to recover them in metallic form in a photo-driven catalytic process. The photocatalytic ability of the ICT complex to induce oxidation reactions is significantly improved since the complete degradation of organic dye methyl orange occurs under exclusive excitations with visible light photons.

Optimizing the surface modification of cohesive polyethylene powders in a vibrated plasma-spouted bed: Exploring agglomerate size impact on coarser particle addition mechanism

Ultrafine polymer powders have garnered attention owing to their superior physical properties and reactivity. Nonetheless, the cohesive nature of these powders notably impedes efficient plasma surface modification, thereby limiting potential applications. The effects of optimizing the fluidization of cohesive powders on plasma treatment within a plasma-spouted bed were investigated in a prior study, wherein surface modification was significantly improved by incorporating coarser particles and vibration. However, the optimal conditions and mechanisms by which adding coarser particles to a vibrated plasma-spouted bed contributes to this enhancement remain unelucidated. This study entailed an investigation of the influence of gas flow rate, agglomerate properties, and plasma distribution in optimizing the wettability modification of ultrafine powders. Results indicate that increased gas flow rate, coarser particle size, and quantity lead to the formation of smaller, more uniform-sized agglomerates. Furthermore, the contact angle of the treated powder demonstrated a linear decrease with the reduction of average agglomerate size within a suitable gas velocity range, suggesting that enhanced exposure of the powder surface to plasma contributes to the optimization of plasma treatment. However, high-gas velocity may trigger particle entrainment and diminish surface modification, as evidenced by the limited plasma distribution primarily at the bottom of the reactor.

Influence of Colloidal Additivation with Surfactant‐Free Laser‐Generated Metal Nanoparticles on the Microstructure of Suction‐Cast Nd–Fe–B Alloy

Development of new powder feedstocks using nanoparticles (NPs) has the potential to influence the microstructure of as‐built parts and overcome the limitations of current powder‐based additive manufacturing (AM) techniques. The focus of this study is to investigate the impact of NP‐modified magnetic microparticle powder feedstock on the microstructure of suction‐cast Nd–Fe–B‐based alloys. This particular casting method has been recognized for its ability to replicate, to some extent, the melting and rapid solidification stages inherent to metal powder‐based AM techniques such as powder bed fusion using a laser beam. Two types of NP materials, Ag and ZrB2, are used, and their effects on the grain size distribution and dendritic structures are evaluated after suction casting. Ag NPs result in smaller, more uniform grain sizes. ZrB2 NPs result in uniformly distributed grain sizes at much lower mass loadings. The results show that feedstock powder surface modification with low‐melting‐point metal NPs can improve permanent magnets’ microstructure and magnetic properties, at below 1 vol%, equal to submonolayer surface loads. Herein, the potential of using NPs to develop new powder feedstocks for AM is highlighted, significantly improving the final part's properties.

Surface modification of recycled tire rubber powders with Tannic acid and Nano-TiO2 for enhanced performance and photocatalytic properties of Rubberized Cement-Based materials

The utilization of recycled rubber powder in civil engineering is currently insufficient, leading a significant hurdle to the environmentally friendly disposal of waste tires. To mitigate the adverse effects of rubber powder (R) in cement-based materials and enhance their application in road materials, this study aims to explore a novel modification approach. Tannic acid (TA) and TiO2 (<100 nm, SBET = 43.22 m2/g) were used to modify the surface of R through a simple adhesion self-assembly reaction, resulting in the formation of R-TA-TiO2 composites. A series of characterization tests, such as WCA, AI, FTIR, XRD, SEM, EDS, BET, XPS and UV–Vis-DRS, indicated that the hydrophilicity and chemical activity of the modified R-TA-TiO2 were significantly improved, and its surface possessed numerous cross-linking and stable sites for photocatalytic activity. Leaching and photocatalytic experiments confirmed the excellent heavy metal ion immobilization ability and photocatalytic performance of R-TA-TiO2. The results of basic mechanical tests and microscopic characterization of cement mortar revealed that the modified rubber enhanced the bonding ability between modified rubber and cement mortar, mitigated the negative effects in cement mortar, and exhibited pro-cement hydration ability. The flexural and compressive strengths of the modified rubber-cement mortar were considerably increased compared to those of the untreated rubber-cement mortar. Moreover, the modified rubber-cement mortar demonstrated excellent photocatalytic properties, and cyclic adsorption experiments verified its photodegradation stability and repeated properties. Microscopic characterization further showed that the modified rubber-cement mortar maintained its internal stable structure during photodegradation, indicating its potential for use in green road materials.

Surface Modification of Coal-Based Coke Powder with Pitch Powder for Lithium Ion Batteries

Surface Modification of Coal-Based Coke Powder with Pitch Powder for Lithium Ion Batteries

BNNS formation through surface modification of hBN nanopowders with a silane coupling agent

The production of BNNSs through the surface modification of nano-sized hBN powders with vinyltrimethoxysilane (VTS) as a silane coupling agent was realized using the newly introduced process route. It aimed to investigate the effects of shear forces generated by ultrasonication and stirring, which were applied during hydroxylation before silanization, and also VTS concentration on surface chemistry, exfoliation, dispersibility, and stabilization of hBN nanopowder. SEM images exhibited that stirring used before ultrasonication throughout hydroxylation improved the dispersibility of BN platelets. Followed by hydroxylation through ultrasonication, the silanization with 0.5 mg/mL VTS resulted in weak absorbances between 1225–995 cm−1 on FTIR spectrum, dispersed and translucent BN platelets, reduction of Raman peak intensity at 1368 cm−1, and an increase of zeta potential (from −10.1 mV to −19.0 mV) as indications of BNNS formation and also improved dispersibility and stability of dispersions. A higher VTS concentration than 0.5 mg/mL concluded with aggregation and poor dispersibility, associated with depletion flocculation. In addition, the number of translucent BN platelets with a lateral size of ∼ 200 nm increased, Raman peak intensity further decreased, and zeta potential reached −28.8 mV after silanization with optimal VTS content (0.5 mg/mL) since both stirring and ultrasonication were applied along hydroxylation. These results indicate the production of thinner BNNSs with high crystallinity and higher dispersion stability.

Laser powder bed fusion of electrically/thermally conductive component by developing inert Cr2O3-coated Cu powder

To enhance the compatibility of Cu with laser powder bed fusion, pre-alloying or powder surface modification of introducing high laser-absorbing alloying elements is currently adopted. However, this only addresses the densification issue but sacrifices the more important electrical/thermal performance because of their supersaturated solid solution in Cu. A secondary heat treatment is required though it is highly risky in damaging the dimension of geometrically complex component. Here, a novel strategy of employing the high laser-absorbing inert Cr2O3 instead of solid-solution alloying elements for powder surface coating was effective in achieving the desired synergy of densification (99.5%) and electrical/thermal conductivity (91.8% IACS and 371 W m−1 K−1), by which no additional heat treatment is needed. A heat sink was built to verify these positive effects. The electrical/thermal conductivity obtained is equal to those for the printed Cu alloys after long-term heat treatment. This strategy is universally applicable to other inert candidates.

Removal of Methylene Blue from Aqueous Solutions by Surface Modified Talc.

In this study, raw talc powder surface modification was conducted, and the powder was modified in two different methods using acid washing and ball milling. Modified talc was characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In order to investigate the adsorption capacity of modified talc on dyes, adsorption experiments were carried out with methylene blue (MB) in aqueous solutions as the target contaminant. The findings of the characterization revealed that both modifications increased the adsorption capacity of talc, which was attributed to changes in specific surface area and active groups. The influence of process parameters such as contact time, pH, dye concentration, and adsorbent dosage on the adsorption performance was systematically investigated. Modified talc was able to adsorb MB rapidly, reaching equilibrium within 60 min. Additionally, the adsorption performance was improved as the pH of the dye solution increased. The isotherms for MB adsorption by modified talc fitted well with the Langmuir model. The pseudo-second-order model in the adsorption kinetic model properly described the adsorption behavior. The results show that the modified talc can be used as an inexpensive and abundant candidate material for the adsorption of dyes in industrial wastewater.

Chemically modified jackfruit leaves as a low-cost agro-waste adsorbent for Pb(II) removal from synthetic wastewater

There is an emerging need to develop an economical, efficient and agro-waste-based adsorbent for the removal of toxic heavy metal ions from various aqueous media. In the present investigation, jackfruit leaves (Artocarpus heterophyllus) have been chosen as a suitable agro-waste-based material for the efficient removal of Pb(II) from wastewater. The surface modification of jackfruit leaf powder (JLP) has been done by chemical modification with 20% isopropyl alcohol followed by treatment with (i) alkali-sodium hydroxide (AIJLP) and (ii) tartaric acid (TIJLP). In comparison to JLP depicting BET surface area of 29 m2/g, the chemical modification resulted in about a 1.5-fold increase and 2.5-fold increase in the surface area of TIJLP (50 m2/g) and AIJLP (72 m2/g), respectively. Therefore, batch experiments were performed for Pb(II) adsorption using AIJLP for the optimization of equilibrium conditions viz., Pb(II) concentration, pH and contact time. Under optimized conditions, AIJLP showed a loading capacity of 87.7 mg/g from the Langmuir model at pH 5.0. Kinetic data were best fitted with a pseudo-second-order model. The characterizations of the adsorbents have been performed by FESEM with EDX, FTIR, TGA, XPS and surface area analyzer (BET). The pore size and pore volume have been analyzed by the BJH method to understand the adsorption mechanism. Reusability studies reveal that AIJLP could efficiently remove more than 95% of Pb(II) in up to five cycles. All these results recommend the AIJLP as a promising adsorbent for the remediation of Pb(II) from wastewater.

Surface modification of silk fibroin powder and its application in oil–water separation

The recent increase in maritime trade and transportation has increased the seriousness of environmental pollution caused by offshore oil leakage. In this study, silk fibroin (SF) powder is modified using chitosan and sodium stearate, and is used for oil–water separation. The structure of the modified SF powder is characterized through Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The modified SF powder exhibits better selectivity for oil than the original SF powder, for oil–water separation. Its oil-absorption capacity for soybean oil is 5.5965 g·g−1, which is nearly twice that of the original SF powder. The oil absorption capacity for engine oil is 5.3823 g·g−1, which is more than twice that of the original SF powder. This work provides a new method and concept for the study of oil–water separation.

Novel solid-state metal powder surface modification process for additive manufacturing of metal matrix composites and alloys

Although metal additive manufacturing has been widely studied owing to its flexible product shape design, the material selection window for metal additive manufacturing remains narrow owing to limited feedstocks. To address the challenges in additive manufacturing, an innovative metal powder fabrication process was developed in this study. This process is known as surface modification and reinforcement transplantation (SMART), and it efficiently produces surface-modified feedstock powders, such as spheroidized, surface-alloyed, surface-coated, or composite powders, which facilitate the exploration of new alloys and composites via additive manufacturing. In this study, the working principles of the SMART process were established, and some practical applications of the SMART process were considered by fabricating specialized metal additive manufacturing feedstocks such as carbon nanotube-coated, Mo alloyed, and TiC particle-reinforced Inconel 625 powders. Furthermore, Mo-alloyed and TiC particle-reinforced powders were utilized in the directed energy deposition process to validate the performance of the SMART powder by fabricating Mo-controlled alloy and TiC particle-reinforced composites. The SMART process was compared with the existing processes and proved to be advantageous. Therefore, this study provides a novel method for producing feedstock powders for additive manufacturing.

Surface modification of silica powder by mild ball milling

Surface modification of silica particles without a catalyst or solvent was performed using mild ball milling. The effects of the amount of the modifier, hexatrimethoxysilane (HTMS), ball milling time, and the washing process were investigated. HTMS was physically and chemically adsorbed on the silica surface by ball milling; the adsorbed HTMS reacted with the silica particles on the surface during heat treatment. The adsorption amount of HTMS in silica particles increased with the increase in the milling time to 6 h. The modified silica particles were well dispersed in the cyclohexane because the silica was successfully modified by HTMS. In addition, the number of hydroxyl groups on the silica surface affected the adsorption ratio of HTMS; chemical adsorption could be increased using silica with a large number of hydroxyl groups. Therefore, this simple method, by which the amount of chemical adsorption can be easily modulated, is a valuable tool for the homogeneous modification of silica powder.

Few-layered Ti3C2 MXene-coated Ti–6Al–4V composite powder for high-performance Ti matrix composite

A few-layered Ti3C2 MXene-coated Ti–6Al–4V composite powder was developed via powder surface modification by using fluidization technology. The obtained MXene coating demonstrated the advantages of uniform dispersion, high purity and good thermal stability. Also, the coating enabled the massive retention and uniform distribution of MXene in the sintered composite. Compared to the bare Ti–6Al–4V alloy, the yield strength of MXene/Ti–6Al–4V composite was increased from 895 to 1297 MPa, while maintaining the similar strain. The thermal conductivity of composite was approximately four-fold compared to that of Ti–6Al–4V alloy, which is attributed to the intrinsically high thermal conductivity and the uniform distribution characteristics of the remained Ti3C2 MXene in the composite.

Improving relative density and mechanical strength of lunar regolith structures via DLP-stereolithography integrated with powder surface modification process

Three-dimensional (3D) printing is one of the most promising techniques for on-site manufacturing and is expected to become a key technology for the construction and maintenance of lunar bases. In this study, powder surface modification was integrated with digital light process (DLP)-based 3D printing to improve the mechanical properties of 3D printed lunar regolith simulant (CUG-1A) structures. A silane coupling agent (KH570) was utilised to modify the CUG-1A powder, and the underlying surface modification mechanism was elucidated. In addition, the effects of the silane coupling agent on the rheological properties, wettability, cure depth and dispersity of the slurries were investigated. It was revealed that the introduction of the silane coupling agent improved the wettability between the CUG-1A powder and photocurable resin, which effectively decreased the slurry viscosity. In addition, powder surface modification enhanced the homogeneity of CUG-1A particle distribution, which is beneficial for obtaining a uniformly distributed liquid phase during the sintering process, thus promoting the sintering densification of the printed sample. The relative density and flexural strength of the CUG-1A sample prepared by the modified powder sintered at 1100 °C reached 86.47% and 91.13±5.50 MPa, being 6.5% and 22.5% higher than the values of sample prepared by the unmodified powder, respectively. Finally, complex shaped lunar regolith simulant structures were successfully fabricated via DLP-stereolithography integrated with powder surface modification, which indicating powder surface modification is an effective way to fabricate 3D printed lunar regolith simulant components with high density and mechanical strength.

Optimizing Hydrolysis Resistance and Dispersion Characteristics via Surface Modification of Aluminum Nitride Powder Coated with PVP-b-P(St-alt-ITA) Copolymer.

Developing new coating modification technology of aluminum nitride (AlN) powder for higher hydrolysis resistance is the key to prepare high-performance AlN ceramic substrate with water-based wet process in the future. In the this paper, The poly(vinyl pyrrolidone)-b-poly(Styrene/Itaconic anhydride) (PVP-b-P(St/ITA))block copolymer with PVP as the independent chain segment was designed and synthesized through reversible addition fragmentation chain transfer (RAFT) polymerization, which was used for the study on coating modification, hydrolysis resistance, and dispersion performance of AIN powder. The study results show that, when using PVP macromolecular chain transfer agent (PVP-CTA) for the RAFT chain extension and polymerization in St/ITA binary system, the molecular weight increases linearly and the molecular weight distribution tends to decrease with the monomer conversion rate, which is in line with the activity-controlled characteristics of RAFT polymerization. The copolymer PVP-b-P(St/ITA) was used to for surface modification treatment of submicron AlN powder to generate esterification reaction, which was absorbed and bound to the powder surface. Hydrolysis resistance and dispersion experiments were conducted for modified powder, and the crystal phase and micro structure of modified powder were analyzed and observed through XRD, SEM, and TEM. It was found that copolymer modification had no effect on the powder crystal phase. A 8–21 nm passivation layer was coated on the surface, which can exist stably for 10 h in 60 °C water. Zeta potential and laser particle analyzer tests showed that modified powder featured excellent water-based slurry dispersion performance, and certain self-dispersing characteristics. The highest Zeta potential appeared in pH 6~7, and the particle granularity was distributed uniformly with the median particle diameter of 875 nm. The powder hydrolysis resistance and dispersion performance are significantly improved.

Surface modification of Si3N4 powder for hydrolysis control

The hydrolysis of Si3N4 powder was controlled by surface modification with Al(H2PO4)3 and Mg(H2PO4)2 with TEOS. The existence of Al(H2PO4)3 and Mg(H2PO4)2 catalyzed the hydrolysis of TEOS. From experimental results, the Si3N4 powder after surface modification exhibits a greatly-improved hydrolysis resistance than the initial Si3N4 powder in water at 60 and 120 °C. The surface modification had no clear influence on the dielectric loss of Si3N4 powders. By XPS analysis, the powders after surface modification showed the presence of P, Al, and Mg elements. It was proposed that the surface modification agent forms a strong bonding with the surface of Si3N4 particles.