SiO2 Powder Research Articles

Fabrication of Aluminium Matrix Composite Powder Reinforced with Silicon Dioxide Tailings for Non-Asbestos Brake Pads (NOB)

Tin mining tailings consist of 80-90% sand and the rest mud. The high levels of Silicon Dioxide (SiO2) in these tailings are hard and can be used as an added material in the manufacture of composites. This research aims to study the physical and mechanical properties of metal matrix composites reinforced with SiO2 powder processed by powder metallurgy, as an effort to provide a replacement material for Non-Asbestos (NOB) motorbike brake linings. The impact of hot compaction pressure in the form of two pressing directions, including 4600, 4500 and 4400 Psi, with a pressing hold of 15 minutes and sintering which includes 30, 20 and 10 minutes, at a temperature of 600 ºC was studied for its effect on hardness and density. Mechanical blending was used with a horizontal ball mill in the ratio of 10:1 at a speed of 90 rpm for 4 hours. The test results showed that the greater the hot compaction pressure and the longer the sintering, the higher the hardness and density values. The highest hardness reached 81.7 HB and the highest density of 2.385 g/cm3 occurred at a bidirectional hot compaction pressure of 4600 Psi, with the lowest wear rate of 0.333 mm3/m. This occurs as a result of the increase in hot compaction has an impact on increasing the contact between powder particles resulting from mechanical alloying to be tighter as a result of which the cavity and porosity decrease

Nano Powder SiO2 from Rice Husk and its Industrial Applications: A Concept of Wealth from Waste

The rice Husk (RH) is a renewable biomass product and through thermochemical processes like pyrolysis and gasification, silica-rich RH is transformed into biofuels (such as bio-oil, vapors, and charcoal) and biochar at the same time. RH catalysts can convert bio-oil into more renewable biofuel (biodiesel). Using RH silica materials to purify gas or undergo catalytic reforming, vapors from the breakdown of organic waste can be transformed into syngas, which have more value and can be utilized to create energy or make chemicals. Biochars created from RH are usually used to produce materials for silicon batteries, mend soil, clean up pollutants, and accomplish other things. This study looked at recent improvements in how RH silica products are created and how they can be used in the future, notably in manufacturing materials that benefit the environment and save energy. RH-silica compounds have environmental benefits, can eliminate organic and heavy metal contamination through integrated processes and adsorption, and are used as a catalyst in fertilization, and water purification, including gas cleaning. Lastly, biomass with a lot of silica could be a source of cheap starting materials for creating high-value silica/silicon compounds that can be employed in the actual world.

Development and mechanical properties of nano SiO2 modified photosensitive resin for high-strength and high-brittleness 3D printing in rock reconstruction

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses.

Protection behavior of Ti-SiO2 modified potassium silicate coating on K447a alloy at 1000 °C

Potassium silicate coatings cured by calcium hydrogen phosphate and modified by fillers of Ti and SiO2 powders were prepared on K447A alloy at 120 °C. The influences of Ti, SiO2 and both powders on the oxidation behavior of the coated specimens were investigated at 1000 °C for 100 h in static air by thermogravimetry, SEM, XRD and EPMA. The bare K447A alloy suffered severe oxidation at 1000 °C, and the TGO was found to be composited of an outer layer of mixtures of NiCr2O4, CoAl2O4 and rutile TiO2, and an inner α-Al2O3 layer. The potassium silicate coating without filler showed local damages where formation and rapid rupture of bubbles occurred and consequently the local substrate was oxidized. The SiO2 powder in the coatings is more capable of reducing O diffusion thru the coatings than the Ti powder, while the latter is more effective in getting rid of bubble rupture than the former. Thus, the coating modified by 10 wt% Ti and 20 wt% SiO2 showed the best protective performance.

Effect of precursor morphology on the electrochemical performance of porous Si anodes prepared by magnesiothermic reduction

The magnesiothermic reduction of SiO2 to Si is a promising route for preparing high-energy-density Si-based anode materials for lithium-ion batteries. However, the effect of the initial morphological properties of SiO2 on the electrochemical performance of Si remains unclear. Herein, porous Si (PSi) particles were prepared from four different SiO2 precursors, namely, spherical SiO2 particles with diameters of 0.3 and 20 μm (denoted SiO2-0.3 and SiO2-20, respectively), fumed SiO2 powder (denoted SiO2-F), and well-ordered mesoporous SiO2 particles (denoted SiO2-K). Highly crystalline PSi particles were obtained after magnesiothermic reduction and subsequent HCl and HF etching. PSi prepared from SiO2-0.3 maintained its precursor morphology to some extent, whereas highly irregular Si particles were produced from SiO2-20, SiO2-F, and SiO2-K. Among the PSi particles, those prepared from SiO2-0.3 delivered the highest reversible capacity (1427 mAh g–1 at 0.1 A g–1) after 50 discharge–charge cycles. Because of the unique hierarchically porous morphology of PSi prepared from SiO2-0.3, the expansion of its electrode thickness was suppressed below 140 %. Moreover, owing to its nanosized Si domains and good electrode wetting, PSi prepared from SiO2-0.3 demonstrated improved electrochemical properties compared with those prepared from SiO2-F and SiO2-K.

Environmental protection and performance enhancement of hydrocarbon compressor based vapour compression refrigeration system using dry powder SiO2 nanoparticles: an experimental analysis

Environmental protection and performance enhancement of hydrocarbon compressor based vapour compression refrigeration system using dry powder SiO2 nanoparticles: an experimental analysis

A way to control sintering deformation of Al2O3 components by gradient shrinkage

Sintering deformation is a great hindrance to the development of ceramic components with complex shapes. In this work, single-face coating method has been used to prepare the special shaped Al2O3 components by taking advantage of the difference in shrinkage between substrate and coating. By adjusting the content of SiO2 in the coating material which consisted of SiO2 and Al2O3 powder, the sintering deformation of Al2O3 ceramics coated with the above material would be controlled during the sintering process. The sintering behavior of Al2O3 green body with and without single-face coating were studied through visual in-situ tests combined with photographing technology. By comparing the images of specimens under different sintering temperatures (defined this method as the image relative method), the warped deformation and the shrinkage behavior of the above specimens were discussed. Moreover, the relationship between curvature radius and shrinkage rate was deduced. Results indicate that, due to the discrepancy in shrinkage of substrate and coating, the deformation of samples occurred in the heating process. And the shrinkage, the elasticity modulus and the ratio of the sectional coating area to substrate area play a major role in determining the shape of ceramics. The way to fabricate the shape controlled ceramic components by the gradient shrinkage is a novel and effective method, which can be used for the plate and shell products with complex shapes.

Preparation of porous β-Si3N4/Si5AlON7 composite ceramics for digital light processing and study of mechanical and dielectric properties

Porous β-Si3N4/Si5AlON7 composite ceramics are anticipated to serve as high-temperature wave-transparent materials, yet the fabrication of high-performance porous β-Si3N4/Si5AlON7 composite ceramics remains a significant challenge. Addressing this issue, this study introduces a technique for crafting high-performance porous β-Si3N4/Si5AlON7 composite ceramics. This method involves the homogeneous blending of SiO2 and Si3N4 powders, followed by digital light processing and high-temperature liquid-phase sintering at 2000 °C. The impact of SiO2 content on various properties of the ceramic slurry and the resultant ceramics was thoroughly examined, including rheology, curing depth, microstructural morphology, phase composition, flexural strength, hardness, dielectric constant, and dielectric loss. It was observed that a SiO2 content of 30 % enables the slurry to fulfill the criteria for digital light processing, leading to the production of porous β-Si3N4/Si5AlON7 composite ceramics that exhibit outstanding mechanical and dielectric properties. Specifically, these ceramics demonstrated a flexural strength of 149.2 ± 7.2 MPa and a hardness of 11.8 ± 1.1 GPa. Moreover, at a frequency of 10 GHz, the ceramics exhibited a dielectric constant of 4.02 and a dielectric loss of 0.11, highlighting their potential as high-temperature wave-transparent materials.

Enhanced synthesis of sponge-type multiwalled carbon nanotubes using SiO2-Fe2O3 catalysts via aerosol-assisted chemical vapor deposition: Electrochemical and absorption capacity studies

Carbon nanotube sponges synthesized at the laboratory scale typically use a Fe-based organometallic catalyst, but low-cost alternatives with a higher yield ratio are needed for large-scale production. This work introduces a catalyst made from a mixture of silicon dioxide (SiO2) and hematite (Fe2O3) as an innovative alternative for the high-yield production of spongy-type multi-walled carbon nanotubes (ST-MWCNTs). We used a ball-milled mixture of SiO2 and Fe2O3 powders as the catalyst and toluene and N, N-dimethylformamide as carbon and nitrogen sources in an aerosol-assisted catalytic chemical vapor deposition system. Incorporating SiO2 into the Fe-based catalyst increased production yield to 184 % of the catalyst weight. The synthesized ST-MWCNTs exhibited a high crystallinity ratio (ID/IG = 0.34) with a unique entangled bundle-type nanotube configuration. At the same time, the presence of Si atoms and oxygen-type functionalities, demonstrated by X-ray photoelectron spectroscopy, modified their electrochemical behavior, making them suitable for supercapacitor or sensor applications. Additionally, the spongy structure demonstrated a reversible absorption capacity of over 15 times its weight with organic solvents like gasoline or ethylene glycol. This new catalyst configuration opens alternatives for generating higher amounts of 3D carbon nanomaterials with potential energy storage, water filtration, and environmental remediation applications.

Extraction and green template-free synthesis of high-value mesoporous γ-Al2O3 and SiO2 powders from coal gangue

The study successfully demonstrated an eco-friendly approach for synthesizing mesoporous alumina and mesoporous silica from coal gangue, in line with green chemistry rules. By employing natural breakdown and increased dissolution of coal gangue through specific chemical treatments, along with optimal leaching conditions, this study achieved a dissolution efficiency of over 98% for aluminum. This process, which includes leaching, separation, simultaneous precipitation, selective dissolution, gel formation, and calcination, produced mesoporous alumina and mesoporous silica without the need for templates. The results presented that the synthesized mesoporous alumina and silica had purities of 98.81% and 99.08%, respectively. Additionally, the synthesized mesoporous alumina and silica had specific surface areas of 340.15 and 392.85 m2/g, and average pore sizes of 7.27 and 3.25 nm, confirming the desirable physical properties of the synthesized γ-Al2O3 and SiO2. These products offer a sustainable solution to environmental issues caused by coal accumulation, with promising applications across various industries.

Microstructure Analysis and Powder Bed Fusion of Inconel 738 Powder Materials Mixed with Nano-Sized Ceramic Powders

Powder materials strengthened by oxide dispersion are generally made by in-situ method; direct oxide dispersing in matrix powders during atomization. There is also ex-situ method; oxides dispersing by mixing with matrix powders. In this study powder mixtures (Inconel 738 matrix powder + SiO2 powder + Al2O3 powder) were mechanically manufactured by ex-situ process, a lowenergy ball milling method. Then, specimens of the as-mill powders were manufactured by laser powder bed fusion (L-PBF) method and spark plasma sintering (SPS) process. The microstructures of each prepared specimen were compared according to process variables. SEM, EDS, XRD, and Electron Backscatter Diffraction (EBSD) analyses were applied in this study.

Production of dense forsterite with ultra low dielectric loss using ZrO2 additive

Forsterite was synthesized with MgCO3 and SiO2 powders using a solid-state method at 1200–1300°C. The ceramic specimen with the highest forsterite phase content was sintered with the ZrO2 sintering aid at mass fractions of 0.5, 1.0, and 1.5 wt% at 1400°C for 4 h. The dielectric constant and loss tangent were also measured via the waveguide method at 8–12 GHz. The formation of enstatite and cristobalite was minimized through precise synthesis temperature control. Phase measurement by the Rietveld method showed that specimen F28 contained more than 99.8% forsterite. It was found that ZrO2 reduced the pore volume percent and increased the density even at low mass fractions. A liquid phase on the grain boundaries was demonstrated. The solid ceramic specimen F28-15Z showed a dielectric constant of 6.5 and high quality factor of 189000.

Growth of CsPbX3 nanocrystals using sol–gel SiO2 solid powders as reactors without capping agents towards anomalous stable emission membranes

To overcome the poor stability of metal halide perovskite nanocrystals (NCs) prepared in organic solvents, a solid reaction method at high temperature was developed using sol–gel porous SiO2 as a reactor. Sol-gel SiO2 powders were used to encapsulate CsPbX3 NCs at high temperatures (600–800 °C) in air to get SiO2/CsPbX3 glass by dispersing growth cites in advance and no ligands added. After NaOH etching, a thin dense SiO2 shell was remained on the surface of CsPbX3 NCs (named as CsPbX3@SiO2).The photoluminescence (PL) quantum yield of the CsPbX3@SiO2 was 86.7 %, in which their PL peak wavelengths were adjusted from 410-707 nm by changing halogen components. The dense SiO2 shell on CsPbX3 NCs blocked the connection of CsPbX3 cores with water and oxygen in the external environment, resulting in CsPbX3@SiO2 revealed extraordinary high stability. After immersing in water for half year, the PL intensity of CsPbX3@SiO2 composites was remained unchanged and the composites still revealed bright PL after heat-treating in boiling water for 14 h. These highly stable composites were used to fabricate a white light-emitting diode, in which the color coordinates are located at (0.36, 0.33), and the color temperature reaches 5169 K which belongs to the warm white light range.

Preparation of a Gradient Anti-Oxidation Coating for Aircraft C/C Composite Brake Disc and Its High-Temperature In Situ Self-Healing Performance.

We studied a gradient anti-oxidation coating of C/C composite materials for aircraft brake discs with a simple process and low costs. The gradient coating consists of two layers, of which the inner layer is prepared with tetraethyl orthosilicate (Si (OC2H5)4), C2H5OH, H3PO4 and B4C, and the outer layer is prepared with Na2B4O7.10H2O, B2O3, and SiO2 powder. The experimental results show that after being oxidized at 700 °C for 15 h, the oxidation weight loss of the sample with the coating was only -0.17%. At the same time, after 50 thermal cycles in air at 900 °C, the sample's oxidation weight loss was only -0.06%. We conducted the 1:1 dynamic simulation test for aircraft brake discs, and the brake disc did not oxidize, thus meeting the requirements for aircraft use. In addition, the anti-oxidation mechanism of the coating was analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal analysis (DSC-TGA), and high-temperature in situ SEM.

Effect of annealing temperature for structural, electrical, and ammonia sensing properties of pristine ZnO and ZnO/SiO2 nanoparticles

The main objective of this research was to study the electrical and gas-sensing properties of Zinc oxide (ZnO) nanoparticles. The samples were divided into two conditions in the preparation process. In the first condition, ZnO powder was annealed at temperatures of 650, 700, and 750 ๐C for 2 h, while the second condition involved mixing ZnO powder with SiO2 powder and annealing at temperatures of 650, 700 and 750 ๐C for 2 h. The characteristics of the prepared samples were studied by scanning electron microscopy (SEM) and the X-ray diffraction technique (XRD). The SEM images showed the agglomeration of the particles with micron-sized diameters. In addition, the XRD patterns of all samples exhibited the hexagonal structure of ZnO. Assessment of the electrical properties of the samples was carried out by forward bias from 0 – 15 V and reverse bias from 0 V to -15 V. The I – V characteristic curves showed diode-like rectifying behavior.The gas-sensing property of the samples was investigated by using ammonia gas, and ZnO nanoparticles annealed at 750 ºC for 2 h were found to have the highest sensitivity.

3D printing of high-purity complex SiC structures based on stereolithography

Complex Silicon carbide (SiC) structures are hardly achievable via traditional manufacturing methods, while stereolithography 3D printing technology effectively shapes sophisticated structures with high precision. However, it is a huge challenge to prepare SiC slurry for stereolithography 3D printing with excellent curing ability due to the increased light absorption of SiC powder. Therefore, a novel approach to fabricating high-purity SiC structures is proposed in this study based on the stereolithography 3D printing process, where SiO2 powder is used as an additive to increase the curing thickness from 27.8 μm to 53.0 μm. Moreover, phenolic epoxy resin (PEA) is introduced as a carbon source to transform SiO2 to SiC during sintering. As a result, there is almost no SiO2 phase or SiOC remaining in the final parts when the addition of PEA reaches 50 wt% related to the resin weight after sintering at 1600 °C for 4 h. Based on the SiC/SiO2/PEA slurry systems prepared, high-purity silicon carbide with complex structures can be successfully fabricated in one step without any pre-oxidation or precursor impregnation processes. This approach provides valuable insights into additive manufacturing of high-purity complex SiC structures.

Synthesis of spherical SiO2 powders from water glass and colloidal Sol through ultrasonic spray pyrolysis

Synthesis of spherical SiO2 powders from water glass and colloidal Sol through ultrasonic spray pyrolysis

Hydrophobic and antibacterial properties of textiles using nanocomposite chitosan and SiO2 from rice husk ash as-coating

This research aims to develop hydrophobic and antibacterial properties of textiles using chitosan and silica oxide (SiO2) nanocomposite coating. SiO2 was extracted from rice husk ash and chitosan from crustacean shells. SiO2 and chitosan powder were pulverized using High Energy Milling (HEM). The nanocomposite was synthesized using the sol-gel method with concentration variations of 0.2 %:0.4 %, 0.4 %:0.6 %, 0.6 %:0.8 %, and 0.8 %:1 %. Textile coating was carried out by dip coating method with variations of 1x, 2x, 3x, and 4x dyeing. The crystal structure and size of the nanocomposites were obtained using X-ray Diffraction (XRD). Surface morphology and particle size were obtained using a Scanning Electron Microscope (SEM). The contact angle was measured using the sessile drop method. The bacterial activity tests were conducted by measuring the surface temperature of textiles with a thermal camera after being irradiated with UV-C. The ability of textiles to inhibit bacterial growth was tested using Staphylococcus aureus bacteria. The results showed that the smallest crystal size obtained was 30.21 nm. The amount of particle size and contact angle are significantly influenced by the quality of Citosan-SiO2 and coloring changes. The smallest particle size obtained is 32 nm. The highest value of contact angle obtained was 161° The average surface temperature of the textile after being irradiated with UV-C reached 40.7 °C. The highest zone of inhibition obtained was 17 mm and is in the strong category. This research shows that textiles coated with chitosan-SiO2 can inhibit bacterial growth and have potential applications in the clothing industry.

Porous MCM‐41 Silica Materials as Scaffolds for Silicon‐based Lithium‐ion Battery Anodes

AbstractAiming for specific energy improvements, lithium‐ion battery (LIB) research explores Si based materials as potential alternatives for the negative electrode/anode. Si exhibits a high specific capacity when lithiated, accompanied by a large volumetric expansion. To mitigate expansion induced failures, composite materials with finely distributed Si inside a scaffold have been established. Potential scaffolds to create such Si composites are nano porous SiO2 materials, such as MCM‐41. MCM‐41 exhibits a fine nanostructure, and the synthesis allows precise tuning of the pore properties and thus, after filling with Si, of Si morphology and Si content in the composite. In this work, insights into relevant MCM‐41 synthesis parameters are acquired, with special attention towards specific pore volumes and pore sizes of the SiO2 powders. Materials characterization is performed using nitrogen sorption analysis, X‐ray scattering, electron microscopy and thermogravimetric analysis. Selected MCM‐41 scaffolds are processed to Si composites and integrated into LIB electrodes. The specific capacity and the stability of the Si−SiO2 composites are evaluated by PITT and galvanostatic cycling. They show capacities above 800 mAh g−1, i. e. more than twice the specific capacity of industry standard graphite, and last over 200 charge/discharge cycles before their capacity loss exceeds 25 %.

Nonoxidative dehydrogenation of propane using boron-incorporated silica-supported Pt Sites synthesized by atomic layer deposition.

Nonoxidative dehydrogenation of propane to propylene using Pt-based supported catalysts is an active research area in catalysis because catalyst attributes of Pt sites can be controlled by careful design of active sites. One way to achieve this is by the addition of a second metal that may impart a change in the electron density of active sites, which in turn affects catalytic performance. In this study, bimetallic Pt and B sites were deposited on powder SiO2 using atomic layer deposition (ALD). Boron was first deposited on SiO2 via half-cycle ALD using triisoproplyborate as the B source. Following calcination, Pt deposition was performed via half-cycle ALD using trimethyl(methylcyclopentadienyl)platinum(IV) as the Pt source. The synthesized catalysts were reduced under H2 at 550 °C and characterized using inductively coupled plasma optical emission spectroscopy for elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO to examine the properties of Pt, and time-resolved X-ray absorption near edge structure spectroscopy to examine the changes in the reducibility of Pt sites. The samples were then tested for nonoxidative dehydrogenation of propane at 550 °C using a fixed-bed plug-flow reactor to examine the role of B on the catalytic performance. Characterization results showed that the addition of B imparted an increase in electron density and affected the reducibility of Pt sites. In addition, incorporating B on SiO2 created anchoring sites for Pt ALD. The amount of Pt deposited on B/SiO2 was 2.2 times that on SiO2. Catalytic activity results revealed the addition of B did not change the initial activity of Pt sites significantly, but improved propylene selectivity from 80% to 87% and stability almost threefold. The enhanced selectivity and stability of PtB/SiO2 is most presumably due to favored desorption of propylene and mitigating coke formation under reaction conditions, respectively.