Silica Inclusions Research Articles

Green synthesized metal nanoparticle incorporated titania silica and its application in the photodegradation of Rhodamine B

Photocatalytic activity of Titania has a very intriguing mechanism with numerous potential uses such as air and water cleaning. The inclusion of silica improves its catalytic capabilities. The use of titania silica nanoparticles for photocatalytic activity in environmental applications is limited due to their activity in the UV region rather than the visible range. Titania silica nanoparticles were synthesised using the sol-gel method. Metal nanoparticles of vanadium, manganese and silver were synthesised and integrated into the titania silica using a green method. To clarify the structure property correlations for titania silica materials, several characterisation techniques such as SEM-EDAX, IR analysis, UV-Visible spectroscopy and XRD were applied. The photocatalytic activities of titania alone, titania silica and titania silica including the various metals were studied.

Review on Impact of Nano Silica Inclusion on Fresh and Hardened Properties of Self Compacting Concrete.

Abstract In the building sector of days, one of the buzzwords is self-compacting concrete. One of the more sophisticated results of concrete research is SCC, which has the ability to compact on its own weight without exhibiting segregation or bleeding and can flow readily through extremely crowded areas of reinforcement. the assessment of silica’s impact on the properties of both fresh and hardened concrete in self-compacting concrete (SCC). Workability, durability, and mechanical characteristics of self-compacting parks (SCC). In the experiment, various weight percentages of nano-silica—between 1% and 6%—were added to concrete as a cement-priming step. This experiment aims to investigate the effects of varying nano-carbon dioxide contents. Regarding the characteristics of concrete.

Investigation of Inclusion Characteristics in Ferrosilicon Killed High Silicon Steels

Industrially, the silicon requirement of liquid steel is often met with ferrosilicon (FeSi) instead of high‐purity silicon addition. FeSi, a silicon‐rich alloy, contains impurities typically inherited from its manufacturing stage. Therefore, FeSi addition results in the formation of complex inclusions in the liquid steel. Herein, a detailed inclusion characterization of the samples obtained from the melting experiments for a wide range of silicon concentrations has been carried out to examine the effect of FeSi impurities. Pure silica inclusions evolve to silica‐ and/or alumina‐based Si–Al–(Ti)–O–(TiN) complex inclusions with the increasing addition of FeSi to the steel melt. Reduction of silica by aluminum or titanium, the presence of titanium in the steel melt, and/or TiN inclusions formed at the periphery of oxide inclusions restrict the growth of oxide inclusions, resulting in small‐sized (average) oxide inclusions. The underlying mechanism of such complex (Si–Al–Ti–O–N)‐based inclusions has been explained with the aid of microstructural characterization and thermodynamic calculations. Moreover, the steel–crucible (alumina) interface has also been investigated for inclusion deposits and crucible–steel interaction.

An experimental study on high strength self-compacting concrete inclusion of zeolite and silica fume as a potential alternative sustainable cementitious materials

One of the major sources of carbon dioxide and other greenhouse gases around the world is the cement industry. They make up 6–8 % of global warming. Therefore, by conducting this experiment, we may examine the possibility of replacing cement with different cementitious materials which include zeolite,silica fume and fly ash. These mineral additives will lessen the need for cement while enhancing the properties of the concrete that has just been hardened and also in fresh state. The objective of this experiment is to explore the impact of zeolite and silica fume on the physical and durability qualitiesof high strength, self-compacting concrete utilising nano silica that has been optimised. In the course of this study, various concrete mixtures were cast with zeolite and silica fume substituted for cement in varying amounts, and there was also a control mix for reference. These additives arereplacedcement in multiples of 5 up to 20 %. The preferred dosage as 2 % Nano silica is substituted as a regular mineral additive in all mixtures. Workability tests on the fresh qualities of concrete mixtures are conducted and the EFNARC stipulations are met by these experimental findings. All the concrete mixes' parameters, including strengths like splitting tensile and compressive were identified. Tests such as the Rapid chloride permeability test, the abrasion test, water absorption and desorption test were used to evaluate the concrete's durability.

Smart sustainable concrete: enhancing the strength and durability with nano silica

A detailed investigation was conducted to analyse the mechanical and durability features of a mixture of binary cement concrete modified with nanomaterials. In the context of the concrete matrix, the substitution of fractional cement content was carried out using Nano silica (NS) at concentrations of 1%, 2%, and 3%. Four distinct cementitious blends were subjected to a comprehensive match of tests, which encompassed compressive strength, flexural strength, split tensile strength, static modulus of elasticity, bulk density, water absorption, permeability, carbonation resistance, acid attack resistance, and rapid chloride penetration. The compositions of the mixes were investigated through the use of various microstructural analysis techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (SEM-EDS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The research revealed significant improvements in the mechanical and durability characteristics of the material. An increment in the mechanical and durability properties of mixtures were seen due to inclusion of marble power and Nano silica due to enhanced pozzolanic activities of composite and its filling effect. It is worth mentioning that Nano silica has shown the potential to mitigate the degradation caused by exposure to sulfuric acid. The SEM-EDX analysis demonstrated a decrease in the Ca/Si ratio when compared to the reference combination, suggesting an increase in the consumption of calcium hydroxide (CH) and the creation of a more compact calcium-silicate-hydrate (C-S-H) gel. The X-ray diffraction (XRD) findings indicate that NS has the ability to act as an accelerator for pozzolanic processes. This is achieved by consuming calcium hydroxide (CH) and promoting the creation of extra calcium silicate hydrate (C-S-H), which ultimately enhances the overall performance of the concrete mixture.

Investigation On Tensile Properties Of Aluminum 7075 - Silica Particles -Boron Fiber- Reinforced Hybrid Metal Matrix Composites

Hybrid metal matrix composites (MMCs), particularly those using an Aluminum 7075 (Al7075) base combined with silica particles and boron fibers, have emerged as a focal point in engineering for their superior strength-to-weight ratio. This study examines a composite of Al7075 reinforced with varying amounts of silica particles (0%, 2%, 4%, 6%) and boron fibers (1%, 3%, 5%, 7%). The research aims to discern the impact of these reinforcements on the composite's tensile properties. Employing the stir casting technique, these reinforcements were melted into the Al7075 matrix. The composites underwent tensile testing to gauge their mechanical performance, with a tensometer measuring tensile strength. The findings indicate that the inclusion of silica and boron fibers enhances tensile strength, with the greatest increase of 43.5% rise in tensile stress observed in the sample with 6% silica and 7% boron fiber. Variance analysis reveals that silica contributes 85.51% to the strength, boron fiber contributes 12.70%, and there is an error margin of 1.49%. Furthermore, a comparison of experimental, regression, and Artificial Neural Network (ANN) predicted values confirms consistency within an error margin of 5.86%.

Room-temperature strength of the interfacial bond between silica inclusions and iron

The strength of the interface between iron (Fe) and individual spherical silica (SiO2) inclusions of 5 ± 1 µm diameter is measured by means of in-situ micro-cantilever bending tests conducted under displacement control within a scanning electron microscope, using a wedge indenter tip. Attention is paid to ensure that reported data are not affected by either the electron beam during in-situ testing or by focused ion beam milling, used to produce the cantilevers. For the latter, a simple yet effective strategy, validated using finite element modeling, is devised to shift the peak interfacial stress towards the beam center, thereby relocating the fracture initiation position away from potential FIB-induced artefacts at the beam edge. All bend beams tested fractured along the Fe/SiO2 interface, with no visible evidence of silica microcracking or iron plastic deformation. The rapidly cooled iron matrix features a submicron ferrite grain size, causing its yield strength to exceed 1 GPa. Using classical Euler-Bernoulli beam theory, the estimated Fe/SiO2 interfacial tensile strength yields values ranging from 0.9 to 2.3 GPa, proving that SiO2 inclusions are strongly bonded to the Fe matrix at room-temperature. There is, thus, potential for engineering inclusion-containing Fe-based alloys that, under monotonic loading conditions, do not compromise the mechanical integrity of the ferrous matrix.

Advancing the mechanical integrity and fragmentation behavior of reactive projectiles

A multivariant statistical approach was used to identify treatment conditions that improve the survivability of structural reactive material (SRM) projectiles upon launch and enhance energy release upon impact. The study included both mechanical testing of projectiles as well as their reactive characterization. The projectiles were launched in a high-velocity impact-ignition testing system and impacted an anvil for vented chamber calorimetry. This study examined a link between ultimate compressive stress and combustion performance. Two treatments were applied to consolidated aluminum projectiles including annealing and addition of silica (SiO2) inclusions. Results showed annealing at moderate temperatures resulted in intact SRM projectiles upon launch. Adding small concentrations (1–2 wt. %) of SiO2 to the SRM promoted fragmentation and combustion performance upon impact. Compared to the untreated projectiles, annealing with SiO2 inclusion processing treatments improved the energy conversion efficiency from 37–84% (for untreated projectiles) up to 54–98%. Increasing interparticle dislocation recovery by annealing while balancing inclusions promoting fragmentation upon impact was the key to optimizing combustion performance for SRM ballistic impact applications.

Properties of concrete with partial replacement of cement with different percentages of micro silica and nano silica

Researchers are continuously investigating new sustainable alternatives to cement to reduce the harmful environmental impacts of the concrete industry. Particularly, the studies mainly focus on the effect of fully or partially replacing cement with recycled or different types of materials on the mechanical properties of concrete. Out of the various materials investigated, the inclusion of micro silica (MS) and nano silica (NS) to partially replace cement has shown promising results. However, more research is still required to determine the suitable quantity of MS and NS in the concrete mix without adversely affecting its strength. Therefore, this research aims at studying the effect of partially replacing cement with MS and NS to enhance the strength and workability of concrete. The influence of different percentages of MS and NS in the concrete mix was investigated. Two types of tests were performed on five concrete mixes to find the optimum concrete mix including slump tests and compressive strength tests. Test results showed that the addition of NS was beneficial in terms of improving the workability of the concrete mix. In fact, the highest enhancement in the slump value was in the mix that had 8% MS and 2% NS with 28% increase compared to the control mix, followed by 9% MS and 1% NS mix with 26% increase. In addition, using 9% of MS and 1% of NS provided the highest enhancement in the compressive strength with 40.7% improvement compared to the control mix. Therefore, based on the results of this study, it is recommended to partially replace cement with 9% MS and 1% NS to improve the overall performance of concrete.

Hydrogel-Inducing Graphene-Oxide-Derived Core-Shell Fiber Composite for Antibacterial Wound Dressing.

The study reveals the polymer-crosslinker interactions and functionality of hydrophilic nanofibers for antibacterial wound coatings. Coaxial electrospinning leverages a drug encapsulation protocol for a core-shell fiber composite with a core derived from polyvinyl alcohol and polyethylene glycol with amorphous silica (PVA-PEG-SiO2), and a shell originating from polyvinyl alcohol and graphene oxide (PVA-GO). Crosslinking with GO and SiO2 initiates the hydrogel transition for the fiber composite upon contact with moisture, which aims to optimize the drug release. The effect of hydrogel-inducing additives on the drug kinetics is evaluated in the case of chlorhexidine digluconate (CHX) encapsulation in the core of core-shell fiber composite PVA-PEG-SiO2-1x-CHX@PVA-GO. The release rate is assessed with the zero, first-order, Higuchi, and Korsmeyer-Peppas kinetic models, where the inclusion of crosslinking silica provides a longer degradation and release rate. CHX medicated core-shell composite provides sustainable antibacterial activity against Staphylococcus aureus.

Libyan Desert Glass: New evidence for an extremely high-pressure-temperature impact event from nanostructural study

Abstract The origin of Libyan Desert Glass (LDG) found in the western parts of Egypt close to the Libyan border is debated in planetary science. Two major theories of its formation are currently competing: (1) melting by airburst and (2) formation by impact-related melting. While mineralogical and textural evidence for a high-temperature event responsible for the LDG formation is abundant and convincing, minerals and textures indicating high shock pressure have been scarce. This paper provides a nanostructural study of the LDG, showing new evidence of its high-pressure and high-temperature origin. We mainly focused on the investigation of Zr-bearing and phosphate aggregates enclosed within LDG. Micro- and nanostructural evidence obtained with transmission electron microscopy (TEM) are spherical inclusions of cubic, tetragonal, and orthorhombic (Pnma or OII) zirconia after zircon, which indicate high-pressure, high-temperature decomposition of zircon and possibly, melting of ZrO2. Inclusions of amorphous silica and amorphous Al-phosphate with berlinite composition (AlPO4) within mosaic whitlockite and monazite aggregates point at decomposition and melting of phosphates, which formed an emulsion with SiO2 melt. The estimated temperature of the LDG melts was above 2750 °C, approaching the point of SiO2 boiling. The variety of textures with different degrees of quenching immediately next to each other suggests an extreme thermal gradient that existed in LDG through radiation cooling. Additionally, the presence of quenched orthorhombic OII ZrO2 provides direct evidence of high-pressure (>13.5 GPa) conditions, confirming theory 2, the hypervelocity impact origin of the LDG.

Characteristics of various non-metallic inclusions in ancient cast iron and solid-state decarburized iron products from a government-run iron workshop during the Han Dynasty in Dongpingling Ruins, Shandong Province

With low content of impurity elements and the near absence of large slag inclusions, ancient Chinese cast iron used to be viewed as a kind of pure iron material. Thus, some crucial non-metallic inclusions in cast iron had been missed in previous studies. Here, we dedicated to analyze a series of pig iron and solid-state decarburized iron implements excavated from a Han dynasty official iron workshop at the Dongpingling site, and proposed to reveal the characteristics of non-metallic inclusions in these iron products. Judging by low impurity elements, the iron samples were identified with 5 categories of non-metallic inclusions, including silicate inclusions, sulfide inclusions, silica inclusions, endogenous oxide inclusions (agglomeration of multiple oxide) and those recombined by them. In addition, formation mechanism of each inclusion has been discussed as well.

Strong silicon oxide inclusions in iron

Oxide inclusions are ubiquitous in steel and are known to affect, generally in a negative sense, the mechanical performance of steel products. Micromechanical properties of those phases are therefore important, yet they have remained largely unexplored. We present strength measurements performed on individual silicon oxide inclusions in iron. The inclusions are produced in laboratory-fabricated samples by silicon deoxidation of high-purity iron melts containing dissolved oxygen. Spherical silica inclusions of diameter ∼3 µm thus produced are notched using ion milling and then tested in bending for their strength, by loading under displacement control in-situ within a scanning electron microscope. Results show that silicon oxide inclusions thus precipitated within iron are amorphous in structure, exhibit a smooth outer surface, and have fracture strains in the range from 8 to 17%, corresponding to fracture stress levels on the order of 10 GPa. The strength of silicon oxide inclusions precipitated in iron can hence approach the highest values so far measured in dry silica. The presence within iron and its alloys of precipitated silica thus need not be deleterious, and might perhaps even be exploited to produce novel high-strength materials.

Effect of silica fume inclusion on the strength, shrinkage and durability characteristics of natural pozzolan-based cement concrete

In the present work, effect of inclusion of silica fume on the performance of natural pozzolan-based cement concrete was investigated. Natural pozzolan, obtained from volcanic rocks, was used as the main supplementary cementitious material to partially replace the Portland cement. Silica fume was admixed at an optimum dosage, optimally selected based on the performance of several trial mixtures, in an attempt to improve the performance of the natural pozzolan-based cement concrete. Compressive strength, drying shrinkage, water penetration depth, coefficient of chloride diffusion, carbonation depth, reinforcement corrosion, loss of strength due to exposure to sulfate and salt weathering were measured to evaluate the performance of the concrete mixtures. Inclusion of silica fume to the blend of natural pozzolan and Portland cement significantly improved the performance of concrete. Reduction in the early age compressive strength of natural pozzolan-based cement concrete was compensated for by the addition of silica fume. Inclusion of silica fume to the natural pozzolan-based concrete significantly improved the durability characteristics without significant increase in the shrinkage. Though the addition of silica fume increased the carbonation depth, the increased carbonation depth was much less than the cover thickness normally provided over reinforcing steel, ruling out the possibility of reinforcement corrosion.

Development of drying shrinkage model for alkali-activated slag concrete

The current study aims to develop a drying shrinkage model for alkali-activated slag concrete (AASC). Three water-to-binder (W/B) ratios (0.44, 0.47 and 0.50), two fly ash contents (0 and 25%) and three silica fume contents (0, 5% and 15%) were studied. Slump, compressive strength and the drying shrinkage test lasting for over 300 d were performed. The results showed that: (1) Increasing both the W/B ratio and fly ash content increased the slump of the concrete, while a 5%-10% silica fume had little effect; (2) The compressive strength of the concrete was decreased with increasing both the W/B ratio and fly ash content, while it was improved with the addition of 5% silica fume; (3) Inclusions of fly ash and silica fume contributed to the reduction of the final drying shrinkage; (4) The current prediction models for drying shrinkage behavior of Portland cement-based concrete was not suitable for AASCs. Based on the results, a novel drying shrinkage prediction model with higher reliability for sodium silicate-activated slag-based concrete cured at the standard environment (20 ± 2 °C and RH of 60 ± 5 %) was developed, which is mainly derived from the model of ACI 209. The well-fitted results of this developed model fully indicated the relatively wide applicability of this model. However, given the complexity of the binder composition of AASC, this model still needs to be further upgraded in future.

Effect on mechanical, durability and micro structural properties of high strength self compacting concrete with inclusion of micro and nano silica

The aim is to study the strength, durability and microstructural properties of high strength self compacting concrete (SCC). 25% cement is replaced by fly ash (10%) and Ground granulated blast furnace slag (GGBS) (15%) for all the mixes except control mix (M1). Micro silica (MS) and Nano silica (NS) were added at different percentages to make high strength SCC. As a cost reduction and to promote renewable material Manufactured Sand (M-Sand) used as a fine aggregate instead river sand. To determine the fresh properties of SCC followed the EFNARC 2002 guidelines. The Compressive strength test was conducted to find strength properties of SCC. The results showed that addition of MS and NS drastically decreases the fresh properties but increases the strength properties of SCC. Ultrasonic pulse velocity test was conducted to find dynamic modulus of SCC. To find the resistance of chloride ingress in to concrete by conducting Rapid chloride permeability test (RCPT). Further microstructure of SCC studied using SEM images. Finally cost analysis was performed for each mix and its results indicated as ratio of strength/cost. The combination of MS and NS in a mix (M7) showed the optimum compressive value, optimum durability and improved micro structure among all the mixes. But in ratio of strength/cost a mix M2 showed optimum result.

Prediction of strength and shrinkage of ternary blended concrete with fly ash, slag and silica fume

In the recent years, there has been increased in concern on shrinkage response of concrete systems as abundant cases of premature deterioration were reported. The major factors affecting the deterioration of a concrete system are quality, composition and the surrounding environment. In connection with this, the work concentrates on the study of long-term effects on materials used in the concrete (supplementary cementitious materials SCMs) such as fly ash, slag and silica fume as a blended concrete system. To carry out the experimental work, nine concrete mixes were designed for varying proportions of SCMs and w/b. Evolution of compressive strength, elastic modulus, shrinkage and selected durability parameters were tested under a controlled laboratory condition. Based on the work, it was found that the inclusion of fly ash, slag and silica fume on the concrete systems enhance the compressive strength in long-term, also the shrinkage response of the ternary systems shows a substantial reduction in the measured strain. Durability performance like chloride penetration and sorptivity had a better performance in comparison with the conventional concrete systems.

Parametric Effects on Slump and Compressive Strength Properties of Geopolymer Concrete using Taguchi Method

This paper represents the parametric effects on slump and compressive strength of aluminosilicate based Geopolymer concrete using by Taguchi method. A total of nine mix proportions were considered to evaluate the effect of sodium hydroxide (NaOH) solution, Solution/Binder (SB) ratio and the percentage of superplasticizer. Results indicated that the highest slump of 165 mm and 28 days compressive strength of 68.37 MPa was obtained for aluminosilicate based Geopolymer concrete with the superplasticizer, Solution to Binder (SB) ratio and extra water) parameters. By using the selected (Signal-to-Noise (SN) ratio graphs, the best combination of parameters for slump and compressive strength properties was also obtained. The mix with the best combination of parameters was considered and partially replaced with silica fume and rice husk ash. The inclusion of additional silica (in form of silica fume and rice husk ash as Ground Granulated Blast Furnace Slag (GGBFS) replacement), most significantly influenced the slump and compressive strength properties.

Chemical stability of hollow glass microspheres in cementitious syntactic foams

Recent studies have shown cementitious syntactic foams (CSF) to have great potential as a low density and high strength structural material. However, CSFs are made with hollow glass microsphere (HGM) inclusions and cementitious materials with amorphous silica inclusions such as glass are known to have a potential for the deleterious alkali silica reaction (ASR). In this study, CSFs containing HGMs are tested for ASR expansion and compressive strength along with solid particles of soda-lime and borosilicate glass to compare. Results show that in the 30–90 μm average particle size range, only solid borosilicate particles lead to more than 0.2% expansion of the composite material in an accelerated ASTM C1260 lab test for ASR, which is considered as the limit for deleterious effects. Similarly, compressive strength tests show that only solid borosilicate particles lead to reduced compressive strengths (from ~95 to ~40 MPa) in the long term, while CSFs showed no sign of loss of compressive strength even at extremely alkaline conditions. Scanning electron microscopy investigations suggest that CSFs are safe from ASR expansion of the composite and internal stresses due to their hollow geometry, which provides reservoir space for the alkaline silica gel expansion and mitigates the ASR effects.

Effect of silica fume on the ultrasonic pulse velocity of cemented sand

One of the geotechnical engineering strategies for dealing with weak soils in a construction site is to modify their mechanical properties with the aid of soil improvement techniques. Chemical stabilization of soil using cement is one of these effective approaches that can considerably enhance workability and shear strength parameters of soil. However, very limited investigations have been carried out to reveal the effect of silica fume on the ultrasonic pulse velocity (UPV) and the ultrasonic stiffness (Eu) of cement-treated sandy soil. For this purpose, in the present research, a series of UPV tests were performed on sand-cement-silica fume specimens. The cement percentages were 3, 5 and 7% and silica fume contents were 0, 0.25, 0.5 and 1% by weight of dry sand. The cylindrical samples were prepared and cured for 3, 7, 14, 28, 42 and 56 days and tested. The results show that inclusion of silica fume to the cemented sand increases UPV and Eu which this enhancement is more pronounced at longer ages.