What Is Silica Sol: Mechanism of Action, Application Scenarios, and Selection Criteria for Nanosilica Dispersions
What Is Silica Sol: Mechanism of Action, Application Scenarios, and Selection Criteria for Nanosilica Dispersions
1. What is silica sol?
Silica sol is a stable colloidal dispersion formed by dispersing nanoscale amorphous silica particles in water. Its main components are silicon dioxide (SiO₂) and water. Its appearance may be transparent, translucent, milky white, or opalescent, depending on particle size, solids content, and dispersion state.
Silica sol is not a suspension made simply by adding ordinary silica powder to water. Ordinary powder dispersions tend to settle and agglomerate, and usually require additional dispersants or mechanical dispersion to maintain their state. In silica sol, the silica particles a re already at the colloidal scale. Most conventional aqueous silica sols rely on surface charge and a hydration layer on the particles to maintain stability. There are also different grades, such as acidic, deionized, aluminum-modified, silane-modified, or sterically stabilized types, which can remain stable under appropriate pH, ionic strength, and storage conditions.
Several easily confused materials should be distinguished:
Material | Main form | Difference from silica sol |
Silica sol | Aqueous colloidal dispersion | Nanosilica particles are already stably dispersed in water and can be used directly in slurries, coatings, impregnation liquids, polishing slurries, and other systems. |
Silica gel | Gel or dried porous solid | Mostly used for adsorption, drying, carriers, and related purposes; it is not a liquid colloidal dispersion. |
Water glass | Sodium silicate or potassium silicate solution | A soluble silicate system with obvious alkalinity and ionic characteristics; it is not equivalent to colloidal silica. |
Precipitated silica and fumed silica | Powder | Require redispersion before use; their dispersion difficulty, viscosity behavior, and formulation behavior differ from those of silica sol. |
The core feature of silica sol is that it is a flowable liquid dispersion during use, and after drying, gelation, or heat treatment, it can transform into a silica-based inorganic structure.
2. Why can silica sol provide bonding, film-forming, and reinforcement effects?
The function of silica sol comes from the dispersion, contact, dehydration, aggregation, and network formation of nanosilica particles within a material system. It is not an ordinary organic adhesive, but a material that can form inorganic connections at interfaces, within pores, and between particles.
① Small particles allow entry into fine spaces.
Silica sol particles are usually at the nanoscale and can enter gaps between powder particles, pores in porous materials, fiber surfaces, and microstructures in coatings. This makes silica sol suitable for impregnation, pore filling, coating, slurry preparation, polishing, and inorganic material forming.
② Surface silanol groups enable interaction with inorganic interfaces.
Silica particles have silanol groups on their surfaces, which can interact with ceramic powders, metal oxides, glass, mineral fillers, refractory materials, and other surfaces through adsorption, hydrogen bonding, or condensation-related interactions. As water evaporates and particles come closer together, the particles form inorganic bonding structures through contact packing, hydrogen bonding, silanol condensation, and further strengthening of the siloxane network during subsequent heat treatment.
③ The liquid state makes processing easier.
Silica sol can enter material systems through mixing, impregnation, spraying, brushing, coating, pouring, polishing, and other processes. It provides fluidity at the formulation stage and leaves behind a silica structure after drying or heat treatment.
④ An inorganic skeleton forms after drying or heat treatment.
In casting shells, ceramics, refractory materials, and catalyst shaping, silica sol can connect powders or particles into structures with mechanical strength. In coatings, it can improve hardness, wear resistance, and heat resistance. In polishing systems, it can influence material removal and surface quality through both particle action and surface chemistry.
3. Where is silica sol mainly used?
The applications of silica sol can be understood according to its function in a system. In different scenarios, silica sol plays different roles, and the required product specifications also differ.
Functional role | Typical application direction | Problem solved |
Inorganic binder | Investment casting shells, ceramics, refractory materials, catalyst shaping | Binds inorganic powders, refractory particles, or fibers into structures with mechanical strength. |
Film-forming and surface modification component | Waterborne coatings, silicate coatings, packaging coatings, wear-resistant coatings | Improves coating hardness, wear resistance, stain resistance, anti-blocking properties, or heat resistance. |
Pore-filling and reinforcing material | Concrete, floor coatings, porous inorganic materials, ground and rock reinforcement | Enters pores and forms silica-based structures, improving density, strength, and durability. |
Polishing and precision processing material | Surface treatment of semiconductors, glass, sapphire, metals, and precision substrates | Controls removal rate, roughness, and surface defects through particle size, pH, and dispersion state. |
Catalyst and carrier-related material | Catalyst binder, carrier shaping, spray-forming aid | Provides shaping strength, thermal stability, and adjustable pore structure. |
Dispersion, flocculation, and interface-control material | Pigment dispersion, papermaking, fiber treatment, liquid-system purification | Uses surface charge and interparticle interactions to regulate system stability or flocculation behavior. |
In these applications, silica sol does not play the same role in every system. In investment casting, the key concerns are slurry stability, dry strength, and high-temperature shell performance. In coatings, the focus is film uniformity, surface hardness, and compatibility. In precision polishing, the focus is particle size distribution, impurity control, and surface defects. In catalyst shaping, the focus is shaping strength, pore structure, and ionic residues.
4. Typical example: What problems does silica sol solve in investment casting?
Investment casting is a representative application of silica sol. During shell making, refractory powders need to be formulated into a slurry. Through dipping or coating, stuccoing, drying, and firing, a ceramic shell capable of withstanding metal pouring is formed. The shell must have sufficient strength, good dimensional stability, and good surface quality.
In this system, silica sol mainly solves four types of problems:
Problem in the shell-making process | Role of silica sol |
Refractory powders need to form a slurry suitable for coating | Provides an aqueous dispersion medium and bonding foundation, giving the slurry workable application properties. |
The face coat needs to conform to the wax pattern and form a fine surface | Nanosilica particles help form a relatively uniform face-coat structure. |
The shell needs initial strength after drying | Colloidal particles form inorganic bonding between particles after dehydration. |
The shell needs heat resistance and deformation resistance during firing and pouring | The silica network and refractory materials jointly provide structural support. |
In this example, silica sol does not solve only a single bonding problem. It simultaneously affects slurry workability, dry strength, high-temperature stability, and casting surface quality. This also shows that the role of silica sol in inorganic material systems is closely related to the process. It is not enough to look only at whether silica sol is included in the formulation; it is also necessary to consider how it functions during mixing, drying, and heat treatment.
5. How should silica sol products be selected?
When selecting silica sol, silica content alone is not enough. Particle size, solids content, pH, stabilizing ions, metal impurities, surface modification, and storage stability all affect actual performance. Selection should begin by identifying the role of silica sol in the system, and then determining which indicators need the most attention.
5.1 Used as an inorganic binder: focus on whether it can connect powders stably
When silica sol is used in investment casting, ceramics, refractory materials, or catalyst shaping, its main role is to connect inorganic particles, fibers, or refractory powders into structures with strength.
Key question | Indicators to focus on | Evaluation focus |
Is the slurry stable? | Particle size, pH, viscosity, powder compatibility | Whether rapid thickening, settling, flocculation, or caking occurs after mixing. |
Does it have strength after drying? | Solids content, particle size, effective silica dosage | Whether powdering, cracking, or insufficient strength occurs after drying. |
Does the structure remain after high-temperature treatment? | Sodium content, impurities, heat-treatment behavior | Whether excessive shrinkage, deformation, or strength loss occurs after firing. |
Is the process easy to control? | Viscosity, open time, storage stability | Whether it is suitable for dipping, impregnation, spraying, extrusion, or forming. |
In these applications, higher solids content should not simply be understood as better. Higher solids content can increase the amount of residual effective silica, but it can also increase viscosity, drying shrinkage, and cracking risk. Small-particle-size silica sol has a higher specific surface area and stronger particle contact and bonding effects, but it may also be more sensitive to salts, pH changes, and drying conditions. Large-particle-size silica sol usually has lower viscosity and allows a wider concentration range, but it may not be advantageous for fine-pore penetration or high-specific-surface-area bonding.
5.2 Used as a coating additive: focus on whether it improves surface properties without damaging film formation
When silica sol is used in waterborne coatings, silicate coatings, wear-resistant coatings, ceramic coatings, or packaging coatings, the usual goal is to improve hardness, wear resistance, stain resistance, anti-blocking properties, heat resistance, or surface hydrophilicity.
Key question | Indicators to focus on | Evaluation focus |
Is the coating transparent or uniform? | Particle size, particle size distribution, dispersion state | Whether whitening, loss of gloss, roughness, or a gritty feel appears. |
Is it compatible with the resin? | Surface modification, pH, surface charge | Whether flocculation, emulsion breaking, cratering, or discontinuous film formation occurs. |
Does it improve surface performance? | Addition level, particle size, post-film distribution | Whether hardness, wear resistance, stain resistance, and anti-blocking properties improve. |
Does it cause cracking? | Solids content, addition level, drying speed | Whether cracks result from excessive inorganic phase content or overly rapid shrinkage. |
In coating systems, excessive silica sol addition may increase hardness, but it can reduce flexibility and may even cause cracking, whitening, reduced adhesion, or surface roughness. Ordinary unmodified silica sol has limited compatibility with some organic resins. In acrylic, polyurethane, epoxy, and related systems, small-scale compatibility tests should be carried out first, and surface-modified silica sol should be selected when necessary.
5.3 Used as a polishing material: focus on controlling removal rate and surface defects at the same time
When silica sol is used for polishing semiconductors, glass, sapphire, metals, and precision substrates, its core task is not bonding, but controlling material removal through particle action and surface chemistry.
Key question | Indicators to focus on | Evaluation focus |
Can the surface be removed stably? | Particle size, concentration, pH | Whether the removal rate is stable. |
Does scratching occur? | Particle size distribution, large particles, agglomerates | Whether scratches, pits, or local defects appear. |
Does surface roughness meet the requirement? | Particle size, morphology, pH, dispersion state | Whether the polished surface is flat, uniform, and low-defect. |
Is it suitable for high-cleanliness applications? | Metal impurities, ionic residues, cleanliness | Whether sodium, potassium, metal ions, or particle contamination are introduced. |
Polishing-grade silica sol should not pursue small particle size alone. If the particle size is too small, removal efficiency may be insufficient. If the particle size is too large or the distribution is too broad, the risk of scratching increases. For precision processing and electronic materials, large particles, agglomerates, and metal impurities are often more important than the average particle size.
5.4 Used for pore filling and inorganic reinforcement: focus on whether it can enter pores and leave an effective structure
When silica sol is used in concrete, floor coatings, porous inorganic materials, ground and rock reinforcement, or surface densification, the focus is penetration, gelation, and silica-based structure formation. In cement-based materials, nanosilica may also react with calcium sources in hydration products, promoting the formation of calcium silicate hydrate and thereby improving density, strength, and durability.
Key question | Indicators to focus on | Evaluation focus |
Can it enter the pores? | Particle size, viscosity, solids content | Whether it can penetrate the target pores rather than remaining on the surface. |
Does it form effective reinforcement? | Solids content, reactivity, gelation behavior | Whether strength, wear resistance, and impermeability improve after treatment. |
Is it compatible with the substrate? | pH, ionic environment, substrate alkalinity | Whether rapid destabilization or precipitation occurs after contact with the substrate. |
Does it affect application workability? | Viscosity, open time, gel time | Whether premature gelation, insufficient penetration, or surface crusting occurs. |
This type of application requires a balance between penetration and final residue. If the solids content is too low, reinforcement is insufficient. If the solids content is too high, system viscosity increases, which may make it difficult to enter fine pores and may instead form an enriched surface layer.
5.5 Used in catalysts, ceramics, and high-temperature systems: focus on whether it affects pore structure and activity after shaping
When silica sol is used in catalyst shaping, ceramic powder binding, or carrier preparation, shaping strength, heat-treatment behavior, and pore-structure changes should all be considered.
Key question | Indicators to focus on | Evaluation focus |
Is shaping strength sufficient? | Solids content, particle size, addition level | Whether powdering or breakage occurs after extrusion, tableting, granulation, or coating. |
Is the pore structure blocked? | Particle size, addition level, drying and firing conditions | Whether specific surface area, pore volume, and pore size distribution change significantly. |
Are unwanted ions introduced? | Sodium content, metal impurities, stabilizer type | Whether catalytic activity, acid sites, or high-temperature performance are affected. |
Is it stable after heat treatment? | Silica network, sintering behavior | Whether shrinkage, cracking, or structural collapse occurs after firing. |
In catalysts, high-purity ceramics, and electronic materials, low-sodium, ammonium-stabilized, or high-purity silica sol is practically meaningful. This is because sodium, potassium, and metal impurities may affect catalytic activity, dielectric properties, high-temperature stability, or cleanliness.
6. What should be noted when using silica sol?
Silica sol is a colloidal dispersion, not an ordinary aqueous solution. During use, pH, electrolytes, multivalent metal ions, addition sequence, drying conditions, and storage conditions need to be controlled.
6.1 Avoid local strong-acid, strong-alkali, or high-salt shock
Conventional alkaline silica sol usually relies on negative charge on the particle surface for stability. Strong acids, high salt levels, and multivalent ions are more likely to weaken colloidal stability, causing flocculation, thickening, or gelation. Strong alkali does not necessarily directly weaken the negative charge, but local strong alkali can bring high ionic strength, silicate formation, or alkaline shock to the formulation, so it should also be prevented from directly contacting local silica sol. When a formulation contains acids, alkalis, salts, multivalent metal ions, or crosslinking agents, they should be diluted or premixed first, then added slowly under uniform stirring.
6.2 The addition sequence should reduce local destabilization
In multi-component systems, the addition sequence of silica sol directly affects stability. A relatively reliable operating sequence is:
1. First confirm the pH of the base system.
2. Then confirm whether the system contains high concentrations of salts, multivalent metal ions, or highly reactive additives.
3. Disperse the powder or resin system first, then slowly add silica sol.
4. Prepare a small test sample and at least check whether thickening, flocculation, settling, phase separation, or gelation occurs.
5. Scale up only after the small sample is stable.
Acids, alkalis, salts, multivalent metal salts, and similar components should not be added dropwise directly into a local region of silica sol.
6.3 Drying speed should match film thickness and solids content
After drying, silica sol leaves behind an inorganic silica structure. If a single coating layer is too thick, the solids content is too high, or drying is too fast, the surface layer may shrink first while internal water cannot escape in time, leading to cracks, whitening, uneven strength, or internal defects.
Condition | Control purpose |
Single-layer thickness | Reduce drying shrinkage and cracking risk. |
Drying temperature | Avoid overly rapid skin formation on the surface. |
Humidity and ventilation | Allow water to be released uniformly. |
Solids content | Balance effective silica residue and shrinkage stress. |
Heat-treatment program | Avoid rapid structural shrinkage, cracking, or pore-structure collapse. |
6.4 Avoid freezing, contamination, and long-term exposure during storage
Silica sol should be protected from freezing, high-temperature sunlight exposure, long-term exposure to air, and impurity contamination. After opening, prolonged exposure can lead to water evaporation, surface skin formation, and local concentration increase. Residual salts, acids, alkalis, or metal ions in containers, pipelines, pumps, or stirrers may also destabilize silica sol.
During storage and use, the cleanliness of containers should be kept consistent, and cross-contamination between different systems should be avoided. For electronic, catalytic, and high-purity ceramic applications, ionic contamination introduced by packaging materials and transfer systems should also be considered.
7. How should gelation, precipitation, cracking, or insufficient strength be investigated?
When silica sol fails in use, it should not be judged simply as “an unsuitable product.” The first step should be to investigate whether the system conditions have damaged colloidal stability, or whether the process conditions do not match the characteristics of the silica sol.
Problem observed | First suspected issue | Investigation sequence |
Rapid thickening or gelation after mixing | Sudden pH change, excessive electrolyte, multivalent metal ion shock | Check addition sequence, salt concentration, acid/alkali addition method, and local concentration. |
Precipitation or flocculation after standing | Incompatibility with powders, resins, or additives | Check powder surface, resin emulsion stability, dispersants, and pH. |
Coating whitening or loss of gloss | Particle size too large, poor compatibility, drying too fast, film too thick | Check particle size, addition level, film thickness, and drying conditions. |
Coating or shell cracking | Solids content too high, single layer too thick, large drying shrinkage | Reduce single-layer thickness and adjust solids content and drying speed. |
Insufficient bonding strength | Insufficient effective silica, mismatched powder surface, insufficient heat treatment | Check solids content, particle size, powder surface, drying, and firing conditions. |
Scratches after polishing | Broad particle size distribution, presence of large particles or agglomerates | Check filtration, particle size distribution, storage stability, and cleanliness. |
Activity decline after catalyst shaping | Pore structure blocked, sodium or impurities affecting active sites | Check silica sol addition level, sodium content, and pore structure after firing. |
Batch-to-batch performance fluctuation | Changes in product grade, storage time, or operating conditions | Fix the grade and record solids content, pH, viscosity, particle size, and addition sequence. |
During troubleshooting, the “phenomenon” should be matched with the corresponding “parameters.” Gelation and flocculation are mostly related to colloidal stability; cracking is mostly related to solids content, film thickness, and drying speed; insufficient strength is mostly related to the amount of effective silica, powder surface, and heat treatment; polishing defects are mostly related to large particles, agglomeration, and cleanliness.
8. Product Selection Guide for Silica Sol-Related Products: From Colloidal Stability and Silica Source Selection to Surface Modification and Application Validation
Research or experimental objective | Suggested table to consult first | Why start with this table | Suggested linked table | Selection guidance |
Establish a basic understanding of silica sol and compare the differences among silica sol, silica powder, silica gel, and silicate-based silica sources | Table 1 | Table 1 focuses on silica sol itself, nanosilica, fumed silica, silica gel, sodium silicate, potassium silicate, and silicate ester-type silica sources. It helps distinguish liquid colloids, silica powders, and soluble silicate systems. | Table 2 | First clarify whether the research object is ready-to-use silica sol, silica powder, a silicate solution, or a sol-gel silica source, and then determine whether pH adjustment and stability control are needed. |
Study silica sol preparation, silicate neutralization, or sol-gel reactions | Table 1 | Table 1 includes silicate silica sources, silicate ester silica sources, and high-purity chlorosilane silica sources, which can be used to distinguish aqueous silicate routes, silicate ester hydrolysis-condensation routes, and controlled hydrolysis routes. | Table 2 | Sodium silicate, sodium metasilicate, and potassium silicate are suitable for aqueous silicate systems; tetraethyl orthosilicate and tetramethoxysilane are suitable for sol-gel reactions; silicon tetrachloride releases hydrogen chloride upon contact with water and is not a routine choice for preparing ordinary aqueous silica sol. |
Adjust the pH, colloidal stability, gel time, and flocculation behavior of silica sol | Table 2 | Table 2 focuses on hydrochloric acid, nitric acid, glacial acetic acid, ammonia solution, sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium aluminate, which are suitable for acidification, alkalization, aluminum modification, and charge-control experiments. | Table 1 | First confirm the initial pH and ionic environment of the silica sol or silicate system, and then observe thickening, gelation, settling, and flocculation changes through small-scale tests. |
Carry out experiments related to silica sol inorganic bonding, refractory slurries, ceramic forming, or investment casting shells | Table 4 | Table 4 lists kaolin, quartz sand, titanium dioxide, activated alumina spheres, and zirconia dispersion, which can serve as inorganic substrates for validating silica sol bonding, compounding, coating, and post-firing performance. | Tables 1 and 2 | First select the inorganic material to be bonded or coated, and then match it with silica sol itself, silica sources, and acid-base stability conditions, with emphasis on slurry stability, dry strength, cracking, and structure after heat treatment. |
Compare the differences between silica sol and silica powder in coatings, filling, reinforcement, and rheology control | Table 1 | Table 1 includes silica sol, nanosilica, fumed silica, high-purity silica, and silica gel, allowing comparison between liquid colloidal systems and powder systems in terms of dispersion, film formation, and drying behavior. | Tables 3 and 4 | First use Table 1 to establish a material-form comparison, and then choose Table 3 or Table 4 depending on whether resin compatibility, surface hydrophobization, or inorganic compounding is needed. |
Build silica sol-resin, silica sol-coating, or organic-inorganic hybrid systems | Table 3 | Table 3 focuses on amino, epoxy, methacryloxy, mercapto, vinyl, methyl, and phenyl silanes, which can be used to regulate the interfacial bonding between silica sol and resins, coatings, or composite materials. | Tables 1 and 2 | First select the corresponding functional group according to the resin or coating system, and then control silane hydrolysis conditions, silica sol pH, and mixing sequence to avoid emulsion breaking, flocculation, and film defects. |
Study surface hydrophobization, silanol end-capping, and interfacial energy regulation of silica sol-related materials | Table 3 | Hexamethyldisilazane, trimethylchlorosilane, methyl silanes, and phenyl silanes in Table 3 are suitable for hydrophobizing silica surfaces, reducing silanol groups, and regulating organic compatibility. | Table 1 | First confirm whether the modification target is a dried silica sol product, silica powder, or silica gel, and then select a silylation reagent and evaluate water absorption, dispersibility, and surface compatibility. |
Carry out research on catalyst supports, shaping binders, or composite oxide supports | Table 4 | Table 4 includes activated alumina spheres, zirconia dispersion, titanium dioxide, and kaolin, which can be used for silica sol coating, bonding, carrier modification, and construction of composite oxide structures. | Tables 1 and 2 | First select the carrier or oxide substrate, and then link it with silica sol itself, low-impurity silica sources, and pH regulators, with attention to shaping strength, pore structure, metal impurities, and stability after calcination. |
Study precision polishing, surface planarization, or particle dispersion stability | Table 1 | Silica sol, nanosilica, and fumed silica in Table 1 can be used to compare particle morphology, dispersion stability, particle-size effects, and surface interactions. | Table 2 | Start with particle size, solids content, and dispersion state, and then use pH regulators to control system stability and the surface reaction environment, with emphasis on scratching, agglomeration, and surface roughness. |
Troubleshoot gelation, precipitation, whitening, cracking, or insufficient strength during silica sol use | Table 2 | Table 2 corresponds to pH, electrolytes, multivalent ions, and charge-control issues, making it an important starting point for judging colloidal destabilization, rapid gelation, and flocculation. | Tables 1, 3, and 4 | For gelation and precipitation, first check pH, salt concentration, and addition sequence; for whitening and compatibility issues, link to Table 3; for insufficient strength and cracking, link to Tables 1 and 4 to check solids content, particle size, substrate, and drying conditions. |
Table 1 | Products Related to Silica Sol, Silica Materials, and Silica Sources
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Silica sol itself | — | Silica sol | Silica content: 29%–31% | Used in experiments involving silica sol bonding, film formation, impregnation, pore reinforcement, and inorganic network formation. It can serve as a basic sample for evaluating solids content, gelation conditions, dry strength, and system compatibility. | |
Nanosilica powder | 7631-86-9 | Silicon dioxide nanopowder | ≥99% metals basis, 30 nm | Used to compare powder dispersion behavior with silica sol, and to study the effects of nanosilica on coating hardness, filling reinforcement, rheological changes, and composite material interfaces. | |
High-purity silica powder | 60676-86-0 | Silicon dioxide | ≥99.5% metals basis, −325 mesh | Can be used as an inorganic filler, ceramic formulation component, and silica material reference sample for comparing liquid silica sol dispersions with silica powders in forming, sintering, and filling applications. | |
Fumed silica | 112945-52-5 | Silica, fumed | ≥99% | Used in coatings, adhesives, composite materials, and rheology-control experiments. It can be compared with silica sol to evaluate the behavior of dry silica powder in thickening, anti-settling, reinforcement, and dispersion stability. | |
Porous silica material | 112926-00-8 | S743367 | Silica gel with moisture indicator | Reagent grade | Used to understand the morphological difference between silica gel and liquid colloidal silica sol. It can serve as a reference material for studying moisture absorption, pore structure, and gelation products. |
Soluble silicate silica source | 1344-09-8 | Sodium silicate | For refractory material binders | Used in refractory material bonding, silicate systems, and silica sol preparation-related experiments. It can be used to compare water glass systems with silica sol systems in terms of alkalinity, bonding, and drying shrinkage. | |
Soluble silicate silica source | 1312-76-1 | Potassium silicate | Liquid, modulus 3.1–3.4 | Used in potassium water glass, inorganic coatings, and silicate binder systems. It can be studied together with silica sol to evaluate the effects of alkali metal ions, modulus, and silica network formation on coating performance. | |
Metasilicate silica source | 6834-92-0 | S102095 | Sodium metasilicate | SiO₂, 44%–47% | Used in alkaline silicate systems, silica sol precursor preparation, and inorganic binder systems. It can be used to regulate the silica source, alkalinity, and silicate reaction conditions. |
Metasilicate silica source | 10213-79-3 | Sodium metasilicate pentahydrate | ≥95% | Used in hydrated metasilicate systems, alkaline cleaning, and silica material precursor experiments. It can be used to compare the effects of different hydration states on dissolution, alkalinity, and silica-source dosing. | |
Metasilicate silica source | 13517-24-3 | Sodium metasilicate nonahydrate | AR, ≥98% | Used in metasilicate solution preparation, silicate gelation, and aqueous inorganic binder systems. It can be used to control silica-source concentration and alkaline environment. | |
Alkoxide silica source | 78-10-4 | Tetraethyl orthosilicate | Reagent grade, ≥98% | Used in sol-gel preparation of silica, siloxane networks, and organic-inorganic hybrid materials. It can be used to compare hydrolysis-condensation pathways and film structures with those of aqueous silica sol. | |
Alkoxide silica source | 681-84-5 | T110592 | Tetramethoxysilane (TMOS) | ≥98% | Used in sol-gel processes, silica network construction, and transparent gel material experiments. It can be used to study the hydrolysis-condensation rate of methoxysilanes and silica structure formation. |
High-purity chlorosilane silica source | 10026-04-7 | Silicon tetrachloride | PrimorTrace™ Ultra, ≥99.9999% metals basis | Used in high-purity silicon chemistry, silica precursors, and preparation of silicon-containing materials. It is suitable for experiments focused on metal impurity control and high-purity silica-based system construction. |
Table 2 | Products Related to Acid-Base Adjustment, Stabilization Systems, and Colloidal Stability
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Acidic regulator | 7647-01-0 | H485680 | Hydrochloric acid fuming 37% | Guaranteed reagent, suitable for analysis, max. 0.001 ppm Hg | Used in silica sol acidification, silicate neutralization, gelation-condition adjustment, and acid-stability experiments. It can be used to investigate how acid addition affects gelation, flocculation, and particle aggregation. |
Acidic regulator | 7697-37-2 | N116238 | Nitric acid | Guaranteed reagent, 65%–68% | Used in acidic silica sol, silicate hydrolysis, and inorganic surface-treatment experiments. It can be used to adjust acidity while reducing chloride introduction in some high-purity systems. |
Weak acid regulator | 64-19-7 | Acetic acid | Guaranteed reagent, ≥99.5% | Used for mild acidification, silane hydrolysis, and acidity adjustment in silica sol-silane composite systems. It can reduce the risk of rapid gelation caused by strong acid shock. | |
Alkaline regulator | 1336-21-6 | A112077 | Ammonia solution | Guaranteed reagent, 25%–28% | Used in ammonium-stabilized systems, silane hydrolysis-condensation, and adjustment of alkaline environments in silica sol. It can reduce fixed alkali metal ion residues in high-purity or catalytic systems. |
Alkaline regulator | 1310-73-2 | S111498 | Sodium hydroxide | Guaranteed reagent, ≥96% | Used in sodium silicate systems, alkaline silica sol stability, and silica source dissolution experiments. It can regulate highly alkaline environments and help study the effects of sodium ions on colloidal stability and post-firing performance. |
Alkaline regulator | 1310-58-3 | Potassium hydroxide | Anhydrous, ≥99.95% metals basis | Used in potassium-stabilized silica sol, potassium water glass, and high-purity alkaline systems. It can be used to study the effects of potassium ions on silica networks, inorganic coatings, and residual ions. | |
Alkaline regulator | 1310-65-2 | Lithium hydroxide | Suitable for analysis, guaranteed reagent, ≥98% | Used in lithium-stabilized or low-impurity alkaline silica sol-related experiments. It can be used to study the effects of different alkali metal ions on particle stability, residual ions, and inorganic material performance. | |
Aluminum modification and charge-control component | 1302-42-7 | Sodium aluminum oxide | ≥98% | Used in aluminum-modified silica sol and surface charge regulation studies. Under controlled pH, addition sequence, and ionic environment, it can be used to explore aluminum-modified or cationic silica sol-related systems. |
Table 3 | Products Related to Silane Coupling, Surface Modification, and Hydrophobization
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Amino silane coupling agent | 13822-56-5 | (3-Aminopropyl)trimethoxysilane | Chloride ion ≤13 ppm | Used for amination of silica sol surfaces, interfacial coupling between inorganic particles and resins, coating adhesion, and composite compatibility studies. It can introduce reactive amino interfaces. | |
Amino silane coupling agent | 919-30-2 | (3-Aminopropyl)triethoxysilane | ≥98% | Used for amino modification of silica surfaces, inorganic filler coupling, and silica sol-organic resin composite systems. It can improve interfacial bonding with epoxy, polyurethane, and some waterborne resins. | |
Epoxy silane coupling agent | 2530-83-8 | 3-Glycidyloxypropyltrimethoxysilane | ≥97% | Used for epoxy functionalization of silica sol and silica surfaces. It can connect inorganic silica surfaces with epoxy, amine, or hydroxyl systems and is commonly used for interfacial modification in coatings, adhesives, and composites. | |
Methacryloxy silane coupling agent | 2530-85-0 | 3-(Trimethoxysilyl)propyl methacrylate | ≥97%, contains 100 ppm BHT stabilizer | Used to introduce polymerizable double bonds onto silica sol surfaces. It is suitable for studies on silica dispersion and interfacial bonding in acrylic resins, UV-curable coatings, and organic-inorganic hybrid materials. | |
Mercapto silane coupling agent | 4420-74-0 | (3-Mercaptopropyl)trimethoxysilane | ≥95% | Used for thiol functionalization of silica surfaces and interfacial modification in sulfur-containing systems. It can be used in rubber, metal surfaces, functionalized silica sol, and sulfur-containing reactive interfaces. | |
Vinyl silane coupling agent | 2768-02-7 | Vinyltrimethoxysilane | ≥98% (GC) | Used for vinyl modification of silica sol or inorganic fillers. It can participate in interfacial bonding in unsaturated resins, crosslinking systems, and polymer composites. | |
Vinyl silane coupling agent | 78-08-0 | Triethoxyvinylsilane (TEVS) | ≥97% | Used for vinyl functionalization of silica surfaces and coupling of inorganic fillers. It can be used in polymer modification, coating crosslinking, and silica sol organic compatibility studies. | |
Alkyl silane modifier | 1185-55-3 | Trimethoxymethylsilane | ≥98% | Used for methylation and hydrophobic adjustment of silica sol surfaces. It can reduce the hydrophilicity of silica surfaces and improve interfacial matching of the inorganic phase in coatings and composite materials. | |
Alkyl silane modifier | 2031-67-6 | Triethoxymethylsilane | ≥98% | Used for constructing methyl siloxane networks and hydrophobic modification of silica sol surfaces. It can be used in water-resistant coatings, organic-inorganic hybrid films, and silica surface modification experiments. | |
Aryl silane modifier | 2996-92-1 | Trimethoxyphenylsilane | ≥98% (GC) | Used to introduce phenyl structures onto silica surfaces. It can regulate the compatibility of silica sol with aromatic resins, heat-resistant coatings, and organic-inorganic hybrid systems. | |
Hydrophobizing silylation reagent | 999-97-3 | Hexamethyldisilazane (HMDS) | AR, ≥98% | Used for surface silylation and hydrophobization of dried silica, silica gel, or dried silica sol products. It can reduce silanol groups and adjust water absorption and interfacial energy; it is not suitable for direct addition to ordinary aqueous silica sol. | |
Hydrophobizing silylation reagent | 75-77-4 | Chlorotrimethylsilane (TMCS) | ≥99% (GC) | Used for silanol end-capping and hydrophobic modification of dried silica gel, silica powder, or dried silica sol products. It is moisture-sensitive and hydrolyzes to release hydrogen chloride, so it is not suitable for direct addition to ordinary aqueous silica sol. |
Table 4 | Supporting Materials for Casting, Ceramics, Catalysis, and Inorganic Composite Applications
Category | CAS No. | Aladdin Cat. No. | Name | Specification or Purity | Product Features and Applications |
Ceramic and refractory filler | 1332-58-7 | K431904 | Kaolin | Heavy, powder | Can be used in silica sol-bonded ceramics, refractory slurries, and inorganic coating experiments to evaluate the effects of layered aluminosilicate fillers on rheology, drying shrinkage, forming strength, and post-firing structure. |
Siliceous refractory aggregate | 14808-60-7 | S121694 | Common quartz sand | SiO₂ ≥90%, 0.105–0.71 mm | Can be used in silica sol-bonded sand molds, refractory materials, and particle packing structure experiments to evaluate the effects of silica sol on interparticle bonding, dry strength, and structural stability after heat treatment. |
Oxide functional filler | 13463-67-7 | T431947 | Titanium(IV) oxide | Guaranteed reagent, ≥99% | Can be used in silica sol composite coatings, photocatalyst supports, and inorganic filler systems to evaluate dispersion, film formation, surface activity, and durability after compounding titanium dioxide with silica sol. |
Catalyst support material | 1344-28-1 | Activated alumina spheres | Used as catalyst support, particle size 5–7 mm | Can be used in silica sol loading, coating, and catalyst shaping studies to evaluate the effects of silica sol on surface bonding, pore-structure regulation, and coating stability of alumina supports. | |
Oxide nano-dispersion material | 1314-23-4 | Zirconium(IV) oxide | Nanoparticles, dispersion, <100 nm particle size (BET), 5 wt.% in H₂O | Can be used in silica sol-zirconia composite dispersions, heat-resistant coatings, ceramic membranes, and catalyst support studies to evaluate the effects of composite oxide networks on thermal stability and mechanical properties. |
Note: The above products are representative Aladdin products. More product specifications can be searched on the Aladdin website by product name, CAS number, or catalog number.
References
[1] Ralph K. Iler. The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties, and Biochemistry. Wiley, 1979.
[2] Horacio E. Bergna, William O. Roberts. Colloidal Silica: Fundamentals and Applications. CRC Press, 2005.
[3] Nouryon. What is Silica - Levasil® Colloidal Silica.
[4] Nouryon. Levasil® Aqueous Dispersions of Colloidal Silica.
[5] Nouryon. Functionality for Levasil® Colloidal Silica.
[6] Kurt Obermeier GmbH. Silica Sol.
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