Types and Applications of Powder Spheroidization Technology
Powder spheroidization technology, an indispensable component of modern industry and science, can improve the surface characteristics and physical properties of powders, optimize material performance, and meet multifunctional requirements. Currently, powder spheroidization technology has penetrated numerous fields, including pharmaceuticals, food, chemicals, environmental protection, materials, metallurgy, and 3D printing.
Spherical powder preparation technology involves multiple disciplines, including expertise in chemistry, materials science, and engineering. Below, we will explore the various technologies involved in powder spheroidization.
Mechanical Shaping Method
Mechanical shaping methods primarily utilize a series of mechanical forces, such as collision, friction, and shear, to plastically deform and adsorb particles. Continuous processing results in denser particles, and sharp edges are gradually smoothed and rounded by the impact force. Mechanical shaping methods utilize high-speed impact mills, media stirred mills, and other pulverizing equipment to produce fine powder materials. Combined with dry and wet grinding, these methods yield powder materials with finer particle size, narrower particle size distribution, and a certain spheroidization rate.
Mechanical shaping is widely used in the spheroidization and shaping of natural graphite, artificial graphite, and cement particles. It is also suitable for crushing and pulverizing brittle metal or alloy powders. Mechanical shaping utilizes a wide range of low-cost raw materials, fully utilizing existing resources. It offers advantages such as simplicity, environmental friendliness, and industrial scalability. However, this method is not very selective in terms of materials, and cannot guarantee the sphericity, tap density, and yield of the processed particles. Therefore, it is only suitable for producing spherical powders with lower quality requirements.
Spray Drying
Spray drying involves atomizing a liquid substance into droplets, which are then rapidly evaporated in a hot air stream, solidifying into solid particles. The advantages of spray drying are its simplicity and ease of controlling product properties. It is primarily used in the fields of military explosives and batteries.
Gas-Phase Chemical Reaction
Gas-phase chemical reaction uses gaseous raw materials (or evaporates solid raw materials into a gaseous state) to produce the desired compound through a chemical reaction. This compound is then rapidly condensed to produce ultrafine spherical powders of various substances.
Hydrothermal Method
The hydrothermal method utilizes a reactor under high temperature and pressure conditions, using water or an organic solvent as the reaction medium for a chemical reaction. Particle size can be effectively controlled by adjusting parameters such as the hydrothermal temperature, hydrothermal time, pH, and solution concentration.
Precipitation Method
The precipitation method combines metal ions with a specific precipitant through a chemical reaction in a solution, generating tiny, semi-solid colloidal particles and forming a stable suspension. Subsequently, by further adjusting precipitation reaction conditions, such as static aging, slow stirring, or changing the solution environment, these colloidal particles gradually aggregate and grow toward spherical shape, forming a primary spherical precipitate. The resulting precipitate is then dried or calcined to ultimately produce a spherical powder material.
Sol-Gel Method
The sol-gel method typically involves three stages: sol preparation, gel formation, and spherical powder formation. Heat treatment can further improve the structure and properties of the spherical powder, enabling precise control of the particle size and morphology.
Microemulsion Method
The microemulsion method is a liquid-liquid two-phase system preparation method. This method involves adding an organic solvent containing a dissolved precursor to an aqueous phase to form an emulsion containing tiny droplets. Spherical particles are then formed through nucleation, coalescence, agglomeration, and heat treatment. Microemulsion methods are widely used in the preparation of nanoparticles and organic-inorganic composite materials.
Plasma Spheroidization
With the rapid development of high-tech and the urgent need for new nanomaterials and novel preparation processes, the research and application of plasma chemistry are gaining increasing attention. Plasma spheroidization, characterized by high temperature, high enthalpy, high chemical reactivity, and controllable reaction atmosphere and temperature, is ideal for producing high-purity, small-particle spherical powders.
Other methods include deflagration, Gas Combustion Flame Pelletization, Ultrasonic Atomization, Centrifugal Atomization, wire cutting, punching, and remelting, and pulsed micropore spraying.
How to modify the surface of silicon nitride powder?
Surface modification of silicon nitride powder primarily involves treating the surface of the powder through various physical and chemical methods to improve the physical and chemical properties of the particles.
Surface modification can reduce the mutual attraction between powder particles, allowing for better dispersion of the powder in the medium and improving the dispersibility of the powder slurry. It can also enhance the surface activity of the silicon nitride powder, increasing its compatibility with other substances and thus developing new properties.
The main principle of powder surface modification is that the interaction between the powder and the surface modifier enhances the wettability of the powder surface and improves its dispersion in aqueous or organic media.
1. Surface Coating Modification
Surface coating modification technology utilizes physical or chemical adsorption to uniformly attach the coating material to the surface of the coated object, forming a uniform and complete coating layer. The coating layer formed during the coating process is typically a monolayer.
Coating modification is generally categorized as inorganic and organic. Inorganic coating primarily involves depositing appropriate oxides or hydroxides on the surface of ceramic particles to modify the powder, but this modification only affects physical properties. Organic coating, on the other hand, involves selecting organic substances as coating materials. These organic substances bond with groups on the surface of the powder particles and selectively adsorb onto the surface, imparting the properties of the coating layer to the powder.
This modification technology offers low cost, simple steps, and easy control, but the resulting results are often limited.
2. Surface Acid and Alkali Treatment
Ceramic molding processes generally require ceramic slurries with high solids content and low viscosity. The charge density on the powder surface significantly influences the rheological and dispersibility of the slurry. Washing the ceramic powder surface (acid and alkaline treatments) can alter the surface charge properties of the powder. As the name suggests, this modification method involves thoroughly mixing and washing the silicon nitride powder with acid or alkaline solutions of varying concentrations.
At the same time, alkaline treatment at a certain concentration can also react with the surface of ceramic powders. Research by Wang Yongming et al. has shown that alkaline washing can reduce the silanol content on the surface of silicon carbide powder, lowering its degree of oxidation, altering the electrostatic repulsion between particles, and improving the rheological properties of the slurry.
3. Dispersant Modification
Based on the differences between different types of ceramic powders, selecting an appropriate dispersant or designing a new one plays a key role in increasing the solid content of the ceramic slurry. The type and amount of dispersant added can significantly alter the effect on ceramic properties.
Dispersants generally have both hydrophilic and hydrophobic structures, and it is through the interaction between these hydrophilic and hydrophobic groups that they adjust the dispersion properties of the ceramic slurry. Dispersants include surfactants or polymer electrolytes, with surfactants including cationic and anionic surfactants.
Polymer electrolytes include polyvinyl sulfonic acid, polyacrylic acid, polyvinyl pyridine, and polyethyleneimine. Dispersants can undergo adsorption reactions with the powder surface, including chemical and physical adsorption, leveraging interparticle forces (van der Waals forces and electrostatic repulsion) and the potential for steric effects.
4. Surface Hydrophobicity Modification
Surface hydrophobicity modification involves converting the hydroxyl groups in ceramic powder into hydrophobic groups, such as hydrocarbon groups, long-chain alkyl groups, and cycloalkyl groups. These organic groups bind to the ceramic powder surface, exerting a strong hydrophobic effect, enabling better dispersion in the dispersion medium and preventing agglomeration.
When polymers are grafted onto the surface of silicon nitride powder, the long polymer chains attach to the powder surface, while the hydrophilic chains at the other ends extend into the aqueous medium. Throughout the dispersion process, the powder particles experience both interparticle repulsion and steric hindrance created by the long polymer chains, resulting in better slurry dispersion.
Kaolin's four innovative application areas and prospects
Kaolin, a 1:1 layered silicate mineral, boasts numerous properties, including dispersibility, plasticity, sinterability, refractory properties, ion exchangeability, and chemical stability, making it widely used in various industrial fields. Currently, kaolin's applications are primarily concentrated in traditional industries such as ceramics, papermaking, and refractories.
1. High-Performance Composites
The application of kaolin in composites can improve the surface properties (such as adsorption capacity) of materials.
The benefits of kaolin in composites include enhancing adsorption, enhancing electrical properties, improving thermal stability/fire resistance, and improving mechanical stability. However, practical applications still present challenges, such as insufficient dispersibility and interfacial compatibility of kaolin in composites, which may limit its effectiveness.
Future research directions include developing more efficient and green kaolin surface modification technologies to improve its dispersibility and compatibility with matrix materials; exploring the design of multifunctional kaolin-based composites to meet the needs of specific applications, such as energy harvesting, wastewater treatment, and fire safety; and further increasing kaolin's specific surface area and number of active sites through nanoscale processing and molecular manipulation, thereby enhancing its performance. Furthermore, efforts should be made to promote low-cost and environmentally friendly production processes for kaolin composites, and to integrate intelligent manufacturing technologies to achieve large-scale application.
2. Porous Materials: Molecular Sieve Field
Molecular sieves are materials with an ordered pore structure that selectively adsorb different molecules. They are widely used in oil refining, petrochemicals, agriculture, and water treatment. Kaolin, a common and inexpensive natural mineral rich in silica and alumina, can be directly used to synthesize zeolite molecular sieves. Compared with traditional and potentially toxic silicon and aluminum sources, kaolin is not only environmentally friendly but also reduces costs and simplifies the synthesis process.
Kaolin not only activates silicate and alumina activity through simple pretreatments such as calcination and acid leaching, but also further enhances molecular sieve performance through templating agent manipulation and temperature optimization.
3. Biomedicine
Kaolin is a type of nanosilicate clay mineral characterized by excellent biocompatibility, high specific surface area, chemical inertness, colloidal properties, and thixotropy. In the biomedicine field, research is gradually shifting from basic drug carrier applications to more complex biomedical applications such as gene therapy and 3D bioprinting. Kaolin's applications have expanded from simple physical support and drug release to complex systems promoting cell growth and gene delivery.
4. Energy Storage
Energy storage has always been a hot topic. Seeking efficient and sustainable energy storage solutions is one of the key paths to addressing global energy challenges. Kaolin, with its unique structure and multifunctionality, has become an ideal candidate for energy storage. Kaolin is used in a variety of energy storage devices such as lithium-ion batteries, supercapacitors, and microbial fuel cells.
The future application prospects of kaolin are as follows:
a. Research and development of innovative materials will focus on kaolin nano-processing and surface modification technologies, aiming to enhance its performance in electronics, energy storage, and other fields. For example, kaolin-based nanocomposites can be developed by combining them with polymers or carbon-based materials to improve mechanical strength and conductivity.
b. Kaolin has the potential to provide solutions to environmental issues such as water treatment and soil remediation, particularly in the removal of heavy metals and adsorption of pollutants.
c. The integration of interdisciplinary technologies will promote the innovative application of kaolin in the biopharmaceutical field, integrating biotechnology to develop drug delivery systems or bioactive scaffolds.
d. With the increasing market demand for environmentally friendly materials, companies should strengthen collaboration with R&D institutions to transform innovative discoveries into competitive products, such as high-temperature, durable kaolin ceramics or lightweight composites.
e. With the global emphasis on sustainable development, policy support and economic feasibility will influence the direction of kaolin R&D and application. Therefore, the industry needs to closely monitor resource availability and cost optimization, while strengthening risk management and enhancing global competitiveness to cope with the complex international environment.
SDS-modified barium sulfate for cosmetic use
Cosmetic opacifiers are key ingredients for achieving effects such as concealing blemishes and brightening skin; their dispersibility and stability directly affect product performance and shelf life.
Barium sulfate is widely used in cosmetics due to its high refractive index, good opacity, and chemical stability. However, its tendency to agglomerate limits its application in cosmetics.
This study investigates the dispersibility and stability of barium sulfate in cosmetic matrices by preparing ultrafine barium sulfate using ball milling, and optimizing surface modification and dispersion processes.
1. Modification Methods
(1) Pretreatment of Barium Sulfate
Industrial-grade barium sulfate was dried and sieved through a 200-mesh screen in batches. For each batch, 100g of barium sulfate was mixed with 0.5g of stearic acid on a two-roll mill for 3 min. The rolls were then adjusted to the minimum gap and passed through 6 times, followed by a final pass with a 2mm gap, completing the initial mixing. The mixed barium sulfate was dried at 80°C for 4h to obtain the pretreated product.
(2) Surface Modification
Using 100 parts of the base formulation, different proportions of the pretreated barium sulfate were added and subjected to surface modification at 60°C. During modification, 1.5 parts of sodium dodecyl sulfate were added, and the mixture was thoroughly mixed. The rolls were adjusted to the minimum gap and passed through 6 times before being flattened, yielding the modified barium sulfate.
(3) Preparation of Dispersion
The modified barium sulfate was dispersed into the base formulation at different ratios using a combination of mechanical stirring and ultrasonic dispersion. Specifically, a certain amount of modified barium sulfate was weighed, added to deionized water, and ultrasonically dispersed for 10 min. The base formulation was then slowly added under stirring, and the mixture was stirred for another 30 min.
2. Optimal Modification Process and Performance Evaluation
(1) Optimal Modification Process
Through systematic research, the optimal process conditions were determined: Industrial-grade barium sulfate was sieved through a 200-mesh screen and dried at 60°C for 4h. Sodium dodecyl sulfate was used as the surface modifier at 1.5% of the barium sulfate weight, and the modification was performed at 60°C for 2h. In the dispersion process, the barium sulfate content was controlled at 15%–20%, the dispersion temperature at 60°C, the dispersion time at 15 min, and the system pH maintained at 8.0–8.5. A combination of mechanical stirring and ultrasonic dispersion was used.
Under these conditions, the resulting dispersion system exhibited the following characteristics: a uniform particle size distribution with a main particle size of 0.8–1.2 μm; good dispersant stability with no significant sedimentation within 7 days; and excellent coverage with a uniform and continuous film.
(2) Application Evaluation in Cosmetics
The prepared barium sulfate dispersion was evaluated in cosmetic formulations: Adding 15% of the modified barium sulfate dispersion to a foundation cream resulted in good coverage and a pleasant user experience, with good compatibility with the base matrix and no phase separation.
Adding 20% of the dispersion to a concealer formulation significantly improved coverage, maintained good stability, and provided a natural and long-lasting effect.
The application evaluation results demonstrate that the barium sulfate dispersion prepared using the optimized process exhibits excellent performance in cosmetic applications. ALPA specializes in ultrafine grinding and classification to maximize your product's value. Specializing in ultrafine grinding and classification of Barite.
The potential of montmorillonite in the field of new energy
Montmorillonite (MMT) is a layered silicate mineral. In its structure, the high-valence aluminum atoms in the aluminum-oxygen octahedra can be easily substituted by lower-valence atoms, resulting in a negative charge between the layers. To maintain the stability of the interlayer structure, montmorillonite adsorbs cations such as Na+, Ca2+, Mg2+, Al3+, and K+ from its surroundings. This characteristic gives montmorillonite strong adsorption and cation exchange capabilities. This unique structure and exchange capacity endow montmorillonite with significant potential for applications in the field of new energy technologies.
Lithium Battery Materials
(1) For Solid-State Electrolytes
Numerous studies have shown that montmorillonite (MMT), as a novel inorganic filler, can significantly improve the ionic conductivity and mechanical properties of solid polymer electrolytes (SPEs).
(2) Constructing Artificial SEI Layers
In artificial solid electrolyte interphase (SEI) films, layered montmorillonite-lithium (Li-MMT) imparts good mechanical properties to the SEI layer and provides Li+ transport channels, which helps suppress lithium dendrite growth. Benefiting from the fast Li+ channels in Li-MMT, a Li-LiFePO4 full cell assembled with a Li-MMT SEI layer exhibits superior rate performance, and maintains a high capacity retention of 90.6% after 400 cycles at 1C rate.
(3) Separator Optimization
MMT is used to optimize separators due to its excellent adsorption properties. Compared with commercial PE separators, the Li-MMT-modified separator has a higher Li+ concentration at the electrode/electrolyte interface, which reduces selective lithium deposition, weakens local current density, and suppresses dendrite growth.
(4) Optimizing Liquid Electrolytes
In lithium metal battery systems, compared to PEO electrolytes, montmorillonite exhibits stronger affinity with metallic lithium, with a zeta potential of +26 mV, which promotes the enrichment of lithium ions near the montmorillonite surface. With the adsorption and separation of lithium ions, the overpotential slightly increases to -57.7 mV, guiding lithium ions to migrate from montmorillonite and deposit on the copper current collector surface.
(5) Carrier Materials
Supercapacitors
Template Materials
Some natural minerals have specific morphologies, such as attapulgite, montmorillonite, halloysite, and diatomite, which are commonly used as templates to synthesize porous carbon materials with specific morphologies. Furthermore, conductive polymers with specific morphologies can be synthesized using the mineral template method. (2) Electrode Carrier Materials
To obtain active materials with specific morphologies, and simultaneously enhance the specific capacitance and improve the cycling stability, active materials can be loaded onto the surface of minerals such as montmorillonite and halloysite.
Methane Storage Materials
Currently, researchers are exploring the use of adsorption-based natural gas storage technology, which is economical, convenient, and safe, as an alternative to traditional compressed natural gas and liquefied natural gas technologies. Studies have shown that clay minerals play a positive role in the formation and development of shale gas reservoirs and possess gas storage capabilities.
Electrocatalytic Materials
Electrocatalysis is a type of catalysis that accelerates charge transfer reactions at the electrode/electrolyte interface, and has been widely used in fields such as electrochemical hydrogen evolution, oxygen evolution, and NOx reduction. Clay minerals such as montmorillonite have been widely used as carriers for photoelectrocatalytic electrode reaction components to prevent particle aggregation, improve the stability of sensitizer molecules, and enhance reaction selectivity.
Phase Change Thermal Energy Storage Materials
Phase change thermal energy storage materials (PCMs) are a new type of functional material that utilizes the heat absorption or release during phase change for thermal energy storage and release. Natural minerals play an important role in the field of phase change thermal energy storage. On one hand, natural minerals themselves are excellent inorganic phase change materials, and can be processed into high-performance phase change thermal energy storage materials after adding appropriate nucleating agents and thickeners. On the other hand, the porous structure of minerals can serve as an excellent carrier for phase change thermal energy storage materials.
Titanium dioxide powder coating modification
Surface modification of titanium dioxide powder (titanium white) is an important method to enhance its performance (such as dispersibility, weather resistance, gloss, and chemical stability). Common surface modification techniques can be broadly categorized into three types: inorganic coating, organic coating, and composite coating. The following is a detailed classification and brief introduction of these methods:
Inorganic Coating Modification
This method involves coating the surface of titanium dioxide particles with a layer of inorganic oxides or salts, forming a physical barrier to improve its chemical stability and optical properties.
1. Oxide Coating
Principle: Metal oxide hydrates (such as SiO₂, Al₂O₃, ZrO₂ etc.) are precipitated onto the surface of titanium dioxide particles, forming a uniform coating layer.
Process: Typically, a liquid phase deposition method is used, where metal salts (such as sodium silicate, aluminum sulfate) are added to the titanium dioxide slurry, and the pH is adjusted to precipitate the metal oxide hydrates onto the surface.
2. Composite Oxide Coating
Principle: Coating with two or more metal oxides (such as Al₂O₃-SiO₂, ZrO₂-SiO₂ etc.), combining the advantages of each component.
Features: Superior overall performance; for example, Al₂O₃-SiO₂ coating can simultaneously improve dispersibility and weather resistance, suitable for demanding automotive coatings and coil coatings.
3. Salt Coating
Principle: Using metal salts (such as phosphates, silicates, sulfates, etc.) to form an insoluble salt layer on the surface of titanium dioxide particles.
Organic Coating Modification
This method involves reacting organic compounds with the hydroxyl groups on the surface of titanium dioxide, forming an organic molecular layer to improve its compatibility with organic media. 1. Coupling Agent Coating
Principle: Utilizing the amphiphilic structure of coupling agents (such as silanes, titanates, and aluminates), one end binds to the hydroxyl groups on the titanium dioxide surface, while the other end reacts with the organic matrix (e.g., resin, polymer).
Functions:
Silane coupling agents: Improve the dispersibility of titanium dioxide in aqueous systems, commonly used in water-based coatings and inks.
Titanate/aluminate coupling agents: Enhance compatibility in oily systems such as plastics and rubber, reducing agglomeration during processing.
2. Surfactant Coating
Principle: Surfactants (such as fatty acids, sulfonates, and quaternary ammonium salts) adhere to the titanium dioxide surface through physical adsorption or chemical reaction, forming a charge layer or hydrophobic layer.
3. Polymer Coating
Principle: Grafting polymers (such as acrylates, epoxy resins, and siloxanes) onto the titanium dioxide surface through polymerization reactions.
Functions:
Form a thick coating layer, further protecting against chemical attack and improving weather resistance and mechanical properties.
Enhance compatibility with specific resins, suitable for high-performance composites and coatings.
4. Organosilicon Coating
Principle: Utilizing the low surface energy of polysiloxanes (silicone oil, silicone resin, etc.) to coat titanium dioxide particles.
Functions: Reduce surface tension, improve dispersibility and lubricity, commonly used in inks and cosmetics.
Composite Coating Modification
Combining the advantages of inorganic and organic coatings, a dual coating process (sequential or simultaneous) achieves complementary performance.
1. Inorganic-Organic Sequential Coating
Process: First, form a physical barrier with inorganic oxides (e.g., SiO₂), then perform organic modification with coupling agents or polymers.
Features: Balances weather resistance and compatibility, suitable for high-performance architectural coatings or automotive OEM paints. 2. Inorganic-Organic Simultaneous Coating
Process: Inorganic and organic coating agents are introduced simultaneously into the same reaction system to form a core-shell structure.
Features: The coating layer exhibits stronger adhesion and significantly improved performance, suitable for high-end applications (e.g., aerospace coatings, nanocomposites).
Other Special Coating Technologies
1. Nanoparticle Coating
Principle: Using nanoparticles (e.g., nano-SiO₂, nano-ZnO) for coating enhances UV protection and transparency, commonly used in sunscreen cosmetics and optical coatings.
2. Microencapsulation
Principle: Encapsulating titanium dioxide particles in polymeric microcapsules, releasing the titanium dioxide by controlling the capsule rupture conditions (e.g., temperature, pH), suitable for smart coatings and controlled-release systems.
The selection of different coating methods depends on the application (e.g., coatings, plastics, inks, cosmetics) and performance requirements (weather resistance, dispersibility, compatibility, etc.).
Six major modification methods of nano zinc oxide
Nano zinc oxide is a new type of functional fine inorganic chemical material. Due to its small particle size and large specific surface area, it possesses unique physicochemical properties in chemistry, optics, biology, and electronics. It is widely used in antimicrobial additives, catalysts, rubber, dyes, inks, coatings, glass, piezoelectric ceramics, optoelectronics, and daily chemical applications, and holds great promise for development and utilization.
However, due to its large specific surface area and high specific surface energy, nanozinc oxide exhibits strong surface polarity, prone to self-agglomeration, and is difficult to disperse evenly in organic media, significantly limiting its nano-effect. Therefore, dispersion and surface modification of nanozinc oxide powders are essential treatments before nanomaterials can be applied in matrices.
1. Surfactant Modification
Surfactant modification involves the electrostatic interaction of surfactants to form an organic coating on the surface of nanomaterials, thereby improving their compatibility with organic matrices.
Although surfactant modification is a simple process, its effectiveness is generally poor, making it difficult to form a stable and robust coating on the surface of nanomaterials.
2. Mechanochemical Modification
Mechanochemical modification uses mechanical forces to alter the physical and chemical properties of nanomaterials, thereby enhancing their affinity and reactivity with other substances.
However, mechanochemical modification typically takes a long time and generally has poor results for nanomaterials.
3. High-energy Modification
High-energy modification involves the polymerization of organic compound monomers using plasma or radiation treatment, which then coats the nanomaterial's surface.
High-energy modification generally achieves better results than the previous two methods, but it has disadvantages such as high energy consumption and technical difficulty.
4. Esterification Modification
Esterification is a surface modification method that utilizes the carboxylic acid groups in modifiers such as higher fatty acids or unsaturated organic acids to react with hydroxyl groups on the surface of a nanomaterial to achieve esterification.
The esterification method is simple, but its modification effect is poor and it usually needs to be used in conjunction with a coupling agent.
5. Polymer Grafting
Polymer grafting involves first grafting a polymer monomer onto the surface of a nanomaterial, then initiating a polymerization reaction to extend the carbon chain, and finally allowing the polymer to coat the entire nanomaterial.
The polymer grafting method is complex to operate, and the modification effect is affected by various factors, making it difficult to achieve widespread application.
6. Coupling Agent Modification
A coupling agent is based on a silicon or metal element, with two different groups on either side that can connect to inorganic and organic matrices. These three components work together to achieve chemical modification of the nanomaterial. Nano-zinc oxide was modified with APS silane coupling agent. Both modified and unmodified nano-zinc oxide were dispersed in anhydrous ethanol to prepare printing inks for use as electron transport layer materials in photovoltaic cells. The performance of the two inks was then compared. The results showed that the modified nano-zinc oxide was better dispersed in anhydrous ethanol and remained agglomerated for 12 months. The electron transport layer material prepared with this agent exhibited higher electron transfer efficiency and could meet device performance standards at thinner thicknesses.
Nano-zinc oxide was chemically modified using silane coupling agents bearing glycyloxy and amino functional groups. Both modified and unmodified nano-zinc oxide were incorporated into epoxy coatings for weathering resistance testing. The results showed that the epoxy coatings incorporating nano-zinc oxide modified with the glycyloxy silane coupling agent exhibited significantly smaller changes in contact angle, color, and carbonyl groups after 450 hours of accelerated weathering, demonstrating significantly improved weathering resistance compared to epoxy coatings containing unmodified nano-zinc oxide.
The coupling agent method is the most promising modification method due to its simple process, good modification effect, and low cost.
Comparing the various surface modification methods mentioned above, and considering both modification effect and difficulty, it can be seen that the esterification method and the coupling agent method are more suitable for surface modification of nanomaterials.
Calcined alumina has become an important support for the development of the ceramic industry
Calcined alumina, an inorganic non-metallic material made from industrial alumina calcined at high temperatures, possesses many remarkable properties. Firstly, its high hardness is one of its hallmarks. Its Mohs hardness reaches 9, second only to diamond. This makes ceramic products made from it exceptionally wear-resistant, maintaining a good appearance and structural stability over long-term use. Secondly, it possesses excellent high-temperature resistance, capable of withstanding temperatures exceeding thousands of degrees Celsius without deformation or damage, a characteristic that makes it particularly useful in the field of high-temperature ceramics. Furthermore, calcined alumina exhibits excellent chemical stability and is not susceptible to chemical reactions with other substances, ensuring the stable performance of ceramic products.
The Main Functions of Calcined Alumina in Glazes
Due to its high purity, high hardness, and excellent chemical stability, calcined alumina is widely used in glazes, particularly for household ceramics, architectural ceramics, and specialty ceramics. In practical applications, it not only significantly improves the hardness and wear resistance of the glaze surface, effectively reducing scratches and wear during use, thereby extending the service life of ceramic products; it also enhances the glaze's chemical stability, reducing the risk of acid and alkali corrosion, and improving the product's stain resistance and durability. Furthermore, the appropriate addition of calcined alumina can adjust the glaze's melting temperature and viscosity, improving its fluidity, avoiding defects such as pinholes and glaze shrinkage, and resulting in a smoother and more even glaze surface. Furthermore, its unique optical properties can help control the glaze's gloss, adding a delicate texture to matte glazes and enhancing the gloss uniformity of glossy glazes to meet the design requirements of various ceramic products.
In pigment applications, calcined alumina can provide a stable carrier for metal oxide pigments (such as iron oxide and cobalt oxide), inhibit the volatilization or diffusion of pigments at high temperatures, and prevent the glaze from blooming and fading. Especially in high-temperature glazes, it can lock the color concentration and tone consistency, helping to achieve rich and lasting ceramic decorative effects. It is a key support for promoting the development of ceramic colored glazes towards high performance and high stability.
Action mechanism of rare earth oxides in magnesia-calcium refractories
The properties of an element determine its performance, and rare earth elements are no exception. Their performance is closely related to their properties. The primary factors determining their physical properties (such as hardness, crystal structure, and melting point) are their atomic and ionic radii. Rare earth metals have high melting points that increase with increasing atomic number, though this trend is not very consistent. Rare earth elements typically lose their outer s and d orbital electrons, forming a +3 valence state, thus forming rare earth oxides. This +3 valence state is the characteristic oxidation state of rare earth elements. Rare earth oxides have melting points exceeding 2000°C and are nonvolatile. They are mixed conductive semiconductors with both electronic and ionic conductivity. Electronic conductivity refers to the conduction of electrons and holes, while ionic conductivity refers to the movement of oxygen ions within oxygen vacancies, essentially oxygen ion conduction.
In addition to using rare earth elements directly as matrix components or functional centers based on the optical and magnetic properties of 4f electrons, their chemical properties, such as their chemical reactivity and large ionic radius, can also be leveraged to modify the material's microstructure, thereby improving its performance. Rare earth-doped functional semiconductor ceramics are a major example. Adding rare earth oxides to refractory materials not only enhances and improves the material's inherent strength and toughness, but also reduces sintering temperatures and production costs.
Due to their non-toxicity, high efficiency, and unique physical and chemical properties, rare earth compounds are increasingly being used in a wide range of applications, evolving from primary applications in metallurgy, chemical engineering, and ceramics to advanced applications in high-performance composite materials such as hydrogen storage and luminescence. Research on the application of rare earth oxides in ceramic materials has attracted widespread attention. Studies have shown that the addition of rare earth oxides significantly improves the performance of ceramic materials, ensuring their quality and performance for diverse applications. Furthermore, rare earth oxides, as fluxes, can promote sintering, improve the ceramic's microstructure, and provide doping and modification.
Rare earth oxides, as additives, improve the properties of refractory materials, demonstrating their unique and significant benefits in enhancing performance and imparting new functions. Adding small amounts of rare earth oxides increases the density of magnesia-calcium refractories, improving their density and corrosion resistance.
Rare earth oxides are used as additives in magnesia-calcium refractories to improve their sinterability, compactness, microstructure, crystalline phase composition, room-temperature flexural strength, and fracture toughness, thereby meeting market performance requirements for magnesia-calcium refractories. There are three main mechanisms for adding rare earth oxides to magnesium-calcium refractory materials. (1) Additives as flux can promote sintering. The sintering temperature of magnesium-calcium refractory materials is generally high, and there are many factors that are not conducive to densification during the sintering process. Adding rare earth oxides can solve this problem. Due to the unique properties of rare earth oxides, adding rare earth oxides to refractory materials can change their internal structure, thereby promoting the sintering of magnesium-calcium refractory materials. (2) Rare earth oxides can improve the microstructure of magnesium-calcium refractory materials. The addition of rare earth oxides can improve the internal microstructure of the refractory materials. This reduces the grain boundary migration rate, inhibits grain growth, and is conducive to the formation of a dense structure. (3) Doping modification of rare earth oxides. Doping rare earth oxides in the process of preparing refractory materials will cause the sample's crystal form to change, thereby causing its volume to change. This change can greatly improve its bending resistance and toughness. Research on adding additives to improve and optimize the relevant properties of materials in the preparation process of refractory materials has always attracted people's attention. In the current research, the main focus is on the problem that magnesia calcium sand raw materials are difficult to sinter and easy to hydrate. The main additives include ZrO2, Fe2O3, Al2O3, rare earth oxides, etc.
Application of barium sulfate in 10 industries
Barium sulfate is an unfamiliar term to most people, and even those unfamiliar with chemistry might consider it a dangerous chemical. However, barium sulfate is ubiquitous in our daily lives, often appearing in the form of manufactured products. For example, most plastic products in our homes, air conditioners, plastic car parts, supermarket bags, paints, coatings, and glass may all contain barium sulfate.
Application of barium sulfate in ten major industries
1. Petroleum Industry: 200-mesh and 325-mesh barite powder for oil and gas field drilling mud additives.
2. Chemical Industry: Barite salt plants use barite as a raw material to produce lithopone, precipitated barium sulfate, and barium carbonate.
3. Paint and Coating Industry: Barite can be used as a filler in paints and coatings, replacing more expensive raw materials such as precipitated barium sulfate, lithopone, titanium dioxide, and activated silica. It is suitable for controlling paint viscosity and achieving a bright and stable color.
4. Plastics Industry: Barite can be used as a filler in ABS plastic raw materials, adding a bright gloss while also improving strength, stiffness, and wear resistance.
5. Rubber Industry: Barite powder with a mesh size below 500 can be widely used as a filler in rubber products, reducing costs while improving hardness, acid and alkali resistance, and water resistance. It also provides excellent reinforcement for natural and synthetic rubber.
6. Paper Industry: Highly fine barite powder can be used as a filler and coating filler in whiteboard and coated paper to enhance whiteness and surface coverage. Product specifications: 325 mesh, 400 mesh, 600 mesh, 800 mesh, 1250 mesh, 1500 mesh, 2000 mesh, 2500 mesh, 3000 mesh, 4000 mesh, 5000 mesh, 6000 mesh.
7. Cement Industry
Adding barite and fluorite composite mineralizers to cement production can increase the whiteness and strength of cement. It can be used to make barium cement, barite mortar, and barite concrete, which can be used in buildings requiring X-ray protection.
8. Glass Industry
It can be used as a deoxidizer, clarifier, and flux to increase the optical stability, gloss, and strength of glass.
9. Construction Industry
It can be used as a concrete aggregate, paving material, to reinforce buried pipes in swampy areas, and as a replacement for lead sheeting in shielding at nuclear facilities, atomic power plants, and X-ray laboratories, extending the life of road surfaces.
10. Ceramic Industry
Barite powder can also be used as a high-quality filler in ceramics and other industries. Currently, the use of barium sulfate in the ceramics industry is decreasing, while the use of wollastonite powder is increasing.
The applications in the ten industries mentioned above are all critical and essential to people's livelihoods. This demonstrates the significant role and wide range of applications of barium sulfate, an inorganic non-metallic mineral powder.