What are the uses of titanium dioxide?
Titanium dioxide is an important inorganic chemical pigment, the main component of which is titanium dioxide. There are two production processes for titanium dioxide: sulfuric acid process and chlorination process. It has important uses in industries such as coatings, inks, papermaking, plastics and rubber, chemical fibers, and ceramics.
The particle size distribution of titanium dioxide is a comprehensive indicator, which seriously affects the performance of titanium dioxide pigment and product application performance. Therefore, the discussion of hiding power and dispersibility can be directly analyzed from the particle size distribution.
The factors affecting the particle size distribution of titanium dioxide are relatively complex. The first is the size of the original hydrolysis particle size. By controlling and adjusting the hydrolysis process conditions, the original particle size is within a certain range. The second is the calcination temperature. During the calcination of metatitanic acid, the particles undergo a crystal transformation period and a growth period. Control the appropriate temperature to keep the growing particles within a certain range. Finally, the product is crushed. Usually, the Raymond mill is modified and the analyzer speed is adjusted to control the crushing quality. At the same time, other crushing equipment can be used, such as: universal mill, air flow mill and hammer mill.
Titanium dioxide has three crystal forms in nature: rutile, anatase and brookite. The brookite belongs to the orthorhombic system and is an unstable crystal form. It will transform into rutile at above 650°C, so it has no practical value in industry. The anatase is stable at room temperature, but it will transform into rutile at high temperature. Its transformation intensity depends on the manufacturing method and whether inhibitors or promoters are added during the calcination process.
Titanium dioxide (or titanium dioxide) is widely used in various structural surface coatings, paper coatings and fillers, plastics and elastomers. Other uses include ceramics, glass, catalysts, coated fabrics, printing inks, roofing granules and fluxes. According to statistics, the global demand for titanium dioxide reached 4.6 million tons in 2006, of which the coating industry accounted for 58%, the plastic industry accounted for 23%, the paper industry accounted for 10%, and others accounted for 9%. Titanium dioxide can be produced from ilmenite, rutile, or titanium slag. There are two production processes for titanium dioxide: sulfate process and chloride process. The sulfate process is simpler than the chloride process and can use low-grade and relatively cheap minerals. Today, about 47% of the world's production capacity uses the sulfate process, and 53% of the production capacity uses the chloride process.
Titanium dioxide is considered to be the best white pigment in the world and is widely used in coatings, plastics, papermaking, printing inks, chemical fibers, rubber, cosmetics and other industries.
Titanium dioxide (titanium dioxide) has stable chemical properties and does not react with most substances under normal circumstances. In nature, titanium dioxide has three types of crystals: brookite, anatase and rutile. The brookite type is an unstable crystal form with no industrial utilization value. The anatase type (A-type) and the rutile type (R-type) both have stable lattices and are important white pigments and porcelain glazes. Compared with other white pigments, they have superior whiteness, tinting power, hiding power, weather resistance, heat resistance, and chemical stability, especially non-toxicity.
Titanium dioxide is widely used in coatings, plastics, rubber, ink, paper, chemical fibers, ceramics, daily chemicals, medicine, food and other industries.
Dolomite is used in various industries
The chemical formula of dolomite is [CaMg(CO3)2], also known as dolomite limestone. Dolomite accounts for about 2% of the earth's crust. Dolomite sediments are common all over the world, mainly sedimentary rocks or equivalents of changed structures.
Dolomite is one of the widely distributed minerals in sedimentary rocks and can form thick dolomite. Primary sedimentary dolomite is directly formed in sea lakes with high salinity. A large amount of dolomite is secondary, formed by limestone being replaced by magnesium-containing solutions. Marine sedimentary dolomite is often interbedded with siderite layers and limestone layers. In lake sediments, dolomite coexists with gypsum, anhydrite, rock salt, potassium salt, etc.
Application of dolomite in various fields:
Metallurgical industry
Magnesium has good thermal conductivity and electrical conductivity. It is a non-magnetic and non-toxic metal. Magnesium alloys are light, durable, high-strength, high-toughness, and good mechanical properties. They are widely used in aviation, automobiles, precision castings, defense industry, and other industries. In the magnesium smelting industry. Dolomite is one of the important raw materials for the production of magnesium metal. The domestic silicothermic method is generally used to refine magnesium metal. The output accounts for about 20% and about 67% of the total amount of magnesium metal. The silicothermic method is to calcine and decompose dolomite to obtain a mixture of MgO and CaO. After the calcined powder is ground and sieved, it is mixed according to the molar ratio of Mg to Si of 2:1, and an appropriate amount of fluorite is added as a catalyst. The mixed lumps are made into balls and reduced with silicon at 1150-1200C to generate calcium silicate and magnesium. Dolomite is an important auxiliary material for steelmaking and sintering in the metallurgical industry.
Building materials industry
As the raw material of magnesium cementitious materials: dolomite is calcined at a certain temperature. Dolomite is partially decomposed to generate magnesium oxide and calcium carbonate, and then magnesium oxide solution and aggregate are added to stir and form, and high-strength ferro-ammonia cement materials are generated after curing. Ferro-ammonia cementitious materials are mostly used in the production of large packaging boxes and the 8th generation of Suifeng Street. They have broad application prospects in the development of new construction structures. Dolomite accounts for about 15% of the float glass mixture.
Chemical Industry
In the chemical industry, marbling is mainly used to produce magnesium compounds, which is also the best way to increase the added value of marbling products. The main industrialized chemical products are magnesium oxide, light magnesium carbonate, magnesium hydroxide, and various magnesium salt products. Light magnesium carbonate is also called industrial hydrated basic magnesium carbonate or basic magnesium carbonate. The molecular formula can be expressed as xMgCO3 yMg(OH)2 zHO. White monoclinic crystal or amorphous powder, non-toxic, odorless, relative density 2.16, stable in air. Slightly soluble in water, the aqueous solution is weakly alkaline. Easily soluble in acid and ammonium salt solution, reacts with acid to generate magnesium salt and releases carbon dioxide. High temperature pyrolysis turns into magnesium oxide.
Other applications
In agriculture, dolomite can neutralize acidic substances in the soil and be used for soil improvement. At the same time, the magnesium contained in dolomite can be used as magnesium fertilizer to supplement the magnesium in crops: dolomite is added to feed as a feed additive to increase the calcium and magnesium intake of poultry and livestock and enhance the nutrition of poultry and livestock.
In the field of environmental protection, after hydration and digestion of calcined dolomite powder, it mainly contains magnesium hydroxide and calcium hydroxide, which can absorb gases such as carbon dioxide and sulfur dioxide in flue gas. Therefore, calcined dolomite powder can be used for flue gas carbon dioxide separation (ECRS); dolomite can also be used in gasification furnaces to remove H2S from flue gas: using the high surface energy and adsorption of calcium hydroxide and magnesium hydroxide generated by hydration of active magnesium oxide in calcined dolomite powder, calcined dolomite can be used as a filter material for domestic water treatment, and can also be used to remove metal ions such as iron and manganese in industrial wastewater.
Varieties and applications of fine alumina
Fine alumina has many varieties and is widely used. It is the preferred material in many fields.
Therefore, "wide source of raw materials", "can be found everywhere", "cheap price" and "simple preparation" have become labels for alumina. Scarcity makes things valuable. These labels can easily lead people to misunderstand that alumina is a low-end material. First of all, the editor believes that these labels cannot determine whether alumina is low-end or not, but they can show that alumina is a very cost-effective material in many fields. Secondly, even from the perspective of price, technical content, performance and other aspects, alumina is not lacking in "high-end products". These "high-end products" play an irreplaceable role in high-precision fields such as semiconductors and aerospace.
Alumina fiber
The main component of alumina fiber is alumina (Al2O3), and the auxiliary components are SiO2, B2O3, MgO, etc. It is a high-performance inorganic fiber and a polycrystalline ceramic fiber with various forms such as long fiber, short fiber, and whisker. It has excellent properties such as high strength, high modulus, and corrosion resistance.
The application field of Al2O3 fiber is relatively wide. Al2O3 short fiber can be compounded with resin, metal or ceramic to prepare high-performance composite materials, and manufacture industrial high-temperature furnaces such as heating furnaces, kiln linings and electronic component calcining furnaces; Al2O3 continuous fiber reinforced composite materials have excellent properties such as high strength, high modulus and high stiffness. Its matrix is not easy to oxidize and fail during use. It also has excellent creep resistance and will not cause grain growth at high temperatures to cause the performance of the fiber to decrease. It is internationally recognized as a new generation of main materials for high-temperature resistant hot end components and has huge development potential; in addition to the above properties, functional Al2O3 nanofibers also have excellent properties such as low thermal conductivity, electrical insulation and high specific surface area. They are widely used in reinforced composite materials, high-temperature thermal insulation materials, catalytic filtration materials, etc.
High-purity alumina
High-purity alumina (4N and above) has the advantages of high purity, high hardness, high strength, high temperature resistance, wear resistance, good insulation, stable chemical properties, moderate high-temperature shrinkage performance, good sintering performance and optical, electrical, magnetic, thermal and mechanical properties that ordinary alumina powder cannot match. It is one of the high-end materials with the highest added value and the widest application in modern chemical industry.
At present, high-end high-purity alumina is mainly used for lithium battery electrode additives, solid-state battery electrolyte fillers, and wafer grinding and polishing in the semiconductor industry.
Spherical alumina
The morphology of alumina powder particles will directly affect its application performance in many fields. Compared with the common irregular, fibrous or flaky alumina powder particles, spherical alumina has a regular morphology, higher packing density, smaller specific surface area and better fluidity. It is widely used as thermal conductive filling material, polishing material, catalyst carrier, surface coating material, etc.
In industrial production, what are the classifications of barium sulfate?
Barium sulfate, for most people, the chemistry is not very well understood, in their eyes, barium sulfate is a dangerous chemical. In fact, in our daily life, barium sulfate can be said to be everywhere, but they usually appear in our lives in the form of manufactured products.
For example, most plastic products in our homes, air conditioners, some plastic accessories in cars, plastic bags used in supermarkets, etc., paints and coatings used in life, glass, etc. may contain barium sulfate.
In the physics and chemistry textbooks, the chemical formula of barium sulfate is BaSO4, which is generally a white rhombus, colorless and odorless, with a density of 4.499 and a melting point of up to 1580℃. Its chemical properties are very stable, insoluble in water, acid-resistant, alkali-resistant, non-toxic, non-magnetic, and can also absorb X-rays and gamma rays. In nature, barium sulfate is also called barite, a natural ore, generally in the shape of a forked crystal block, and its color is mainly determined by the type and amount of impurities it contains. Pure barite is colorless and transparent. Barite has no direct harm to the human body and can be directly contacted.
In industry, there are many classifications of barium sulfate, and the common ones are as follows:
1. Heavy barium, also known as barite powder or natural barium powder. It is made by people selecting natural barium sulfate ore (baryte) and then washing, grinding, drying and other processes. It has many impurities and its quality is mainly determined by the ore itself, but its price is low. It is usually used as a filler in the production of white pigments or low-grade coatings, plastics, and ink industries. It plays a role in reducing costs and improving gloss.
2. Precipitated barium sulfate, also known as industrial barium sulfate or precipitated barium. It is made by artificial processing. Unlike heavy barium, precipitated barium contains almost no impurities. It is slightly soluble in water and insoluble in acid. It is non-toxic in itself, but if it contains soluble barium, it can cause poisoning. Precipitated barium sulfate in industry is mainly generated by the reaction of barium sulfate with sulfuric acid, the reaction of barium chloride with sulfuric acid or sodium sulfate, and the reaction of barium sulfide with sodium sulfate. Precipitated barium sulfate is used as a filler in the fields of medicine, medium and high-end coatings and inks, plastics, rubber, glass, ceramics, etc. due to its stability and different specific indicators. People usually divide it into coating-grade precipitated barium sulfate, plastic-grade precipitated barium sulfate, etc. according to different applications. Its price is higher than that of heavy barium.
3. Modified barium sulfate, which is divided into modified barium sulfate and modified precipitated barium sulfate, is to enhance the performance of barite powder or precipitated barium sulfate in a certain aspect through relevant treatment. The application is similar to precipitation, and it mainly depends on its relevant properties. Among them, the one that has been further processed and refined is also called modified ultrafine barium sulfate or modified ultrafine precipitated barium sulfate. The price is higher than precipitated barium sulfate.
4. Nano-grade precipitated barium sulfate is to control its D50 (median particle size distribution) between 0.2μm-0.4μm through deep processing of modified precipitated barium sulfate. Nano-grade precipitated barium sulfate is mainly used in high-end paints, coatings and other industries.
10 major application areas of silicon micropowder
Silica powder is a kind of inorganic non-metallic material with wide applications. Silica powder is a micron-level powder obtained by crushing and pulverizing high-purity quartz ore by physical or chemical methods. Its particle size is generally between 1-100 microns, and the commonly used particle size is about 5 microns. With the advancement of semiconductor manufacturing processes, silica powder below 1 micron has gradually been widely used.
Silica powder has a series of advantages such as excellent dielectric properties, low thermal expansion coefficient, high thermal conductivity, high chemical stability, high temperature resistance, and high hardness. It can be widely used in copper clad laminates, epoxy molding compounds, electrical insulation materials, and adhesives. In addition, it can also be used in coatings, rubber, plastics, cosmetics, and honeycomb ceramics.
1 Copper clad laminate
Adding silicon powder to copper clad laminate for electronic circuits can improve the linear expansion coefficient and thermal conductivity of printed circuit boards, thereby effectively improving the reliability and heat dissipation of electronic products.
2 Epoxy molding compound (EMC)
Filling silicon powder into epoxy molding compound for chip packaging can significantly improve the hardness of epoxy resin, increase thermal conductivity, reduce the exothermic peak temperature of epoxy resin curing reaction, reduce linear expansion coefficient and curing shrinkage, reduce internal stress, and improve the mechanical strength of epoxy molding compound, making it infinitely close to the linear expansion coefficient of the chip.
3 Electrical insulation materials
Silicon powder is used as epoxy resin insulation filler for electrical insulation products. It can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during the curing process, reduce internal stress, and improve the mechanical strength of the insulating material, thereby effectively improving and enhancing the mechanical and electrical properties of the insulating material.
4 Adhesives
Silicon powder, as an inorganic functional filling material, is filled in adhesive resin, which can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during curing, improve the mechanical strength of the adhesive, and improve the heat resistance, anti-permeability and heat dissipation performance, thereby improving the bonding and sealing effect.
5 Plastics
Silicon powder can be used in plastics in products such as polyvinyl chloride (PVC) flooring, polyethylene and polypropylene films, and electrical insulation materials.
6 Coatings
In the coatings industry, the particle size, whiteness, hardness, suspension, dispersibility, low oil absorption, high resistivity and other characteristics of silicon micropowder can improve the corrosion resistance, wear resistance, insulation and high temperature resistance of the coating. Silicon micropowder used in coatings has always played an important role in coating fillers due to its good stability.
Spherical silica powder has good fluidity and large specific surface area, which makes it suitable for cosmetics such as lipstick, powder, foundation cream, etc. In powder products such as powder, it can improve fluidity and storage stability, thereby playing a role in preventing caking; the smaller average particle size determines its good smoothness and fluidity; the larger specific surface area makes it have better adsorption, can absorb sweat, fragrance, nutrients, and make cosmetic formulas more economical; the spherical shape of the powder has good affinity and touch to the skin.
8 Honeycomb ceramics
Automobile exhaust filter DPF made of honeycomb ceramic carrier for automobile exhaust purification and cordierite material for diesel engine exhaust purification is made of alumina, silica powder and other materials through mixing, extrusion molding, drying, sintering and other processing.
9 Rubber
Silicon powder is a reinforcing material for rubber. It can enhance the comprehensive properties of rubber, such as strength, toughness, elongation, wear resistance, finish, anti-aging, heat resistance, anti-slip, tear resistance, acid and alkali resistance, etc. It is indispensable in the production process of rubber products.
10 Artificial quartz
Silicon powder is used as a filler in artificial quartz board, which can not only reduce the consumption of unsaturated resin, but also improve the wear resistance, acid and alkali resistance, mechanical strength and other properties of artificial quartz board. The filling ratio of silicon powder in artificial marble is generally about 30%.
Key raw material for solid electrolytes—Zirconia
ZrO2 is an oxide material with high temperature resistance, high hardness and good chemical stability. It has high melting point and boiling point, so it can maintain stable physical and chemical properties in high temperature environment. In addition, ZrO2 also has a low thermal expansion coefficient and good electrical insulation properties. This makes it one of the preferred raw materials for LLZO solid electrolyte.
High hardness: The hardness of ZrO2 is second only to diamond, and it has high wear resistance.
High melting point: The melting point of ZrO2 is very high (2715℃). The high melting point and chemical inertness make ZrO2 a good refractory material.
Excellent chemical stability: ZrO2 has good resistance to chemicals such as acids and alkalis and is not easily corroded.
Good thermal stability: ZrO2 can still maintain good mechanical properties and chemical stability at high temperatures.
Relatively large strength and toughness: ZrO2, as a ceramic material, has a large strength (up to 1500MPa). Although the toughness is far behind some metals, compared with other ceramic materials, zirconium oxide has a higher fracture toughness and can resist external impact and stress to a certain extent.
There are various preparation processes for ZrO2, including pyrolysis, sol-gel, vapor deposition, etc. Among them, pyrolysis is one of the most commonly used preparation methods. This method reacts zircon and other raw materials with alkali metal or alkaline earth metal oxides at high temperature to generate zirconate, and then obtains ZrO2 powder through acid washing, filtration, drying and other steps. In addition, the performance of ZrO2 can be regulated by doping different elements to meet the needs of different solid-state batteries.
The application of ZrO2 in solid-state batteries is mainly reflected in oxide solid electrolytes, such as lithium lanthanum zirconium oxide (LLZO) and lithium lanthanum zirconium titanium oxide (LLZTO), which exist in garnet-type crystal structures. In these solid electrolytes, ZrO2 occupies a very important proportion. For example, in the mass of LLZO before sintering, ZrO2 accounts for about 25%. In addition, in order to reduce the interface resistance in solid-state batteries and improve the efficiency of lithium ion migration, the positive and negative electrode materials usually need to be coated with materials such as LLZO. At the same time, oxide semi-solid batteries also need to construct a layer of ceramic diaphragm composed of materials such as LLZO, which further increases the amount of ZrO2 used in solid-state batteries.
With the continuous development of solid-state battery technology and the expansion of its application fields, the demand for ZrO2 as a solid electrolyte raw material will continue to grow. In the future, ZrO2 is expected to play a more important role in the field of solid-state batteries by further optimizing the preparation process, regulating performance and reducing costs. At the same time, with the continuous emergence of new solid-state electrolyte materials, ZrO2 will also face more intense competition and challenges. However, with its unique properties and broad application prospects, ZrO2 will still have an irreplaceable position in the field of solid-state batteries.
Inventory of 20 kinds of inorganic powders for plastics
Plastics are important products for production and daily life in today's society. The use of inorganic powders can effectively improve the physical and chemical properties of plastic products and enhance the performance of plastic products.
Wollastonite
Wollastonite is a natural calcium silicate (CaSiO3) with a light white needle-like structure. The aspect ratio (L/D) of processed wollastonite can reach more than 15/1. It is a fibrous inorganic reinforcing filler in plastics.
Talc
Talc has a flaky structure and has a significant reinforcing and modifying effect in plastics and rubber. It can improve the tensile strength, impact performance, creep resistance, heat resistance, tear resistance, etc. of plastic products.
Barium sulfate
The natural ore (barite) is crushed, washed and dried to obtain barite powder (also called heavy barium sulfate). Barium sulfate has excellent properties such as chemical stability, scratch resistance, heat resistance, high refractive index, outstanding sound insulation, heat preservation, and high gloss.
Mica
Mica is a layered aluminum silicate mineral with a unique structure. In addition to its reinforcing effect, it can also improve the air tightness, optical properties, and insulation properties of plastics.
Glass beads
Glass beads have the advantages of high temperature resistance and low thermal conductivity. When used to fill plastics, they can not only increase the wear resistance, pressure resistance, and flame retardancy of the material, but also its special spherical surface can improve the processing fluidity of the material; in addition, it has good surface gloss, which can increase the surface gloss of the product and reduce the adsorption of dirt on the surface.
Magnesium hydroxide
The chemical formula of magnesium hydroxide is Mg(OH)2. It can be prepared by chemical methods or obtained by crushing brucite ore. Magnesium hydroxide has a flame retardant effect. After surface modification, it can be filled into plastics to achieve the effect of smoke suppression.
Aluminum hydroxide
Aluminum hydroxide is a compound with the chemical formula Al(OH)x. It is used as a flame retardant, smoke suppressant and filler in PVC. Since it reduces the mechanical strength of thermoplastics when used in them, it is mostly used in thermosetting plastics.
Zeolite
Zeolite is a framework-shaped, hydrated alkali or alkaline earth metal aluminum silicate mineral. Its specific gravity, nanoporous structure, adsorption and chemical resistance can provide new development space for expanding the application of plastic products.
Kaolin
When used for filling and modification of plastics, it can improve the insulation strength of plastics. Without significantly reducing the elongation and impact strength, it can improve the tensile strength and modulus of thermoplastics with low glass transition temperatures. It can act as a nucleating agent for polypropylene, which is beneficial to improving the rigidity and strength of polypropylene. It has a significant infrared barrier effect.
Glass fiber (GF)
Glass fiber has high mechanical strength, elastic modulus, heat resistance and insulation, and is usually used to reinforce composite materials. GF can effectively make up for the shortcomings of biodegradable plastics, and can also significantly reduce the cost of products and expand the application range of biodegradable plastics.
Montmorillonite
Montmorillonite is a hydrophilic layered silicate material. Because of its nanometer size, it has a nano effect and can effectively improve the performance of polymers. Especially after modification, its application range is wider.
Other inorganic powders
Nano silicon dioxide has relatively stable chemical properties and a large specific surface area, which can effectively improve the strength, wear resistance and aging resistance of resin-based materials.
Rutile titanium dioxide can increase the reflectivity of light as a plastic filler and play the role of a light shielding agent.
Fly ash has the advantages of small specific gravity, high hardness and good fluidity.
Carbon black is generally used in the plastic industry for coloring, UV protection or conductivity.
Black inorganic minerals such as black talc and black calcite can partially replace carbon black. While fully utilizing mineral resources, the production cost has obvious advantages.
Using bentonite as an additive for degradable materials can replace starch and other chemical additives to reduce costs.
Halloysite has unique tubular nanostructures and good water dispersibility, different properties of inner and outer walls, high adsorption, biocompatibility and other unique and excellent physical and chemical properties.
Molybdenum disulfide is an inorganic compound composed of molybdenum and sulfur, and its chemical formula is MoS2.
Application of fumed silica powder materials
Since its introduction, fumed silica has attracted widespread attention due to its excellent properties. It is currently widely used in various industries, such as reinforcing rubber, adding it to plastics as a filler, adding it to inks as a thickener, adding it to cosmetics as a high-grade filler, etc. It is also used in coatings, paints, and adhesives. Fumed silica also shows excellent properties different from other materials in terms of magnetism, catalysis, melting point, etc., so it is also used as a functional additive. In recent years, nanotechnology has developed rapidly and achieved remarkable results. Fumed silica has a nanometer-scale particle size, is non-toxic and has high purity. Therefore, it has attracted the attention of researchers in some emerging fields and has made beneficial progress.
Application of fumed silica in the field of oxidative desulfurization
With the use of fossil fuels, the emission of sulfides is gradually increasing, leading to serious environmental pollution, destroying the ecosystem, and endangering human health. Therefore, deep desulfurization of fuel oil has gradually become an environmental problem that needs to be solved urgently. Hydrodesulfurization is a relatively developed technology that can remove most sulfides. However, the removal effect of heterocyclic sulfides and their derivatives is not good. Therefore, predecessors have studied and developed a variety of desulfurization technologies such as adsorption, extraction, and oxidative desulfurization (ODS). Among them, the ODS method has mild reaction conditions, simple operation process, and efficient desulfurization.
Application of fumed silica in food hygiene
A three-sided filler composed of fumed silica, iron and tea polyphenols, fumed silica fully increases the effective active quantity of iron and tea polyphenols, and significantly reduces Gram-positive Staphylococcus aureus and Gram-negative Staphylococcus. In addition, with the increase of loading, the antioxidant activity is affirmed, reaching a maximum value of 67%, and the specific migration limit of iron is lower than the limit applicable in the current food contact material regulations.
Application of fumed silica in the rubber field
Fumed silica is also commonly used in the preparation of silicone rubber. For room temperature vulcanized silicone rubber, fumed silica can not only improve its tensile strength, but also act as a thickener and thixotropic agent to control the performance of room temperature silicone rubber to a certain extent. Fumed silica can also be used to fill silicone resins, especially those used in the electronics field and silicone rubber mixing.
Application of fumed silica in ink and coating
In industry, people often add fumed silica to ink and coating to improve their rheological properties, and it also acts as a dispersant and anti-settling agent. Fumed silica is also added to some high-end coatings, such as marine ship coatings and industrial repair coatings, mainly due to the thixotropic and matting properties of fumed silica. In some high-solid content coatings with high environmental requirements, fumed silica is usually added to improve the thixotropic and dispersing properties of the coating. In industrial inks, an appropriate amount of fumed silica is generally added to adjust its rheological properties.
Application of fumed silica in the field of lithium batteries
Lithium metal soft-pack batteries have high energy density, light weight, lower cost and are more suitable for large-scale production. However, due to the characteristics of metallic lithium, the uncontrollable growth of Li dendrites during charging and discharging greatly hinders the cycle stability and commercialization of lithium batteries. Based on the nano characteristics and unique dielectric constant of fumed silica, the physical and chemical properties of lithium electrodes can be effectively improved, the growth of Li dendrites can be avoided, and the number of charge and discharge times of lithium batteries can be increased.
Application of fumed silica in mechanical polishing
Chemical mechanical polishing (CMP) is a leading technology for semiconductor device processing at this stage. CMP in the microelectronics field requires high slurry concentration and low impurity ion content. Both precipitated silica and fumed silica can meet this requirement, but precipitated silica is difficult to achieve high purity requirements. Fumed silica is the most ideal choice, and has low impurity ion content. It is easier to make the substrate material in the process flat for easy processing.
High value-added deep processing and utilization of bentonite
At present, the montmorillonite content of industrial bentonite primary processed products is generally 40%-65%, and it also contains certain clays (illite, kaolinite, halloysite, chlorite, allophane, etc.) and non-clays (zeolite, quartz, cristobalite, feldspar, calcite, pyrite, rock debris, iron oxides and organic matter).
The premise of high value-added deep processing and utilization of bentonite is to use mineral processing and purification technology to increase the montmorillonite content to more than 80%. The purified product is called montmorillonite.
Montmorillonite is a natural layered mineral with a huge specific surface area and non-uniform charge distribution. It has good water absorption, dispersion, dissociation, thixotropy, lubrication, adsorption, exchange and other abilities. It can be sold directly as a montmorillonite-based raw material, or it can be further inorganically or organically modified to produce catalyst carriers, inorganic gels, organic bentonite, organic/inorganic nanocomposites, lithium-based bentonite and other high value-added products.
1. Human medicinal montmorillonite
The application of montmorillonite in the pharmaceutical industry can be divided into two categories:
Medicinal raw materials: digestive tract mucosal protective agents, bactericidal and antibacterial agents, etc.
Medicinal excipients: excipients, suspending agents, filter agents, etc.
In medicine, montmorillonite stomach medicines are currently used in large quantities, and their preparations have been widely used in clinical practice. The montmorillonite stomach medicine preparations that have been developed successively include powders (high-purity montmorillonite, excipient-dispersed montmorillonite), granules, gels, suspensions, etc.
2. Montmorillonite for veterinary medicine and animal health care
Before using montmorillonite, it must be confirmed that it is non-toxic (arsenic, mercury, lead, and cristobalite do not exceed the standard). Its mechanism of curing and maintaining health for animals is similar to that of human stomach medicine, but it needs to be specially formulated and used for the prevention and treatment of diarrhea, dysentery, hemostasis, anti-inflammatory and other diseases in animals. It can remove mold and heavy metals in feed without toxic side effects; it also has a strong adsorption effect on heavy metals, harmful gases, bacteria, etc. in the digestive tract, thereby playing a role in animal health care.
3. Montmorillonite for feed ingredient enhancers
Montmorillonite has good adsorption, swelling, dispersion and lubricity, and can be used as an animal feed additive.
4. Montmorillonite for feed mildew inhibitors
Montmorillonite acts as a carrier in feed mildew inhibitors. Montmorillonite (mildew remover) is used to remove mycotoxins from feed and raw materials. Whether it is in vitro evaluation or animal testing, its effect is unquestionable.
5. Montmorillonite for dairy enhancers, etc.
Dairy farming is an important area of feed consumption. After adding montmorillonite to feed, the various macro and trace elements contained in it are components of enzymes, hormones and some bioactive substances in the cow's body, which can activate the activity of enzymes and hormones in the body, improve the function of the body's immune system, reduce feed consumption, enhance disease resistance and improve milk production performance.
6. Montmorillonite for cosmetics
Montmorillonite can effectively remove and absorb residual makeup, dirt impurities and excess oil in the skin texture, tighten overly coarse pores, accelerate the shedding and exfoliation of aging cells, dilute melanocytes, and improve skin color.
Surface modification of ceramic powders
Surface modification of ceramic powders is a key technology used to improve their performance in various applications, such as dispersibility, fluidity, compatibility with binders, and uniformity and density of the final product. Several main surface modification methods and their effects can be summarized.
Organic carboxylic acid esterification reaction
The esterification reaction between organic carboxylic acid and the hydroxyl groups on the surface of powders such as alumina can change the highly polar polyhydroxyl surface structure into a non-polar organic surface structure covered by long hydrocarbon chains, thereby eliminating the hard agglomeration between powders, reducing the internal friction during the pressing process, greatly improving the uniformity and density of ceramic green bodies and products, and significantly improving the strength of products.
Liquid phase chemical coating technology
The surface modification and surface coating of powders are used to improve the dispersibility of powders and change the phase structure and properties of powders. This includes the use of different polymer layers, such as polyethylene, polystyrene, and polymethyl methacrylate, which are polymerized on the surface of ultrafine ZrO2 and SiC powders by low-temperature plasma polymerization.
Use of stearic acid and adipic acid
The carboxyl groups in stearic acid and adipic acid undergo esterification reaction with the hydroxyl groups on the surface of nano zirconium oxide powder particles to form a monomolecular film on their surface, so that the surface-modified nano zirconium oxide powder is converted from polar to non-polar, while showing good flow properties.
Oxidation pretreatment
By oxidizing pretreatment of Si3N4 powder, a coating mainly composed of Si2N2O can be obtained on the surface. This treatment can significantly reduce the viscosity of the slurry, increase the amount of liquid phase during sintering, promote densification, and inhibit the nucleation of b-Si3N4.
High-energy ball milling method
Introducing nano-Al2O3 into ZrB2 through high-energy ball milling to form ZrB2-Al2O3 composite ceramic powder, and then performing organic functional modification can significantly improve the dispersibility of the powder in epoxy resin, and the modified composite material exhibits higher heat resistance.
Barium oxalate coprecipitation method
Selecting BaTiO3 powder produced by barium oxalate coprecipitation method as the matrix raw material, adding MgO to modify the surface of the powder particles can prevent grain growth, increase density, expand the firing temperature range and increase hardness.
Silane coupling agent coating modification
Using silane coupling agent KH-845-4 to coat and modify nano-Si3N4 ceramic powder can significantly improve the suspension stability, thermogravimetric, particle size distribution and other physical properties of the powder in the solvent.
Emulsion polymerization modification
Ultrafine ZrO2 ceramic powder is added to the polymer emulsion of methyl methacrylate (MMA) and styrene (ST) to prepare polymer-coated ceramic powder. This method can significantly improve the ability of powder to avoid agglomeration and is used for injection molding to prepare uniform and fluid ceramic injection materials.