Wollastonite is a single-chain calcium silicate mineral with molecular formula CaSiO3 and structural formula Ca3[Si3O9]. It belongs to the triclinic system and usually appears as needle-like or fibrous aggregates. It is white to light gray with a glassy luster and has a pearly luster on the cleavage plane. More properties: hardness 4.5-5.0, expansion coefficient 6.5×10-6 mm/(mm-°C), melting point 1540°C, density 2.78-2.91g/cm3.
Wollastonite has low electrical conductivity, good insulating properties, little water solubility and oil absorption. The unique needle-like physical structure and stable chemical properties of wollastonite determine its good wear resistance, reinforcing effect, high-temperature resistance, corrosion resistance, etc. It is also non-toxic, tasteless, and non-radioactive, and is widely used in functional coatings, rubber, plastics, friction materials, construction materials, papermaking, metallurgy, and many more industries.
Wollastonite fiber, an environmentally-friendly inorganic mineral, is one of the most ideal functional fillers with excellent performance across the world.
Wollastonite Fiber Products
Relying on unique mineral resources, Hoyonn adopts advanced equipment and automatic control technology for mineral purification, fiber crushing, airflow crushing, classification, surface modification, packaging, and product testing. With advanced technology, stable quality, and strict management, we can produce wollastonite fiber products with high purity and high aspect ratio, and the particle size can reach as low as 6000 mesh.
Wollastonite fiber is an environmentally-friendly and high-performance functional filler. It can completely replace asbestos mineral fiber or partially replace glass fiber, playing an outstanding role in improving the properties of end-use products and reducing production costs.
Wollastonite fiber is characterized by good wear resistance, thermal stability, insulation, low oil absorption, needle-like structure, high aspect ratio, etc. It is a high-quality filling material for plastic and rubber products.
- Improve wear resistance and scratch resistance.
- Improve impact strength and bending strength, and give the end-use products obvious electrical and thermal insulation properties.
- Improve thermal stability and dimensional stability.
- Improve surface smoothness.
- Wollastonite used in light-colored rubber can replace a large amount of titanium dioxide, clay, or riddling powder to achieve a reinforcing effect. It can improve the coverage ability of the white colorant, and improve the surface whiteness.
- Wollastonite filled in SBR, fluorine rubber, and silicone rubber after organic modification can improve their tensile strength, tear strength, tearing elongation, and wear resistance and can also reduce costs.
After surface modification, the surface of wollastonite is lipophilic, thus improving its wetting and dispersion properties in non-polar SBR. And as the sodium oleate molecule in the treatment agent is double-bonded, it can participate in vulcanization, enhance cross-linking, and greatly improve the reinforcing effect.
Wollastonite fiber is featured good wear resistance, corrosion resistance, and UV resistance. When used as a functional filler for paints and coatings, it can not only improve the mechanical properties of the coating film but also play an important role in reducing costs.
- Wollastonite can be used as a body pigment to partially replace titanium dioxide, and it has the effect of covering and increment, which can also reduce costs. It can increase the thickness of the paint film, make the film solid and wear-resistant and reduce the cracking problem. This filler can adjust the rheological properties of the paint, such as thickening, anti-sedimentation, etc.
- Its high refractive index allows the paint product to show purer and brighter colors, making the pigments evenly distributed along the surface. This feature also enables the coating film to have the ability to block visible light and ultraviolet light penetration, improving the anti-aging ability of the coating film.
- Wollastonite fiber can be used in polypropylene anti-corrosion coatings, and its needle-like structure can make the coating have high surface gloss, good resistance to water erosion, and the ability to buffer PH.
- The low expansion coefficient of wollastonite fiber can improve the thermal stability of high-temperature-resistant coatings.
- Its low oil absorption property can reduce the consumption of binder substances.
Wollastonite is used as a raw material for many ceramic products – glazed tiles, sanitary porcelain, household porcelain, artistic porcelain, power porcelain, radio porcelain of high frequency and low consumption, chemical ceramics, colorants, glass, molds, etc. The main functions of wollastonite used in the ceramic industry are:
- Reduce the firing temperature: Wollastonite has an obvious solvent effect in the billet of architectural and sanitary ceramics. Using an appropriate amount of it can greatly reduce the firing temperature of the billet. Especially in the current trend of energy saving and low-temperature firing process, it is a good choice of using wollastonite in the billet raw materials.
- Shorten the firing cycle: Because of the small ignition loss and low thermal expansion rate (linear expansion and uniform change) of wollastonite, no obvious heat absorption/exothermic effect or phase change will occur within 1200 degrees. So it is very suitable for the fast firing process, shortening the firing cycle and saving energy.
- The comprehensive effect of wollastonite due to its energy saving, low-temperature firing, time-saving, and improvement of physical and chemical properties of end-use products can promote the improvement of the production process, kiln structure and firing process, and operation methods.
- Because of its low expansion coefficient and low water solubility, using wollastonite can reduce firing shrinkage in firing, thus significantly reducing product flexure or cracks and making it easy to shape.
- Wollastonite can optimize the glaze quality. Adding wollastonite to the glaze of household ceramics with the proper amount can replace part of the quartz and limestone raw materials, and can completely avoid the glaze pinhole or glaze bubble defects caused by the decomposition of carbon dioxide gas from limestone. In the firing process, wollastonite can reduce the high-temperature viscosity of the glaze and optimize surface gloss and smoothness.
- The needle-like structure and wear resistance of wollastonite can improve the mechanical strength and wear resistance of ceramic products.
Advantages of choosing wollastonite as the protective slag for the metallurgical base:
- It can reduce the types of base materials for slag preparation and simplify the process. More importantly, it can ensure the composition stability and uniformity of the slag.
- Wollastonite protective slag is highly adaptable to various steel types, such as ordinary carbon steel, high-quality carbon steel, and low-alloy steel.
- Wollastonite doesn’t contain crystalline water or carbonate. In the melting process, it can greatly reduce the moisture, volatiles, and any resulting exhaust problem, thus reducing the possibility of steel surface brittleness and longitudinal cracks.
- It is good at adsorbing and dissolving inclusions.
- In the continuous casting process, the viscosity change of wollastonite protective slag is very little with temperature change. So it has good thermal stability.
- Wollastonite protective slag added to the crystallizer can quickly melt to form a molten layer of suitable thickness, and uniformly cover the liquid steel surface, thus isolating the air and preventing secondary oxidation. The protective slag layer can also insulate the steel liquid. Since the viscosity of wollastonite slag is low, it can form a thin and uniform glass layer on the surface of the cast billet with good lubrication and protection effects, while doesn’t affect the crystallization or cooling process.
- The fluorine-free protective slag can avoid fluorine harms – environmental pollution, human body harm, or equipment corrosion.
- Wollastonite base material can be formulated with low or no carbon slag suitable for a variety of continuous casting requirements. It helps to reduce the carbon addition to the billet during the continuous casting process and improves the qualified rate of the billet. It can also improve lubrication conditions, increase pulling speed, reduce pulling accidents, improve efficiency and reduce production costs.
With the advantages of being non-toxic, tasteless, and non-radioactive, wollastonite fiber can completely replace harmful asbestos or partially replace glass fiber, which greatly reduces environmental pollution. On the premise of not sacrificing the performance of building materials, it can greatly reduce the production cost as an ideal raw material for green building materials.
As an inorganic mineral fiber product, the application of wollastonite fiber is quite mature in many types of building materials, such as calcium silica board, cement fiberboard, fireproof and sound insulation board, etc. It can improve the impact resistance, bending strength, and wear strength of building materials, while the products have good corrosion resistance, sound insulation, heat insulation, fireproof, and electric insulation.
The particle size of wollastonite fiber used in building materials ranges from 100 to 800 mesh. The particle size, aspect ratio, and purity of the fiber determine its application in different kinds of building materials products.
The special needle-like structure and unique mechanical properties of wollastonite fiber for high-end friction materials can greatly enhance their friction resistance and heat resistance. When the fiber is filled with friction material, it can improve its friction flexibility and stability.
Wollastonite can replace asbestos in the field of friction and braking. Research has found that the friction material with the addition of wollastonite has increased friction coefficient, higher braking flexibility, lower wear rate, stable performance, no abrasion on the pair, and no noise. Wollastonite doesn’t contain toxic substances and is environmentally friendly.
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Hoyonn Chemical has been in the polymer industry since 2001. We specialize in mineral development, powder processing, R&D innovation, and global sales of barium sulphate and various functional fillers and additives. We have our plants and know-how to supply worldwide customers from powder coatings, paints, plastics, rubber, ink, and more industries.
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