The Preparation Methods of Spherical Quartz Powder
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Update time : 2021-11-01 16:18:56
Spherical quartz powder has excellent properties such as smooth surface, large specific surface area, high hardness and stable chemical properties. Spherical powder has good fluidity and is evenly mixed with resin to form a film. The amount of resin added is small, and the filling amount of quartz powder is high.
The higher the filling amount of quartz powder, the lower the thermal conductivity, and the smaller the thermal expansion coefficient of the molding compound. The closer to the thermal expansion coefficient of monocrystalline silicon, the better the performance of the electronic components produced.
Spherical quartz powder is purified and ultra-finely pulverized from natural quartz stone and passed through a certain high temperature field to make its phase, crystal and shape change instantaneously, from solid state to molten state to solid state, from crystalline state to amorphous, a powder obtained from irregular angular particles into regular spherical particles. Its preparation methods currently generally include high-temperature plasma melting method, high-temperature melting injection method and gas combustion flame method.
High Temperature Plasma Melting
The high-temperature plasma melting method uses high-temperature gas generated by AC or DC arc plasma as a heat source to spray quartz powder into a plasma flame. The powder is heated and melted and instantly vaporized, then quenched, and collected by a cyclone and a cloth bag. The spherical silicon powder is obtained. It is characterized by high heating temperature, which can obtain a temperature field that is more than 5 times higher than chemical combustion (above 3000K). High temperature, high heat and high active atmosphere make the chemical reaction proceed very quickly, resulting in the rapid formation of high temperature phase compounds that are difficult to synthesize by chemical liquid phase method. (Such as nitrides, carbides and borides, etc.); when the reaction material leaves the plasma, the particles will no longer grow after rapid cooling; the plasma state of different atmospheres can be formed according to different needs, and the range of reactants is wide.
However, plasma technology is very difficult. First, the plasma temperature field is affected by the magnetic and electrical properties of the plasma. The temperature field is small and concentrated. The stable high temperature field of the heating device is not easy to control, and the temperature range is not easy to adjust; secondly, the plasma energy The generation of the and jet is realized by the current passing through the ionized gas medium. Too much dilution of the plasma will interrupt the current and lose its effect. These factors make it difficult to control the spheroidization rate of the product, and it is difficult to form a large-scale production.
High Temperature Melt Injection
The high-temperature melt injection method is to put the material in a high-temperature field to melt it into a melt. At the moment the melt flows out, it is sprayed with high-pressure air through the ejector, and the melt is dispersed and broken into mist by the high-speed airflow. The small droplets are rapidly cooled again, and the small droplets naturally shrink naturally into spherical particles with a smooth surface when they are cold. The high temperature melt spraying method is the easiest method to ensure spheroidization and amorphous rate. However, a series of key technologies such as furnace high temperature materials, viscous quartz melt atomization and prevention of secondary pollution have not broken through, and it is very difficult to manufacture high-purity spherical quartz powder.
Gas Combustion Flame Method
The gas combustion flame method uses acetylene, hydrogen, natural gas and other fuel gases as raw materials, and uses oxygen or air as supporting gas to produce a clean flame through the combustion of a closed furnace. At the same time, the angular quartz powder is transported into the flame along with the airflow. When the angular powder passes through the high-temperature flame field, it is first melted into amorphous particles. When it leaves the high-temperature field and is rapidly cooled, it immediately shrinks into spherical particles, and is collected by the cyclone to obtain the finished product. This method involves theories of thermodynamics, gas and particle hydrodynamics. Compared with plasma high-temperature flames, firstly the temperature field is relatively low, and secondly, there are fewer influencing factors. It no longer involves electromagnetic theory and the flow of ions in the electromagnetic field. The problem of movement makes it easier to control various factors affecting conditions, simplifying equipment manufacturing, easy to achieve industrialization, and better development prospects.
Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional oxide powder supplier with over 12 years experience in chemical products research and development. We accept payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.
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