Silica specific surface area test - Database & Sql Blog Articles

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SiO2 is also known as silica. It is widely distributed in nature, such as quartz and quartz sand. White or colorless, the higher the iron content is light yellow. Density 2.2 ~ 2.66. Melting point 1670 ° C (scaly quartz); 1710 ° C (cristobalite). The boiling point is 2230 ° C and the relative dielectric constant is 3.9. It is insoluble in water and slightly soluble in acid. It acts in the form of particles and acts on molten alkali. Used in glass, water glass, pottery, enamel, refractory, ferrosilicon, molding sand, elemental silicon, etc.
Use silicon standard solution. Water glass, a material for the preparation of silicon compounds. A mask film and a protective layer for diffusion of impurities in transistors and integrated circuits are used to form a silicon dioxide film as an integrated circuit device. Glass industry.
The physical physical properties of silica, also known as silica, chemical formula SiO? (silica specific surface area test by the 3H-2000 series of fully automatic nitrogen adsorption specific surface area tester distribution test,
Silicone specific surface area testing professional manufacturer Besed, high test accuracy, good repeatability, providing professional pre-sales technical support and excellent after-sales service) There are both crystalline silica and amorphous silica in the boundary. Kind. Sandy silica.
Crystalline silica is classified into quartz, tridymite and cristobalite due to its different crystal structure. Pure quartz is a colorless crystal, and large, transparent prismatic quartz is called crystal. If the crystal containing trace impurities has different colors, there are amethyst, sap, crystal and so on. Ordinary sand is a fine quartz crystal with yellow sand (more iron impurities) and white sand (less impurities, purer). In the silica crystal, the four valence electrons of the silicon atom form four covalent bonds with four oxygen atoms, the silicon atoms are located at the center of the regular tetrahedron, and the four oxygen atoms are located at the four vertex angles of the regular tetrahedron. ? is the simplest form of composition, only the ratio of the number of atoms of silicon and oxygen in the silica crystal. Silica is an atomic crystal.
The bond energy of Si-O bond in SiO? is very high, and the melting point and boiling point are high (melting point 1723 ° C, boiling point 2230 ° C).
The diatomaceous earth existing in nature is amorphous silica, which is the remains of lower aquatic plant diatoms. It is a white solid or powdery, porous, light and soft solid with strong adsorption.
The specific surface area of ​​silica is a very important parameter. The specific surface area is the surface area per gram of solid material in m2/g; the national standard for silica specific surface area testing is a low temperature nitrogen adsorption BET multipoint method based on BET theory (GB/T 19587-2004). The main point of the specific surface area measured by the nitrogen adsorption BET multi-point method is: in the range of 5-30% nitrogen partial pressure, the adsorption amount of the adsorbent (the powder to be tested) to nitrogen is measured at different partial pressure points of nitrogen, and adsorption is made. The isotherm, the specific surface area of ​​the adsorbent can be calculated by the BET formula to determine the saturated adsorption amount of the monolayer when the surface of the adsorbent is covered with nitrogen molecules to cover the monolayer. 3H-2000BET-A silica specific surface area test is a high-precision analytical instrument based on national specific surface test standards, with 7 domestic leading technologies; such as the only integrated in-situ purge processing function in China, for chromatographic ratio The problem of purging treatment between different nitrogen partial pressure points of the surface test makes the purging treatment between different nitrogen partial pressure points more convenient and efficient, and reduces the influence of continuous testing on accuracy; the only program-controlled wind and heat assistance in China The device is removed, so that after the full automation is realized, the sharp and rapid desorption peak is obtained, and the background error is reduced. The only chromatographic concentration detection system in China makes the nitrogen partial pressure detection accuracy increase by 10 times with respect to the flow rate method; the six-way valve injector Program control, the only domestic quantitative tube program-controlled switching function; the only domestic particle size report function; the instrument parameter software display, at the same time, the large-screen LCD hardware display on the instrument, making the instrument working state parameters clear at a glance, the operation is more reliable; and liquid nitrogen Temperature monitoring, detector gas shutoff protection, detector thermostat, important part sound prompts, make 3H-2000BET-A II The specific surface area test of silicon oxide meets and surpasses the performance of similar instruments in foreign countries in terms of test accuracy, stability and safety, and ease of operation. The 3H-2000 series silica specific surface area test has a large number of customers in China, which is the specific surface area of ​​silica. Test famous brands.
The chemical properties are relatively stable. Do not dissolve in water or react with water. It is an acidic oxide and does not react with ordinary acids. Gaseous hydrogen fluoride reacts with silica to form gaseous silicon tetrafluoride. It reacts with a hot concentrated alkali solution or a molten base to form a silicate and water. It reacts with various metal oxides at high temperatures to form silicates. Used in the manufacture of quartz glass, optical instruments, chemical vessels, ordinary glass, refractory materials, optical fibers, ceramics, etc. Silica is inactive and does not interact with halogens other than fluorine, hydrogen fluoride, hydrogen halides, and sulfuric acid, nitric acid, and perchloric acid (except hot concentrated phosphoric acid). Common concentrated phosphoric acid (or pyrophosphoric acid) can corrode silica at high temperatures to form heteropolyacids [2]. Melting borate or borohydride at high temperatures can also corrode silica. In view of this property, boric acid The salt can be used as a flux in ceramic firing, in addition to which hydrogen fluoride can also dissolve the acid in the silica to form a water-soluble fluorosilicic acid: SiO? + 4HF = SiF4↑ + 2H?O
Acid oxygenity:
Silica and basic oxides
SiO? + CaO = (high temperature) CaSiO3
Silica can be dissolved in concentrated hot alkaline solution: SiO? + 2NaOH = Na2SiO3+ H?O
(The reason why the reagent bottle of the alkali can not use the glass stopper and the rubber stopper)
At high temperatures, silica can be reduced by carbon, magnesium, aluminum: SiO?+2C=(high temperature)Si+2CO↑ If c is excessive, a reaction occurs: Si+C=high temperature=SiC (corundum)
Silicic acid anhydride: silicon dioxide (SiO2).
Silica does not react with water, that is, it does not form silicic acid when it comes into contact with water. However, it is artificially prescribed that silica is an acid anhydride of silicic acid. Application of silica is an important part in the manufacture of glass, quartz glass, water glass, optical fiber, and electronics. Raw materials for optical instruments, handicrafts and refractories are important materials for scientific research. When the crystallization of silica is perfect, it is crystal; after silica gelation and dehydration, it is agate; the colloid of water containing silica becomes solid as an opal; when the crystallite of silica is less than a few microns, it is composed of chalcedony, vermiculite, and secondary. Quartzite. Mineral resources with very stable physical and chemical properties of silica. Crystals are trigonal oxide minerals, ie low-temperature quartz (a-quartz), which is the most widely distributed mineral species in quartz family minerals. The generalized quartz also includes high temperature quartz (b-quartz). Quartz block, also known as silica, is mainly used to produce quartz sand (also known as silica sand), and is also a raw material for quartz refractories and fired ferrosilicon.
Glass and glass engraving flat glass, float glass, glass products (glass jars, glass bottles, glass tubes, etc.), optical glass, glass fiber, glass equipment, conductive glass, glass cloth and anti-radiation special glass and other main raw materials. Special use: glass lettering: first apply a layer of paraffin on the glass bottle, then use the sharp instrument to engrave the word, then use hydrofluoric acid to smear on the wax of the lettering, and wait for the piece of lettering to appear. Principle: Hydrofluoric acid etches silica.
Raw materials and glazes for ceramics and refractory porcelain, high silica bricks for kiln, ordinary silica bricks and silicon carbide.

Raw materials or additives such as metallurgical silicon metal, ferrosilicon alloy and silicon aluminum alloy, and flux.
Building concrete, cementitious materials, road building materials, artificial marble, cement physical property testing materials (ie cement standard sand).
A raw material such as a chemical silicon compound and water glass, a filler of a sulfuric acid column, and amorphous silica can be used as an adsorbent.
Main raw materials for mechanical casting sand, abrasive materials (blasting, hard grinding paper, sandpaper, abrasive cloth, etc.). .
Electronic high-purity metal silicon, communication optical fiber, etc.
Rubber and plastic add silica to rubber to improve the wear resistance of rubber. It can reduce the rolling resistance of the tire while improving the wear resistance and wet skid resistance of the tire. The tensile strength, tear strength, abrasion resistance, and the like of the rubber using silica are improved.
Coating filler (which can improve the weatherability of the coating), can be used to produce matting agent, and can also be used as a coating thickener.
Foods and pharmaceuticals are mainly used in the food industry to prevent agglomeration of powdered foods to maintain a free-flowing type of food additive or to adsorb liquid flavors, oils, vitamins, etc., so as to be in powder form, such as powdered fats and oils. Solid fragrances and solid wines. (Example: milk powder)
It can be used as a flow aid, a catalyst carrier, etc. in the production of pharmaceuticals.

Therefore, the silica specific surface area test needs to be tested with the 3H-2000 series fully automatic nitrogen adsorption specific surface area tester. The 3H-2000 series silica specific surface area tester can fully meet the silica test needs, and the silica specific surface area test. The professional manufacturer of the instrument, Besider, the silicon dioxide specific surface area tester has high test accuracy, fast speed and good repeatability. It has obtained many national technical patents, providing professional pre-sales technical support and excellent after-sales service.

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