black silicon carbide three kinds of law

Synthesis
There are H&X brown aluminum oxide nitridation of silicon powder, silicon dioxide and silicon tetrachloride reduction method. In large-scale industrial production, silica reduction method is more valued by the people. Reduction of silica silica powder 100 parts (by weight, hereinafter the same), mixed with 35 parts of carbon black, 100 parts of urea resin, and then 800 parts of water, 0.1 parts of aluminum oxide (as used in nuclear reactor), 1 part of oxalic acid H&X silica sand supplier parts of ammonium and nonionic surfactants (as a dispersant), for strong stirring, and aqueous ammonia was added with stirring to adjust the Ph of 9.0. Good slurry was spray-dried material, the resultant was dried in an electric furnace in a nitrogen atmosphere for 3 h at 1480 ℃ reduction nitridation reaction. Then restore the reaction product in. 720 ℃, the air carried off the carbon treatment, to obtain silicon nitride powder products.

Application of silicon carbide abrasive energy saving

1, the application of H&X fused silica manufacturers building materials, industrial grinding wheels using its thermal conductivity. Thermal radiation, high strength characteristics of high fever, manufacturing sheet metal kiln, kiln furniture can not only reduce capacity, but also improve the installed furnace capacity and product quality, shorten the production cycle, baked glazed ceramic sintering is ideal for indirect materials. 2, the application of energy saving aspect of the thermal stability and good thermal conductivity for heat, fuel consumption decreased by H&X quartz sand suppliers to 35% fuel savings, increased productivity by 20-30%. Especially with the discharge conveyor mining plant put inside the pipe, which is 6-7 times the normal level of abrasion wear resistant material. Silicon carbide powder is widely used in refractory, wear-resistant flooring, ceramic foam, specialty coatings, corrosion-resistant paint, flow separation and environmental protection industries.

The crystal structure of silicon carbide powder

Feature
Green, crystal H&X white fused alumina suppliers, high hardness, strong cutting ability, stable chemical properties, good thermal conductivity. Microscopic shape of a hexagonal crystal, silicon carbide 9.2 Mohs hardness, Vickers hardness of 3000 - 3300 kg / mm 2, a Knoop hardness of 2670-2815 kg / mm, hardness 3300 kg per cubic millimeter. Higher than corundum abrasives and second only to diamond, cubic boron nitride and boron carbide. Density is generally considered to be H&X garnet 80 mesh g / mm 3, the bulk density of silicon carbide abrasive nature of the 1.2 - between 1.6 g / mm 3, a specific gravity of 3.20 to 3.25. Green silicon carbide based petroleum coke and quality silica as the main raw material, add salt as an additive, smelting electric arc furnace. Hardness between corundum and diamond, corundum higher mechanical strength.

Black silicon carbide features and other purposes

Since silicon carbide chemical stability, high thermal conductivity,H&X carbide silicon expansion coefficient, good wear resistance, except for the abrasive used, there are many other uses, such as: a special process the silicon carbide powder coating on the turbine impeller or cylinder body wall, can improve the wear resistance and extend the life of 1 to 2 times; for advanced refractory material, heat shock, small size, light in weight high strength, good energy saving effect. A low-grade silicon carbide (containing about 85% SiC) is an excellent deoxidizer, with its speed steel to accelerate and facilitate control of the chemical H&X pink fused aluminium oxide, to improve the quality of steel. In addition, silicon carbide heating element is also used extensively for the production of silicon carbide.
The great hardness of silicon carbide having excellent thermal conductivity, is a semiconductor, resistant to oxidation at high temperatures.

Gypsum is also calcium silicon material

In particular, gypsum also be included in the calcium granules material.
Gypsum calcium Calculated: Laboratory Gypsum we calculated a substantially sulfur trioxide, calculate the content of CaSO4, the content of dihydrate gypsum, and the content of CaO (Ca according SO3: 40, O: 16, H: 1, S: 32).
SO3 molar mass of 32 +16 * 3 = 80g/mol; (S to 32, O to 16); CaO molar mass of 56g/mol; (Ca to 40, O to 16); CaSO4 molar mass = 56 +80 136g/mol (written CaO · SO3); CaSO4 · 2H2O: water molar mass of 18, the molar mass of blast grit 172g/mol.
Then when a single laboratory out phosphogypsum SO3 content of 30% of the time, CaO content = 30% * 56/80 = 21%, CaSO4 content of 30% +21% = 51%, the content of gypsum dihydrate = 30 % * 172/80 = 64.5%

The main purpose of the garnet and main component

The main purpose
(1) the steel structure, hull blast, Bridges, etc;
(2) metal, stone, glass, water knife cutting;
(3) the chemical, petroleum, pharmaceutical, water treatment filter medium;
(4) marble, optical lens, glass, leather and other materials of grinding;
(5) Brown Corundums wheel, oilstone, emery cloth and sand paper raw materials;
(6) the highway pavement, airport runway, prevent slippery, wear-resisting rubber paint, such as wear-resistant materials;
(7) is widely used in construction field, high-grade really stone paint exterior wall decoration interior decoration elegant temperament. The ideal new nonmetal wear-resisting flooring aggregate.
The main characteristics
The uvarovite highest value, but also the most rare
Main ingredients
Chemical composition: Al3Be2 [SiO4] 3
Crystallization characteristics: garnet belong to cubic system gem, the family on the crystal structure, belongs to the island silicate, common crystal morphology is rhombic dodecahedron, 38 sides and four corners shape, crystal visible grain growth.
Crystal system: belong to cubic system.
Refractive index: 1.74 to 1.90.
Hardness: 7-8.
Density: 3.5 to 4.3 grams per cubic centimeter.
Origin: Sri Lanka, India, Madagascar, the United States, China and other countries. More than a dozen provinces and autonomous regions in China are found to have gem grade garnet mineral.
Color: variety
Pyrope: red, purple, yellow and red
Almandine: brown, red, purple
Spessartine: yellow, orange, orange red
Grossular: brown yellow, yellow, yellow, green
Andradite: yellow, green, black
Uvarovite: green

Silicon carbide purpose

Black silicon carbide semiconductor can handle "extreme environment", it is alleged that silicon carbide wafer can withstand even Venus or near the sun's heat. Previous studies show that even at a temperature of 560 degrees Celsius, silicon carbide wafer in the absence of cooling device is still functioning normally. calcium siliconwafer has wide applied prospects in the field of communication, can let the high-definition TV transmitters provide a clearer signal and image; Also can be used in jet and automobile engine, monitoring the motor running. At the same time, it also can be used in the field of space exploration, help nuclear-powered spacecraft perform more complex tasks. French physicist predicted that in the field of chip manufacturing silicon carbide replace silicon has been far too.

Silicon carbide powder production steps are as follows

Silicon carbide powder production process there are five main steps:
First, take the silicon carbide materials, through the crusher, and sieved to less than 5mm of silicon carbide particles, and then shaping machine shaping them to no more than 2mm of silicon carbide particles, and the particles of which accounted for 80 Oval % or more, performs, pickling to remove impurities, and then during drying
Second, milling, the dried particles of silicon carbide powder mill crushed into d50 = 9.5-11.5μm silicon carbide powder, crushed when the mill is set to host the current 65-75A, fan flow is set to 40-50m3/min, analysis machine speed of 400 - 600 rpm / min for milling process.
Third, grading, grading machine with vortex flow silicon carbide powder grading, grading, vortex flow fan air classifier is 25-43m3/min, classifier wheel rotational speed of 2600 - 3300 rev / min, from grading mouth ceded ds94 = 6.5-5.5μm particle size of the finished product A, cyclone separation ds94 ≤ 5.5μm mouth semi-finished products;
Fourth, the vortex type air classifier with cyclone mouth impeller semi separated gas stream classifier then re-classifying, grading, the impeller of the fan air flow classifier 25-10m3/min, classifier wheel rotation speed is 1300 - 1700 rev / min, separated from the particle size classification mouth ds94 = 4.5-3.0μm finished product B, then the separated product cyclone mouth. Fifth, testing, according to the standard detected in the production of silicon carbide powder is qualified.

Silicon carbide powder production process

Silicon carbide powder production process, characterized by the following steps:
(A) take the silicon carbide raw material, crushing machine, crushing and sieving to not more than 5mm of silicon carbide particles, and then shaping machine shaping them to no more than 2mm of silicon carbide particles, and the particles of which accounted for 80 Oval % or more, and then its acid cleaning, drying;
(2) above the dry mill with silicon carbide particles smash into d50 = 9.5-11.5μm silicon carbide powder, crushed when the mill is set to host the current 65-75A, fan flow is set to 40 - 50m3/min, analysis machine speed of 400 - 600 rpm / min;
(3) and then use the vortex air classifier silicon carbide powder grading, grading, vortex flow fan air classifier is 25-43m3/min, classifier wheel rotational speed of 2600 - 3300 rev / min, from grading mouth ceded ds94 = 6.5-5.5μm particle size of the finished product A, cyclone separation ds94 ≤ 5.5μm mouth semi-finished products;
(4) The cyclone vortex air classifier mouth separated by semi-impeller type air classifier and then a second grading, grading, impeller fan air classifier flow 25-10m3/min, classifier wheel rotational speed of 1300 - 1700 rev / min, separated from the particle size classification mouth ds94 = 4.5-3.0μm finished product B, then the separated product cyclone mouth.

Corundum smelting general method of operation

Corundum smelting belong mineral hot furnace melting, smelting There are three main ways: Fixed furnace melting block method, dumping furnace smelting and refining flow mode method, because large-scale investment exile smelting, present, China mainly uses a fixed block method and dumping melting furnace furnace smelting two ways:
1, the dumping of the furnace (method) the production of corundum crystalline aggregates many small crystal size, and the distribution of high glass phase in the grain boundary, so that poor toughness, brittleness, shedding from sharp abrasive resistance, good compactness, compared with bonded abrasives and refractories adapted.
2, frit furnace (France) produced corundum, crystal aggregates small crystal size large, glassy less, so poor brittleness, toughness, wear resistance is good. Because crystals, toughness and brittleness better this way produced corundum smelting more adapted to the manufacture of coated abrasives. It is still the largest production and use of abrasive abrasive.
In recent years, due to bauxite resources for corundum smelting bauxite serious decline in quality, in particular commodity quality corundum difficult to achieve downstream product quality requirements, so corundum abrasives production, processing and post-processing becomes increasingly more important.

How to correctly select the corundum

1, white fused alumina abrasive, slightly higher than the hardness of corundum, but poor toughness, easy to cut into the workpiece during grinding, good self-sharpening, less heat, grinding ability, high efficiency. Chromium corundum abrasive is its derived varieties.
2, corundum abrasive, the main component of Al2O3, with medium hardness, toughness, particle Fengrui, relatively inexpensive, suitable for machining high tensile strength of the metal. Microcrystalline corundum abrasives and black corundum abrasives are its derived varieties.
Many of my friends in the purchase of corundum, grit and other abrasives, there will be carefully selected, select the correct product corundum blasting machines and other equipment will not affect the operation of the machine can cause serious trouble, corundum and other abrasives are generally divided into steel cut wire shot, alloy balls, white cast iron balls just in the use of corundum, because of the hardness of corundum is low and difficult to break, to maintain the shape of a blunt garden, on the leaves to shock, move-based, so the In this case the role of blade grinding suffered weak, partial grinding surface cracks and scratches a little more. In the scanning electron microscope samples for imported true for low-times be observed, that the lateral wear surface of a bulk wave, ripple motion perpendicular to the direction of the projectile.
3, single crystal corundum abrasive material particles are composed of a single crystal, and has a good polygonal cutting edge, high hardness and toughness, grinding ability, less grinding heat, the disadvantage is the high cost of production, yield lower, so the price is relatively high. White fused alumina abrasive is crystalline compound, slightly lower hardness, crystal size is fine, good wear resistance.
4, black silicon carbide abrasive, green silicon carbide abrasive, abrasive cubic silicon carbide, silicon carbide abrasive cerium, etc., are silicon carbide abrasive, the main ingredient is silicon carbide SiC, high hardness, brittleness, sharp abrasive grains, good thermal conductivity, strong wear resistance, more suitable for processing hard and brittle metallic and non-metallic products.

For green silicon carbide powder characteristics and magnetic introduction of knowledge

Green silicon carbide powder characteristics Green, high hardness and cutting ability, chemical stability, good thermal conductivity. High purity, brittle, microhardness 3280-3400 kg / mm2. It is made of abrasive, suitable for processing high hardness, brittleness of the material, green silicon carbide powder Scope: do bonded and coated abrasives, and polishing and so on. Suitable for machining cast iron, tungsten carbide, titanium, high-speed steel. Can grind glass, ceramics, stone, agate and jade and other non-metallic materials, fine jewelry, heating elements and thermal elements. Such as carbide, optical glass, glass and ceramics brittle ma non-metallic materials, can also be used to manufacture high-grade Sic Refractory, electric components and electrical component products. Green silicon carbide powder separator Green silicon carbide material to be crushed by magnetic separation. Generally the wet milled material into a concentration of 25% to 40% of the slurry, a wet magnetic separation to remove the ball into the iron. Production of smaller, can be used wet permanent magnetic blocks. When the large-scale production, can be wet magnetic separator, such as CST162 electromagnetic iron machine. The aircraft magnetic field strength of 7000 Oe or more, stopping every 20 ~ 30min filters cleaned once removed, can make the material magnetic material content to 0.002% or more.

Several preparation of silicon carbide ceramics

Because of the excellent performance of silicon carbide ceramic, silicon carbide ceramics so people very recognized, so the research and development of silicon carbide ceramics are also very much, following preparation of silicon carbide ceramics speak several ways.
(1) Although SiC hot temperatures above 2000 degrees and pressures above 350MPa can SIC hot pure dense, but usually a method or the use of additives. Pressing additives types: a class of impurities in silicon carbide form a liquid phase by liquid phase sintering promotion; one is reduced forms a solid solution with SiC grain boundary to promote sintering.
(2) atmospheric pressure sintered silicon carbide SiC is also named as sintered silicon carbide, sintered at temperatures above 2100 degrees, generating high-purity, high-density silicon carbide ceramics.
(3) reaction bonded silicon carbide SiC reaction, also known as self-adjoint SIC. Silicon carbide powder and graphite powder mixed at a ratio of body pressed into blocks, heated to 1650 degrees, and C by a gas phase reaction.