The synthesis of silicon carbide and main purpose

By the sand and the right amount of carbon in electric furnace heating. Figure XIV - 8 Lely furnace A - graphite tube; B - adiabatic area; C - graphite rod; D - graphite heater; E - single crystal growth of crucible; F - temperature measurement with observation seam; G - temperature window silica carbide reduction method of the average particle size of 0.01 microns 1 silica powder H&X Al2O3 powder and average particle size of 0.05 mu m 2 carbon powder and the average particle size of 0.1 mu m fine crystalline under beta 0.04 a mixed type of silicon carbide powder, and then into graphite containers, in the argon gas flow (flow: 2 L/min), at 1600 ℃ for 5 h reaction, then the reaction product in air, heat for 2 h at 700 ℃, to remove residual carbon, made beta type silicon carbide powder products. The equation is as follows: SiO2 + 2 + 3 csic co starting material of silicon carbide fiber is the boiling point is 70 ℃ liquid dimethyl dichlorosilane. With the function of sodium metal. In an inert organic solvent is higher than the boiling point of sodium, sodium was scattered, molten state in which dripped with dimethyl dichlorosilane, hydrochloric acid reaction at the same time generate poly silane. Will gather silane in inert atmosphere heated to above H&X Alumina Oxide, the heat transfer reaction and polymerization reaction, generate intermediate carbon silane. The melt spinning fiber. Get of carbon silane fiber in high temperature calcination process processing, bridging reaction because the oxygen in the air, often in a nitrogen atmosphere heat treatment, the temperature is 1200 ~ 1500 ℃ was high strength of silicon carbide fibers. Figure XIV - 9 A - hydrogen gas instead should be synthetic device entry; B - hydrogen purification device; C - meter; D - constant temperature bath; E - temperature measurement using prism; F - gas exports; G - quartz glass tube; H - base material; I - high frequency induction coil;

The main analytical test methods silicon carbide powder:

The main purpose
For H&X garnet abrasive inch monocrystalline silicon, polycrystalline silicon, gallium arsenide, wire-cut quartz crystal. Processing materials are engineered solar photovoltaic industry, the semiconductor industry, piezoelectric crystal industry.
The main analysis of silicon carbide detection methods:
Determine the content of silicon carbide in the silicon carbide hardness. SiC particle size on the line cutting a great impact, but the most important thing is the shape of the silicon carbide particles. Because when H&X Aluminium hydroxide wire cutting silicon carbide particles to change the shape of the free state of cutting efficiency and cutting quality to be an important influence.
Detection methods: silicon content requires atomic absorption detection (high detection efficiency, more accurate values​​).
Silicon carbide particle resistance method requires particle analyzer (high efficiency).
Silicon carbide grain type detection requires Reith RA200 particle analyzer. (Particle shape can be analyzed more accurate roundness factor)

Detailed calcium silicon ratio and concrete

calcium silicon than the larger, more vulnerable to sulfate attack concrete and alkali-aggregate reaction. Besides ettringite recrystallization will decompose, resulting in poor stability. One of these is generally mixed with volcanic ash admixture purpose is to improve the material and silica fume silica, calcium granules than concrete, so that the mechanical properties and durability of concrete to achieve better. Theoretically hydrated calcium silicate silicon ratio is between 1.7 to 2.3 at. Over this range, the concrete will be a problem.

Calcium silicon ratio calculation

Production process parameters are:
Pouring calcium metal granules 43 ℃, mold is 4.20m × 1.20m × 0.6m, surface Baotou 5% water feed ratio was 0.62. Determined by trial production with the ratio of:
m (cement): m (lime): m (fly ash): m (gypsum) = 8:24:65:3;
3, calcium silicon ratio calculation method:
C / S = ((8 × 59.37% +24 × 71.5% +65 × 2.6% +3 × 30%) / 56) / ((8 × 22.7% +24 × 5.5% +65 × 46.2%) / 60) = 0.76
56 and 60, respectively, calcium oxide, silicon dioxide molar mass [1]
4, the production of aerated concrete optimal calcium silicon ratio range:
① cement - lime - fly ash aerated concrete series of 0.75 to 0.80
② cement - lime - sand aerated concrete range from 0.64 to 0.68;
③ cement - lime - metal tailings aerated concrete series of 0.55 to 0.62.
5, in the actual production of aerated concrete, when the mixing ratio of calcium silicon ratio is less than optimal calcium silicon ratio, with the strength of the products (cement, lime) to increase the amount of binder increased. When the mixing ratio of calcium silicon ratio greater than optimal calcium silicon, continue to increase the amount of binder strength products are no longer rising even decline.

Precautions when calcium

If improper food ingredients calcium silicon, while containing excessive intake of phytic acid, oxalic acid, tannic acid foods (such as spinach, etc.) and with fatty foods (mainly lard and fat), and calcium will combine and reduce the absorption of calcium. In addition, some high-quality protein (such as beef, fish, seafood, lean pork, etc.), released in the intestine during digestion of amino acids, can reduce intestinal acidity and calcium easily absorbed form of calcium, can also reduce calcium absorption. So calcium addition, to avoid interactions and the impact of food ingredients to reduce the loss of calcium.
There are a variety of hormones hormones can promote intestinal absorption of calcium, the most important is the active vitamin D3. Low levels of active vitamin D3 elderly, affecting calcium absorption and utilization. While calcium white fused alumina suppliers need active vitamin D3. Other hormones promote intestinal calcium absorption are: estrogen, androgens, growth hormone, calcitonin. Postmenopausal women, estrogen decreases intestinal calcium absorption decreases estrogen supplementation can increase intestinal calcium absorption, increase bone mass. Estrogen replacement therapy, should begin as soon as possible after menopause, adhere to at least 75 years of age. Other hormones may also be appropriate to add to increase the calcium effect. Of course, we must supplement the hormone under the guidance of experienced doctors.
Reduce outdoor sports activities too little can lead to osteoporosis or accelerated osteoporosis. If you insist on outdoor sports, receive sunlight a day, and even refused to accept the active vitamin D3. In China, the southerners than the northerners bone content, which is due south over the northern sunlight received sufficient reason.