silicon carbide powder production in a more general question

Summary: Positive silicon carbide abrasive sinister waste generated during the H&X buy silica process is the production of a more widespread problem, the extent of the problem due to the existence of the plant production conditions and the stability of the firing process varies. According to incomplete statistics, sinister waste accounted for 0.04 to 2.60 percent of total production abrasive. But domestic causes silicon carbide abrasive black H&X silicon carbide manufacturers is still lack of systematic research, while the black heart of the matter and its causes are caused by the need for discussion.
Keywords: silicon carbide abrasive waste firing process sinister production conditions roasting process binders total grains

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.

Quantitative analysis THAUMASITE formation mechanism

Abstract : Two experimental methods designed synthetic THAUMASITE to study erosion mechanism of cement-based silica sand manufacturers THAUMASITE 's . X-ray diffraction , Raman spectroscopy of cement -based materials instars qualitative analysis of reaction products , and using the Rietveld method for quantitative characterization. The results showed that: THAUMASITE in ettringite can still form an environment , it can be directly described reaction ; in the presence of ettringite formation environment THAUMASITE also be generated , indicating that the carbon and sulfur wollastonite formation mechanism Woodfordite transition mechanism exists. The presence of ettringite increases the yield of thaumasite . In comparison , Woodfordite transition mechanism is more likely to occur than the direct formation mechanism , and the two mechanisms can coexist simultaneously.
Keywords : quantitative Rietveld method based materials THAUMASITE cement analysis
Funds: China Building garnet manufacturers Academy , State Key Laboratory of Green Building Materials Open Fund " cement-based materials THAUMASITE quantitative characterization " ( 533001 ) funded projects
CLC : TU528
Snapshot text :
Thaumasite stone (CaCO3 CaSiO3 CaSO4 15H2O) is due to cement-based materials under long-term immersion in sulfate environment , and with adequate water sources and the environment carbonate produced [ 1 ] . THAUMASITE formation mechanism is now more recognized in two ways: one is the erosion of the environment sulfate , aggregate or carbonized get carbonates, adequate water and hardened cement paste in C-S-H react directly .

Calcium silicon ratio to ensure the use of best quality aerated concrete

Summary : Positive since 2010 " aerated concrete production waste pulp mill technology and mix back silicon carbide price " [ 1 ] After the article was published, received many calls and letters from enthusiastic readers , and claimed that in almost identical conditions , but also that the parameters ( temperature , pressure, time , quality, etc. ) under the same circumstances, but with the same cast a tie instability phenomenon than the production of aerated concrete : the slurry in the mold box sent gas height vary greatly, sometimes hair dissatisfied , sometimes overflowing slurry , high or low quality products , fused aluminium oxide
Keywords : silicon calcium fly ash aerated concrete mix concrete production than raw computing process conditions optimal hydration products of cement lime
CLC : TU528
Snapshot text :
Since 2010 , " aerated concrete production waste pulp mill technology and mix back calculation " [ 1 ] after the article was published, received many calls and letters from enthusiastic readers , and claimed that in almost identical conditions , which is the parameters ( temperature , pressure, time , quality, etc. ) under the same circumstances, but with the same cast a tie instability phenomenon than the production of aerated concrete : the slurry in the mold box sent gas is high.

What people should calcium?

Carborundum Abrasives, for many people think that only children and rickets patients only need. In fact, this view is not comprehensive. Clinically there are many patients, they need calcium.
Typical symptoms of diabetes in people with diabetes is "a little", ie polydipsia, polyphagia, polyuria and weight loss due to osmotic diuresis, increased excretion of calcium in vivo, thus leading to the occurrence of diabetes, bone disease, there bone thinning, osteoporosis and even pelvic deformity or pathologic fracture.
Senile osteoporosis through middle age, endocrine dysfunction, too little activity, inadequate calcium intake and other factors, bone metabolism disorders, osteogenesis reduce excessive loss of calcium, osteoporosis, bone degeneration, performance of leg pain, pathological fractures and even hunched phenomenon.
Some pregnant women pregnant leg pain, leg cramps. Because fetal growth and development, the demand for calcium metal granules increases lead to calcium deficiency in pregnant women. In addition, low birth weight children, premature children, malnourished children, children with chronic diarrhea, should pay attention to calcium. Due to calcium deficiency in children will not only affect growth and development, but also due to calcium deficiency secondary to a variety of diseases.
Epilepsy patients in recent years, scientific research shows that long-term use of anti-epileptic drugs, the body in varying degrees of low bone mineral density and bone metabolism. Once calcium is often difficult to control epilepsy and therefore require long-term use.
"Three drink" by long-term heavy drinking or regular tea, coffee should pay attention to calcium. Bone metabolism disorders due to alcohol consumption occurs, it can lead to osteoporosis, long-term drinking coffee, due to the diuretic effect, so that calcium excretion, easily lead to calcium deficiency in vivo.
Hypoparathyroidism "A side" dysfunction or lack of, can lead to reduction in intestinal calcium absorption, causing lower serum calcium. Patient developed numbness, tingling, stiffness, spasms and a series of symptoms.

Eat less salt calcium method

For all those who are applicable. For example : the rapid growth of the girls, and more salt , calcium excretion increased, reducing absorption can lead to bone demineralization , bone dysplasia . Incidence of women , osteoporosis in post -menopausal Another example is already very high, if more salt , not only silicon carbide grit the amount of calcium , the loss of calcium also increases will accelerate its osteoporosis . In one study , the daily salt intake in postmenopausal women reduced to 4.4 grams of 10.6 grams , calcium excretion and serum calcium concentrations are greatly reduced. If you continue to re- hypertensive patients is a high -salt diet , their urinary calcium excretion than people with normal blood pressure is much higher , leading to potentially dangerous bone demineralization is also larger than normal blood pressure . Instead, eat less salt , but they can reduce urinary calcium , bone density increased.
According to WHO recommended standards, the daily amount of salt to five grams is appropriate, not to exceed 6 grams. We know that people 24 hours of discharge is 3-5 grams of salt , then the food garnet suppliers 5 grams of salt per day , it lost considerable numbers and supplements to meet the normal needs. The daily amount of salt should be limited to less than 5 grams , is not easy. This need to change our eating habits for the job . Because in our country, especially in the northern residents , the amount of salt in general ones, and more than 12 grams per day , in some places , up to 20-30 grams . People should eat salty traditional habit , all of a sudden change over, is quite difficult. But people know eat less salt can be calcium , calcium can also be no cost truth , we have gradually , appropriate to reduce the amount of salt in their daily lives , I think it can be done.
In other places , there are potassium , magnesium and sodium salts of the market, the amount of sodium salt of only 65% ​​of such ordinary salt . If you eat this salt , the salt itself has been reduced to 1/ 3 of the . Chinese autumn stone , the main ingredient is potassium chloride, bought it fine, mix with half the salt , can also play a role in reducing salt 1/2 .

How trace elements such as silicon, calcium supplement

Investigation of many experts in the world that: Calcium deficiency is a serious threat to human disease , the global population suffer from mental and millions of great physical suffering , directly affects the improvement of human quality. Experts called on all sectors of society should be highly valued !
Fetus from maternal calcium obtained , used to make 99% of the bone , leaving only 1% in the form of free calcium ions in the blood is called " serum calcium silicon ." However, data shows that: after the birth , everyone into the different levels of calcium deficiency situation. People of any age are calcium , children and the elderly are more serious. Scientists found that since the age of 20 , the total weight of the bones to an annual rate of 1% decline, after the age of 50 , bone weight has been reduced by 30% overall - this is a scientific and startling conclusion .
As the " calcium hunger" , leading to the body's so-called "calcium move ." That is, the calcium bones constantly escape into the blood to maintain normal levels of serum calcium. The proportion between serum Carborundum Abrasives with calcium must maintain a long-term balance , otherwise , it will produce "calcium move " so abnormal calcium metabolism imbalance. A person within a few days or a month or calcium hunger temporarily affect serum calcium , but if things go on, calcium deficiency disease occurs : the child showed sparse hair , anorexia, irritability, night terrors , rickets , etc. ; youth skeletal dysplasia , eye disorders ; pregnant waist, leg pain , and affect fetal development , even teratogenic etc. ; osteoporosis in the elderly , degenerative bone hyperplasia , stone disease , hypertension , diabetes, dementia and so on.
Obviously, calcium plays an important role in the life course .

Garnet sand Detail

garnet sand, garnet abrasive raw materials, with high hardness, high temperature stability, chemical resistance, uniform particles, high grinding efficiency, no scratches and other characteristics suitable for water jet cutting industry;. Various metals, plastics , wood and other surfaces sandblasted industry; ultra-fine grinding machinery industry, precision casting and for CRT glass, optical glass, silicon and other grinding industries;
Garnet sand origin
China garnet sand origin especially Inner Mongolia, Jiangsu Lianyungang, Rizhao most representative Mongolia garnet hardness, but mainly for the wind to wash the dust content is relatively large, the impact of cutting speed, the other, mostly small workshop production, deep Habitat inland transport costs are very high; Jiangsu Lianyungang garnet sand has been a major producer of domestic pomegranate sand, bright colors, hardness in general, open pit, mostly for local small workshop production, and therefore cheap low cost cheap, quality control is not strictly , often have a variety of impurities, often waterjet plug phenomenon, by the end of 2011, Lianyungang local government closed the mine, prohibit any person opened indiscriminate mining, which led to a very tight supply of garnet sand; Shandong Rizhao garnet sand for the deep mine, blackish dark red color, hardness, starting in 2011 in the domestic market, is less well known and therefore another origin, supply capacity, quality and stability, maritime land are more convenient, the next few years The main origin of Chinese garnet silica sand price.
Garnet sand process data and physicochemical properties
1, chemical analysis: (%)
SiO2 :36 - 40 AL2O3 :20 - 24 Fe2O3 :4 - 6 TiO2 :0-0 .5 MgO :8-13 FeO :22 - 24 CaO :6 - 9 MNO :0-0 .5
2, Hardness: Mohs 7.5-7.9;
3, specific gravity: 3.98
4, strength: Tough
5, gloss: shiny glass
6 forms: angular, irregular
7, crystal shape: isometric crystal system, octahedral corners
8 Streak: White
9 colors: cherry red, orange-red based
10, cleavage: Texture little, irregular cleavage plane
11 Transparency: Transparent
12, melting point: 1340 ℃
13: Magnetic: weak magnetic
14: Water Absorption: non-absorbent
15: Dispersion: Self-diffusion
16: Uniformity: homogeneous body
17, pathological response: None
18, the silicon content of hazardous freedom: None

Corundum coating knife cutting wear a variety of reasons

The color is white corundum state, its simple structure, flexibility is softer than corundum, high reliability and a very wide range of applications. Metal cutting process, resulting in the tool wear is mainly due to the contact between the tool and the workpiece and the friction and blade near the extreme high temperature and pressure conditions. Cutting area of ??any one unit change in contact conditions will affect the tool wear, these conditions include tool material, tool coating and tool geometry specifications, there are other conditions and the physical properties of the workpiece material, corundum cutting tool parameters and the appropriate conditions , cooling and lubrication conditions, the process of cutting machine tool vibration greater or more serious causes the tool to jump fluctuate overload.
Because of different cutting conditions when machining different materials, corundum tool wear mechanism is different: at low cutting speeds, often dominated by abrasive wear; speed cutting, with the cutting speed, cutting temperature increases, bond wear and chemical wear more and more prominent. This paper mainly Ti (C, N) ceramic coated carbide cutting Cr12 mold steel knife tool wear failure analysis studies.
Corundum diffusion wear when cutting steel, cutting temperatures often reach 800 ~ 1000 ℃, or even higher, diffusion wear of carbide cutting tools become one of the main reasons for wear, beginning from 800 ℃, cemented carbide Co, C, W will spread to the chip and other elements to be taken in; the chips to the alloy of Fe diffusion, to form a new, low hardness, high brittleness of the composite carbide. The diffusion of Co, WC, TiC and other carbides reduced due to the Co binder reduce the bond strength with the substrate, which would accelerate the wear of the tool. Meanwhile, the temperature rises to a certain degree of adhesion occurs, therefore, diffusion wear and adhesive wear is often occur simultaneously.
In the tool wear surface morphology observed in the process, we found that more or less the clearance face of the tool, there are some small round particles. To explore these little balls of ingredients, using EDS energy dispersive spectroscopy analysis performed on the part. Found that these pellets mainly composed of a metal Fe and O, presumed to be iron oxides. Corundum ball shape is round, can not be generated in the cutting chips. According to theory of metal crystallization, to form such a round spherical objects, the most likely route is through the liquid - solid transition to achieve, because the liquid substance in order to have a minimum surface energy, with automatic shrink into a ball trend. In high-speed cutting, the temperature is high, although the cutting groove wear areas there is no theoretical temperature at the tip and the rake is high, but the trench oxidation and diffusion regions violent, especially from high-speed chip flow, Tool wear resulting in a trench area in contact with the sharp edges of the chip generates strong friction, wear the trench area and micro contact the local temperature is high, reaching some of the chips on a micro melting temperature, so he formed a lot small balls.
To reduce the corundum small tool wear, cutting parameters can be optimized to ensure product quality and processing efficiency in the case of small cutting parameters selection cutting force for cutting; coating material composition can be optimized to improve the coating material machinability, using advanced multi, multi-layer, gradient coating system, by increasing the intermediate layer to improve the coating and the substrate adhesion and corundum coated cutter when appropriate substrate pretreatment.

Corundum: What are the main component of corundum

Corundum name comes from India, Department of Mineralogy name, gemology gemstone conditions have called on Ruby (Ruby), Sapphire (Sapphire). Isomer like corundum Al2O3 There are three main variants, namely α-Al2O3, β-Al2O3, γ-Al2O3,, according to X-ray diffraction analysis indeed there is η-Al2O3 (equiaxed), ρ-Al2O3 (Crystal Department of uncertainty), χ-Al2O3 (hexagonal system), κ-Al2O3 (hexagonal system), δ-Al2O3 (tetragonal), θ-Al2O3 (monoclinic [1]). Corundum variety of colors, there is a colorless, white, yellow (pigment ion Ni, Cr), yellow (pigment ion Ni), red (pigment ion Cr), blue (pigment ion Ti, Fe), green (pigment ion Co, Ni , V), purple (Ti, Fe, Cr), brown, black (pigment ion Fe, Fe), incandescent violet, purple under fluorescent effect (pigment ion V).
Corundum glass luster, hardness 9. Weighting 395-410. In the high-temperature aluminum-rich C depleted silicon formed under conditions, mainly related magmatism, contact metamorphism and regional metamorphism.
Corundum is bauxite mining as the main raw material refining furnace artificial materials with corundum, green silicon carbide powder. Yu do abrasives and refractories. Called high purity white fused aluminum oxide, a small amount of impurities is called as a brown corundum.

Corundum smelting knowledge of skills

First, the broken arc
Features: No current show, the furnace no sound, no flashing between the electrodes.
Cause: arcing rod fixation is not good, take the stick shift too early to melt less; feeding too fast, aluminum oxide immersed interrupting the current path, string lumps formed by the reaction furnace, electrode whereabouts blocked.
Solution: do check before arcing; furnace conditions more stable carbon rod fishing again; attention feed rate; strings furnace ground activities electrode; re-arcing.
Second, the string furnace
Characteristics: melt the solid powder material flows back and forth rapidly, stirring up a lot of aluminum oxide powder, sometimes resulting in broken arc, generally occurs within 10h after the open furnace.
Cause: rim material layer is thick, hearth melting surface is small, feeding uneven, resulting in uneven heating, a certain part of the melt furnace and the furnace wall contact or pressure is large, and a large number of cold spray molten material flows .
Solution: the first few h using a lower voltage, expanding melt surface, increasing the amount of fluid; serious lumps when broken, flat charge, thorough treatment.
Third, blasting
Features: sudden roaring furnace, profuse heat, fireball, no lining, the shooting at the furnace shell redness, causing severe leakage furnaces.
Cause: bottom, lining damp, moist ingredients, outside water immersion, the material layer is too thick, improper operation, causing the furnace pressure is too large.
Solution: prevent the bottom wet; controlling raw water; strengthen operations, to ensure uniform material layer; without lining furnace to increase the cooling water; timely processing, broken agglomerates, flat charge.
Fourth, the "pull lining"
Features: lining reaction melt and the melt somersault jumps over the material layer, serious, feeding is difficult to suppress, or even missing stove accidents.
Cause: improper operation, feeding inequality or discomfort, the outer electrode material layer is too thin, too close to the furnace wall electrode spacing, low voltage and so on.
Solution: Add corundum lack lateral electrode material, size 20-40mm; adjust the voltage or the distance between electrodes; reduce the current, lower input power, increase the amount of cooling water; shutdown processing when necessary.