What is the danger of Silane?

 Silane is a kind of fire at room temperature under normal temperature and pressure; it can burn explosively in air or halogen gas. Its fire and explosion are the result of reaction with oxygen. Silane is very sensitive to oxygen and air, that is, use other gases to dilute, if the concentration is not low enough. Can still ignite spontaneously. When silane contains 2% in argon, 2.5% in nitrogen, and 1% in hydrogen, it can still catch fire. Silane concentration is not combustible when it is less than 1%, spontaneously combusts when it is greater than 3%, and may burn when it is 1% to 3%. As long as it has a certain concentration of silane, it will react explosively with oxygen at a temperature of -180°C. 

1.It is a very toxic special gas. How strong is it?

Contact with silane can cause eye irritation. Inhalation can cause headache, nausea, mucous membranes and respiratory tract irritation. Although silane is reported to have an unpleasant smell and a disgusting garlic smell, it should not be used as a warning signal for the presence of dangerous concentrations of gas. When you smell it, you have been caught.

The main danger of silane comes from its ability to spontaneously burn in contact with air and its toxicological properties. And we need to continue silane treatment.

2. Silane Uses

Silane has now become the most important special gas used in semiconductor microelectronics processes for the preparation of various microelectronic films, including single crystal films, microcrystalline, polycrystalline, silicon oxide, silicon nitride, and metal silicides. The microelectronic applications of silane are still developing in depth: low-temperature epitaxy, selective epitaxy, heteroepitaxial. Not only for silicon devices and silicon integrated circuits, but also for compound semiconductor devices (gallium arsenide, silicon carbide, etc.). It also has applications in the preparation of superlattice quantum well materials. It can be said that silane is used in almost all advanced integrated circuit production lines in modern times.

 

3. The safety risk of silane

Silane is a spontaneous combustion gas with a wide range of combustion, but when it is released into the air, it does not necessarily burn immediately. Sometimes it may not burn at all. Understanding this can allow us to improve the design and operation of the system. Safety, and procedures for response in the event of an accident. The combustion of silane has a considerable relationship with its release method and changes in the surrounding environment. Water mist can reduce smoke and dust, but you must be careful not to extinguish any flames caused by silane. The fire can only be extinguished by cutting off the source of the silane leakage. If the silane flame is extinguished before the source of the silane leak is cut off, the silane will accumulate and cause an explosion. The flammability limit of silane is very wide, and the diluted silane will expand the flammable range instead of reducing the flammable range. The lower limit of the flammable limit of silane is 2%, and the flammable range is much lower than this concentration when different diluents are introduced.

How to Use Boric Acid Powder?

 

Article Directory:

1. How to use boric acid powder

2. What are the application fields of boric acid

Three, what to do with boric acid poisoning

How to use boric acid powder?

• How to use boric acid powder

It is recommended that the boric acid solution must be cold water, the towel should be thick, and the time should be at least 30 minutes. It takes 3-5 minutes to change towels frequently with the solution.

It is contraindicated to wash the affected area with hot water. The role of boric acid is to disinfect, sterilize and relieve itching. It is generally prepared at a concentration of 0.3%, that is, 3 grams of boric acid powder with 1000 ml of cold water, generally used Soak 6 layers of gauze and twist until no dripping, apply on the face for 20 minutes at a time, twice a day, you can use it repeatedly. Use it for one day at a time and remix it the next day.

• What is the effect of applying boric acid solution on the face?

The boric acid solution is a colorless and clear solution with a weak acid reaction. 2 to 3% solution is used for washing and cleaning skin and mucous membranes (cavity wounds. When lye splashes into the eyes, rinse with clean water and then with boric acid solution.

Under normal circumstances, boric acid solution is a topical bactericide, disinfectant, astringent and preservative. It has inhibitory effect on a variety of bacteria and molds. The principle of action is that it can combine with amino groups in bacterial proteins to play a role. It can be used for washing and disinfecting skin, mucous membranes, wounds, oral cavity, vagina, bladder, etc. It can also be used for otitis, burns, scalds, eczema, etc.

• What is boric acid

Boric acid is a white crystalline powder or colorless scales with a pearly luster. It is irritating and can be used as a chemical reagent and in the production of insecticides for cockroaches and beetles. It is also used as a hemostatic and preservative in medicine. White powdery crystals or scaly lustrous crystals on the triclinic axis surface, with a slippery feel and no odor. Dissolved in water, alcohol, glycerin, ethers and essential oils, the aqueous solution is weakly acidic. It is widely used in the glass (optical glass, acid-resistant glass, heat-resistant glass, glass fiber for insulating materials) industry, which can improve the heat resistance and transparency of glass products, increase the mechanical strength, and shorten the melting time.

What are the application fields of boric acid?

• Flame retardant

  The borate added to celluloid material can change its oxidation reaction and promote the formation of "carbonization". Therefore, it is flame retardant. Boric acid used alone or together with borax has a special effect on reducing the flammability of celluloid insulation materials, woodware, and cotton tyres in mattresses.

• Glass and fiberglass

  It is used to produce high-grade glass and glass fiber such as optical glass, acid-resistant glass, organic boron glass, etc. It can improve the heat resistance and transparency of the glass, increase the mechanical strength, and shorten the melting time. How to use boric acid powder

• Enamel and ceramics

  The enamel and ceramic industries are used in the production of glazes, which can reduce the thermal expansion of the glaze and lower the curing temperature of the glaze, thereby preventing cracking and deglazing, and improving the gloss and fastness of the product.

• Pharmaceutical industry

  Used in the production of boric acid ointments, disinfectants, astringents, preservatives, etc.

• metallurgy

  Used as an additive and co-solvent in the production of boron steel, so that boron steel has high hardness and good rolling ductility. Boric acid can prevent surface oxidation of metal welding, brazing and sleeve welding. It is also a raw material for ferro-boron.

• leather

  It is used for ashing off the surface of bare leather to prevent gray spots on the leather surface after retanning.

• Anti-rust

  Boric acid can be used as rust inhibitor, lubricant and thermal oxidation stabilizer. It is added to lubricants, brake fluids, metalworking fluids, water treatment agents and fuel additives.

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What to do with boric acid poisoning?

When oral boric acid poisoning is taken, induce vomiting immediately and use 2% to 5% sodium bicarbonate solution (do not use borax poisoning), normal saline or lukewarm water and other gastric lavage. After gastric lavage, pour sodium sulfate into catharsis. The boric acid contaminated in other parts also needs to be washed with saline, water or soapy water. Intravenous infusion of dextrose saline and plasma is helpful for treating shock and accelerating the excretion of poisons. Or intravenous infusion of normal saline. If there is acidosis, apply appropriate amount of sodium lactate or sodium bicarbonate solution. After correcting dehydration and acidosis, continue to inject 5%-10% glucose and sodium-containing solution intravenously to maintain alkaline urine and facilitate the excretion of boric acid. Severe patients can consider therapies such as exchange blood, hemodialysis or peritoneal dialysis. Others are symptomatic treatment.

The treatment of borax poisoning is similar to that of boric acid, but no alkaline solution is used for gastric lavage. In addition to the application of sedatives for convulsions, 10% calcium gluconate 10-20ml can be used, and 20-40ml glucose solution is added for slow intravenous injection.

The Harm of Silane

 Silane is a colorless gas that reacts with air and can cause suffocation. The gas usually burns in contact with air and emits dense white amorphous silica fumes. Its primary hazard to health is that its spontaneous flame can cause severe thermal burns, which can even be fatal if severe. If flame or high temperature acts on a certain part of the silane cylinder, the cylinder will explode before the safety valve is activated. If the pressure is too high or the speed is too fast when the silane is discharged, it will cause a hysteresis explosion. If the leaked silane does not ignite spontaneously, it will be very dangerous. Keep it away. Personnel dealing with emergency situations must have personal protective equipment and fire protection adapted to the situation. Do not try to extinguish the fire before cutting off the gas supply.

 

Silane gas

Silane gas is an indispensable material in the production process of solar cells because it is the most effective way to attach silicon molecules to the surface of the battery. In an environment above 400°C, silane gas decomposes into gaseous silicon and hydrogen. After the hydrogen is burned, pure silicon is left. In addition, silane gas can be said to be everywhere. In addition to the photovoltaic industry, there are many manufacturing plants that require silane gas, such as flat panel displays, semiconductors, and even coated glass manufacturing plants.

 

Diphenylsilane

Hazard identification

The most important hazards and effects:

Eye contact: Diphenylsilane can irritate the eyes. The decomposition of silane produces amorphous silica. Eye contact with amorphous silica particles can cause irritation.

Inhalation:

1. Inhalation of high concentrations of silane can cause headache, nausea, dizziness and irritate the upper respiratory tract.

2. Silane can irritate the respiratory system and mucous membranes. Excessive inhalation of silane can cause pneumonia and kidney disease due to the presence of crystalline silica.

Eye contact: Rinse immediately with water for at least 15 minutes, not too fast, and open eyelids at the same time. Make the victims "0" shaped eyes, and immediately seek ophthalmological treatment.

3. Exposure to high concentrations of gas can also cause thermal burns due to spontaneous combustion. Ingestion: Ingestion is unlikely to be a way of exposure to silane.

Skin contact: Silane can irritate the skin. The decomposition of silane produces amorphous silica. Skin contact with amorphous silica particles can cause irritation.

What Are Aromatic Derivatives?

 Aromatic derivatives, usually refers to hydrocarbons containing a benzene ring structure in the molecule. It is a kind of closed chain and has the basic structure of benzene ring.

Most of these compounds found in the early history have aromatic taste, so these hydrocarbons are called aromatic hydrocarbons, and the later discovered hydrocarbons that do not have aromatic taste also use this name.

Structure and expression of benzene

(1) The structure of benzene

Modern physical methods prove that the six carbon atoms and six hydrogen atoms of a benzene molecule are in the same plane, so it is a plane molecule. The six carbon atoms form a regular hexagon. The carbon bond length is equal, about 140 pm, between single and double bonds. The carbon-hydrogen bond length is 108pm, and all bond angles are 120°.

(2) The aromaticity of benzene

From the structural point of view, benzene has a planar cyclic structure, the bond length is completely equalized, and the hydrocarbon ratio is 1. In terms of properties, benzene has special stability: the heat of hydrogenation of cyclohexene ΔH=-120kJ/mol, the heat of hydrogenation of 1,3-cyclohexadiene ΔH=-232kJ/mol (due to the increase of its conjugated double bond To improve its stability). The heat of hydrogenation of benzene ΔH=-208kJ/mol. When 1,3-cyclohexadiene loses two hydrogens and becomes benzene, it not only does not absorb heat, but emits a small amount of heat. This shows that benzene is much more stable than the corresponding cyclohexatrienes. When 1,3-cyclohexadiene becomes benzene, the molecular structure has undergone a fundamental change, which has led to the formation of a stable system.

Benzene is difficult to oxidize and add, and is prone to electrophilic substitution reaction, which is obviously different from ordinary olefins.

Benzene also has special spectral characteristics. The hydrogen on the benzene ring is in the low field of nuclear magnetic resonance.

The above characteristics show that benzene has typical aromatic characteristics.

Aromatic Derivatives

(3) Benzene expression

How to express the structure of benzene? Since the British physicist and chemist Farady M (Faraday) first separated benzene from illuminating gas in 1825, people have been exploring the expression of benzene structure. Scientists have put forward various hypotheses about the structural formula of benzene; the more representative structural formulas of benzene are:

The structure of benzene and its expression have been discussed for more than 140 years. Although various opinions have been put forward, satisfactory results have not yet been obtained and further discussion is needed.

Structure of biphenyl

The simplest biphenyl is biphenyl. In biphenyl, each benzene ring maintains the structural properties of benzene. The single bond connecting the two benzene rings can rotate freely, but when the four ortho-position hydrogen atoms of the biphenyl are replaced by relatively large groups, the rotation of the single bond will be hindered, and a pair of Photoactive isomers.

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 Product Features

The aqueous solution is weakly acidic, and boric acid is a stable crystal, which usually does not undergo chemical reactions when stored. When the temperature and humidity change drastically, it will recrystallize and agglomerate.

Product Usage

Boronic acid is one of the basic raw materials for the production of other borides. The boron compounds produced by it are widely used in national defense and other industrial departments and scientific research units.

Used in glass, enamel, ceramics, metallurgy, electroplating, leather, dyes, paints, printing and dyeing, pesticides, fertilizers, textiles, electronic components and other industries. Used as analytical chemical reagents, buffers, wood preservatives, dye stabilizers, fabric fire retardants, insecticides, pH regulators, disinfectants, leather finishing agents, printing and dyeing auxiliaries, and agricultural production of fertilizers containing boron trace elements , It has fertilizer effect on many crops, can improve crop quality and increase yield.

Glass and fiberglass

It is used to produce high-grade glass and glass fiber such as optical glass, acid-resistant glass, organic boron glass, etc. It can improve the heat resistance and transparency of the glass, increase the mechanical strength, and shorten the melting time.

Enamel and ceramics

Boric acid is one of the components of glazes and pigments in the enamel and ceramic industries. It can reduce the thermal expansion of the glaze, lower the curing temperature of the glaze, thereby prevent cracking and deglazing, and improve the gloss and fastness of the product.

Flame retardant

The borate added to the celluloid material can change its oxidation reaction and promote the formation of "carbonization". Therefore, it is flame retardant. Boric acid used alone or together with borax has a special effect on reducing the flammability of celluloid insulation materials, woodware, and cotton tires in mattresses.

metallurgy

Used as an additive and cosolvent in the production of boron steel, so that boron steel has high hardness and good rolling ductility. Boric acid can prevent surface oxidation of metal welding, brazing and sleeve welding. It is also the raw material of ferro-boron alloy.

 

Boronic Acid

Anti-rust

Boric acid can be used as rust inhibitor, lubricant and thermal oxidation stabilizer. It is added to lubricants, brake fluids, metalworking fluids, water treatment agents and fuel additives.

Binder

Boric acid is one of the ingredients in the manufacture of corrugated paper adhesives, and also the peptizer for the manufacture of cool protein and dextrin adhesives. Boric acid greatly improves the wet glue strength by cross-linking the hydroxyl group.

chemical industry

Used in the production of various borates, such as sodium borohydride, ammonium hydrogen borate, cadmium borohydride, potassium borohydride, etc.

In the production process of nylon intermediates, phenylboronic acid cas no catalyzes the oxidation of hydrocarbons and generates esters to increase ethanol production, thereby preventing further oxidation of hydroxyl groups to generate ketones or hydroxy acids.

Storage and transportation characteristics

Store in a cool, dry, and well-ventilated warehouse. Do not store in the open, and avoid rain or moisture.

During transportation, ensure that the package is completely sealed to avoid rain or moisture.