Adding a chemical etching solution to the etching machine: ferric chloride

 

Chemical formula: FeCl3=FeCl3·6H2O

 

I. The best conditions for the etching solution

 

Baume: 38°—42°

 

Liquid temperature: 45°-50°

 

PH measurement interval: 1PH-3PH

 

Oxidant FeCl3

 

2. New drug water reaction process

 

The etching of stainless steel by ferric chloride etching solution is an "oxidation---reduction" process:

 

1. Oxidation reaction: 2FeCl3+Fe=3FeCl2

 

Ferric chloride + stainless steel + water = ferrous chloride + sheet etching finished product + water + stainless steel impurities

 

3. Reasons for the reduction of medicinal properties and methods of reduction

 

As the chemical reaction progresses, the etchant liquid is lowered because the ferric chloride is oxidized to ferrous chloride. At this time, it is necessary to reduce the ferrous chloride to ferric chloride to increase the acidity of the solution. Need to add sodium chlorate solution (reducing agent), hydrochloric acid (inhibitor)

 

2. Reduction reaction: 2FeCl2+NaClO+2HCL=2FeCl3+NaCl+H2O

 

Ferrous chloride + sodium chlorate + hydrochloric acid = ferric chloride + sodium chloride + water (ferrous iron hydroxide is produced due to the easy hydrolysis of ferrous ions in water: FeCl2+H2O=, Fe(OH)2+HCL Therefore, in order to prevent the hydrolysis and deterioration of ferrous chloride, some hydrochloric acid is often added to the ferrous chloride solution.)

 

3. Since hydrochloric acid is easily volatilized, the following reactions occur as the chemical reaction proceeds:

 

6FeCl2+NaClo+3H2O=4FeCl3+2Fe(OH)3 ↓+NaCl

 

Ferrous chloride + sodium chlorate + water = ferric chloride + iron hydroxide (precipitate) + sodium chloride

 

(Where iron hydroxide is a precipitate, so as the chemical reaction time is lengthened, a viscous substance will appear in the medicine box. To remove the viscous sediment, physical filtration is required, such as: filter filtration or purified water. Device)

 

Definition and understanding

 

Ferric chloride is a covalent compound and is currently the most cost-effective and widely used chemical for stainless steel US304 in the etching (corrosion) industry. Ferric chloride is easily soluble in water and has strong water absorption and absorbs air. The water in the water is declining. FeCl3 is melted with 6 crystal waters, FeCl3·6H2O, also known as bound water. Crystal water is a water molecule incorporated into a compound, which is not liquid water. Many crystals contain water of crystallization, but not all crystals contain water of crystallization. When a solute crystallizes out of a solution, a certain number of water molecules are bound to the crystal. Such a water molecule is called crystal water. In the crystalline material, a certain amount of water molecules combined with ions or molecules by chemical bonding force are affected by the outside world. For example, under the condition of gradually increasing temperature, CuSO4·5H2O can gradually lose crystal water and sequentially transform into CuSO4·3H2O, CuSO4·H2O, and CuSO4. When heated, some hydrates may undergo a hydrolysis reaction with the crystal water contained therein to be converted into an oxide or a basic salt. When a hydrate is exposed to drier air, it slowly loses crystal water, which turns into a powdery anhydrate from hydrate crystals. This process is simply understood as weathering, that is, when buying solid three When ferric chloride is used, some of the crystal water has been lost, so it is especially important to choose a regular manufacturer of ferric chloride. Some solid ferric chloride will automatically absorb water and convert into hydrate in the air with high humidity. This process is called deliquescence. After deliquescent, the crystal water of ferric chloride has been destroyed, and the original mineral lattice is destroyed. When it is destroyed, other atoms can be recombined to form another compound, which forms ions other than the crystal water FeCl3·6H2O and molecules CuSO4·3H2O, CuSO4·H2O, CuSO4. Therefore, when purchasing ferric chloride, try to select the shortest weathering time. , the shortest production date of solid ferric chloride. For stainless steel US304 corrosion, ferric chloride has the lowest volatilization rate relative to other chemicals, the lowest production cost, the smallest environmental pollution, and the strong circulation due to the widespread use of sewage treatment plants. Stainless steel in the long-term corrosion process will destroy the mineral lattice of ferric chloride itself. In order to prolong the use time of ferric chloride, many people will add some small amounts of strong acids, such as hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, etc. Or an oxidized product that reacts with ferric chloride itself to reduce the crystallization water that has been destroyed, thereby improving the corrosiveness of ferric chloride to stainless steel. In fact, no matter what kind of chemicals are used, as long as it can be reduced to 6 water (crystallization The best condition of water) is fine, but in addition to the following, our factory gives the parameters of the optimal value of US304 stainless steel ferric chloride corrosive solution based on years of experience.

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