What harm does galvanizing do to people

Zinc is an indispensable element for our body, but if our body is directly exposed to zinc, the harm is very great, especially the current chemical galvanizing is extremely harmful. Although the state strictly controls the galvanizing industry, the potential harm it causes is immeasurable. Long-term contact with galvanizing will cause our body's trace elements to exceed the standard, and the harmful gases produced by galvanizing will be absorbed by the human body, which is even more harmful.

First of all, the electroplating industry is a highly polluting industry. Electroplating uses a large number of toxic and harmful materials, such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, chromic acid, sodium hydroxide, sodium cyanide and a large number of metal salts. These chemical materials will emit different degrees of gas during storage and use. Some gases will irritate the eyes, nose, throat, and skin and cause inflammation; some gases, such as nickel salt vapor, will cause skin allergies in some people; inhalation of large amounts of chromic acid gas will also cause damage to human organs and even cause cancer; cyanide is very easily absorbed by the human body and can enter the body through the mouth, respiratory tract or skin. Cyanide, in particular, is easily absorbed by the human body and can enter the body through the mouth, respiratory tract or skin, causing respiratory failure or even acute poisoning and death.

And because hot-dip galvanizing generally requires lead, tin, and zinc, if there is long-term contact, especially the staff around the zinc pot need to regularly check whether these elements exceed the standard. If they exceed the standard, they need to leave for a period of time or change their job.

However, please note that the above hazards can be completely avoided as long as proper management and prevention are carried out. The state lists the electroplating industry as an industry subject to mandatory clean production audits. Local economic committees and environmental protection departments will also include electroplating companies in the mandatory clean production audit list. Electroplating companies must undergo clean production audits. Enterprises that have passed the clean production audit will have greatly improved both their process level and environmental conditions. Not only will the amount of gas generated be significantly reduced, but the gas must also be treated to meet the standards before being discharged into the air. By then, the conditions in the factory where you work will definitely be greatly improved.

The above is what I introduced to you about the harm of galvanizing to the human body. In fact, whether hot-dip galvanizing or electro-galvanizing, the waste gas and waste water generated during production are harmful substances, which are usually harmful to the human body. Everyone should pay more attention to taking protective measures during work to minimize the inhalation of harmful gases. If it really causes great harm to your health, you can consider changing to a better working environment.

1. The appearance is smooth, without zinc nodules or burrs, and is silvery white;

2. The thickness is controllable and can be selected arbitrarily within 5-107μm;

3. No hydrogen embrittlement, no temperature damage, can ensure the mechanical properties of the material remain unchanged;

4. It can replace some processes that require hot-dip galvanizing;

5. Good corrosion resistance, neutral salt spray test up to 240 hours.

Application range: steel nails, iron nails, fasteners, water pipe joints, scaffolding fasteners, wire rope Ma steel chucks, etc.

3 Principles of galvanizing

In the plating tank containing the galvanizing solution, the cleaned and specially pre-treated workpiece to be plated is used as the cathode, and the plated metal is used as the anode, and the two poles are respectively connected to the positive and negative poles of the DC power supply. The zinc plating solution consists of an aqueous solution containing a compound of the plating metal, conductive salts, buffers, pH adjusters and additives. After power is turned on, the metal ions in the zinc plating solution move to the cathode under the action of the potential difference to form a coating. The metal of the anode forms metal ions that enter the zinc plating solution to maintain the concentration of the metal ions being plated [1]. In some cases, such as chrome plating, an insoluble anode made of lead or lead-antimony alloy is used, which only serves to transfer electrons and conduct current. The concentration of chromium ions in the electrolyte needs to be maintained by regularly adding chromium compounds to the plating solution. During galvanizing, the quality of the anode material, the composition of the galvanizing solution, temperature, current density, power-on time, stirring intensity, precipitated impurities, power supply waveform, etc. will all affect the quality of the coating and need to be controlled in a timely manner.

1. Alkaline cyanide zinc plating

2. Alkaline zincate galvanizing

3. Ammonium salt zinc plating

4. Potassium salt zinc plating

5. Ammonium potassium mixed bath zinc plating

6. Sulfate zinc plating

7. Chloride zinc plating[2]

Post-treatment of galvanized layer

1. Dehydrogenation

2. Passivation

3. Coloring

1. Principle

Since zinc is not easy to change in dry air, a very dense zinc carbonate film can be formed on the surface in humid air. This film can effectively protect the interior from corrosion. And when the coating is damaged for some reason and a small substrate is exposed, the zinc and the steel substrate form a micro-battery, making the fastener substrate the cathode and protected. It is widely used in industries such as automobile transportation, but what is needed is a trivalent chromium passivation layer and a zinc-nickel alloy plating sealing coating to reduce the harmful and toxic layer of hexavalent chromium passivation.

2. Performance characteristics

The zinc coating is thick, with fine, uniform crystals and no pores, and has good corrosion resistance. The zinc layer obtained by electroplating is relatively pure and corrodes slowly in acid, alkali and other mists, which can effectively protect the fastener matrix. The zinc coating is passivated with chromic acid to form white, colorful, military green, etc., which is beautiful and has a certain decorative effect. Since the zinc coating has good ductility, it can be cold punched, rolled, bent and other forming methods without damaging the coating.

3. Scope of application

The fields involved in electrogalvanizing are becoming more and more extensive. The application of fastener products has spread to machinery manufacturing, production of galvanized chain link fences, electronics, precision instruments, chemicals, transportation, aerospace, etc., which are of great significance in the national economy.

5 Factors affecting galvanizing

In the actual production process, the common factors affecting the speed and quality of galvanizing are:

(1) Pretreatment is not thorough. There is an oxide film on the surface of the workpiece, which affects the normal deposition of zinc.

(2) Poor electrical conductivity. The current is consumed in the wire, and too little current is distributed to the workpiece surface.

(3) The workpiece has a high carbon content. High carbon steel, cast iron parts, etc. will reduce the hydrogen evolution potential, accelerate hydrogen evolution on the workpiece surface, and reduce current efficiency.

(4) The workpieces are tied too tightly. During galvanizing, the workpiece is partially shielded, resulting in a too thin coating.

(5) The plating solution temperature is too low. When the plating solution temperature is low, the delivered current density decreases accordingly, and the deposition rate of the coating will inevitably decrease.

(6) The sodium hydroxide content in the plating solution is too high. When the sodium hydroxide content is high, the current efficiency decreases accordingly.

(7) The additive content in the plating solution is low. A low additive content will affect the dispersion ability and the coating will appear too thin in some areas.

(8) The area of ​​the plated component was underestimated, and the current density delivered during plating was too small.

(9) The workpiece suspension method is improper and the distance between it and the zinc anode is too large. The position should be adjusted.

(10) Excessive corrosion of the workpiece. Lowering the hydrogen evolution potential will reduce the efficiency of the accelerating current for hydrogen evolution on the workpiece surface, thereby affecting the zinc deposition rate. An appropriate amount of corrosion inhibitor should be added to the pickling solution. If the oxide scale is too thick in some areas, it should be removed mechanically first, and more inspections should be carried out during the pickling process.

(11) Anodic passivation. The effective area is reduced, affecting the normal distribution of current.

(12) The sodium hydroxide content is low. If the sodium hydroxide content is too low, the current density cannot be increased and the anode is passivated.