CN111206197B - Hot galvanizing plating assistant and use method thereof - Google Patents

Hot galvanizing plating assistant and use method thereof Download PDF

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CN111206197B
CN111206197B CN201911307798.3A CN201911307798A CN111206197B CN 111206197 B CN111206197 B CN 111206197B CN 201911307798 A CN201911307798 A CN 201911307798A CN 111206197 B CN111206197 B CN 111206197B
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agent
plating assistant
plating
film
zinc
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CN111206197A (en
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周林
李实秾
周业翔
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Hunan Chuanglin New Material Technology Co ltd
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Hunan Chuanglin New Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
    • C23C22/50—Treatment of iron or alloys based thereon

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Coating With Molten Metal (AREA)

Abstract

A novel hot galvanizing plating assistant agent and a using method thereof are disclosed, wherein the plating assistant agent is prepared by taking zinc chloride, potassium chloride, nickel fluoride, a passivating agent, an oxygen scavenger, a complexing agent, a plating assistant film thickness control agent and water as components; every 1L (liter) of plating assistant agent comprises the following components in parts by weight: 50-100g of zinc chloride, 10-40g of potassium chloride, 5-30g of nickel fluoride, 0.05-0.50g of passivator, 0.5-2.0g of deoxidant, 0.5-1.0g of complexing agent, 0.2-1.0g of plating assistant film thickness control agent and the balance of water; the components are mixed to prepare 1 liter of solution to form the plating assistant agent. The plating assistant agent achieves good plating assistant effect through the synergistic effect of the components and the process conditions of the plating assistant agent; the coating does not need to be heated and dried in use, the dosage of the coating is less than half of that of the ammonium zinc chloride plating assistant agent, the smoke is less, the problem of over-thick zinc coating is solved, the surface of the zinc coating is smooth and clean, the plating is not leaked, the cost is low, and the quality is good.

Description

Hot galvanizing plating assistant and use method thereof
Technical Field
The invention relates to a chemical assistant and a using method thereof, in particular to a plating assistant for hot galvanizing and a using method thereof. The plating assistant agent achieves good plating assistant effect through the synergistic effect of the components and the process conditions of the plating assistant agent; the coating does not need to be heated and dried in use, the dosage of the coating is less than half of that of the ammonium zinc chloride plating assistant agent, the smoke is less, the problem of over-thick zinc coating is solved, the surface of the zinc coating is smooth and clean, the plating is not leaked, the cost is low, and the quality is good.
Background
The steel is a general term for iron-carbon alloy with carbon content between 0.02% and 2.11% by mass. The steel contains not only carbon but also impurity elements such as sulfur and phosphorus. In a humid environment, the non-metal elements are used as cathodes, the iron elements are used as anodes, electrochemical corrosion occurs, and the corrosion speed is further accelerated along with the formation of rust. The amount of steel corroded every year in the world accounts for about 10-20% of the steel yield in the year, which not only causes huge direct economic loss, but also greatly shortens the service life of steel equipment and buildings. Therefore, the research on the most economical and effective method for protecting steel and preventing corrosion has been a major issue for decades.
The corrosion prevention method for steel mainly comprises three methods: firstly, a coating method; second, metal coating method; and thirdly, a cathodic protection method. Since the paint coating is a pure barrier protection, once the paint layer is damaged, or aged, the underlying steel of the paint will corrode. The cathodic protection method is very limited in application and is mainly used for protecting steel close to the marine environment. In the metal plating method, inert metals such as copper, silver, gold and the like are plated, and the function of the metal is isolation protection as in the case of a paint coating, and once the plating is damaged, steel corrosion is accelerated at the damaged part. Hot dip galvanizing not only has an isolation protection function, but also has a cathode protection function, so that rust is not generated even if a galvanized layer is damaged, and the development direction of steel corrosion prevention is changed. In the hot-dip galvanizing process, if oil stains or iron rust exist on the surface of steel, liquid zinc cannot be well combined with a steel matrix, and large-area skip galvanizing occurs. At present, oil removal and rust removal processes are adopted in hot-dip galvanizing production to prevent plating leakage. The time interval between the oil and rust removing process and the galvanizing process of the steel piece always exists, and the steel to be galvanized is oxidized and rusted by oxygen in the air in the period and under the condition of instantaneous high temperature of entering zinc liquid, and finally, the plating leakage is caused. In order to prevent this phenomenon, the steel after being degreased and derusted is usually immersed in a plating assistant solution, so that the plating assistant forms a salt film on the surface of the steel to block the oxidation of air.
At present, the well-established formula of the plating assistant agent is zinc chloride-ammonium chloride plating assistant agent, the molar ratio of the zinc chloride to the ammonium chloride plating assistant agent is based on 1:3, and the ratio of the zinc chloride to the ammonium chloride plating assistant agent is properly adjusted according to different materials. The plating assistant principle is as follows: at room temperature, the plating assistant film isolates air, greatly reduces the diffusion of oxygen molecules to the steel substrate, and prevents iron oxide from generating and attaching on the steel surface. Because the zinc chloride can be partially hydrolyzed into the complex acid H in the presence of water2[Zn(OH)2Cl2]Has strong acidity, even a small amount of oxygen enters into the plating assistant film to oxidize a small amount of iron atoms, iron elements can not form oxides to be attached to the surface of steel, but Fe2+The form of the compound exists in the plating assistant film, and the purity and the activation state of the steel surface are kept. When the assistant-plated steel enters the liquid zinc with the high temperature of 430-450 ℃ for galvanizing, the steel is heated by the liquid zinc until the temperature is 200 ℃, and the zinc chloride plays a role. When the surface temperature of the steel rises to more than 200 ℃, the ammonium chloride in the salt film of the plating assistant agent can be decomposed into HCl and NH3Corrosion of steel substrates by HClThe iron oxide can not be formed on the steel matrix, and the activation state of the steel matrix is maintained.
Because the zinc chloride-ammonium chloride plating assistant agent is decomposed into HCl and NH at the high temperature in the galvanizing process3Recombine into NH when meeting normal temperature air4Cl fine particles, forming a dense smoke. In recent years, in order to reduce environmental pollution and ensure the health of workers, technicians in the hot galvanizing industry concentrate great efforts on developing smokeless or low-smoke plating assistant formulas, such as: CN 103741084B is a multi-purpose ammonium-free plating assistant agent for hot dipping and a using method thereof; CN 103173706B batch hot-dip galvanizing smokeless plating assistant and a use method thereof; CN 103898429A is a smokeless plating assistant agent and the application method; CN 103938142B is a plating layer thinning ammonium-salt-free plating assistant agent for hot galvanizing by a solvent method; CN 106244963A is a plating assistant agent for hot galvanizing and a method; CN 108220853A is an environment-friendly hot galvanizing plating assistant; CN 110172658A hot galvanizing plating assistant agent and a hot galvanizing process method. These patents have in common that: the method reduces the amount of the plating assistant agent smoke dust by adding less or no ammonium chloride and replacing the ammonium chloride with other raw materials, does not analyze from the principle of the plating assistant process and finds a countermeasure, and the use of the methods increases the using amount of the plating assistant agent, and the plating assistant effect is still not ideal and the cost is much higher. Therefore, the smokeless plating assistant agents are still in the research and trial stage, and have no large-scale production application.
The key point of the plating assistant of the traditional zinc chloride-ammonium chloride plating assistant agent is as follows: firstly, the ammonium chloride is decomposed at high temperature to generate two gases of hydrogen chloride and ammonia to isolate air, so that the steel matrix is prevented from being oxidized by oxygen in the air; secondly, the strong acidity of hydrogen chloride gas generated by decomposing ammonium chloride is utilized to remove oxides on the surface of the steel and keep the surface of the steel clean. The decomposed hydrogen chloride and ammonia are recombined into ammonium chloride particles in the air at normal temperature, and the ammonium chloride particles are scattered in the galvanizing factory and the periphery of the galvanizing factory, which affects the health of workers and pollutes the environment, so that improvement is needed. The inventor analyzes the reasons of the smoke generated by the plating assistant agent, finds that the smoke is mainly generated by ammonium chloride, and the zinc chloride also generates the smoke, and needs to research and develop the plating assistant agent which has no smoke or low smoke and good plating assistant effect, and not only needs to reduce or not use the ammonium chloride, but also needs to consider reducing the using amount of the zinc chloride. However, the plating assistant agent has the adverse effect on the plating assistant effect because the two main components are reduced or not used. The key point of the invention is to overcome the adverse effect and ensure that the low-smoke or smokeless plating assistant formula has the plating assistant effect of the traditional zinc chloride-ammonium chloride plating assistant.
Disclosure of Invention
The invention aims to provide a novel plating assistant agent for hot galvanizing and a plating assistant method thereof aiming at the defects of large smoke and poor smokeless plating assistant effect of the conventional plating assistant agent, and the plating assistant agent for hot galvanizing and the plating assistant method thereof achieve good plating assistant effect through the synergistic effect of all components of the plating assistant agent and process conditions; the coating does not need to be heated and dried in use, the dosage of the coating is less than half of that of the ammonium zinc chloride plating assistant agent, the smoke is less, the problem of over-thick zinc coating is solved, the surface of the zinc coating is smooth and clean, the plating is not leaked, the cost is low, and the quality is good.
In order to achieve the purpose, the invention provides a plating assistant agent for hot galvanizing, which is characterized in that: zinc chloride, potassium chloride, nickel fluoride, a passivator, an oxygen scavenger, a complexing agent, a plating assistant film thickness control agent and water are used as components to prepare a plating assistant; every 1L (1 liter) of the plating assistant agent comprises the following components in parts by weight: 50-100g of zinc chloride, 10-40g of potassium chloride, 5-30g of nickel fluoride, 0.05-0.50g of passivator, 0.5-2.0g of deoxidant, 0.5-1.0g of complexing agent, 0.2-1.0g of plating assistant film thickness control agent and the balance of water; the preparation method comprises the following steps: adding 500g of water into a stirring kettle, starting a stirrer, sequentially adding other components, stirring for 15 minutes to completely dissolve the components, and then adding water to make the total amount of the solution be 1 liter to form the plating assistant.
Further, the passivating agent is Gemini quaternary ammonium salt cationic surfactant, the molecule of which has two hydrophobic groups and two hydrophilic groups, and the hydrophilic groups are linked through chemical bonds by means of linking groups; the biquaternary ammonium salt and the iron matrix with negative electricity form chelate adsorption, and under the chemical bond action of the intermediate linking group, the problem of mutual electrostatic repulsion among molecules when single quaternary ammonium salt is adopted is avoided, and the close arrangement among adsorbed molecules is ensured; the oxygen scavenger is hydrazine hydrate,At least one of hydrazine and hydrazine salt, hydroxylamine and its salt, sodium borohydride and hexamethylenetetramine; the complexing agent is at least one of citric acid and its salt, tartaric acid and its salt, and is prepared from complexing agent and Fe2+The ions form a complex compound to prevent the deposition of iron oxide on the surface of the steel matrix; the assistant plating film thickness control agent is at least one of perfluorobutyl trimethyl quaternary ammonium iodide and FCI-2.
Further, the Gemini (Gemini) quaternary ammonium salt cationic surfactant has the following molecular structure: cl-[CmH2m+1(CH3)2N+(CH2)n N+(CH3)2 CmH2m+1] Cl-Is denoted as Gemini-m-n-m, wherein m = 12-18; n = 2-6.
Furthermore, the molecular structure of the perfluorobutyl trimethyl quaternary ammonium iodide of the assistant plating film thickness control agent is C4F9N(CH3)3I: the molecular structure of FCI-2 is: f [ CF (CF)3)CF2O]2CF(CF3)CONH(CH2)3N(C2H5)2CH3I。
Furthermore, the PH value of the plating assistant agent is controlled to be 2-4.
Furthermore, the temperature of the plating assistant agent is controlled to be 65-85 ℃.
A plating assistant method using the plating assistant agent for hot galvanizing comprises the steps of immersing a part to be plated with zinc in a plating assistant solution which takes zinc chloride, potassium chloride, nickel fluoride, a passivating agent, a deoxidant, a complexing agent, a plating assistant film thickness control agent and water as components after oil removal, rust removal and water washing, soaking for 3-6 minutes, taking out, placing in the air, naturally drying for 5-15 minutes, and then plating zinc.
Furthermore, the PH value of the plating assistant agent solution is controlled to be 2-4.
Further, the dipping temperature of the plating assistant agent solution is controlled to be 65-85 ℃.
Furthermore, the galvanizing is carried out by improving the surface condition of the piece to be galvanized through zinc chloride, potassium chloride, nickel fluoride, a passivator, an oxygen scavenger, a complexing agent and a plating assistant film thickness control agent in the plating assistant agent to help galvanizing; wherein:
the deoxidant is adopted, and the strong reducibility of the deoxidant is utilized, so that the oxygen in the plating assistant can be removed, the oxygen content in a film of the plating assistant is greatly reduced, the film can be decomposed into a reducing atmosphere at the high temperature of galvanization, and the high-temperature oxidation of a steel matrix is prevented;
then a passivating agent is used in a matching way, a layer of compact adsorption film which is equivalent to a metal passivation film is formed on the steel matrix, and the oxygen molecules are efficiently prevented from permeating and diffusing to the surface of the steel matrix; the passivating agent is Gemini quaternary ammonium salt cationic surfactant, molecules of the Gemini quaternary ammonium salt cationic surfactant have two hydrophobic groups and two hydrophilic groups, and the hydrophilic groups are linked through chemical bonds by virtue of linking groups; the biquaternary ammonium salt and the iron matrix with negative electricity form chelate adsorption, and under the chemical bond action of the intermediate linking group, the problem of mutual electrostatic repulsion among molecules when single quaternary ammonium salt is adopted is avoided, and the close arrangement among adsorbed molecules is ensured;
then complexing agent is used to match with weak acid environment, and complexing agent and Fe are used2+The ions form a complex compound, so that a very small amount of iron ions are formed into the complex compound and exist in the plating assistant film, and iron oxide is not formed and deposited on the surface of the steel matrix to form skip plating;
potassium chloride is taken as a coating reinforcing agent to promote the drying of the coating assistant agent film, and a large number of fine crystals are precipitated from the potassium chloride along with the volatilization of water in the coating assistant agent film to become hard fixed points of the film layer, so that the phenomenon that the coating assistant film shrinks due to the increase of surface tension in the drying process to cause the film layer to break is prevented, and a steel substrate without the coating assistant film is formed;
the nickel fluoride is used as an aluminum oxide dissolving agent and a zinc coating thickness control agent, and firstly, fluoride ions can react with aluminum oxide to form hexafluoroaluminate, so that a hard aluminum oxide film on the surface of liquid zinc is cracked, and the wetting effect of the liquid zinc on a steel matrix is not hindered; secondly, nickel ions can be reduced into simple substance nickel by zinc, and a nickel-zinc compound is adsorbed between a zeta phase and an eta phase of a zinc coating to hinder mutual diffusion of zinc and iron atoms and slow down iron-zinc reaction;
the fluorocarbon chain surfactant below C4 is used as a plating assistant film thickness control agent, and the characteristic of low surface tension of a fluorocarbon surfactant aqueous solution is utilized, so that the wetting angle between the plating assistant and a steel substrate can be reduced, a plating assistant film layer is thinned, and the fluorocarbon chain surfactant below C4 basically has no bioaccumulation, and belongs to an environment-friendly assistant;
in the process of manufacturing and using the plating assistant agent, the PH value is controlled to be 2-4 because the weak acid environment is favorable for preventing iron oxide from depositing on the surface of the steel matrix and strengthening the activation effect of the plating assistant agent on the surface of the matrix; controlling the temperature to be 65-85 ℃, namely heating the steel material by using the plating assistant agent, so that the plating assistant agent film can volatilize water by using the heat of the steel matrix under the condition of not drying; controlling the plating assistant time for 3-6 minutes, so that the steel substrate has enough time to absorb heat from the plating assistant agent, and the active ingredients in the plating assistant agent have enough time to perform adsorption reaction with the steel surface; thereby improving the effect of the plating assistant agent.
The invention has the advantages that:
the invention adopts the deoxidant, thus greatly reducing the oxygen content in the plating assistant film; then a passivating agent is used in a matching manner to form a compact adsorption film on the steel substrate, so that the permeation of oxygen molecules to the surface of the steel substrate is efficiently blocked; then, a complexing agent is used to be matched with a weak acid environment, so that a small amount of iron ions are formed into a complex compound to be present in the plating assistant film, and iron oxide is not formed to be deposited on the surface of the steel matrix to form skip plating. The plating assistant agent product does not need to be heated and dried in use, the using amount of the plating assistant agent product is less than half of that of the zinc ammonium chloride, the smoke is less, the environmental pollution is less, the galvanizing quality is good, and the plating assistant agent product has the characteristics of high efficiency and low cost; the following advantages are mainly provided:
1. the invention provides a method for improving the plating efficiency of the zinc chloride-ammonium chloride plating assistant agent, which takes zinc chloride as a core through the analysis and research of the plating assistant mechanism of the zinc chloride-ammonium chloride plating assistant agent; potassium chloride is taken as a coating reinforcing agent; nickel fluoride is used as an alumina dissolving agent and a zinc coating thickness control agent; taking Gemini type quaternary ammonium salt as a passivating agent; at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene methylamine is taken as an oxygen scavenger; at least one of citric acid and tartaric acid is taken as a complexing agent; the plating assistant agent formula takes fluorocarbon chain surfactant with basically no bioaccumulation perfluorocarbon chain below C4 as plating assistant film thickness control agent, which accords with the 'stockholm convention of persistent organic pollutants' issued by the United nations Environmental Planning Agency (EPA) in 2009;
2. according to the invention, Gemini type quaternary ammonium salt is used as a passivating agent, and the double quaternary ammonium salt and a negatively charged iron substrate form chelate adsorption, so that under the chemical bond action of an intermediate linking group, the problem of intermolecular electrostatic repulsion when single quaternary ammonium salt is adopted is avoided, and the close arrangement of adsorbed molecules is ensured. The adsorption film is equivalent to a layer of metal passivation film and prevents oxygen molecules from diffusing to the steel matrix; thereby reducing the dosage of zinc chloride-ammonium chloride and reducing key substances generating smoke;
3. the invention takes at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene methylamine as an oxygen scavenger, and utilizes the strong reducibility of the substances, so that the oxygen in the plating assistant can be removed, and the substances can be decomposed into reducing atmosphere at the high temperature of galvanizing to prevent the high-temperature oxidation of the steel matrix; thereby reducing the dosage of zinc chloride-ammonium chloride and reducing key substances generating smoke;
4. the invention uses at least one of citric acid and tartaric acid as complexing agent, and utilizes their energy and Fe2+The ions form a complex compound to prevent the deposition of iron oxide on the surface of the steel matrix; thereby reducing the dosage of zinc chloride-ammonium chloride and reducing key substances generating smoke;
5. the invention takes the fluorocarbon chain surfactant below C4 as the control agent of the thickness of the plating assistant film, and utilizes the characteristic of low surface tension of the aqueous solution of the fluorocarbon surfactant, so that the wetting angle between the plating assistant and the steel matrix can be reduced, the film layer of the plating assistant is thinned, and the fluorocarbon chain surfactant below C4 basically has no biological accumulation, and belongs to an environment-friendly assistant; the plating assistant agent has thin plating film thickness and less plating assistant agent consumption;
6. the PH value of the plating assistant agent is controlled to be 2-4 because the weak acid environment is favorable for preventing iron oxide from depositing on the surface of the steel matrix and strengthening the activation effect of the plating assistant agent on the surface of the matrix. A pH value higher than4, the iron oxide is deposited on the steel matrix, and the pH value is lower than 2, so that the simple substance iron in the steel matrix is dissolved into Fe2+Entering into a plating assistant agent film to influence the quality of a zinc coating; the invention controls the temperature at 65-85 ℃, and heats the steel material by using the plating assistant agent, so that the plating assistant agent film can volatilize water by using the heat of the steel matrix without drying. When the temperature is lower than 65 ℃, the heating strength of the plating assistant agent on the steel matrix is not enough, and after the steel matrix is taken out of the plating assistant agent, the plating assistant agent film adsorbed on the surface of the steel matrix cannot be completely dried due to low temperature, so that zinc explosion is easy to occur, and the surface finish degree of a galvanized layer is influenced. When the temperature is higher than 85 ℃, the vapor pressure of the moisture in the plating assistant solution increases rapidly along with the increase of the temperature, and a large amount of vapor can be generated in the plating assistant solution, so that the visibility of a production field is influenced, and potential safety hazards are caused. The water vapor also brings out a small amount of volatile acid, which causes corrosion to facilities in a production workshop and influences the health of workers; the invention controls the plating assistant time to be 3-6 minutes, firstly, the steel substrate has enough time to absorb heat from the plating assistant agent, and secondly, the active ingredients in the plating assistant agent have enough time to perform adsorption reaction with the steel surface.
7. The plating assistant agent does not need a drying process, saves energy and improves the galvanizing efficiency; the galvanized product produced by the plating assistant agent overcomes the problem of over-thick galvanized layer, and the galvanized layer has smooth surface, no plating leakage, low cost and good quality.
Detailed Description
The invention will be further illustrated with reference to specific examples.
A plating assistant agent for hot galvanizing is prepared by taking zinc chloride, potassium chloride, nickel fluoride, a passivating agent, an oxygen scavenger, a complexing agent, a plating assistant film thickness control agent and water as components; every 1L (liter) of plating assistant agent solution contains the following components in parts by weight: 50-100g of zinc chloride, 10-40g of potassium chloride, 5-30g of nickel fluoride, 0.05-0.50g of passivator, 0.5-2.0g of deoxidant, 0.5-1.0g of complexing agent, 0.2-1.0g of plating assistant film thickness control agent and the balance of water; the preparation method comprises the following steps: adding 500g of water into a stirring kettle, starting a stirrer, sequentially adding other components, stirring for 15 minutes to completely dissolve the components, and then adding water to make the total amount of the solution be 1 liter to form the plating assistant.
Further, the passivating agent is Gemini quaternary ammonium salt cationic surfactant, the molecule of which has two hydrophobic groups and two hydrophilic groups, and the hydrophilic groups are linked through chemical bonds by means of linking groups; the biquaternary ammonium salt and the iron matrix with negative electricity form chelate adsorption, and under the chemical bond action of the intermediate linking group, the problem of mutual electrostatic repulsion among molecules when single quaternary ammonium salt is adopted is avoided, and the close arrangement among adsorbed molecules is ensured; the oxygen scavenger is at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene tetramine; the complexing agent is at least one of citric acid and salt thereof, and tartaric acid and salt thereof, and the complexing agent and Fe2+ ions form a complex to prevent the iron oxide from depositing on the surface of the steel matrix; the assistant plating film thickness control agent is at least one of perfluorobutyl trimethyl quaternary ammonium iodide and FCI-2.
Further, the Gemini (Gemini) quaternary ammonium salt cationic surfactant has the following molecular structure: cl-[CmH2m+1(CH3)2N+(CH2)n N+(CH3)2 CmH2m+1] Cl-Is denoted as Gemini-m-n-m, wherein m = 12-18; n = 2-6.
Furthermore, the molecular structure of the perfluorobutyl trimethyl quaternary ammonium iodide of the assistant plating film thickness control agent is C4F9N(CH3)3I: the molecular structure of FCI-2 is: f [ CF (CF)3)CF2O]2CF(CF3)CONH(CH2)3N(C2H5)2CH3I。
Furthermore, the PH value of the plating assistant agent is controlled to be 2-4.
Furthermore, the temperature of the plating assistant agent is controlled to be 65-85 ℃.
The action mechanism of each component of the invention is as follows:
the invention takes zinc chloride as a core component, and utilizes the fact that the zinc chloride has extremely high solubility in water, a continuous salt film with certain viscosity can be formed on the surface of steel only by the existence of a small amount of water, and the zinc chloride is melted into a liquid film at the temperature of more than 283 ℃ to prevent the contact of air and a steel matrix. The aqueous zinc chloride is acidic and prevents the formation of iron oxides and the deposition on the steel surface.
The potassium chloride is taken as a coating reinforcing agent, and the potassium chloride does not contain crystal water and can promote the drying of a coating assistant agent film. The potassium chloride precipitates a large amount of fine crystals along with the volatilization of water in the plating assistant agent film to become hard fixed points of the film layer, and the film layer is prevented from cracking and forming a steel matrix without the plating assistant film due to the shrinkage of the plating assistant film caused by the increase of surface tension in the drying process.
The nickel fluoride is used as an aluminum oxide dissolving agent and a zinc coating thickness control agent, and firstly, fluoride ions can react with aluminum oxide to form hexafluoroaluminate, so that a hard aluminum oxide film on the surface of liquid zinc is cracked, and the wetting effect of the liquid zinc on a steel matrix is not hindered; secondly, nickel ions can be reduced into simple substance nickel by zinc, and a nickel-zinc compound is adsorbed between a zeta phase and an eta phase of a zinc coating to hinder mutual diffusion of zinc and iron atoms and slow down iron-zinc reaction;
the Gemini type quaternary ammonium salt is used as a passivating agent, chelating adsorption is formed by a biquaternary ammonium salt and an iron substrate with negative electricity, and under the chemical bond action of an intermediate linking group, the problem of intermolecular electrostatic repulsion when a single quaternary ammonium salt is adopted is avoided, and the close arrangement of adsorbed molecules is ensured. The adsorption film is equivalent to a metal passivation film and prevents oxygen molecules from diffusing to the steel matrix.
At least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene methylamine is used as an oxygen scavenger, and the strong reducibility of the substances is utilized, so that the oxygen in the plating assistant can be removed, and the substances can be decomposed into reducing atmosphere at the high temperature of galvanizing to prevent the high-temperature oxidation of the steel matrix.
At least one of citric acid and tartaric acid is used as complexing agent, and is used for complexing with Fe2+The ions form a complex to prevent the deposition of iron oxide on the surface of the steel substrate.
The fluorocarbon chain surfactant below C4 is used as the plating assistant film thickness control agent, the characteristic of low surface tension of the fluorocarbon surfactant aqueous solution is utilized, the wetting angle between the plating assistant and the steel matrix can be reduced, the plating assistant film layer is thinned, and the fluorocarbon chain surfactant below C4 basically has no biological accumulation, and belongs to an environment-friendly assistant.
The PH value of the plating assistant agent is controlled to be 2-4 because the weak acid environment is favorable for preventing iron oxide from depositing on the surface of the steel matrix and strengthening the activation effect of the plating assistant agent on the surface of the matrix. When the pH value is higher than 4, the iron oxide is deposited on the steel matrix, and when the pH value is lower than 2, the simple substance iron in the steel matrix is dissolved into Fe2+Entering into a plating assistant agent film to influence the quality of a zinc coating; the invention controls the temperature at 65-85 ℃, and heats the steel material by using the plating assistant agent, so that the plating assistant agent film can volatilize water by using the heat of the steel matrix without drying. When the temperature is lower than 65 ℃, the heating strength of the plating assistant agent on the steel matrix is not enough, and after the steel matrix is taken out of the plating assistant agent, the plating assistant agent film adsorbed on the surface of the steel matrix cannot be completely dried due to low temperature, so that zinc explosion is easy to occur, and the surface finish degree of a galvanized layer is influenced. When the temperature is higher than 85 ℃, the vapor pressure of the moisture in the plating assistant solution increases rapidly along with the increase of the temperature, and a large amount of vapor can be generated in the plating assistant solution, so that the visibility of a production field is influenced, and potential safety hazards are caused. The water vapor also brings out a small amount of volatile acid, which causes corrosion to facilities in a production workshop and influences the health of workers; the invention controls the plating assistant time to be 3-6 minutes, firstly, the steel substrate has enough time to absorb heat from the plating assistant agent, and secondly, the active ingredients in the plating assistant agent have enough time to perform adsorption reaction with the steel surface.
The using method of the plating assistant agent comprises the following steps:
(1) the PH value adjusting method is that if the PH value of the plating assistant agent is higher, the PH value is adjusted to be lower by 1:1 hydrochloric acid, and if the PH value is lower, the PH value is adjusted to be higher by zinc oxide;
(2) the temperature adjusting method is that the heating heat source is alternating current, and the temperature is controlled by adopting an automatic temperature controller;
(3) the plating assistant operation is that the steel after being degreased, derusted and washed is dipped into the plating assistant agent of the invention for 3-6 minutes, taken out and put into the air, and naturally dried for 5-15 minutes;
(4) the galvanizing operation is controlled according to that the liquid zinc contains 0.01 percent of aluminum, the galvanizing temperature is 438 ℃, the speed of the steel entering the zinc liquid is 2m/min, and the speed of the steel leaving the zinc pot is 10 m/min.
The specific embodiment comprises the following components in percentage by weight:
example 1
The invention relates to a novel hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
100g/L of zinc chloride is added,
10 g/L of potassium chloride is added,
the concentration of nickel fluoride is 8g/L,
Gemini-12-2-12 0.05 g/L，
0.8g/L of hydroxylamine hydrochloride,
1.0 g/L of citric acid,
C4F9N(CH3)3I 0.5 g/L，
the balance of water, the PH value is 3.0, the temperature is 65 ℃, the steel substrate is soaked in the plating assistant agent for 5 minutes, taken out and placed in the air, and galvanized after natural drying for 8 minutes.
Example 2
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
80g/L of zinc chloride is added,
the concentration of the potassium chloride is 20 g/L,
the content of nickel fluoride is 12 g/L,
Gemini-14-3-14 0.30 g/L，
1.5 g/L of hydrazine hydrate,
0.5 g/L of tartaric acid,
FCI-2 0.2 g/L，
the balance of water, the PH value is 2.0, the temperature is 75 ℃, the steel substrate is soaked in the plating assistant agent for 4 minutes, taken out and placed in the air, and galvanized after natural drying for 15 minutes.
Example 3
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
the zinc chloride is 60g/L,
30 g/L of potassium chloride is added,
the content of nickel fluoride is 20 g/L,
Gemini-16-3-16 0.25 g/L，
2.0 g/L of sodium borohydride,
0.6g/L of citric acid,
FCI-2 0.8 g/L，
the balance of water, the PH value is 2.5, the temperature is 70 ℃, the steel substrate is soaked in the plating assistant agent for 6 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 10 minutes.
Example 4
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
50g/L of zinc chloride is added,
the concentration of the potassium chloride is 20 g/L,
30 g/L of nickel fluoride,
Gemini-18-4-18 0.50 g/L，
0.5 g/L of hexamethylenetetramine,
0.5 g/L of citric acid,
0.3 g/L of tartaric acid,
FCI-2 0.2 g/L，
C4F9N(CH3)3I 0.5 g/L，
the balance of water, the PH value is 2.0, the temperature is 80 ℃, the steel substrate is soaked in the plating assistant agent for 3 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 12 minutes.
Example 5
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
75g/L of zinc chloride is added,
25g/L of potassium chloride is added,
5g/L of nickel fluoride,
Gemini-14-3-14 0.35 g/L，
1.2 g/L of sodium borohydride,
0.8g/L of citric acid,
FCI-2 0.6 g/L，
C4F9N(CH3)3I 0.3 g/L，
the balance of water, the PH value is 4.0, the temperature is 85 ℃, the steel substrate is soaked in the plating assistant agent for 5 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 15 minutes.
Example 6
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
90g/L of zinc chloride is added,
40g/L of potassium chloride is added,
15 g/L of nickel fluoride is added,
Gemini-18-6-18 0.40 g/L，
0.6g/L of hydrazine sulfate,
0.5 g/L of hydroxylamine hydrochloride,
0.4 g/L of citric acid,
0.3 g/L of tartaric acid,
FCI-2 1.0 g/L，
the balance of water, the pH value is 3.5, the temperature is 65 ℃, the steel substrate is soaked in the plating assistant agent for 6 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 10 minutes.
Example 7
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
80g/L of zinc chloride is added,
25g/L of potassium chloride is added,
the content of nickel fluoride is 16 g/L,
Gemini-14-3-14 0.15 g/L，
0.8g/L of hydroxylammonium hydrochloride,
0.6g/L of citric acid,
FCI-2 0.4 g/L，
C4F9N(CH3)3I 0.3 g/L，
the balance of water, the PH value is 2.5, the temperature is 85 ℃, the steel substrate is soaked in the plating assistant agent for 3 minutes, taken out and placed in the air, and galvanized after natural drying for 5 minutes.
Example 8
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
70g/L of zinc chloride is added,
25g/L of potassium chloride is added,
the content of nickel fluoride is 18 g/L,
Gemini-14-3-14 0.35 g/L，
1.5 g/L of hydrazine hydrate,
0.6g/L of citric acid,
FCI-2 0.6 g/L，
the balance of water, the PH value is 3.2, the temperature is 78 ℃, the steel substrate is soaked in the plating assistant agent for 4 minutes, taken out and placed in the air, and galvanized after natural drying for 6 minutes.
Example 9
The invention relates to an environment-friendly high-efficiency hot galvanizing plating assistant agent, which comprises the following components in parts by weight:
75g/L of zinc chloride is added,
25g/L of potassium chloride is added,
5g/L of nickel fluoride,
Gemini-14-3-14 0.35 g/L，
1.2 g/L of sodium borohydride,
0.8g/L of tartaric acid,
C4F9N(CH3)3I 0.3 g/L，
the balance of water, the PH value is 2.8, the temperature is 82 ℃, the steel substrate is soaked in the plating assistant agent for 3 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 8 minutes.
Comparative example 1
The conventional zinc chloride-ammonium chloride hot galvanizing plating assistant agent comprises the following components in parts by weight:
125g/L of zinc chloride is added,
150 g/L of ammonium chloride is added,
the balance of water, the PH value is 3.5, the temperature is 62 ℃, the steel substrate is soaked in the plating assistant agent for 6 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 15 minutes.
Comparative example 2
The conventional zinc chloride-ammonium chloride hot galvanizing plating assistant agent comprises the following components in parts by weight:
140g/L of zinc chloride is added,
200 g/L of ammonium chloride is added,
the balance of water, the PH value is 3.3, the temperature is 70 ℃, the steel substrate is soaked in the plating assistant agent for 6 minutes, taken out and placed in the air, and the galvanization is carried out after the steel substrate is naturally dried for 15 minutes.
Comparative example 3
The conventional zinc chloride-ammonium chloride hot galvanizing plating assistant agent comprises the following components in parts by weight:
135g/L of zinc chloride is added into the zinc chloride,
185 g/L of ammonium chloride is added,
the balance of water, the PH value is 3.5, the temperature is 66 ℃, the steel substrate is soaked in the plating assistant agent for 5 minutes, taken out and placed in a baking oven for drying at 110 ℃ for 15 minutes, and then the galvanization is carried out.
Comparative example 4
The conventional zinc chloride-ammonium chloride hot galvanizing plating assistant agent comprises the following components in parts by weight:
125g/L of zinc chloride is added,
150 g/L of ammonium chloride is added,
the balance of water, the PH value is 3.5, the temperature is 65 ℃, the steel substrate is soaked in the plating assistant agent for 6 minutes, taken out and placed in a drying oven for drying at 105 ℃ for 15 minutes, and then galvanization is carried out.
And (3) cooling each galvanized part sample in clean water at 40 ℃, observing the appearance plating missing condition of each sample, and measuring the thickness of the galvanized layer. The experimental phenomena and the quality of the galvanized samples are shown in Table 1.
Table 1 shows the plating assistant conditions of the plating assistant agent of the present invention and the conventional plating assistant agent.
TABLE 1 comparison table of plating assistant agent of the present invention and plating assistant condition of conventional plating assistant agent
Figure DEST_PATH_IMAGE002
The above listed embodiments are only for clear and complete description of the technical solution of the present invention; it should be understood that the embodiments described are only a part of the embodiments of the present invention, and not all embodiments, and the terms such as "upper", "lower", "front", "back", "middle", etc. used in this specification are for clarity of description only, and are not intended to limit the scope of the invention, which can be implemented, and the changes or modifications of the relative relationship thereof are also regarded as the scope of the invention without substantial technical changes. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention has the advantages that:
the invention adopts the deoxidant, thus greatly reducing the oxygen content in the plating assistant film; then a passivating agent is used in a matching manner to form a compact adsorption film on the steel substrate, so that the permeation of oxygen molecules to the surface of the steel substrate is efficiently blocked; then, a complexing agent is used to be matched with a weak acid environment, so that a small amount of iron ions are formed into a complex compound to be present in the plating assistant film, and iron oxide is not formed to be deposited on the surface of the steel matrix to form skip plating. The plating assistant agent product does not need to be heated and dried in use, the using amount of the plating assistant agent product is less than half of that of the zinc ammonium chloride, the smoke is less, the environmental pollution is less, the galvanizing quality is good, and the plating assistant agent product has the characteristics of high efficiency and low cost; the following advantages are mainly provided:
1. the invention provides a method for improving the plating efficiency of the zinc chloride-ammonium chloride plating assistant agent, which takes zinc chloride as a core through the analysis and research of the plating assistant mechanism of the zinc chloride-ammonium chloride plating assistant agent; potassium chloride is taken as a coating reinforcing agent; nickel fluoride is used as an alumina dissolving agent and a zinc coating thickness control agent; taking Gemini type quaternary ammonium salt as a passivating agent; at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene methylamine is taken as an oxygen scavenger; at least one of citric acid and tartaric acid is taken as a complexing agent; the plating assistant agent formula takes fluorocarbon chain surfactant with basically no bioaccumulation perfluorocarbon chain below C4 as plating assistant film thickness control agent, which accords with the 'stockholm convention of persistent organic pollutants' issued by the United nations Environmental Planning Agency (EPA) in 2009;
2. according to the invention, Gemini type quaternary ammonium salt is used as a passivating agent, and the double quaternary ammonium salt and a negatively charged iron substrate form chelate adsorption, so that under the chemical bond action of an intermediate linking group, the problem of intermolecular electrostatic repulsion when single quaternary ammonium salt is adopted is avoided, and the close arrangement of adsorbed molecules is ensured. The adsorption film is equivalent to a layer of metal passivation film and prevents oxygen molecules from diffusing to the steel matrix; thereby reducing the dosage of the key substance zinc chloride-ammonium chloride which generates the smoke;
3. the invention takes at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene methylamine as an oxygen scavenger, and utilizes the strong reducibility of the substances, so that the oxygen in the plating assistant can be removed, and the substances can be decomposed into reducing atmosphere at the high temperature of galvanizing to prevent the high-temperature oxidation of the steel matrix; thereby reducing the dosage of the key substance zinc chloride-ammonium chloride which generates the smoke;
4. the invention takes at least one of citric acid and tartaric acid as a complexing agent, and utilizes the complexing agent and Fe2+ ions to form a complex, thereby preventing the deposition of iron oxide on the surface of a steel matrix; thereby reducing the dosage of the key substance zinc chloride-ammonium chloride which generates the smoke;
5. the invention takes the fluorocarbon chain surfactant below C4 as the control agent of the thickness of the plating assistant film, and utilizes the characteristic of low surface tension of the aqueous solution of the fluorocarbon surfactant, so that the wetting angle between the plating assistant and the steel matrix can be reduced, the film layer of the plating assistant is thinned, and the fluorocarbon chain surfactant below C4 basically has no biological accumulation, and belongs to an environment-friendly assistant; the plating assistant agent has thin plating film thickness and less usage amount, thereby not only reducing the galvanizing cost, but also reducing the generation amount of smoke;
6. the PH value of the plating assistant agent is controlled to be 2-4 because the weak acid environment is favorable for preventing iron oxide from depositing on the surface of the steel matrix and strengthening the activation effect of the plating assistant agent on the surface of the matrix. When the pH value is higher than 4, the iron oxide is deposited on the steel matrix, and when the pH value is lower than 2, the simple substance iron in the steel matrix is dissolved into Fe2+Entering into plating assistantIn the coating, the quality of a zinc coating is influenced; the invention controls the temperature at 65-85 ℃, and heats the steel material by using the plating assistant agent, so that the plating assistant agent film can volatilize water by using the heat of the steel matrix without drying. When the temperature is lower than 65 ℃, the heating strength of the plating assistant agent on the steel matrix is not enough, and after the steel matrix is taken out of the plating assistant agent, the plating assistant agent film adsorbed on the surface of the steel matrix cannot be completely dried due to low temperature, so that zinc explosion is easy to occur, and the surface finish degree of a galvanized layer is influenced. When the temperature is higher than 85 ℃, the vapor pressure of the moisture in the plating assistant solution increases rapidly along with the increase of the temperature, and a large amount of vapor can be generated in the plating assistant solution, so that the visibility of a production field is influenced, and potential safety hazards are caused. The water vapor also brings out a small amount of volatile acid, which causes corrosion to facilities in a production workshop and influences the health of workers; the plating assistant time is controlled to be 3-6 minutes, so that the steel substrate has enough time to absorb heat from the plating assistant agent, and active ingredients in the plating assistant agent have enough time to perform adsorption reaction with the steel surface;
7. the plating assistant agent does not need a drying process, saves energy and improves the galvanizing efficiency;
8. the galvanized product produced by the plating assistant agent overcomes the problem of over-thick galvanized layer, and the galvanized layer has smooth surface, no plating leakage, low cost and good quality.

Claims (6)

1. A plating assistant agent for hot galvanizing is characterized in that: zinc chloride, potassium chloride, nickel fluoride, a passivator, an oxygen scavenger, a complexing agent, a plating assistant film thickness control agent and water are used as components to prepare a plating assistant; every 1L of the plating assistant agent comprises the following components in parts by weight: 50-100g of zinc chloride, 10-40g of potassium chloride, 5-30g of nickel fluoride, 0.05-0.25g of passivator, 0.5-2.0g of deoxidant, 0.5-1.0g of complexing agent, 0.2-1.0g of plating assistant film thickness control agent and the balance of water; the preparation method comprises the following steps: adding 500g of water into a stirring kettle, starting a stirrer, sequentially adding other components, stirring for 15 minutes to completely dissolve the components, and then adding water to make the total amount of the solution be 1 liter to form a plating assistant;
the passivating agent is a gemini quaternary ammonium salt cation watchThe surfactant has two hydrophobic groups and two hydrophilic groups in molecules, the hydrophilic groups are connected through chemical bonds by virtue of connecting groups, and double quaternary ammonium salts and negatively charged iron substrates form chelate adsorption, so that the problem of mutual electrostatic repulsion among molecules when single quaternary ammonium salts are adopted is avoided under the action of the chemical bonds of the intermediate connecting groups, and the close arrangement among adsorbed molecules is ensured; the oxygen scavenger is at least one of hydrazine hydrate, hydrazine and hydrazine salt, hydroxylamine and salt thereof, sodium borohydride and hexamethylene tetramine; the complexing agent is at least one of citric acid and its salt, tartaric acid and its salt, and is prepared from complexing agent and Fe2+The ions form a complex compound to prevent the deposition of iron oxide on the surface of the steel matrix; the assistant plating film thickness control agent is at least one of perfluorobutyl trimethyl quaternary ammonium iodide and FCI-2;
the gemini quaternary ammonium salt cationic surfactant has the following molecular structure: cl-[CmH2m+1(CH3)2N+(CH2)nN+(CH3)2CmH2m+1]Cl-Is denoted as Gemini-m-n-m, wherein m = 12-18; n = 2-6;
the pH value of the plating assistant agent is controlled to be 2-3.2.
2. The plating assistant for hot dip galvanizing according to claim 1, wherein: the plating assistant agent is controlled at 65-85 ℃.
3. A plating assistant method of the plating assistant agent for hot galvanizing according to any one of claims 1 to 2, which comprises the steps of immersing a member to be galvanized in a plating assistant solution consisting of zinc chloride, potassium chloride, nickel fluoride, a passivating agent, an oxygen scavenger, a complexing agent, a plating assistant film thickness control agent and water after oil removal, rust removal and water washing, soaking for 3 to 6 minutes, taking out, placing in the air, naturally drying for 5 to 15 minutes, and then galvanizing.
4. The plating assist method according to claim 3, wherein: the pH value of the plating assistant agent solution is controlled to be 2-3.2.
5. The plating assist method according to claim 3, wherein: the dipping temperature of the plating assistant agent solution is controlled to be 65-85 ℃.
6. The plating assist method according to claim 3, wherein: the galvanizing is carried out by improving the surface condition of the steel material to be galvanized and improving the galvanizing quality through zinc chloride, potassium chloride, nickel fluoride, a passivating agent, an oxygen scavenger, a complexing agent and a plating assistant film thickness control agent in the plating assistant agent, wherein:
the deoxidant is adopted, and the strong reducibility of the deoxidant is utilized, so that the oxygen in the plating assistant can be removed, the oxygen content in a film of the plating assistant is greatly reduced, the film can be decomposed into a reducing atmosphere at the high temperature of galvanization, and the high-temperature oxidation of a steel matrix is prevented;
then a passivating agent is used in a matching way, a layer of compact adsorption film which is equivalent to a metal passivation film is formed on the steel matrix, and the oxygen molecules are efficiently prevented from permeating and diffusing to the surface of the steel matrix; the passivating agent is a gemini quaternary ammonium salt cationic surfactant, the molecule of the surfactant has two hydrophobic groups and two hydrophilic groups, and the hydrophilic groups are linked through chemical bonds by virtue of linking groups; the biquaternary ammonium salt and the iron matrix with negative electricity form chelate adsorption, and under the chemical bond action of the intermediate linking group, the problem of mutual electrostatic repulsion among molecules when single quaternary ammonium salt is adopted is avoided, and the close arrangement among adsorbed molecules is ensured;
then complexing agent is used to match with weak acid environment, and complexing agent and Fe are used2+The ions form a complex compound, so that a very small amount of iron ions are formed into the complex compound and exist in the plating assistant film, and iron oxide is not formed and deposited on the surface of the steel matrix to form skip plating;
potassium chloride is taken as a coating reinforcing agent to promote the drying of the coating assistant agent film, and a large number of fine crystals are precipitated from the potassium chloride along with the volatilization of water in the coating assistant agent film to become hard fixed points of the film layer, so that the phenomenon that the coating assistant film shrinks due to the increase of surface tension in the drying process to cause the film layer to break is prevented, and a steel substrate without the coating assistant film is formed;
the nickel fluoride is used as an aluminum oxide dissolving agent and a zinc coating thickness control agent, and firstly, fluoride ions can react with aluminum oxide to form hexafluoroaluminate, so that a hard aluminum oxide film on the surface of liquid zinc is cracked, and the wetting effect of the liquid zinc on a steel matrix is not hindered; secondly, nickel ions can be reduced into simple substance nickel by zinc, and a nickel-zinc compound is adsorbed between a zeta phase and an eta phase of a zinc coating to hinder mutual diffusion of zinc and iron atoms and slow down iron-zinc reaction;
the fluorocarbon chain surfactant below C4 is used as a plating assistant film thickness control agent, and the characteristic of low surface tension of a fluorocarbon surfactant aqueous solution is utilized, so that the wetting angle between the plating assistant and a steel substrate can be reduced, a plating assistant film layer is thinned, and the fluorocarbon chain surfactant below C4 basically has no bioaccumulation, and belongs to an environment-friendly assistant;
in the process of manufacturing and using the plating assistant agent, the pH value is controlled to be 2-3.2 because the weak acid environment is favorable for preventing iron oxide from depositing on the surface of the steel matrix and strengthening the activation effect of the plating assistant agent on the surface of the matrix; controlling the temperature to be 65-85 ℃, namely heating the steel material by using the plating assistant agent, so that the plating assistant agent film can volatilize water by using the heat of the steel matrix under the condition of not drying; controlling the plating assistant time for 3-6 minutes, so that the steel substrate has enough time to absorb heat from the plating assistant agent, and the active ingredients in the plating assistant agent have enough time to perform adsorption reaction with the steel surface; thereby improving the effect of the plating assistant agent.
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