1、 Treatment methods for metal surface adjustment
   The process of surface adjustment of phosphide was to use a phosphide surface modifier to change the microscopic state of the metal surface that needs to be phosphized to promote the formation of a crystalline fine, uniform, and dense phosphide film during the phosphizing process.The surface treatment of the workpiece before phosphorization greatly affects the quality of the phosphorization film, especially the acid cleaning or high temperature strong base cleaning has the most significant influence on the thin-layer phosphorization.The results of this study show that a full oxide layer of Fe3O4 and Fe3O4 with a thickness of 10A-50A exists on the surface of cold rolled steel sheets, from which phosphate crystallization is generated to obtain a complete dense phosphide film.If acid washed, the ferric oxide oxide layer is too thin and incomplete, so it is difficult to get a good uniform phosphine film, and also because the acid washed surface produces carbon evolution that also affects the phosphine film formation.For high temperature or strong base cleaning, because the active points on the steel sheet surface transform into oxide or hydroxide, the crystal nuclei that make up the phosphide film are reduced, thus prompting the generation of sparse and coarse crystallization, which affects the quality of the phosphide film, especially low-temperature thin-layer phosphide and low zinc phosphide are particularly sensitive to pretreatment and make it difficult to form an excellent phosphide film without surface adjustment treatment.
   To overcome the various adverse effects caused by surface pretreatment, some organic or inorganic compounds are often added at the first step of the phosphine process to make surface adjustments, which can be either soluble or stirred to disperse the material in water, which is capable of changing the metal surface state, accelerating the phosphinization process, and reducing the temperature of the phosphine solutionPrompted the formation of a composite chemical of crystalline fine dense phosphide films.This is the basic function of metal surface tailoring agents.The surface tailoring agent was applied in the surface tailoring procedure before phosphorization to adsorb on the metal surface in the form of microparticles, which become a layer of crystalline cores with uniform distribution and a larger number of phosphorescence crystals.Due to the large number of crystal cores on the metal surface, during the crystallization growth process, the crystals can quickly connect with each other, which limits the continued growth of crystals, and thus makes the phosphide film crystallization fine and uniform.
2、 Mechanism of action of surfactants
   Foreign researchers have used scanning electron microscopy (SEM) to study the formation process of phosphide film and found that the phosphization takes place in two steps.The first is the formation of a crystal nucleus of phosphate on the surface active sites, followed by the continued growth of the crystal nucleus.Before phosphization, an increase in the number of active sites was found after the surface was treated with dilute hydrochloric acid.The amount of active sites, directly affects the quality of the phosphide film.Titanium containing phosphate solutions were first found to have a surface activating effect.After treatment with colloidal Ti, the grain size and properties of the phosphide film could be controlled by increasing the surface activation point due to the adsorption of Ti on the surface.Titanium phosphate salts present in the colloidal state then have an activating effect when suspended in aqueous solution.Studies with Auger electron spectroscopy (AES) found that there was only trace of phosphide film formation on surfaces treated with gum Ti where titanium adsorbed, but not on untreated surfaces.The good or bad of the phosphorescence film depends on the activation state of the metal surface.Ti colloidal particles in Ti containing surface adjustment fluids have a stronger activation effect than water-soluble Ti containing compounds, and other components such as surfactants also have an activation effect.Domestic researchers observed by SEM that the phosphorization process consists of an immersion period, an amorphous deposition period, and a nucleation growth period.During the immersion period, the grains of different iron elements on the surface of the machined surface are subject to different degrees of erosion, and this inhomogeneity of erosion is caused by the different orientation of grains.When the manufacturing surface is contaminated with carbon or there is segregation of carbon, it reduces the amount of adsorption to colloidal Ti, reducing the nucleation point of the phosphide film.It has been pointed out that the crystalline component of the surface adjustment agent is the more Ti4 + (crystallization origin) the colloidal titanium oxyphosphate tetrasodium adsorbed on the metal surface, the higher the coverage.As observed by SEM, the colloidal titanium mainly attached near the intergranular crack caused by corrosion, and formed a network structure when the surface adjustment time was 50 s, and a large number of crystallization origins formed a network crystallization core.Normally, hydrolysis of negatively charged titanium phosphate colloids produces Ti (OH) 4 with high activity to attach to the workpiece surface in a physisorbed manner.The number of crystal nuclei determines how finely the phosphine film is refined, and a high coverage gives the phosphine film a more meticulously compact and continuous film with reduced film weight.It is known from experiments that phosphine films of high titanium are gray, uniform, and dense, while those of low titanium are sparse and yellow.The sensitization treatment with a weak alkaline solution containing a small amount of titanium salt and buffering effect could obviously improve the fine density, adhesion, and corrosion resistance of the phosphide film due to the formation of a large number of reticular crystalline cores.
   According to the law of epitaxial growth, phosphate crystals must grow in the epitaxial form, so to produce as much phosphate crystallites as possible, to be equally sized, evenly distributed on the metal surface, finely and intimately packed;In addition, such a mechanism of regular, repetitive epitaxially oriented crystal core formation, growth, and growth delay ensures the formation of a primary phosphide layer and subsequent crystal deposition from the substrate, as well as the formation of a fine-grained, approximately the same size, crystal structure film with proper adhesion.The growth of epitaxial nuclei strongly depends on the aggregation phenomenon.On growth of a crystal nucleus, nuclei start aggregating sooner or later, such that, on formation of nuclear islands, aggregation increases, at later stages island chains join until only a few grooves are left, and finally these also disappear to achieve a continuous phosphorescence film.The time required for nuclear island aggregation is determined by the size of the nuclear island and the inter Island distance.Therefore, the crystallization of phosphate deposits, which are important in phosphide film formation, is important.Ti system surface adjusters can provide a large number of crystal nuclei of Chin salt crystallization on the metal surface to form a layer of uniform Ti phosphate film, which makes up for the defects of metal surface due to acid washing or alkali washing.Normally, hydrolysis of negatively charged titanium phosphate colloids produces Ti (OH) 4 with high activity, which is attached to the workpiece surface in a physisorbed manner, it fills the corrosion point and forms a large number of reticular crystalline cores, and when the surface of the activation layer is in contact with the phosphorite, sodium ions adsorbed on the surface of titanium phosphate colloids exchange with zinc ions in the phosphorite fluid to produce phosphorite grains,These grains then provide a platform for epitaxial growth of the phosphide layer.How many active sites these adsorbed Ti form on the metal surface necessarily directly affects the crystalline size of the phosphine film.The smaller the colloidal Ti ions, the more colloidal Ti adsorbed per unit area and the finer the phosphine film crystallized.
3、 The role of surfactant
(1) To improve the impurities brought in by the previous step pretreatment, especially the ones with complex shapes.To improve the bad workpiece condition brought by the degreasing trough.It also ameliorates the undesirable effect of phosphizing caused by the evolution of carbon on the workpiece surface by acid cleaning
(2) The surface adjustment allows the film thickness of the phosphide film to be stabilized
(3) It reduces the amount of residue inside the phosphide solution
(4) Reducing the consumption of phosphine solution
(5) Reducing the consumption of enhancers
(6) Reducing the phosphorization process temperature
(7) Orienting the phosphide film toward favorable orientation for crystallization
   To this end, some promoters such as nitrate, chlorate, nitrite, etc.can be added;Also add some substances that can form a crystal core and can turn human phosphide solution along with the metal, such as zinc phosphide can add colloidal titanium, oxalic acid, polyphosphate, zinc phosphide can add insoluble zinc phosphate, manganese phosphide can add insoluble manganese phosphate and so on.Among them, titanium and manganese salts are the most important and have significant effects.These substances can activate the surface of metals treated with strong bases and acids to form large and well distributed crystal nuclei, which leads to a uniform, dense, fine, strong binding to the matrix and protective properties of the phosphide film, and can also accelerate the phosphizing speed, shorten the phosphizing time, reduce the consumption of phosphide materials and reduce the phosphizing sediment.
   Surface modifiers before chemical film formation of steel pieces are classified as:surface modifiers for zinc phosphides;Surface modifiers used for zinc phosphide were divided into gum titanium regulators and acid regulators mainly oxalic acid.Manganese phosphides with surface modifying agents.Aluminum and aluminum alloys using surface modifiers.Mg and Mg alloys chemical film formation was performed before application of surface modifiers (generally acidic surface modifiers).
4、 Preparation of titanium salt surface modifiers (gum titanium surface modifiers)
   Preparation of surface adjusters it is here mainly described using powdered titanium salt surface adjusters as an example.Titanium salt surface adjusters are prepared as powdered finished surface adjusters from materials such as phosphate and titanium oxysulfate by heating the reaction in a dedicated apparatus, followed by drying, crushing and other procedures.
   Technical indicators for surface adjustment agents of finished titanium salts
Appearance:white, powdery;
Titanium content:≥ 4%;
Total alkalinity:(0.1% to 0.2% in water) as 3 points to 4 points;
PH:(0.1% to 0.2% in water) 8 to 9.
   This surface adjusts the working fluid, is long-lived, requires only supplements at consumption, maintains the working fluid pH, and generally does not require regular refills.After the workpiece was surface adjusted by titanium salts, it was directly subjected to the human phosphorization procedure without water washing.Sometimes, without surface adjustment slots because of the limited equipment, the addition of surface adjustment agents to a fat tank can also play a role in surface adjustment, but the effect was not as good as using surface adjustment alone.
1.Powdered colloidal titanium salt surfactant (gum titanium modifier) preparation method (a)
   35.2 parts of water were mixed with 12.6 parts of sodium tripolyphosphate at 65 – 80℃, rotating at 5800 R/min in a blender, after 5min 2.6 parts of potassium titanium fluoride were added and the mixture was heated at 70℃ for 5min.Then 49.6 parts of disodium hydrogen phosphate was added and held at 75℃-80℃ for 15 min, followed by slowly warming to 88℃.Silt like mixture was slowly added to 100 parts of anhydrous disodium hydrogen phosphate, mixed well for cooling, the solid-state product was pressed into dry powder, this solid-state powder was formulated with water as phosphine surface adjustment solution.Colloidal titanium salt surfactants can be used for the phosphization of ferrous metals, zinc or aluminum and their alloys.
   Phosphine surfacemodifier powders can be obtained by grinding, preferably by ball milling.The general preparation procedure was as follows:100 ml/L lmol/L zns04 with l00 ml, 1mo1/L na2hp04 was added to 1 l of 0.5.After purification by pouring, it was filtered, and the precipitate was dried.,The principal components of X-ray diffraction analysis were zn2fe (P04) and Fe3 (PO4) 2.Add 50 g of promoter per 1 kg to water containing a small amount of isopropanol, adjust to 10%, and grind for approximately 1 h in a ball mill.By instrumental analysis, the microparticle size was determined to be 5μm.After grinding, the beads were diluted to 1 g/L with tap water to obtain a suspension for phosphine surface adjustment.To chelate the cation and maintain colloidal titanium stability, pyrophosphate salts, polyphosphates were added.When a certain amount of polyphosphate was added to the surface adjustment agent, the polyphosphate reacted with the metal surface to form a film layer, which could lead to defects in the phosphide film during the subsequent phosphizing treatment.
2.Preparation method of powder surface modifiers (surface modifiers) (II)
   Titanium oxysulfate blend 15.2, sodium hydroxide (technical grade) 22.4%, phosphoric acid:(industrial grade) 38%, sodium carbonate (industrial grade) 18.8%, sodium pyrophosphate (industrial grade) 5.2%.
  1) Preparative methods
   Since titanium oxysulfate is produced by the reaction of sodium hydroxide and phosphoric acid to titanium sodium phosphate, which is a drastic exothermic reaction, therefore, care must be taken during formulation to neutralize so that the pH reaches 9-11 and the concentration of titanium ions is 0.01 g/L by the formulation process as follows.
   NaOH titanium oxosulfate mixture in monophosphate, pyrophosphate, neutralized, and pulverized for one test
   2) Formulation note
   Titanium oxysulfate is a less soluble substance and the time to formulate the blend must be above 24 h with constant stirring for its adequate dissolution.
   In addition of human phosphoric acid, the production of titanium sodium phosphate from titanium sodium sulfate is a vigorous exothermic reaction, and when adding it, stir slowly and obliquely to allow adequate reaction, while being aware of safety.
   Neutralization is one of the keys throughout the formulation and the pH must be slowly adjusted to 9-11.
   The surfactant is a colloidal titanium substance and the operator should not be too quick when spiking and should be slowly and uniformly spiking into the tank fluid.When dealing with the workpiece, the frames should be agitated up and down 2 times and 3 times for the adsorption of titanium species.
   3) Analytical methods
   Weigh a "sample" to the nearest 0.1g and put it in a 250ml beaker with distilled water to dissolve, place it in a 500ml volumetric flask after cooling, dilute with water to volume, mix well, and measure with a pH test paper or pH meter method.
3.Surfactant preparation (III)
Component Raw material grade μg/kg by mass component Raw material grade μg/kg by mass
Polyphosphates Ind 180-190 borate Ind thirty
Titanium oxysulfate blend Ind one hundred and fifty 85% phosphoric acid Ind 45-60
Phosphate disodium salt Ind four hundred and twenty ST10 mix Ind twenty
   In the fabrication process, according to the formula, first water is added inside the reaction tank, then polyphosphate is added, in the high-temperature melting state, a pre dissolved mixed liquid of titanium oxysulfate is added, and the reaction at 120℃ produces colloidal titanium oxyphosphate tetrasodium, this process is a vigorous exothermic reaction, when the production should strictly control the temperature at 120℃, the pH value at 11-13 and the reaction time 48 h.To improve the performance of the surface tailoring agents, disodium phosphate salt was added to act as a dispersion and anti flocculation agent, ST10 was added to improve the surface tailoring thermal stability and phosphization speed, and borate was found to mainly prevent excessive phosphide film reaction caused by coloring.The cooled block surfaceadjusters were pulverized to a finished product, and the finer the crushing, the more colloidal titanium adsorbed per unit area, the tighter and finer the crystallization of the phosphide film produced during phosphizing.
Composition of the surfactant
Component names purity Content (g/L)
Sodium polyphosphate Chemically pure three
Potassium fluorotitanate Chemically pure X
Disodium hydrogen phosphate Chemically pure one
Technical indicators
Appearance of solution PH Manner of processing Processing temperature Processing time min
Water clear 4-5 dipping 55-65 0.5-1.5 a modulated versus a non modulated treatment effect contrast
Anterior phosphizing appearance Phosphorescence film appearance Corrosion resistance of phosphide films
Non-regulation Steel gray Black and coarse crystalline Anti copper sulfate puncta for about 1 min
Modulation Light dark red Dark and finely crystalline Anti copper sulphate spot size greater than 2min applicable range
   Gum titanium phosphate metal surface modifier (gum titanium modulator) is suitable for activation treatment prior to metal phosphorization such as steel, aluminum and zinc.If a zinc phosphine is employed, this solution gives quite significant activation;If zinc calcium or manganese phosphines are employed, such solutions are less effective in activation;If an iron phosphine is employed, no surface adjustment treatment is generally necessary.Gum titanium regulators are suitable for the activation treatment prior to zinc phosphization of black metals, aluminum, zinc and other metals.Its application can be quite effective in improving the speed of film formation and the fine density and corrosion resistance of phosphide film.
4.Preparation of liquid surface adjusters
   This surfactant is composed of three parts:an activating component (titanium phosphate), a stabilizing agent (phosphoric acid monophosphate system) and an alkali metal cation (k, Na).Although phosphate solutions of barium, silver, or calcium are also used to improve the quality of the phosphide film, there are various methods of preparation such as titanium salts, sodium phosphates, animal glues, or alkali polysaccharide URONATE solutions;Colloidal titanium salts, orthosilicates, TRIPOLYPHOSPHATES or pyrophosphates, etc., but the surface modifying agents prepared by the present method can treat steel, aluminum and zinc simultaneously with good versatility.At present, the most widely used abroad is also to adopt tripolyphosphate + acid type phosphate + titanium salt system.The following test formulations (group B) were determined by examining the ratio of K, Na, Ti and the ratio of tripolyphosphate to Ti through the test:
Deionized water:240 parts;
Disodium hydrogen phosphate:80 parts;
Sodium tripolyphosphate:50 parts;
Potassium fluorotitanate:5 parts;
NaOH:2 parts;
Stabilizers:150 parts;
Scale inhibitor dispersant:10 parts.
   synthetic method
   Liquid surface adjusters also belong to the Je r n – led L salt system, but overcome the disadvantages of being demanding in temperature and pH when prepared.Deionized water was first heated to 60℃ for one 70℃, and disodium hydrogen phosphate, sodium tripolyphosphate, and sodium hydroxide were added sequentially to raise the temperature to about 100℃.Then human titanium salt and antiscalage dispersant were added, kept for 20min~30min, after adding human stabilizer to form a homogeneous mixture and then removed for cooling.During the synthesis, it should be noted that all operations are performed with constant stirring, while the addition of sodium hydroxide can be increased appropriately as necessary to bring the pH of the final solution between 9 and 9.5.The stabilizing agent was a highly concentrated phosphate and polyphosphate salt aqueous solution, and the antiscalation dispersant was a composite of a polycarbonyl cyclization table and organophosphonic acid.Mainly to eliminate the influence of calcium and magnesium ions in water.
   A long warming process is saved in the preparation of surface tailoring agents without the need for drying, and controlling the temperature and pH value during the synthesis is the key to successful synthesis.
   The grain refinement effect of this surfactant was significant, which enabled the use of low zinc phosphide solutions to be expanded.The workpiece which needs to be acid cleaned is also treated and can form a more uniform and thinner phosphorescence film.
   This surfactant is more capable of treating than currently used solid surfactants, which can treat steel by about 10 m2 per liter working liquid (containing L 0 mg/L--12 mg/l Ti4+), while the solid surfactant working liquid generally has a processing capacity of around 3m2/L.
   This surfactant maintained better activity as well, and when left at room temperature for longer than 4 months, it still maintained better surface adjusted activity.
5、 Effect of colloidal titanium concentration on phosphide film:
   In general, the higher the colloidal titanium concentration as an active substance, the greater the chance of colloidal titanium adsorbing on the surface of metal matrix, the more active center points are formed and the denser the film formation will be.But it wasn't the higher the concentration the better.Generally, titanium content does not exceed 100 mg/L, and too high titanium concentration will lead to an increased chance of colloidal titanium interparticle collisions, which can poly sedimentation of gum titanium regulators, not only the lack of a dense phosphorfilm but also the reduced service life of surface adjusted working solutions.Using the liquid surface adjuster obtained from the formulation of group B, titanium concentration could be controlled in the lower range and a good phosphide film could be obtained.
   Stability and activity in storage:the tests are aimed mainly at the appearance and film forming properties of the surfactants.After 4 months of storage at room temperature before subjecting it to a low zinc phosphide test, the process was still adapted as previously described to compare the handling ability of the working liquid with commercial solid-state surfactants commonly used at home.The tests showed that the phosphide worked well.Surface adjustment working solutions (containing Ti 10 mg/L one 12 mg/L) were still able to form a complete layer of phosphine film after the activation area reached 10 m2/L, while solid-state surface adjustment working solutions were generally only able to continuously treat 3m2/L.
   The core component of the surface tailoring agent is colloidal titanium phosphate tetrasodium, and the more Ti4 ten (crystallization origin) adsorbed on the metal surface, the higher the coverage, the larger the amount of crystallization origin to form reticular crystallization core, the number of crystal nuclei determine the refinement degree of the phosphorescence film, and a high coverage will make the phosphorescence film more meticulously compact and continuous, and the film weight will also decrease.It is known from experiments that phosphine films of high titanium are gray, uniform, and dense, while those of low titanium are sparse and yellow effect of pH the pH of the surface adjustment fluid directly affects the activity of the surface adjustment fluid, which is the most stable and effective pH in the range of 8.2-9.5.During use, the pH value decreases in addition to normal consumption, because of the weak alkaline nature of the surface adjustment fluid, which easily absorbs CO2 in the air to form carbonic acid, the pH value also decreases due to neutralization effect.In addition, the poorly washed residues with water after acid washing are easily carried into the surface adjustment tank and also lower the pH of the surface adjustment agent.At low pH, colloidal titanium phosphate can settle, and the phosphide film becomes sparse, yellow, and rust.
When pH<8.2 and P(Ti4+)<0.020 or="" ph="">=9.5 and P(Ti4+)>0.040 g/L, the phosphide film was rough and thick.The optimal range of pH value was 8.2-9.5, and the detection frequency of pH value in automotive line was 1 time/shift and that of Ti content was 1 time/day to keep both within the process range.
Effect of temperature:Generally allows surface adjustment temperatures above 30℃.Because colloidal systems belong to highly dispersed heterogeneous dispersion systems with huge surface free enthalpy, they are thermodynamically unstable systems, and this temperature state of colloidal titanium phosphate will automatically produce the coalescence of microparticles and become large particles, so that the colloids quickly produce precipitation and fail, the higher the temperature, the more sedimentation.The surface adjusted sedimentation rate reached 18% when the surface adjusted temperature was at 40℃.For a production line in which the surface adjustment temperature exceeds 30 ℃, the optimal way of heat dissipation is to add a wind feeding device to the surface adjustment tank, forcing the basic heat to be transferred to the defatting direction, and adding a fresh water spray before the surface adjustment can also block part of the heat transfer to the surface adjustment tank, if the improvement of the equipment is not satisfactory,Add 0.3g/l-0.5gl of ST10 mix additives to the bath solution.When dealing with car surfaces, high surface adjustment temperatures also cause the anterior phosphine film to dry out on the white body surface, which can easily leave flow marks on the body surface, and it is recommended to add a humidification process before the phosphine groove.
Effects of handling equipment the spray equipment, which phosphates against the workpiece surface with nozzle spray phosphine, can easily create a string because of insufficient trough spacing or nozzle deflection.Splashing of phosphine into the surface adjustment tank reduces the pH of the surface adjustment fluid, causing sedimentation of Ti and affecting the state of phosphine film formation.For immersion treatment troughs, main attention is paid to workpiece leaching time because of the complex shape of the workpiece, which can easily cause carry out contamination, damage surface adjustment performance, but also note that workpiece leaching time is too long to cause corrosion and corrosion of the workpiece.The good or bad of the tank solution cycling directly affects the lifetime of the surface adjustment solution and the quality of the phosphine film, and poor cycling will cause the settling of the surface adjustment agent and the low titanium content of the surface adjustment solution on the tank solution, which will affect the compactness of the phosphine film.The cycled surface adjuster will settle by 10% one 15% within 4h, and the production line is best designed with a cycle cycle of surface adjuster solution at 2 times/h influence of water quality
   The main component of the surface adjuster is colloidal titanium phosphate, while it is milky white colloidal like after matching into the working fluid, and the water with high hardness is extremely prone to cause colloidal titanium agglomerative sedimentation, which cannot recover its surface adjustment function even after settling and is not affected by the production load and must be discharged regularly.It was discharged once a week in spring, fall, and winter seasons, and once a week in summer and high-temperature seasons.The addition of hard water resistant ingredients during surface tailoring production slows colloidal titanium coacervation sedimentation, dominated by the addition of medium molecular weight vegetations.The water hardness of formulated surface adjustment fluids cannot be overestimated, and partially purified water may be considered when the hardness of the water is greater than or equal to 100°DH (1dh=0.178 mmo1/L), or when the conductance of the water is greater than or equal to 200 US/cm, in order to reduce the hardness, but water that is too soft will also decrease the activity of the surface adjustment agents (too small colloidal particles).It is known from experiments that surface adjustment of colloidal titanium salts after sedimentation can cause a sparse and yellowish phosphide film.SEM morphologies of the phosphide films obtained from the surface adjustment solutions formulated with different water quality hardness show that the phosphide films were sparse and mostly film-free at a hardness of 130°DH;When the hardness was 20°DH, the phosphide film was dense and uniform.It is recommended that the water quality hardness is controlled between 20°--100°DH.
   Surface adjustment is essential for phosphizing, and good surface adjustment makes the phosphide film more finely compact and facilitates film formation, which can reduce the cyclic stirring dependence on the phosphide groove.On the premise that all parameters of the phosphine film will be normal, it has been found by analysis that if the phosphine film is sparse or even film free, it can increase Ti4 + content and pH, if the phosphine film has a large area of yellowish or yellow streaks, it can improve pH, the phosphine film flower, and has a heterogeneous color, it can increase Ti4 + content and enhance the tank fluid circulation;Phosphorous film appeared as a white powder film, which could increase Ti4 + content;Water quality hardness should be controlled to less than or equal to 100°DH;The tank fluid temperature is best controlled at less than or equal to 40℃.As long as practical aspects of the manufacturing line are combined, targeted tailoring of the formulation of the surface adjustment liquid and the process used, it is entirely possible to address the problem of yellow hair discharge from phosphide films.
   With the development of the paint industry, the increasing amount of surface tailoring agents in their pretreatment procedures, not only impregnation phosphorization is used before, but spray phosphorization is also widely applied.Meanwhile, it is also applied by the pretreatment before low temperature phosphorization, and current gum titanium surfactants are the most widely used but also suffer from several problems:
6、 Lifetime of surfactants
   Freshly formulated colloidal titanium salt surface adjusters play a great role in promoting fine compactness of the phosphide film, but after a period of time, with or without its use, a failure phenomenon due to flocculation of colloidal titanium will make the phosphide film rough.Colloidal systems belong to highly dispersed heterogeneous dispersed systems with huge surface free enthalpy and are thermodynamically unstable systems that develop a phenomenon of automatically producing coalescence of microparticles into large particles, rendering colloids ineffective by quickly producing precipitation.This surfactant, which is not affected by the production load, must be discharged on a regular basis.In general, they were discharged once a week in spring, fall, and winter seasons, and once a week in summer and high-temperature seasons.Frequent reassortment troughs, which not only increase the consumption of water and materials, but also the generated wastewater add pressure to environmental protection.
   Surface adjustment fluid activity is affected by water mass
   The principal component (colloidal titanium) of the surface adjuster is negatively charged and can remain in a non flocculated and dispersed state in aqueous solution due to the effect of electrical repulsive forces.Most industrial water supplies contain calcium and magnesium ions, and the large number of cations present in water neutralizes the negative charge of colloidal titanium, with a consequent weakening of the electrical repulsive forces and consequently flocculation and precipitation, rendering colloidal titanium inactive.
   Temperature and pH affect the surface adjustment process.Colloidal titanium agglomerates to inactivate surface modifiers at temperatures beyond 35℃ and pH values in the range of 8.0 to 9.5.Therefore, specific temperature and pH ranges must be defined.This makes it difficult to combine a surfactant with a general delipidating agent.
   Surface adjusters allow low concentrations and solutions need to be adjusted frequently.An increase in the colloidal titanium concentration leads to an increase in the colloidal titanium particle collision frequency.Collisions will cause colloidal titanium to agglomerate and precipitate, which will affect the phosphide film grain size, and the current upper concentration that can be used for colloidal titanium is generally 1 mg/L.
   Titanium phosphate metal surfactant is an aqueous solution composed of activators (titanium salts, phosphate) combined with stabilizers (other components).At present, the most used abroad is also the use of tripolyphosphate + acid phosphate dechine salt system, this agent is composed of three parts of activated ingredient (titanium phosphate), stabilizing agent (acid phosphate, polyphosphate) and alkali metal cation (k, Na).
note: titanium salts exhibit poor stability when formulated as a working solution and, in their unused state, also fail naturally and, in general, the working solution should be replaced in 7 days.During normal use, the working fluid may be adjusted or replaced based on total alkalinity and pH changes.
In recent years, our phosphine workers, through their efforts, have developed novel liquid surface tailoring agents, which are colloidal titanium salts used completely without the use of powdered surface tailoring agents, using zinc zinc phosphate iron as the main component.Compared with the current widely used powdered surface adjusting agents, the tank fluid is clear and transparent close to the real solution, which has the characteristics of low material consumption, high stability of the tank fluid, long service life (6 one and 8 months), less waste water emission, and more subtle and dense phosphate membrane.
7、 Analysis and detection of surfactant
   The detection indicators of alkaline surface adjusters mainly include:total alkalinity, the concentrations of colloidal titanium and major metal ions should also be detected during use in order to determine the supplementation, replacement.
1.Detection of total alkalinity:
   Principle:acid base titration method;
   Assay procedure:weigh 2g (accurate to 0.001) of surface adjustment agent in a beaker of 1000 ml, add the appropriate amount of distilled water and dissolve all into a volumetric flask of 1000 ml, add water and dilute to volume, shaking well.Pipet 25 ml of the test sample in a triangular bottle and dilute to 50 ml with distilled water.Add 1 drop to 2 drops of human bromophenol blue indicator.Titrate to yellow with 0.1000 mol/L HCl standard solution.Note the number of milliliters of 0.1000 mo1/L HCl standard solution consumed.
Calcd:total basicity=CHCL*VHCL*10
In the formula:Chci=concentration of HCI standard solution (mol/L);
VHCl=volume of HCl standard solution consumed (ML).
Precision:the difference between the results of two parallel determinations is not more than 0.5%
PH:assay or precision pH test strips with a pH meter.
2.Performance test:
   1) Surface adjustability:
   After mixing this product into working solution at 1.0%, it was used as a phosphine test with its supporting phosphine solution.The phosphide film grains were grain like as qualified as observed on the microscope of crystal phase under the magnification of 500 times.
   2) Phenological tolerance
   Samples kept in room temperature, ventilated, dry conditions for 12 months should not deteriorate.
   Based on the detection results, the solution was adjusted to the range of the process requirements.If it is difficult to adjust, or seriously affects the phosphine properties of the product, a replacement, reconstitution working solution should be given

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