CN102199766B - Method for preparing magnesium lithium alloy cerium salt and molybdate-phosphate-zirconium fluoride conversion coating - Google Patents

Abstract

The invention provides a method for preparing magnesium lithium alloy cerium salt and molybdate-phosphate-zirconium fluoride conversion coating, which comprises: subjecting the magnesium lithium alloy to degreasing, pickling and activating; performing conversion by cerium salt for 10 to 15 minutes in cerium salt conversion solution under conditions of a pH value of 3 to 4 and a temperature of 40 DEG C, and forming a layer of rare earth conversion coating on the surface of the magnesium lithium alloy; and immersing in molybdate-phosphate-zirconium fluoride conversion solution to perform conversion for 12 to 15 minutes under conditions of a pH value of 3.7 to 3.8 and a temperature of 50 to 55 DEG C. The method has better anticorrosion effect and is environment friendly; the bonding force between the conversion coating and the substrate is high; the color of the conversion film is uniform; the anticorrosion performance is high; and the obtained molybdate-phosphate-zirconium fluoride conversion solution has high recycling value and long service life and can be better reduce production and application cost.

Description

Preparation method of magnesium-lithium alloy cerium salt and molybdate-phosphate-zirconium fluoride conversion film

technical field

The invention relates to a preparation method for forming a conversion film on the surface of a magnesium-lithium alloy.

Background technique

At present, more research work on the surface modification of magnesium alloys mainly includes surface alloying, vapor deposition coating, laser treatment, metal coating, anodic oxidation, chemical conversion coating and other methods. Chemical conversion coatings have the advantages of simple operation, low cost, and wide adaptability. The existing chemical conversions commonly used include chromate conversion, phosphate conversion, molybdate conversion, permanganate conversion, rare earth metal salt conversion, tin Salt transformation and organic chemical transformation, etc. The representative chemical conversion treatment is chromate conversion, and the chromate conversion treatment mainly uses chromic anhydride or dichromate as the main component solution for chemical treatment. Because hexavalent chromium is toxic, it is of great significance to research and develop an environmentally friendly chromate-free conversion coating that can replace chromate conversion coatings.

Most of the currently researched chromium-free conversion treatment solutions for magnesium alloys are still in the laboratory stage, and often have the disadvantages of fast solution consumption, easy precipitation or long treatment time, and the formed film is thin, loose and uneven. It is suitable for batch processing of workpieces, and there are very few practical processes. Therefore, it is necessary to further improve the chromium-free conversion treatment solution, such as research on film growth promoters and solution stabilizers, so that it is suitable for large-scale surface treatment of magnesium alloys. Since there is still a certain gap between the existing chromium-free conversion treatment and chromate treatment in terms of wear resistance and self-repairing ability, the development of new chromium-free conversion treatment solutions is still a hot spot in the future, especially rare earth salts and organic derivatives. Treatment, chromium-free conversion treatment solution for compound salts. In short, with the rapid expansion of magnesium alloy application fields and the continuous enhancement of people's environmental awareness, there will be more and more research on chromium-free chemical conversion treatment of magnesium alloys with good appearance and good corrosion resistance, and more and more attention will be paid.

Contents of the invention

The object of the present invention is to provide a kind of magnesium-lithium alloy cerium salt and molybdate-phosphate-fluoride that is easy to operate, mild in condition, energy-saving, less toxic and low in cost, and can greatly improve the corrosion resistance of magnesium-lithium alloy. Preparation method of zirconium conversion film.

The purpose of the present invention is achieved like this:

After degreasing, pickling, and activation, the magnesium-lithium alloy is firstly subjected to cerium salt conversion treatment in the cerium salt conversion solution at a pH value of 3-4 and a temperature of 40°C for 10-15 minutes to form a Layer rare earth conversion coating; then immerse in the molybdate-phosphate-zirconium fluoride conversion solution, and carry out the conversion treatment for 12-15 minutes under the conditions of pH value 3.7-3.8 and temperature 50°C-55°C.

The cerium salt conversion solution is composed of 8g/L cerium nitrate, 10g/L citric acid, 2g/L sodium lauryl sulfate, 0.2g/L thiourea, 0.05g/L sodium fluoride, hydrogen peroxide 10mL/L and distilled water formulated.

The molybdate-phosphate-zirconium fluoride conversion solution consists of sodium molybdate 40-50g/L, sodium dihydrogen phosphate 50-55g/L, sodium citrate 5-8g/L, sodium fluoride 4-5g/L L, sodium nitrate 1-2g/L, zirconium fluoride 10-15g/L and distilled water.

The preparation method of the cerium salt conversion liquid is as follows: cerium nitrate, citric acid, sodium lauryl sulfate, thiourea, and sodium fluoride are dissolved in water to form a solution, and the citric acid solution and the sodium lauryl sulfate solution are added to the nitric acid The solution A was obtained from the cerium solution, the thiourea solution and the sodium fluoride solution were added to the solution A to obtain the solution B, the hydrogen peroxide was added to the solution B and adjusted to 1L with distilled water.

The preparation method of the molybdate-phosphate-zirconium fluoride conversion solution is: sodium molybdate, sodium dihydrogen phosphate, sodium citrate, sodium fluoride, sodium nitrate, and zirconium fluoride are dissolved in water to form a solution, and dihydrogen phosphate Sodium solution was added to sodium molybdate solution to obtain solution C, sodium citrate solution was added to solution C to obtain solution D, sodium fluoride solution was added to solution D to obtain solution E, sodium nitrate solution was added to solution E to obtain solution F , zirconium fluoride solution was added to solution F to obtain solution G, diluted to 1L with distilled water, filtered, and adjusted to pH 3.7-3.8 with glacial acetic acid.

The invention provides a new type of molybdate-phosphate-zirconium fluoride conversion coating after magnesium-lithium alloy cerium salt conversion, which is a magnesium-lithium alloy double-layer conversion coating system. Traditional molybdate conversion coatings are generally used The adjustment of phosphoric acid can not improve the corrosion resistance of magnesium-lithium alloy much, and can only reduce the corrosion current by an order of magnitude. In order to improve the corrosion resistance of the conversion film, the present invention first performs cerium salt conversion on the magnesium-lithium alloy, and then performs molybdate-phosphate-zirconium fluoride conversion, and the pH value of the conversion solution is adjusted by glacial acetic acid. The appearance of the molybdate-phosphate-zirconium fluoride conversion coating prepared by this method is smooth, dense, and non-porous, and the film layer is uniform and brownish black. The surface of the film layer is wiped by hand, and the film layer does not detach and is well combined with the substrate. , can withstand high temperature, the film layer changes from black to gray after calcination at 200°C for 30 minutes, and there is no obvious change in the film layer, and the surface of the film layer is bubbling, peeling and pulverized after being calcined at 300°C for 30 minutes. The corrosion potential of the molybdate-phosphate-zirconium fluoride conversion film is -0.302V, while the corrosion potential of the magnesium-lithium alloy substrate is -1.6645V, and the corrosion potential of the molybdate-phosphate-zirconium fluoride conversion film is 1.3625 higher than that of the substrate V; the corrosion current of the molybdate-phosphate-zirconium fluoride conversion coating is 5.643×10 ^-7 A.cm ^-2 , while the corrosion current of the magnesium-lithium alloy substrate is 1.503×10 ^-3 A.cm ^-2 . The corrosion current of the salt-phosphate-zirconium fluoride conversion coating is 4 orders of magnitude lower than that of the substrate. The open circuit potential-time curve of the conversion film shows that the stable potential of the conversion film is higher, which is -0.8567V.

The microscopic morphology of the molybdate-phosphate-zirconium fluoride conversion coating was observed. The film layer covers a large degree of substrate, is uniform and compact, and has a moderate thickness. The film layer mainly contains Mo, P, Zr, Ce and Mg elements, among which the P content is 35%, which belongs to the high phosphorus conversion film. Orthogonal test results show that solution pH is the most important factor, followed by temperature and time.

The method is a treatment method with good anticorrosion effect and environmental friendliness. The conversion coating has a strong binding force with the substrate, the conversion coating has uniform color and excellent corrosion resistance, and the molybdate-phosphate-zirconium fluoride conversion obtained by the invention The liquid has good recycling value, long life, and can reduce production and application costs very well.

The present invention adopts sodium molybdate as main salt (it is the main film-forming agent that forms molybdate in composite film, and magnesium-lithium alloy is reduced to molybdate in the acidic medium of molybdate, and molybdate is in acidic medium It has weak oxidation in the medium, and forms a molybdate conversion film composed of magnesium oxide and molybdenum compound), and sodium dihydrogen phosphate is used as the secondary main salt (it is the main film-forming agent for forming a phosphate film in a composite film ), citric acid is used as a complexing agent, sodium fluoride is used as an accelerator, sodium nitrate is used as a accelerator, zirconium fluoride is added as an auxiliary film-forming agent and a molybdate conversion film accelerator, and glacial acetic acid is used as a pH regulator. made. The molybdate conversion solution turns blue when used, indicating that the sodium molybdate is reduced. After standing for a period of time, the conversion solution becomes colorless and transparent again and can be reused.

The preparation cost of the method is low, the preparation steps are few, the operation is simple, the reaction conditions are mild, the corrosion resistance of the magnesium-lithium alloy is greatly improved, environmental protection and energy saving, the conditions to be controlled are few and easy to implement, and it is very promising to be applied on a large scale Production.

Description of drawings

Figure 1a is the test result of the polarization curve of the magnesium-lithium alloy molybdate-phosphate-zirconium fluoride conversion coating and the magnesium-lithium alloy substrate after cerium salt conversion, in which: 1 magnesium-lithium alloy substrate, 2 cerium salt conversion Molybdate-phosphate-zirconium fluoride conversion coating;

Figure 1b is the specific analysis data table of the polarization curve;

The polarization curves of different acid-adjusted pH values in Fig. 2;

Polarization curves under different pH conditions in Fig. 3;

Open circuit potential-time curves at different temperatures in Fig. 4a;

Figure 4b is the open circuit potential table after film formation at different temperatures;

Polarization curves of different conversion times in Fig. 5;

Figure 6 EIS online test;

The polarization curve of the molybdate-phosphate-zirconium fluoride conversion film of different sodium molybdate main salt concentration of Fig. 7;

Fig. 8 is the microscopic morphology of the molybdate-phosphate-zirconium fluoride conversion film after magnesium-lithium alloy cerium salt conversion;

Figure 9 Comparison of high temperature resistance;

Figure 10a electron spectrum analysis;

Figure 10b energy spectrum analysis element content table.

Detailed ways

The following examples describe the present invention in more detail:

After degreasing, pickling, and activation, the magnesium-lithium alloy undergoes cerium salt conversion, and a layer of rare earth conversion film is first formed on the surface of the magnesium-lithium alloy. The process condition of cerium salt conversion is:

The preparation method of cerium salt conversion solution is as follows:

(1) weigh 8g/L cerium nitrate, dissolve;

(2) weigh 10g/L citric acid, dissolve;

(3) weigh 2g/L sodium lauryl sulfate, dissolve;

(4) weigh 0.2g/L thiourea, dissolve;

(5) weigh 0.05g/L sodium fluoride, dissolve;

(6) Weigh 10mL/L of hydrogen peroxide;

(7) Add solutions (2) and (3) to solution (1) under stirring conditions;

(8) under stirring conditions, adding solutions (4), (5) to the solution formed in step (7);

(9) Add solution (6) to the solution formed in step (8) under stirring condition;

(10) The magnesium-lithium alloy is converted in the cerium salt conversion liquid (9), the pH value of the conversion liquid is 3-4, the conversion temperature is 40° C., and the conversion time is 10-15 min. After the conversion of the cerium salt, a layer of film appeared on the surface of the sample that was originally slightly gray and black, and the existence of the film could be clearly seen before it was dried. After drying, the surface of the sample was gray with white spots.

Glacial acetic acid is the preparation method and technical specification of the molybdate-phosphate-zirconium fluoride conversion film solution of the magnesium-lithium alloy of the pH regulator as follows (the reagents used in the experiment and distilled water are analytically pure)

1) Take sodium molybdate 40-50g/L and fully dissolve it with a small amount of distilled water;

2) Take 50-55g/L of sodium dihydrogen phosphate and fully dissolve it with a small amount of distilled water;

3) Take sodium citrate 5-8g/L and fully dissolve it with a small amount of distilled water;

4) Take sodium fluoride 4-5g/L and fully dissolve it with a small amount of distilled water;

5) Take 1-2g/L of sodium nitrate and fully dissolve it with a small amount of distilled water;

6) Take zirconium fluoride 10-15g/L and fully dissolve it with a small amount of distilled water;

7) Pour 2) into 1) under full stirring;

8) Pour 3) into the solution formed in step 7) under sufficient stirring;

9) Pour 4) into the solution formed in step 8) under sufficient stirring;

10) Pour 5) into the solution formed in step 9) under sufficient stirring;

11) Pour 6) into the solution formed in step 10) under sufficient stirring;

12) Pour the solution formed in step 11) into a volumetric flask, add distilled water to dilute to a specified volume;

11) filter molybdate-phosphate-zirconium fluoride conversion solution with filter paper;

12) adjust the pH to 3.7-3.8 with glacial acetic acid;

13) Slowly raise the temperature of the molybdate-phosphate conversion solution to 50°C-55°C;

14) Immerse the treated magnesium-lithium alloy sample in the acidic molybdate-phosphate-zirconium fluoride conversion solution for conversion treatment. During the conversion process, the sample should be shaken continuously to desorb the hydrogen adsorbed on the surface of the sample. attached. The conversion time is 12-15min;

15) Take out the magnesium-lithium alloy sample converted from molybdate-phosphate-zirconium fluoride, fully wash it with flowing water, and dry it.

The present invention uses sodium molybdate as the main salt, sodium dihydrogen phosphate as the secondary main salt, citric acid as the coordination agent, sodium fluoride as the accelerator, sodium nitrate as the accelerator, and zirconium fluoride as the auxiliary film-forming agent and accelerator. agent, formulated with glacial acetic acid as a pH regulator. The best process standard that the present invention obtains is: sodium molybdate 40-50g/L, sodium dihydrogen phosphate 50-55g/L, citric acid 5-8g/L, sodium fluoride 4-5g/L, sodium nitrate 1- 2g/L, zirconium fluoride 10-15g/L, glacial acetic acid as pH regulator, pH=3.7-3.8, transformation temperature 50-55℃, transformation time 12-15min. The molybdate-phosphate-zirconium fluoride conversion coating after cerium salt conversion has a large coverage on the surface of the magnesium-lithium alloy, and is relatively uniform and dense, which greatly improves the corrosion resistance of the substrate. The invention has the advantages of simple and easy process, short film forming time, low cost, little influence on the fatigue performance of the magnesium-lithium alloy, low requirement on the matrix material, and is not affected by the matrix material.

Figure 1a is the test result of the polarization curve of the magnesium-lithium alloy molybdate-phosphate-zirconium fluoride conversion coating and the magnesium-lithium alloy substrate after cerium salt conversion, and Figure 1b is the specific analysis data table of the polarization curve.

It can be seen from Figure 1 that after the surface of the magnesium-lithium alloy transformed by cerium salt is transformed by molybdate-phosphate-zirconium fluoride, the corrosion resistance of the sample is improved, and the corrosion potential of the magnesium-lithium alloy substrate is -1.6645V, However, the corrosion potential of the molybdate-phosphate-zirconium fluoride conversion coating is positively shifted to -0.302V, which is 1.3625V higher than that of the substrate. After conversion of molybdate-phosphate-zirconium fluoride, the corrosion current of magnesium-lithium alloy decreased by 4 orders of magnitude, from 1.503×10 ^-3 A·cm ^-2 to 5.643×10 ^-7 A·cm ^-2 . According to the data, after chromate conversion, the corrosion current of magnesium-lithium alloys only drops by 2 orders of magnitude, indicating that the molybdate-phosphate-zirconium fluoride conversion coating on the surface of magnesium-lithium alloys after cerium salt conversion is much stronger than that of traditional chromate. Salt conversion coating has more excellent corrosion resistance.

The traditional molybdate conversion solution is generally adjusted with phosphoric acid. Experiments have found that the corrosion resistance of the conversion film is much higher than that adjusted with phosphoric acid. In order to select a suitable pH-adjusting acid, an experiment to determine the optimal adjusting acid was performed as follows. The solution composition of molybdate-phosphate-zirconium fluoride system conversion solution is sodium molybdate 40g/L, sodium dihydrogen phosphate 52g/L, zirconium fluoride 10g/L, citric acid 5g/L, sodium nitrate 1g/L . The pH value of the conversion solution was adjusted to 3.8 with phosphoric acid and acetic acid, respectively, and the conversion time was 15 minutes. Ensure that the conversion liquid composition, pH and conversion time are consistent, and determine the best adjustment acid by changing the type of acid alone. Figure 2 shows the polarization curves of different acids to adjust the pH value.

Figure 2 shows the polarization curves of different acids to adjust the pH value. It can be seen from Figure 2 that according to the corrosion current, the corrosion resistance of the conversion coating obtained by adjusting the pH with acetic acid is significantly superior to that of the coating obtained by adjusting the pH with phosphoric acid. Small. According to the Tafel curve, acetic acid is more suitable for adjusting the pH value of the molybdate-phosphate-zirconium fluoride conversion system. In order to select a suitable pH value of the conversion solution, the following experiments were carried out to determine the optimum film-forming pH value. The solution composition of molybdate-phosphate-zirconium fluoride system conversion solution is sodium molybdate 40g/L, sodium dihydrogen phosphate 52g/L, zirconium fluoride 10g/L, citric acid 5g/L, sodium nitrate 1g/L . The conversion time was 15 min, and the pH value of the conversion solution was adjusted with acetic acid. Ensure that the conversion liquid composition and conversion time are consistent, and determine the optimal conversion pH value by changing the pH value of the conversion liquid alone. The pH value of the conversion solution has an important influence on the performance of the conversion coating layer, and only when the pH value is maintained within a narrow range can a conversion coating with excellent performance be obtained.

Figure 3 shows the polarization curves under different pH conditions. It can be seen from Figure 3: when pH=3.5-4.0, the corrosion potential is more positive and the corrosion current is smaller. When the pH value reaches 4.5, the corrosion current increases significantly, which is almost the same as the corrosion current of the substrate, indicating that there is almost no film formation on the surface. The optimum pH value of the molybdate-phosphate-zirconium fluoride conversion system is 3.7-3.8.

In order to select a suitable conversion temperature, the following experiments are carried out to determine the optimum film-forming temperature. The solution composition of molybdate-phosphate-zirconium fluoride system conversion solution is sodium molybdate 40g/L, sodium dihydrogen phosphate 52g/L, zirconium fluoride 10g/L, citric acid 5g/L, sodium nitrate 1g/L . The pH value of the conversion liquid was adjusted to 3.8 with acetic acid, and the conversion time was 15 min. Ensure that the conversion solution composition, pH value and conversion time are consistent, and determine the optimal conversion time by changing the temperature of the conversion solution alone.

Figure 4a is the open circuit potential-time graph measured at different temperatures, and Figure 4b is the open circuit potential table after film formation at different temperatures.

It can be seen from Figure 4 that within a certain temperature range, the final stable potential in the open circuit potential curve increases first and then decreases with the increase of temperature. When the temperature is 50°C, the online performance test of the film is the best, and the stable potential is the highest, stable at -0.8567V. When the temperature is 55°C, the stable potential is also higher, stable at -1.4985V, so the conversion temperature is suitable. 50-55°C.

In order to select an appropriate film-forming time, the following experiments are carried out to determine the optimum film-forming time. The solution composition of molybdate-phosphate-zirconium fluoride system conversion solution is sodium molybdate 40g/L, sodium dihydrogen phosphate 52g/L, zirconium fluoride 10g/L, citric acid 5g/L, sodium nitrate 1g/L . The pH value of the conversion solution was adjusted to 3.8 with acetic acid, and the conversion temperature was 50°C. Ensure that the conversion liquid composition, pH and conversion temperature are consistent, and determine the optimal conversion time by changing the conversion time individually. Figure 5 is the polarization curves of the conversion film layer at different conversion times. It can be seen from Figure 5 that the corrosion current of the molybdate-phosphate-zirconium fluoride conversion film obtained by the conversion treatment for 15 minutes is the smallest, but with the increase of the reaction time, the self-corrosion current increases instead. The polarization curve determined that the conversion time should be about 15 minutes.

The graph shows the polarization curves at different conversion times. The temperature is controlled at 50°C, and the magnesium-lithium alloy substrate converted by the cerium salt is immersed in the molybdate-phosphate-zirconium fluoride conversion solution for continuous AC impedance testing, and the formation process of the film can be seen. Fig. 6 is the AC impedance spectrum of the conversion film formation process of the magnesium-lithium alloy converted from cerium salt in the molybdate-phosphate-zirconium fluoride conversion solution. Three AC impedance tests were performed at t=0min (conversion start), t=12min and t=20min respectively. It can be known from Fig. 6 that the test of t=0min and t=12min shows that the impedance and inductive reactance of the film layer are gradually strengthened with the increase of time, indicating the growth process of the film layer. It can be seen from the tests of t=12min and t=20min that the conversion liquid is unfavorable to the growth of the conversion film layer if the conversion time is too long.

Figure 6 is the EIS online test. In order to select a suitable concentration of the main salt of sodium molybdate, an experiment for determining the concentration of the main salt was carried out as follows. The solution composition of molybdate-phosphate-zirconium fluoride system conversion liquid is sodium molybdate gets 15g/L, 30g/L, 40g/L, 50g/L, 60g/L respectively, sodium dihydrogen phosphate 52g/L, Zirconium fluoride 10g/L, citric acid 5g/L, sodium nitrate 1g/L. The pH value of the conversion solution was adjusted to 3.8 with acetic acid, the conversion time was 15 min, and the conversion temperature was 50°C. Fig. 7 is a graph of polarization curves measured under different main salt concentrations. It can be seen from the figure that as the concentration of sodium molybdate increases, the corrosion resistance of the film first increases and then decreases. When the concentration of sodium molybdate is 40g/L, the corrosion resistance of the film is the best. As the concentration further increases, the self-corrosion current increases. Therefore, according to the experimental results, the atmosphere with a suitable concentration of the main salt sodium molybdate is 40 -50g/L.

Fig. 8 is the microscopic morphology of the molybdate-phosphate-zirconium fluoride conversion film after the magnesium-lithium alloy cerium salt conversion. It can be seen from Figure 8 that the conversion coating has a sheet-like structure, which covers the substrate to a large extent, and the film layer is uniform, dense, and moderate in thickness.

In order to explore the heat resistance of the magnesium-lithium alloy molybdate-phosphate-zirconium fluoride conversion film after cerium salt conversion, the prepared samples were calcined at high temperature. High-temperature calcination at 200°C and 300°C for 30min was carried out respectively. Figure 9 is a comparison of the molybdate-phosphate-zirconium fluoride conversion coating after conversion of magnesium-lithium alloy cerium salt without high-temperature treatment and samples after high-temperature calcination at 200°C and 300°C for 30 minutes respectively. It can be seen from Figure 9 that the conversion coating can withstand a certain high temperature. The film layer changes from black to gray after calcination at 200°C for 30 minutes, and there is no obvious change in the film layer. The surface of the film layer is bubbling, peeling, and pulverized after calcination at 300°C for 30 minutes. .

Fig. 10a is an energy spectrum analysis diagram of the magnesium-lithium alloy molybdate-phosphate-zirconium fluoride conversion film layer after cerium salt conversion, and Fig. 10b is a table of energy spectrum analysis results.

It can be seen from Figure 10 that the main elements in the conversion coating are Mo, P, Zr and Mg. Among these elements, Mg mainly comes from the dissolution of the magnesium-lithium alloy matrix, while P, Mo, and Zr come from the molybdate-phosphate-zirconium fluoride conversion solution. Among them, the content of P is relatively high, the atomic percentage reaches 35.6784%, which belongs to the high phosphorus conversion film, the content of Mo is 6.8084%, and the content of Zr is 4.1278%. Because the magnesium-lithium alloy undergoes cerium salt conversion first, the film layer contains Ce, and the content reaches 1.1943%.

Claims (3)

1. the preparation method of a magnesium lithium alloy cerium salt and molybdate-phosphoric acid salt-Zirconium tetrafluoride conversion film; It is characterized in that: after the oil removing of magnesium lithium alloy process, pickling, the activation; Earlier in cerium salt conversion fluid; Under the condition of 40 ℃ of pH value 3-4, temperature, carry out cerium salt conversion processing 10-15min, form one deck rare-earth conversion coatings on the magnesium lithium alloy surface; Immerse molybdate-phosphoric acid salt-Zirconium tetrafluoride again and transform in the solution, under the condition of 50 ℃-55 ℃ of pH value 3.7-3.8, temperature, carry out conversion processing 12-15min;

Said cerium salt conversion fluid is formulated by 8g/L cerous nitrate, 10g/L Hydrocerol A, 2g/L sodium lauryl sulphate, 0.2g/L thiocarbamide, 0.05g/L Sodium Fluoride, ydrogen peroxide 50 10mL/L and zero(ppm) water;

It is formulated by Sodium orthomolybdate 40-50g/L, SODIUM PHOSPHATE, MONOBASIC 50-55g/L, Trisodium Citrate 5-8g/L, Sodium Fluoride 4-5g/L, SODIUMNITRATE 1-2g/L, Zirconium tetrafluoride 10-15g/L and zero(ppm) water that said molybdate-phosphoric acid salt-Zirconium tetrafluoride transforms solution.

2. the preparation method of magnesium lithium alloy cerium salt according to claim 1 and molybdate-phosphoric acid salt-Zirconium tetrafluoride conversion film; It is characterized in that: the compound method of said cerium salt conversion fluid is: cerous nitrate, Hydrocerol A, sodium lauryl sulphate, thiocarbamide, the Sodium Fluoride formation solution that is dissolved in water; Citric acid solution and sodium dodecyl sulfate solution joined obtain solution A in the cerous nitrate solution; Thiourea solution and Fluorinse joined obtain solution B in the solution A, ydrogen peroxide 50 is joined in the solution B transfer to 1L with zero(ppm) water.

3. the preparation method of magnesium lithium alloy cerium salt according to claim 1 and 2 and molybdate-phosphoric acid salt-Zirconium tetrafluoride conversion film; It is characterized in that: the compound method that said molybdate-phosphoric acid salt-Zirconium tetrafluoride transforms solution is: Sodium orthomolybdate, SODIUM PHOSPHATE, MONOBASIC, Trisodium Citrate, Sodium Fluoride, SODIUMNITRATE, the Zirconium tetrafluoride formation solution that is dissolved in water; Sodium dihydrogen phosphate joins and obtains solution C in the sodium molybdate solution; Sodium citrate soln joins and obtains solution D in the solution C, and Fluorinse joins and obtains solution E in the solution D, and sodium nitrate solution joins and obtains solution F in the solution E; Zirconium tetrafluoride solution joins and obtains solution G among the solution F; Adding distil water is diluted to 1L, filters, and regulates pH to 3.7-3.8 with Glacial acetic acid min. 99.5.

Images