CN111705310A - A kind of preparation method of composite metal coating foam metal material - Google Patents

Abstract

The invention discloses a preparation method of a composite metal coating foam metal material, which comprises the following steps: (1) modifying the polyurethane foam; (2) configuring an electroless plating solution A, an electroplating solution and an electroless plating solution B; (3) electroless plating (4) electroplating; (5) heat treatment; (6) heating reduction treatment; (7) electroless plating solution, that is, the composite metal coating foam metal material is obtained. The invention adopts the combination of chemical plating and electroplating, and the prepared composite metal coating foam metal material has bright and dense coating, controllable metal content and coating thickness, has certain strength, large specific surface area, good oxidation resistance and corrosion resistance .

Description

A kind of preparation method of composite metal coating foam metal material

technical field

The invention belongs to the field of composite materials, and in particular relates to a preparation method of a foamed metal material.

Background technique

As a rapidly developing structural and functional material, nickel-iron foam metal material is widely used in catalysts and catalyst carriers, high-temperature liquid filters, heat exchangers and other functional materials, and can also be used as structural materials in automobiles, buildings and other fields. However, the traditional preparation method of foamed nickel-iron material usually involves chemical plating or electroplating of polyurethane sponge after pretreatment steps such as degreasing, pickling, sensitization, and activation, and plating nickel-iron and other alloy layers on the surface of the foam material. Thus, nickel-iron foam metal is prepared. The nickel-iron foam metal material prepared by this method, in the environment of acid, alkali and other corrosive medium, when the surface anti-corrosion layer is corroded, the middle metal layer will be exposed to the corrosive medium, resulting in material failure.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, and to provide a preparation method of a composite metal coating foamed metal material with strong corrosion resistance and good oxidation resistance. In order to solve the above-mentioned technical problems, the technical scheme proposed by the present invention is:

A preparation method of a composite metal coating foam metal material, comprising the following steps:

(1) Degreasing, acidifying, sensitizing and activating polyurethane foam to obtain modified polyurethane foam; the best degreasing effect can be achieved by adjusting the soaking time, concentration and temperature; The formation of the composite coating provides more nucleation sites, which is beneficial to the formation of the composite coating; acidification, sensitization and activation treatments can provide pretreatment for the surface chemical plating of the composite metal coating, which is conducive to easier plating on the surface. Composite metal coating;

(2) by stirring nickel sulfate, nickel chloride and reducing agent to obtain electroless plating solution A; by stirring nickel sulfate, ferrous sulfate, sodium citrate, boric acid and sodium lauryl sulfate to obtain electroplating solution; by stirring nickel sulfate , tin tetrachloride, sodium citrate, chromium chloride, lactic acid, sodium hypophosphite and reducing agent are stirred to obtain electroless plating solution B;

(3) Immerse the modified polyurethane foam in the electroless plating solution A for electroless plating, and keep stirring to ensure the uniformity of the thickness and composition of the plating layer. Physical extrusion to remove excess water, drying (24h at 80°C) to obtain nickel-plated foam;

(4) Immerse the nickel-plated foam material into the electroplating solution for electroplating to thicken the thickness of the coating layer, and continue to stir. After the reaction is completed, take out the product, repeatedly wash it with deionized water until it is neutral, and then dry (dry at 80 °C for 24h) to obtain Nickel-iron foam metal material;

(5) heat-treating the nickel-iron foam metal material under air atmosphere to obtain the nickel-iron foam metal material for removing the polyurethane foam, and simultaneously realize hardening;

(6) In a reducing atmosphere, heating and reducing the nickel-iron foamed metal material of the polyurethane foam, that is, a metal foamed metal material with a dense metal coating is obtained; The alloying elements in the middle coating layer will diffuse to each other, making the coating layer more dense, so as to obtain a dense foam metal material with a metal coating layer with better performance;

(7) Immerse the foamed metal material with dense metal coating into the electroless plating solution B for electroless plating, and continue to stir. After the reaction is completed, take out the product, repeatedly wash it with deionized water until it is neutral, and then dry it (80°C for 24h) A composite metal-coated foam metal material is obtained.

In the above preparation method, preferably, the purity of the polyurethane foam is 99.9%, and the porosity is 85-90%. The above-mentioned porosity and purity have a great influence on the performance of the generated composite metal-coated foam metal material, and the above-mentioned porosity and purity can ensure the comprehensive performance of the composite metal-coated foam metal material.

In the above preparation method, preferably, in the chemical plating solution A, the concentration of nickel sulfate is 10-60g/L, the concentration of nickel chloride is 20-50g/L, and the concentration of reducing agent is 20-80g/L; In the electroplating solution, the concentration of nickel sulfate is 10-30g/L, the concentration of ferrous sulfate is 10-60g/L, the concentration of sodium citrate is 10-50g/L, and the concentration of boric acid is 30-70g/L , the concentration of sodium lauryl sulfate is 0.1-0.6g/L; in the electroless plating solution B, the concentration of nickel sulfate is 10-60g/L, the concentration of tin tetrachloride is 20-50g/L, and the concentration of tin tetrachloride is 20-50g/L. The concentration of sodium is 20-50g/L, the concentration of chromium chloride is 5-50g/L, the concentration of lactic acid is 10-40g/L, the concentration of sodium hypophosphite is 5-20g/L, and the concentration of reducing agent is 10-80g/L. Our research shows that the proportional relationship of each element in the coating has a great influence on the performance of the coating. Through chemical plating and electroplating, the ratio between the elements can be adjusted to obtain a coating with better comprehensive performance.

In the above preparation method, preferably, the reducing agent is hydrazine hydrate, formaldehyde, potassium sodium tartrate, hydrazine sulfate, ethylenediamine, glyoxal, sodium borohydride, acetal, triethanolamine, glycerol, tannic acid or at least one of Mitol.

In the above preparation method, preferably, the reducing agent is obtained by mixing tannic acid and metol in a mass ratio of 1:5. Our research shows that using the above-mentioned reducing agent composition, the reducing agents cooperate with each other and have good compatibility with the electroless plating system of the present invention, which can ensure better comprehensiveness of the coating and better corrosion resistance. Especially in the electroless plating solution B, the synergistic effect of tannic acid, metol and sodium hypophosphite is used, and the effect is better. More preferably, the mass ratio of tannic acid, metol and sodium hypophosphite is 1:5:10.

In the above preparation method, preferably, in the step (3), during electroless plating, a water bath is used to heat to 50-70° C., and the pH value is controlled between 3.0-5.0; in the step (7), during the electroless plating, the The water bath was heated to 60-90°C, and the pH value (adjusted with sodium hydroxide solution and dilute sulfuric acid) was controlled between 3.5-5.5.

In the above preparation method, preferably, during electroplating in the step (4), the pH value of the electroplating process is controlled to be 3.0-5.0, the temperature is 50-70°C, and the current density is 1-5A/dm ² .

In the above preparation method, preferably, during the heat treatment in the step (5), the calcination temperature is controlled to be 200-500°C, and the time is 0.5-3.5h.

In the above preparation method, preferably, in the step (6), the reduction reaction is carried out in an atmosphere containing hydrogen during the heating reduction treatment, the reduction temperature is controlled to be 600-800° C., and the reduction time is 1-4 h. The above reduction temperature is beneficial to the diffusion between the elements in the coating, so that the coating becomes more dense. If the temperature is too high or too low, it is difficult to ensure the density.

In the above preparation method, preferably, the degreasing treatment is to put the polyurethane foam into an alkaline solution (potassium hydroxide solution) of 20-150g/L, then heat it to 70-90°C for 15-45min, and then use Deionized water is washed to neutrality; the acidification is to use 1-5g/L oxalic acid solution for pickling; the sensitization treatment is to add the acidified polyurethane foam to the sensitization solution for ultrasonic treatment, and then deionized Diluted with water and washed until neutral, and dried at 70-90°C for 12-24 hours; the sensitizing solution is a mixed solution of stannous chloride and hydrochloric acid; the activation treatment is to add activated polyurethane foam after sensitization treatment The solution is ultrasonically treated for 30-120min, then diluted with deionized water and washed until neutral, and dried to obtain modified polyurethane foam; the activation solution is a 10-200mg/mL _PdCl2 solution.

In the present invention, polyurethane is used as a raw material, nickel-iron and the like are simultaneously plated on the surface of the polyurethane foam by means of electroplating and chemical plating, and then the polyurethane foam whose surface is plated with a composite metal coating is heat-treated, and the polyurethane foam is removed to finally prepare the nickel-iron foam. metallic material. In the invention, the surface of the polyurethane foam is plated with a metal coating layer containing nickel, iron and the like, wherein the thickness of the coating layer and the proportion of the element content in the coating layer are controllable; Metal foam is conducive to its application in aero-engine oil and gas filters, lightweight rail transit, catalysts and catalyst carriers; and the overall process is simple, the device is simple, the operation is convenient, energy saving and environmental protection, and mass production can be achieved. The invention adopts the combination of chemical plating and electroplating, and the prepared composite metal coating foam metal material has bright and dense coating, controllable metal content and coating thickness, has certain strength, large specific surface area, good oxidation resistance and corrosion resistance .

Compared with the prior art, the advantages of the present invention are:

1. The present invention adopts a one-step reduction method to directly carry out electroplating and chemical plating on the surface of the polyurethane sponge after roughening, pickling, sensitization and activation treatment. The process steps are simple, easy to operate, and easy to maintain.

2. The electroplating and electroless plating solution of the present invention has few chemical materials and low cost, realizes the continuous autocatalytic deposition of nickel and iron on the polyurethane sponge substrate, the deposition speed is fast, and the bright composite coatings of different thicknesses can be obtained, and the plating solution is suitable for Environmental pollution is less.

3. The present invention further adds chemical elements such as phosphorus and tin in the process of chemical plating, which can further improve the corrosion resistance of the coating; and in the process of heat treatment, some metal oxides will also be formed in the coating, which will also improve the resistance of the coating. Corrosive properties.

4. The composite metal coating foam metal material obtained by the present invention has the advantages of certain hardness and strength, light weight, large specific surface area, high through porosity, strong oxidation resistance and corrosion resistance, and the like.

5. The experimental procedure of the preparation method of the present invention is simple, safe and reliable, the equipment is simple, and it is easy to realize continuous preparation.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of the process flow of the preparation method of the composite metal coating foamed metal material of the present invention.

FIG. 2 is a SEM image of the composite metal-coated foam metal material in Example 3. FIG.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1:

As shown in Figure 1, a preparation method of a composite metal coating foam metal material, comprising the following steps:

(1) Degreasing, acidifying, sensitizing and activating the polyurethane foam (15cm×10cm×1cm) to obtain the modified polyurethane foam; wherein, the degreasing treatment is to remove the polyurethane foam with a potassium hydroxide solution with a concentration of 50g/L The oil stain, the degreasing time is 20min, and the temperature is 70℃. Acidizing treatment is to treat the degreasing polyurethane foam in 1g/L oxalic acid solution for 20min, and then wash it with deionized water to neutrality to obtain the acid-washed polyurethane foam; sensitization treatment is to treat the acid-washed polyurethane foam. Treated in a mixed solution of 5g/L of stannous chloride and 5ml/L of hydrochloric acid for 15min, and then washed with deionized water until neutral to obtain sensitized polyurethane foam; The resulting polyurethane foam was treated in a 10 mg/mL palladium chloride solution for 120 min, and then washed with deionized water until neutral to obtain a modified polyurethane foam;

(2) the concentration is nickel sulfate 10g/L, nickel chloride 20g/L and sodium hypophosphite 40g/L obtain electroless plating solution A by magnetic stirring; The concentration is nickel sulfate 10g/L, ferrous sulfate 10g/L, Sodium citrate 10g/L, boric acid 30g/L and sodium lauryl sulfate 0.1g/L were magnetically stirred to obtain electroplating solution; nickel sulfate 10g/L, crystalline tin tetrachloride 20g/L, sodium citrate 20g/L L, the mixed solution of lactic acid 10g/L, chromium chloride 5g/L, sodium hypophosphite 5g/L and sodium borohydride 10g/L, through magnetic stirring to obtain electroless plating solution B;

(3) The modified polyurethane foam is immersed in the electroless plating solution A to carry out the electroless plating process, and the uniformity of the plating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the thickness and composition of the coating layer; the pH value of the electroless plating process is 3.0 , the temperature is 50°C, and the reaction time is 4h; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-plated foam material is obtained after removing excess water by physical extrusion and drying;

(4) The nickel-iron foam material is immersed in the electroplating solution to carry out the electroplating process, and the uniformity of the electroplating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the coating thickness and composition; the pH value of the electroplating process is 3.0, and the temperature is 50 ℃, the current density is 1A/dm ² ; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-iron foam metal material is obtained after drying and heat treatment;

(5) calcining the nickel-iron foamed metal material in an air atmosphere, the calcination temperature is 200 °C, and the heating time is 2 h, to obtain the nickel-iron foamed metal material for removing the polyurethane foam; the reduction treatment is carried out in a hydrogen atmosphere, and the processing temperature is 600 ℃, the heating time is 2h, and the foamed metal material with dense metal coating is obtained;

(6) Put the dense metal-plated foam metal material and the electroless plating solution B in a beaker. During the reaction process, use a water bath to heat to 60° C. for 40 hours of plating. During the plating process, keep the pH at 3.5. After the reaction, the obtained foam The metal material is repeatedly washed in deionized water until neutral, and dried to obtain a composite metal-coated foam metal material.

The composite metal-coated foam metal material obtained in the above-mentioned Example 1 has a three-dimensional network structure as a whole, the appearance is gray-white and semi-bright, the specific surface area is high, the holes are connected to each other, the coating structure is dense, and the porosity is 85-90%. , The product has a certain hardness, good oxidation resistance and corrosion resistance.

Example 2:

A preparation method of a composite metal coating foam metal material, comprising the following steps:

(1) Degreasing, acidifying, sensitizing and activating the polyurethane foam (15cm×10cm×1cm) to obtain the modified polyurethane foam; wherein, the degreasing treatment is to remove the polyurethane foam with a potassium hydroxide solution with a concentration of 100g/L The oil stain, the degreasing time is 10min, and the temperature is 70℃. The acidification treatment is to treat the degreasing polyurethane foam in a 3g/L oxalic acid solution for 20min, and then wash it with deionized water to neutrality to obtain the acid-washed polyurethane foam; the sensitization treatment is to treat the acid-washed polyurethane foam. Treated in a mixed solution of 8g/L of stannous chloride and 10ml/L of hydrochloric acid for 10min, and then washed with deionized water until neutral to obtain sensitized polyurethane foam; The resulting polyurethane foam was treated in a 100 mg/mL palladium chloride solution for 120 min, and then washed with deionized water until neutral to obtain a modified polyurethane foam;

(2) the concentration is nickel sulfate 20g/L, nickel chloride 30g/L and reducing agent formaldehyde 20g/L obtain electroless plating solution A by magnetic stirring; The concentration is nickel sulfate 20g/L, ferrous sulfate 40g/L, Sodium citrate 30g/L, boric acid 50g/L and sodium lauryl sulfate 0.3g/L were magnetically stirred to obtain an electroplating solution; nickel sulfate 30g/L, crystalline tin tetrachloride 45g/L, sodium citrate 30g/L L, the mixed solution of lactic acid 30g/L, chromium chloride 20g/L, sodium hypophosphite 15g/L and sodium borohydride 20g/L, through magnetic stirring to obtain electroless plating solution B;

(3) The modified polyurethane foam is immersed in the electroless plating solution A to carry out the electroless plating process, and the uniformity of the plating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the thickness and composition of the coating layer; the pH value of the electroless plating process is 4.0 , the temperature is 60°C, and the reaction time is 4h; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-plated foam material is obtained after removing excess water by physical extrusion and drying;

(4) The nickel-iron foam material is immersed in the electroplating solution to carry out the electroplating process, and the uniformity of the electroplating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the coating thickness and composition; the pH value of the electroplating process is 4.0, and the temperature is 60 ℃, the current density is 3A/dm ² ; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-iron foam metal material is obtained after drying and heat treatment;

(5) The nickel-iron foam metal material was calcined in an air atmosphere, the calcination temperature was 300 °C, and the heating time was 1.5 h to obtain the nickel-iron foam metal material with the polyurethane foam removed; the reduction treatment was carried out in a hydrogen atmosphere, and the processing temperature was 650 ℃, heating time is 2.5h, and the metal foamed metal material with dense metal coating is obtained;

(6) Put the dense metal-plated foam metal material and the electroless plating solution B in a beaker. During the reaction process, use a water bath to heat to 75° C. for 60 hours of plating. During the plating process, keep the pH at 4.5. After the reaction, the foam is obtained. The metal material is repeatedly washed in deionized water until neutral, and dried to obtain a composite metal-coated foam metal material.

The composite metal-coated foam metal material obtained in the above-mentioned Example 2 has a three-dimensional network structure as a whole, the appearance is gray-white and semi-bright, the specific surface area is high, the holes are connected to each other, the coating structure is dense, and the porosity is 85-90%. , The product has a certain hardness, good oxidation resistance and corrosion resistance.

Example 3:

A preparation method of a composite metal coating foam metal material, comprising the following steps:

(1) Degreasing, acidifying, sensitizing and activating the polyurethane foam (15cm×10cm×1cm) to obtain the modified polyurethane foam; wherein, the degreasing treatment is to remove the polyurethane foam with a potassium hydroxide solution with a concentration of 120g/L The oil stain, the degreasing time is 5min, and the temperature is 75℃. The acidification treatment is to treat the degreasing polyurethane foam in a 5g/L oxalic acid solution for 10 minutes, and then wash it with deionized water to neutrality to obtain the acid-washed polyurethane foam; the sensitization treatment is to treat the acid-washed polyurethane foam. Treated in a mixed solution of 10g/L of stannous chloride and 10ml/L of hydrochloric acid for 10min, and then washed with deionized water until neutral to obtain sensitized polyurethane foam; The resulting polyurethane foam was treated in a 200 mg/mL palladium chloride solution for 120 min, and then washed with deionized water until neutral to obtain a modified polyurethane foam;

(2) the concentration is nickel sulfate 60g/L, nickel chloride 50g/L and potassium sodium tartrate 30g/L obtain electroless plating solution A by magnetic stirring; The concentration is nickel sulfate 30g/L, ferrous sulfate 60g/L, Sodium citrate 50g/L, boric acid 70g/L and sodium lauryl sulfate 0.6g/L were magnetically stirred to obtain electroplating solution; nickel sulfate 60g/L, crystalline tin tetrachloride 50g/L, sodium citrate 50g/L L, the mixed solution of lactic acid 40g/L, chromium chloride 40g/L, sodium hypophosphite 20g/L and potassium sodium tartrate 30g/L, and electroless plating solution B was obtained by magnetic stirring;

(3) The modified polyurethane foam is immersed in the electroless plating solution A to carry out the electroless plating process, and the uniformity of the plating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the thickness and composition of the coating layer; the pH value of the electroless plating process is 5.0 , the temperature is 70°C, and the reaction time is 4h; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-plated foam material is obtained after removing excess water by physical extrusion and drying;

(4) The nickel-iron foam material is immersed in the electroplating solution to carry out the electroplating process, and the uniformity of the electroplating solution is ensured by mechanical stirring, thereby ensuring the uniformity of the coating thickness and composition; the pH value of the electroplating process is 5.0, and the temperature is 70 ℃, the current density is 5A/dm ² ; after the reaction, the obtained product is repeatedly washed in deionized water until neutral, and the nickel-iron foam metal material is obtained after drying and heat treatment;

(5) calcining the nickel-iron foamed metal material in an air atmosphere, the calcination temperature is 500 °C, and the heating time is 1 h, to obtain the nickel-iron foamed metal material with the polyurethane foam removed; the reduction treatment is carried out in a hydrogen atmosphere, and the processing temperature is 750 ℃, the heating time is 3.5h, and the foamed metal material with dense metal coating is obtained;

(6) Put the dense metal-plated foam metal material and the electroless plating solution B in a beaker. During the reaction process, use a water bath to heat to 90° C. for 60 hours of plating. During the plating process, keep the pH at 5.5. After the reaction, the obtained foam The metal material is repeatedly washed in deionized water until neutral, and dried to obtain a composite metal-coated foam metal material.

As shown in Figure 2, the composite metal-coated foam metal material obtained in the above-mentioned Example 3 has a three-dimensional network structure as a whole, the appearance is gray-white and semi-bright, the specific surface area is high, the holes are connected to each other, the coating structure is dense, and the through holes The rate is 85-90%, the product has a certain hardness, good oxidation resistance and corrosion resistance.

Example 4:

A preparation method of a composite metal coating foam metal material is the same as that of Example 3, except that the reducing agents in the chemical plating solution B are tannic acid and metol, and the mass ratio of tannic acid, metol and sodium hypophosphite is 1:5:10.

Claims (10)

1. a preparation method of composite metal coating foam metal material, is characterized in that, comprises the following steps: (1) degreasing, acidifying, sensitizing and activating polyurethane foam to obtain modified polyurethane foam; (2) by stirring nickel sulfate, nickel chloride and reducing agent to obtain electroless plating solution A; by stirring nickel sulfate, ferrous sulfate, sodium citrate, boric acid and sodium lauryl sulfate to obtain electroplating solution; by stirring nickel sulfate , tin tetrachloride, sodium citrate, chromium chloride, lactic acid, sodium hypophosphite and reducing agent are stirred to obtain electroless plating solution B; (3) immersing the modified polyurethane foam in the electroless plating solution A to carry out electroless plating, and stirring continuously, after the reaction is finished, the product is taken out, and the nickel-plated foam material is obtained by drying after repeated washing; (4) immersing the nickel-plated foam material in the electroplating solution for electroplating, and stirring continuously, after the reaction finishes, taking out the product, and drying after repeated washing to obtain the nickel-iron foam metal material; (5) the nickel-iron foamed metal material is heat-treated to obtain the nickel-iron foamed metal material of the polyurethane foam; (6) under reducing atmosphere, heat reduction treatment to remove the nickel-iron foam metal material of polyurethane foam, namely obtain the metal foam material with dense metal coating; (7) Immerse the dense foam metal material of the metal coating into the electroless plating solution B for electroless plating, and continue to stir, after the reaction is completed, take out the product, wash and dry repeatedly to obtain the composite metal coating foam metal material. 2 . The preparation method according to claim 1 , wherein the polyurethane foam has a purity of 99.9% and a porosity of 85-90%. 3 . 3. preparation method according to claim 1, is characterized in that, in described electroless plating solution A, the concentration of nickel sulfate is 10-60g/L, the concentration of nickel chloride is 20-50g/L, the concentration of reducing agent is 20-50g/L. The concentration is 20-80g/L; in the electroplating solution, the concentration of nickel sulfate is 10-30g/L, the concentration of ferrous sulfate is 10-60g/L, the concentration of sodium citrate is 10-50g/L, the concentration of boric acid The concentration of nickel sulfate is 30-70g/L, the concentration of sodium lauryl sulfate is 0.1-0.6g/L; in the electroless plating solution B, the concentration of nickel sulfate is 10-60g/L, and the concentration of tin tetrachloride is 10-60g/L. It is 20-50g/L, the concentration of sodium citrate is 20-50g/L, the concentration of chromium chloride is 5-50g/L, the concentration of lactic acid is 10-40g/L, the concentration of sodium hypophosphite is 5-20g /L, the concentration of reducing agent is 10-80g/L. 4. preparation method according to claim 1 is characterized in that, described reducing agent is hydrazine hydrate, formaldehyde, potassium sodium tartrate, hydrazine sulfate, ethylenediamine, glyoxal, sodium borohydride, acetal, tris At least one of ethanolamine, glycerol, tannic acid or metol. 5. preparation method according to claim 4 is characterized in that, described reducing agent is that tannic acid and metol are mixed in mass ratio of 1:5. 6. The preparation method according to any one of claims 1-5, characterized in that, in the step (3), during electroless plating, a water bath is used to heat to 50-70°C, and the pH value is controlled between 3.0-5.0 In the step (7), during electroless plating, a water bath is used to heat to 60-90° C., and the pH value is controlled between 3.5-5.5. 7. The preparation method according to any one of claims 1-5, characterized in that, during electroplating in the step (4), the pH value of the control electroplating process is 3.0-5.0, and the temperature is 50-70 ℃, The current density was 1-5 A/dm ² . 8 . The preparation method according to claim 1 , wherein, during the heat treatment in the step (5), the calcination temperature is controlled to be 200-500° C. and the time is 0.5-3.5 h. 9 . 9. preparation method according to any one of claim 1-5, is characterized in that, in described step (6), during heating reduction treatment, carry out reduction reaction under the atmosphere containing hydrogen, control reduction temperature to be 600- 800 ℃, the reduction time is 1-4h. 10. The preparation method according to any one of claims 1-5, wherein the degreasing treatment is to put the polyurethane foam into the alkaline solution of 20-150g/L, and then heat to 70-90 ℃ treatment for 15-45min, and then washed with deionized water until neutral; the acidification is to use 1-5g/L oxalic acid solution for pickling; the sensitization treatment is to add the acidified polyurethane foam to the sensitization solution Medium ultrasonic treatment, then diluted with deionized water and washed to neutrality, and dried at 70-90 ° C for 12-24 hours; the sensitizing solution is a mixed solution of stannous chloride and hydrochloric acid; the activation treatment is to sensitize The treated polyurethane foam is added to the activation solution for ultrasonic treatment for 30-120min, then diluted with deionized water and washed to neutrality, and dried to obtain modified polyurethane foam; the activation solution is a 10-200mg/mL PdCl ₂ solution .

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