阅读说明：本技术 一种汽车铸件的表面处理方法 (Surface treatment method for automobile casting ) 是由 魏端华 黄建民 陈涛 敖三林 于 2021-09-01 设计创作，主要内容包括：本发明涉及金属表面处理技术领域,提供了一种汽车铸件的表面处理方法,包括以下步骤：S1、去除汽车铸件表面附着的污垢；S2、将汽车铸件置于表面活性剂溶液中超声处理；S3、将经超声处理后的汽车铸件使用表面处理剂进行处理,所述表面处理剂包括磷酸、咪唑类离子液体、甲叉型膦酸盐、有机酸盐、乙醇或异丙醇、水；S4、对表面处理后的汽车铸件进行清洗,干燥。表面处理剂中的各成分协同作用,提高了表面处理效果；本发明省去了脱脂、除锈工序,可以直接采用表面处理剂处理,大大简化了铸件的表面处理工艺,处理时间短,铸件外观良好,表面质量高,性能优良。(The invention relates to the technical field of metal surface treatment, and provides a surface treatment method of an automobile casting, which comprises the following steps: s1, removing dirt attached to the surface of the automobile casting; s2, placing the automobile casting in a surfactant solution for ultrasonic treatment; s3, treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent, wherein the surface treating agent comprises phosphoric acid, imidazole ionic liquid, methylene phosphonate, organic acid salt, ethanol or isopropanol and water; and S4, cleaning and drying the surface-treated automobile casting. The components in the surface treating agent have synergistic effect, so that the surface treating effect is improved; the invention omits the degreasing and derusting processes, can directly adopt the surface treatment agent for treatment, greatly simplifies the surface treatment process of the casting, and has the advantages of short treatment time, good appearance of the casting, high surface quality and excellent performance.)

1. A surface treatment method of an automobile casting is characterized by comprising the following steps:

s1, removing dirt attached to the surface of the automobile casting;

s2, placing the automobile casting in a surfactant solution for ultrasonic treatment;

s3, treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent, wherein the surface treating agent comprises phosphoric acid, imidazole ionic liquid, methylene phosphonate, organic acid salt, ethanol or isopropanol and water;

and S4, cleaning and drying the surface-treated automobile casting.

2. The method as claimed in claim 1, wherein the surfactant in the surfactant solution in step S2 comprises one or more of sodium fatty alcohol-polyoxyethylene ether sulfate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium α -alkenyl sulfonate, dodecyl dimethyl betaine, cetyl dimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, cationic guar gum, alkylolamide, fatty alcohol-polyoxyethylene ether, and alkylphenol ethoxylate, and the solvent comprises ethanol and/or isopropanol.

3. The surface treatment method for the automobile casting according to claim 1, wherein the ultrasonic treatment in the step S2 is performed at a power of 200-300W for 15-45 min.

4. The method of claim 1, wherein the organic acid salt in step S3 includes one or more of sodium citrate, sodium gluconate, sodium tartrate, sodium salicylate, sodium benzoate, sodium succinate, sodium lactate, sodium acetate, and sodium oxalate.

5. According to claim 1The surface treatment method of the automobile casting is characterized in that in the step S3, the imidazole ionic liquid comprises [ Omim]PF₆、[Omim]BF₄、[Omim]HSO₄、[Omim]H₂PO₄、[Omim]TFSI、[Omim]Tf₂N、[Omim]CF₃SO₃、[Hmim]PF₆、[Hmim]BF₄、[Hmim]HSO₄、[Hmim]H₂PO₄、[Hmim]TFSI、[Hmim]Tf₂N、[Hmim]CF₃SO₃、[Bmim]PF₆、[Bmim]BF₄、[Bmim]HSO₄、[Bmim]H₂PO₄、[Bmim]TFSI、[Bmim]Tf₂N、[Bmim]CF₃SO₃One or more of (a).

6. The method of claim 1, wherein the methylene phosphonate at step S3 comprises one or more of sodium aminotrimethylene phosphonate, sodium ethylene diamine tetramethylene phosphonate, sodium diethylenetriamine pentamethylene phosphonate, sodium triethylene tetramine hexamethomethylene phosphonate, sodium imidazoline dimethylene phosphonate, sodium piperazine dimethylene phosphonate, sodium aminoethyl piperazine trimethylene phosphonate, sodium glycine dimethylene phosphonate, sodium hydroxymethyl glycine dimethylene phosphonate, sodium glutamate dimethylene phosphonate, sodium formamido monomethylene phosphonate, sodium acetamido monomethylene phosphonate, or sodium ureidotetramethylene phosphonate.

7. The surface treatment method for the automobile casting according to claim 1, wherein the surface treatment agent in the step S3 comprises, by weight, 5-25 parts of phosphoric acid, 2-10 parts of imidazole ionic liquid, 2-10 parts of methylene phosphonate, 0.1-5 parts of organic acid salt, 20-80 parts of ethanol or isopropanol, and 10-50 parts of water.

8. The method for surface treatment of automobile castings according to claim 1, wherein said treatment with a surface treatment agent in step S3 specifically comprises spraying and/or dipping.

9. The surface treatment method for automobile castings according to claim 1, characterized by further comprising step S5: and (3) carrying out electrostatic coating treatment on the dried automobile casting, spraying a PPS coating on the surface of the automobile casting, and then baking at 300-400 ℃.

10. The surface treatment method for the automobile casting according to claim 9, wherein the thickness of the PPS coating is 50-100 μm.

Technical Field

The invention relates to the technical field of metal surface treatment, in particular to a surface treatment method of an automobile casting.

Background

An automobile accessory is a product that constitutes each unit of an automobile as a whole and serves the automobile. The automobile parts are various in types, people consume more and more automobiles along with the improvement of living standard of people, and the market of the automobile parts is getting larger and larger. Automobile parts manufacturers have also developed rapidly in recent years. Most of the automobile parts are metal alloy castings which have the characteristics of light weight, good mechanical strength, good electric and thermal conductivity, good die-casting property and the like.

The surface treatment of the automobile casting mainly aims at improving the corrosion resistance of the automobile casting, and also can improve the heat conduction, wear resistance or optical performance and the like of the automobile casting. However, the conventional surface treatment process comprises the following steps: polishing → degreasing → washing → derusting → washing → phosphating → washing → drying, which is not only complicated in process, but also is more likely to cause environmental pollution due to the difficulty in treating a large amount of solution, because a large amount of solution etching is often adopted in the degreasing and derusting process, the treatment cost is high, and the efficiency is low. The traditional treatment process has poor effect, and the painted surface is unstable, easy to peel and has color change after being painted, so that the surface treatment quality of the automobile casting is low, and the production is not facilitated.

Disclosure of Invention

The invention aims to overcome at least one of the defects of the prior art and provide a surface treatment method of an automobile casting with good effect and high efficiency. The purpose of the invention is realized based on the following technical scheme:

a surface treatment method of an automobile casting comprises the following steps:

s1, removing dirt attached to the surface of the automobile casting;

s2, placing the automobile casting in a surfactant solution for ultrasonic treatment;

s3, treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent, wherein the surface treating agent comprises phosphoric acid, imidazole ionic liquid, methylene phosphonate, organic acid salt, ethanol or isopropanol and water;

and S4, cleaning and drying the surface-treated automobile casting.

According to the invention, firstly, the surface active agent and the ultrasonic treatment provide good wettability for metal, the surface of the automobile casting is treated, and more active sites are provided for the surface active agent. The phosphoric acid in the surface treating agent has certain solubility to metal materials, so that certain derusting requirements are met, and the phosphoric acid can form a phosphate coating on the treated surface to provide an anti-corrosion effect. The heteroatom such as N, O contained in the imidazole ionic liquid is coordinated with metal to form a stable conjugated complex, and an adsorption film is formed on the surface of the metal to prevent the metal from being corroded. Although the imidazole corrosion inhibitor is widely applied, the corrosion inhibition performance of the imidazole corrosion inhibitor is not high generally, and the imidazole corrosion inhibitor serving as an organic corrosion inhibitor has the defects common to common organic corrosion inhibitors. The imidazole ionic liquid is a novel material different from general imidazole organic matters, has the characteristics of no toxicity, no pollution, good stability, almost zero vapor pressure, no flammability, no explosion and the like, can improve the corrosion inhibition efficiency of the imidazole corrosion inhibitor, and simultaneously meets the requirements of environmental protection, thereby being very suitable for corrosion protection of metals. The heteroatom such as N, O, P contained in the nitrogen atom and the phosphonic acid group of the methylene phosphonate is coordinated with the metal to form a stable conjugated complex, thereby playing a good corrosion inhibition role; when they act with metals, they form an adsorption layer on the surface of the metal, which can prevent the invasion of acidic substances. The organic acid salt has a chelating effect on metal and ions thereof, and has an effect of inhibiting metal corrosion by forming an adsorption layer on the surface of the metal. The ethanol or isopropanol is used as the solvent of the surface treating agent, so that the solubility of the surface treating agent and the stability of the surface treating agent can be improved, the rust removal and corrosion prevention effects are kept, the surface grease is favorably removed, better conditions are provided for the formation of a phosphating film and an adsorption film through the volatilization of alcohol substances, the drying speed of the surface of a treated metal casting can be accelerated, and the treatment time is shortened. The components in the surface treating agent have synergistic effect, so that the surface treating effect is improved; the invention omits the degreasing and derusting processes, can directly adopt the surface treatment agent for treatment, greatly simplifies the surface treatment process of the casting, has short treatment time, good appearance of the casting and good binding force between the surface film layer and the coating, and is beneficial to the subsequent treatment of the surface of the casting.

Preferably, the surfactant in the surfactant solution in step S2 includes one or more of sodium fatty alcohol polyoxyethylene ether sulfate (AES), sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium alpha-olefin sulfonate, dodecyl dimethyl betaine, hexadecyl dimethyl ammonium chloride (1631), octadecyl trimethyl ammonium chloride (1831), cationic guar gum, alkyl alcohol amide (FFA), fatty alcohol polyoxyethylene ether (AEO), and Alkylphenol Polyoxyethylene Ether (APEO), and the solvent includes ethanol and/or isopropanol.

Preferably, the ultrasonic treatment in the step S2 is performed under the condition of power of 200-300W and time of 15-45 min.

Preferably, in step S3, the organic acid salt includes one or more of sodium citrate, sodium gluconate, sodium tartrate, sodium salicylate, sodium benzoate, sodium succinate, sodium lactate, sodium acetate, and sodium oxalate.

Preferably, the imidazole-based ionic liquid in step S3 comprises [ Omim]PF₆、[Omim]BF₄、[Omim]HSO₄、[Omim]H₂PO₄、[Omim]TFSI、[Omim]Tf₂N、[Omim]CF₃SO₃、[Hmim]PF₆、[Hmim]BF₄、[Hmim]HSO₄、[Hmim]H₂PO₄、[Hmim]TFSI、[Hmim]Tf₂N、[Hmim]CF₃SO₃、[Bmim]PF₆、[Bmim]BF₄、[Bmim]HSO₄、[Bmim]H₂PO₄、[Bmim]TFSI、[Bmim]Tf₂N、[Bmim]CF₃SO₃One or more of (a). The adsorption process is a spontaneous exothermic process, and the corrosion inhibition efficiency is increased along with the increase of the length of the alkyl carbon chain connected with the N (3) atoms on the imidazole ring, so that the alkyl carbon chain selected by the invention has longer length.

Preferably, the methylene phosphonate in step S3 includes one or more of sodium aminotrimethylenephosphonate, sodium ethylenediamine tetramethylenephosphonate, sodium diethylenetriamine pentamethylenephosphonate, sodium triethylenetetramine hexamethomethylenephosphonate, sodium imidazoline dimethylmethylenephosphonate, sodium piperazine dimethylmethylenephosphonate, sodium aminoethyl piperazine trimethylmethylenephosphonate, sodium glycine dimethylmethylenephosphonate, sodium hydroxymethylglycine dimethylmethylenephosphonate, sodium glutamate dimethylmethylenephosphonate, sodium carboxamidomethylmethylenephosphonate, sodium acetylamino monomethylphosphinate, or sodium ureidotetramethylmethylenephosphonate.

Preferably, the surface treatment agent in the step S3 includes, by weight, 5 to 25 parts of phosphoric acid, 2 to 10 parts of imidazole ionic liquid, 2 to 10 parts of methylene phosphonate, 0.1 to 5 parts of organic acid salt, 20 to 80 parts of ethanol or isopropanol, and 10 to 50 parts of water.

Preferably, the treatment with the surface treatment agent in step S3 specifically includes spraying and/or dipping. The invention can directly adopt the spraying or soaking process for treatment, thus greatly simplifying the surface treatment process of the casting.

Preferably further comprises step S5: and (3) carrying out electrostatic coating treatment on the dried automobile casting to further improve the surface corrosion resistance of the casting, namely spraying a PPS coating on the surface of the automobile casting, and then baking at 300-400 ℃.

Preferably, the thickness of the PPS coating is 50-100 μm.

The invention can obtain at least one of the following beneficial effects:

according to the invention, firstly, a better wetting property is provided for metal through a surfactant and ultrasonic treatment, the surface of the automobile casting is treated, and more active sites are provided for the surfactant; then rust removal is carried out through phosphoric acid in the surfactant, a phosphate coating is formed on the surface, imidazole ionic liquid, methylene type phosphonate and organic acid salt respectively act on the metal surface with the casting to form different adsorption films so as to prevent the casting from being corroded, ethanol or isopropanol is used as a solvent to keep the rust removal and corrosion prevention effects, better conditions are provided for forming the phosphate coating and each adsorption film, and the drying speed of the casting can be accelerated. The components in the surface treating agent have synergistic effect, so that the surface treating effect is improved; the invention omits the degreasing and derusting processes, can directly adopt the surface treatment agent for treatment, greatly simplifies the surface treatment process of the casting, has short treatment time, good appearance of the casting and good binding force between the surface film layer and the coating, and is beneficial to the subsequent treatment of the surface of the casting. The automobile casting surface treated by the method can be stored for more than 420h, and has high surface quality and excellent performance. The reagent used by the method is more environment-friendly and can be repeatedly used, so that the environmental pollution is greatly reduced.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The chemicals and equipment used in the following examples are commercially available.

Example 1

A surface treatment method of an automobile casting comprises the following steps:

s1, spraying high-pressure water to the surface of the automobile casting to remove dirt attached to the surface of the automobile casting;

s2, placing the automobile casting into a surfactant solution with the concentration of 10 wt% for ultrasonic treatment, wherein the surfactant is fatty alcohol-polyoxyethylene ether sodium sulfate, and the solvent is ethanol; the power of ultrasonic treatment is 200W, and the time is 45 min;

s3, directly treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent through a spraying process, wherein the surface treating agent comprises 25 parts by weight of phosphoric acid and [ Omim [ ] according to parts by weight]PF₆2 parts of ionic liquid, 2 parts of sodium amino trimethylene phosphonate, 0.1 part of sodium citrate, 80 parts of ethanol and 10 parts of water;

s4, cleaning the automobile casting with ethanol after surface treatment, and then airing;

s5, performing electrostatic coating treatment on the dried automobile casting, spraying a PPS coating with the thickness of 50 mu m on the surface of the automobile casting, and then baking at 300 ℃.

Example 2

A surface treatment method of an automobile casting comprises the following steps:

s1, spraying high-pressure water to the surface of the automobile casting to remove dirt attached to the surface of the automobile casting;

s2, placing the automobile casting into a surfactant solution with the concentration of 15 wt% for ultrasonic treatment, wherein the surfactant comprises sodium dodecyl sulfate and sodium dodecyl benzene sulfonate (the mass ratio is 2: 1), and the solvent is isopropanol; the ultrasonic treatment condition is that the power is 300W, and the time is 15 min;

s3, directly processing the automobile casting subjected to ultrasonic treatment by using a surface treatment agent through a soaking process, wherein the surface treatment agent comprises 5 parts by weight of phosphoric acid and [ Bmim ]]BF₄3 parts of ionic liquid, [ Bmim ]]HSO₄3 parts of ionic liquid, [ Bmim ]]Tf₂3 parts of N ionic liquid, 4 parts of ethylene diamine tetra (methylene phosphonic acid) sodium, 3 parts of acetamido-methylene phosphonic acid sodium, 3 parts of ureido-tetramethylene phosphonic acid sodium, 0.25 part of sodium gluconate, 0.25 part of sodium tartrate, 20 parts of isopropanol and 50 parts of water;

s4, washing the automobile casting with the surface treated by deionized water, and then drying;

s5, performing electrostatic coating treatment on the dried automobile casting, spraying a PPS coating with the thickness of 100 mu m on the surface of the automobile casting, and then baking at 400 ℃.

Example 3

A surface treatment method of an automobile casting comprises the following steps:

s1, spraying high-pressure water to the surface of the automobile casting to remove dirt attached to the surface of the automobile casting;

s2, placing the automobile casting into a surfactant solution with the concentration of 18 wt% for ultrasonic treatment, wherein the surfactant comprises alpha-sodium alkenyl sulfonate, cationic guar gum and alkylolamide (the mass ratio is 1: 1: 1), and the solvent is ethanol; the ultrasonic treatment condition is that the power is 250W, and the time is 30 min;

s3, directly treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent through a spraying process, wherein the surface treating agent comprises 15 parts by weight of phosphoric acid and [ Omim [ ] according to parts by weight]CF₃SO₃2.5 parts of ionic liquid, [ Hmim ]]Tf₂2.5 parts of N ionic liquid, 3 parts of triethylene tetramine hexamethylene phosphonate, 3 parts of imidazoline dimethyl methylene phosphonate, 1 part of sodium salicylate, 1.5 parts of sodium benzoate, 50 parts of isopropanol and 30 parts of water;

s4, cleaning the surface-treated automobile casting by using an ethanol water solution, and then drying at 80-85 ℃;

s5, performing electrostatic coating treatment on the dried automobile casting, spraying a PPS coating with the thickness of 75 mu m on the surface of the automobile casting, and then baking at 350 ℃.

Example 4

A surface treatment method of an automobile casting comprises the following steps:

s1, spraying high-pressure water to the surface of the automobile casting to remove dirt attached to the surface of the automobile casting;

s2, placing the automobile casting into a surfactant solution with the concentration of 20 wt% for ultrasonic treatment, wherein the surfactant comprises alkylolamide and fatty alcohol-polyoxyethylene ether (mass ratio is 1: 1), and the solvent comprises ethanol and isopropanol (mass ratio is 1: 1); the ultrasonic treatment condition is that the power is 280W and the time is 20 min;

s3, directly processing the automobile casting subjected to ultrasonic treatment by using a surface treatment agent through a soaking process, wherein the surface treatment agent comprises 10 parts by weight of phosphoric acid and Omim]HSO₄1.5 parts of ionic liquid, [ Bmim ]]HSO₄2 parts of ionic liquid, 5 parts of glutamic acid dimethyl methylene phosphonic acid sodium, 3 parts of formamido dimethyl methylene phosphonic acid sodium, 1 part of sodium succinate, 1 part of sodium acetate, 1.5 parts of sodium oxalate, 40 parts of isopropanol and 40 parts of water;

s4, cleaning the surface-treated automobile casting by using an ethanol water solution, and drying;

s5, performing electrostatic coating treatment on the dried automobile casting, spraying a 60-micron-thick PPS coating on the surface of the automobile casting, and then baking at 330 ℃.

Example 5

A surface treatment method of an automobile casting comprises the following steps:

s1, spraying high-pressure water to the surface of the automobile casting to remove dirt attached to the surface of the automobile casting;

s2, placing the automobile casting into a surfactant solution with the concentration of 15 wt% for ultrasonic treatment, wherein the surfactant comprises sodium lauryl sulfate and alkylphenol ethoxylates (mass ratio is 2: 1), and the solvent comprises ethanol and isopropanol (mass ratio is 1: 1); the ultrasonic treatment condition is that the power is 200-300W, and the time is 15-45 min;

s3, directly treating the automobile casting subjected to ultrasonic treatment by using a surface treating agent through a spraying process, wherein the surface treating agent comprises 18 parts by weight of phosphoric acid and [ Omim [ ] in parts by weight]HSO₄3.5 parts of ionic liquid and Omim]CF₃SO₃3.5 parts of ionic liquid, 2.5 parts of sodium diethylenetriamine penta (methylene phosphonic acid), 2.5 parts of sodium glycine dimethyl methylene phosphonic acid, 1 part of sodium citrate, 1 part of sodium lactate, 60 parts of ethanol and 25 parts of water;

s4, cleaning the surface-treated automobile casting by using an ethanol water solution, and then drying at 80-85 ℃;

s5, performing electrostatic coating treatment on the dried automobile casting, spraying a PPS coating with the thickness of 80 mu m on the surface of the automobile casting, and then baking at 350 ℃.

Comparative example 1

The imidazole ionic liquid is replaced by imidazole, and the method is otherwise the same as the example 5.

Comparative example 2

The methylene type phosphonate was removed and the other components in the surface treatment agent were increased in the same ratio, and the remainder was the same as in example 5.

Comparative example 3

Step S2 is eliminated, and the rest is the same as in embodiment 5.

The automobile casting samples treated in examples 1 to 5 and comparative examples 1 to 3 were tested for rust removal performance (copper sulfate titration), corrosion resistance, coating adhesion and indoor storage life according to GB 11376-97, GB 6807-86 and GB1720-89 (79). The results are shown in Table 1.

TABLE 1

	Rust removing performance	Corrosion resistance	Coating adhesion	Indoor shelf life
					Example 1	Good taste	103s	Level 1	>420h
Example 2	Good taste	122s	Level 1	>480h
					Example 3	Good taste	114s	Level 1	>450h
Example 4	Good taste	135s	Level 1	>540h
					Example 5	Good taste	130s	Level 1	>520h
Comparative example 1	Good taste	80s	Level 1	<330h
					Comparative example 2	Is preferably used	60s	Stage 2	<240h
Comparative example 3	Is preferably used	43s	Grade 3	<150h

As can be seen from the data in Table 1: compared with comparative examples 1-3, the imidazole ionic liquid has much higher corrosion inhibition and corrosion prevention performance than imidazole, and the methylene phosphonate and the ultrasonic treatment of the pre-used surfactant can greatly improve various surface performances of the automobile casting. The invention has good rust removal effect after the surface treatment of the automobile casting, can form an anticorrosive film layer on the treated surface, and the film layer has good coating binding force, and the treated automobile casting can be stored for more than 420h and has excellent performance.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.