WO2018129870A1 - Stainless steel and plastic combined member, and processing method therefor - Google Patents

Abstract

A stainless steel and plastic combined member, and a processing method therefor. The stainless steel and plastic combined member comprises a stainless steel substrate (1). Honeycomb pores (11) are formed on the surface of the stainless steel substrate (1). An oxide film (12) is formed on the surface having the honeycomb pores (11) by means of electrochemical passivation. The treatment conditions for the electrochemical passivation are that the voltage is 0.5-6 V and the passivation time is 1-30 minutes. The oxide film (12) at least comprises two of an iron oxide, a chromic oxide, and a nickel oxide. A plastic material (2) is formed on the stainless steel substrate (1) by means of injection molding. The plastic material (2) is embedded into the honeycomb pores (11). The oxide film (12) has a good heat insulation effect and improves the combining force between the stainless steel substrate (1) and the plastic material (2).

Description

Combination of stainless steel and plastic and processing method thereof Technical field

The invention relates to the technical field of material processing, in particular to a joint of stainless steel and plastic and a processing method thereof.

Background technique

With the gradual development of materials technology, more and more products use metal and plastic composite forms to form the product structure. This structural design can achieve rich functional effects. For example, in the case where the appearance of the product is required to exhibit metal features and the internal structure needs to be reduced in weight and material cost, a metal-plastic composite design can be used.

Traditional combinations of metal and plastic include adhesive bonding, snap-fit or rivet attachment. However, the conventional composite method has defects such as low composite reliability and a need to increase the fixed connection mechanism. With the development of technology, a composite method of injection molding plastic on a metal surface has appeared in the prior art. In the plastic injection molding process, the plastic is directly injection molded on the metal material using the metal material as a substrate. However, the bonding force between metal and plastic is limited, there is a risk of falling off between the two, and the composite reliability is difficult to improve.

On the other hand, in order to enable plastics to be injection molded and fixed on metal, it is often necessary to chemically treat the metal, and the materials used in the chemical treatment are harmful to the human body, pollute the environment, and have high cost.

Therefore, it is necessary to improve the composite process of metal and plastic materials, improve the structural reliability of the material composite, or reduce the harm of the processed materials to the human body.

Summary of the invention

It is an object of the present invention to provide a new technical solution for the composite of stainless steel and plastic.

According to a first aspect of the present invention, a joint of stainless steel and plastic is provided, The bonding member comprises a stainless steel substrate having a honeycomb-shaped pore formed on the surface of the stainless steel substrate, and an electrochemical passivation treatment, an oxide film is formed on the surface of the honeycomb pore, the electrochemical passivation treatment The processing condition is a voltage of 0.5-6 V, and the passivation time is 1-30 minutes. The oxide film includes at least two of iron oxide, chromium oxide or nickel oxide, and the stainless steel substrate is injection molded. A plastic material embedded in the honeycomb pores.

Optionally, the solution used in the electrochemical passivation treatment is at least one of nitric acid, sulfuric acid, nitrous acid, hypochlorous acid, citric acid, phosphoric acid, chromic acid, permanganic acid and salts thereof.

Alternatively, the plastic material is made of at least one of a polyphenylene sulfide resin, a polybutylene terephthalate resin, a polyamide, a polycarbonate, and a polyolefin.

Optionally, the honeycomb pores have an average pore diameter ranging from 10 to 150 nm, and the honeycomb pores extend from the surface of the stainless steel substrate to an inner depth ranging from 10 to 200 nm, and the thickness range of the oxide film It is 1-20 nm.

Optionally, a surface pore adsorbing agent is adsorbed on the surface of the oxide film, and the pore-piercing agent is terephthalic acid, ethylenediaminetetraacetic acid, p-nitrobenzenesulfonic acid, water-soluble amino acid, ethylenediamine, triethanolamine. At least one of ammonia water, ethyl chloride, and epichlorohydrin.

Optionally, the plastic material is doped with a filler material, and the filler material is at least one of nylon fiber, carbon fiber, glass fiber, aramid fiber, calcium carbonate, magnesium carbonate, silicon dioxide, and clay. The percentage of the filler material in the plastic material ranges from 5 to 40 wt.%.

The invention also provides a method for processing a combination of stainless steel and plastic, comprising: providing a stainless steel substrate; forming a honeycomb pore on the surface of the stainless steel substrate; and electrochemically passivating the stainless steel substrate The surface of the stainless steel substrate forms an oxide film, the processing condition of the electrochemical passivation treatment is a voltage of 0.5-6 V, and the passivation time is 1-30 minutes, and the oxide film includes at least iron oxide and chromium oxide. Or two of the nickel oxides; plastic material is injection molded on the surface of the stainless steel substrate, and a partial structure of the plastic material is embedded in the honeycomb pores to form an integrated combination of stainless steel and plastic.

Optionally, the electrochemical passivation treatment uses a passivation solution having a volume fraction of 5-30% nitric acid, and the electrochemical passivation treatment uses a constant voltage of 0.6-3V.

Optionally, the electrochemical passivation solution has a temperature of 20-40 degrees Celsius and a passivation time of 10-20 minutes.

Optionally, after the electrochemical passivation, the stainless steel substrate is subjected to a boring treatment, and the stainless steel substrate is immersed in the porogen, the porphyrin is terephthalic acid, ethylenediaminetetraacetic acid, p-nitro At least one of benzenesulfonic acid, water-soluble amino acid, ethylenediamine, triethanolamine, aqueous ammonia, ethyl chloride, and epichlorohydrin.

The inventors of the present invention have found that in the prior art, although there are technical solutions for injection-molding some metal materials with plastic materials, there is no improvement in the prior art for the composite manner of stainless steel and plastic materials. A technical solution with high reliability. For the existing compounding scheme, the processed materials used are harmful to the human body and the environment. Therefore, the technical task to be achieved by the present invention or the technical problem to be solved is not thought of or expected by those skilled in the art, so the present invention is a new technical solution.

Other features and advantages of the present invention will become apparent from the Detailed Description of the <RTIgt;

DRAWINGS

The accompanying drawings, which are incorporated in FIG

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of a joint of stainless steel and plastic provided by the present invention.

2 is a schematic view showing the topographical features of the honeycomb pores provided in an embodiment of the present invention.

3 is a schematic view showing the surface structure of a stainless steel substrate provided by the present invention.

detailed description

Various exemplary embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that the relative arrangement of the components and steps, numerical expressions and numerical values set forth in the embodiments are not intended to limit the scope of the invention unless otherwise specified.

The following description of at least one exemplary embodiment is merely illustrative and is in no way Any limitations to the invention and its application or use.

Techniques, methods and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but the techniques, methods and apparatus should be considered as part of the specification, where appropriate.

In all of the examples shown and discussed herein, any specific values are to be construed as illustrative only and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that similar reference numerals and letters indicate similar items in the following figures, and therefore, once an item is defined in one figure, it is not required to be further discussed in the subsequent figures.

The present invention provides a combination of stainless steel and plastic that includes a stainless steel substrate and an injection molded plastic. As shown in FIG. 1, a honeycomb-like pore 11 is formed on the surface of the stainless steel substrate 1, and the honeycomb-shaped pores 11 have a nano-scale pore structure. Alternatively, the honeycomb pores 11 may be formed only in a region on the stainless steel substrate 1 where the plastic material 2 needs to be injection molded. Alternatively, the honeycomb pores 11 may be formed on the entire surface of the stainless steel substrate 1. Specifically, an oxide film 12 is formed on the surface of the honeycomb pores 11, and as shown in FIG. 3, the oxide film 12 is formed by electrochemical passivation treatment. The stainless steel substrate 1 may be placed in a passivation liquid, and the stainless steel substrate 1 is taken out from the passivation liquid after being energized for a certain period of time, and the electrochemical passivation treatment forms oxidation at least on the surface of the honeycomb pores 11. Membrane 12. The oxide film 12 includes at least two of iron oxide, chromium oxide, or nickel oxide. The thickness and composition of the oxide film can be adjusted by adjusting the temperature, time, energization voltage, and type of the passivation solution of the electrochemical passivation treatment. The electrochemical treatment of the present invention has a treatment range of 0.5-6 V and a passivation time of 1-30 minutes.

The joint of the stainless steel and the plastic provided by the invention has the following technical effects. First, the volume of the oxide film formed by the electrochemical passivation treatment is expanded, and the surface forms a fine uneven surface, which increases the surface roughness of the honeycomb pores. The honeycomb pores further enhance the bonding force between the stainless steel substrate and the plastic material.

Second, the oxide film formed by the passivation treatment is grown in situ from the surface of the stainless steel substrate. The oxide film has a stronger bonding force with the stainless steel substrate. Therefore, the stainless steel substrate and the plastic material are not easily separated and damaged during the drawing or shearing process. In particular, the oxide film grown by in-situ oxidation has a distinct and stronger bonding force with respect to the oxide layer formed by impregnation and drying using an acid solution or a salt solution containing metal ions. The oxide film of the present invention is more physically and chemically bonded to a stainless steel substrate. Moreover, the oxide film of the present invention has a denser structure and stronger corrosion resistance than the above-mentioned conventional oxide film. This structural feature ensures the reliability of plastic material injection on the oxide film, and prevents corrosion cracking, mechanical fracture, and the like. .

Further, the present invention can control the passivation liquid, the treatment temperature, the treatment time, the electrification voltage and the like used in the electrochemical passivation treatment, and the material of the oxide film can be mainly iron oxide, chromium oxide or nickel oxide. The above three oxides have a heat transfer coefficient smaller than that of the stainless steel substrate, and the oxide film is equivalent to the stainless steel substrate covered with a heat insulating layer. When the injection molding process is performed, the oxide film can reduce the heat loss of the plastic material and reduce the heat of the plastic material from being lost from one side of the stainless steel substrate. This effect delays the time for solidification and crystallization of the plastic material, so that the plastic material can be more fully filled in the honeycomb pores, and the bottom of the honeycomb pores can also be well filled. In this way, the stainless steel substrate and the plastic material can exhibit better airtightness and the connection reliability is higher.

The solution used in the electrochemical treatment may be at least one of nitric acid, sulfuric acid, nitrous acid, hypochlorous acid, citric acid, phosphoric acid, chromic acid, permanganic acid, and salts thereof. It is also possible to mix a plurality of solutions.

In one embodiment of the present invention, by adjusting the conditions of the passivation treatment, in combination with XPS analysis, Fe, Cr, Ni, and O elements are mainly present in the oxide film at a surface of 12 nm from the surface layer of the stainless steel substrate. Among them, the element content is mainly Fe, Cr, O, and Ni is a little. It can be seen that the thickness of the oxide film is 12 nm or more, which is larger than the natural oxide film of 2-4.8 nm thick of stainless steel, and mainly consists of chromium oxide and iron oxide having a small thermal conductivity, and exhibits a good heat insulating effect.

The honeycomb porous stainless steel substrate prepared by the present technical scheme is optionally embedded in an injection molding die by electrochemical passivation of a volume fraction of 5-30% nitric acid and a constant voltage of 0.6-3 V. A plastic material mixed with PBT + 30 wt% glass fiber was injected at an injection temperature of 300 ° C, and finally injection-molded to obtain a joint of stainless steel and plastic. The area of the plastic and stainless steel joint was 0.5 cm ² and was drawn and stretched on a tensile tester to obtain an average shear breaking force of 29.5 MPa. This has a significant increase in the cutting strength compared to the conventional conventional scheme.

The conventional oxide film is mainly a natural oxide film of iron, or a manganese oxide, a zinc phosphorus oxide or the like. This oxide film has a large thermal conductivity and cannot function as a heat insulator. Moreover, the oxide film which is naturally generated slowly is not only thinner in thickness, but also loose in structure, and the natural oxide film does not have sufficient corrosion resistance, resulting in corrosion damage of the bonded body. Therefore, the passivation treatment of the present invention is a process in which an applied voltage drives the stainless steel to form an oxide film in the passivation region, and the oxide film formed by polarization is thicker. For example, after passivation of SUS304 stainless steel in a dilute nitric acid solution for 20 min, the thickness of the formed oxide film reaches 14.3 nm. At the same time, according to the "metal corrosion manual", the electrochemical passivation is also anodized, and the anode passivation process preferentially corrodes the passivated active metal. Therefore, after electrochemical passivation, stainless steel is mainly composed of chromium oxide and iron oxide. Among them, in the case of 400 ° C, the thermal conductivity of stainless steel is 16.3 W / m · K, the thermal conductivity of ferric oxide is 5.1 W / m · K, the thermal conductivity of ferrous oxide is 15.0 W / m · K, The thermal conductivity of chromium oxide is about 10 W/m·K. In addition, due to the driving of the applied polarization voltage, not only the rate of passivation of the stainless steel is accelerated, but also the chemical passivation treatment time is shortened, and the polarization potential selectively deactivates the active element chromium, and more low heat conduction is formed in the film layer. Coefficient of chromium oxide. Therefore, in the technical solution, the electrochemical passivation film layer is thicker and has higher hardness. Better insulation and corrosion resistance, significantly increasing the bonding between stainless steel and plastic.

On the other hand, since the bonding member provided by the present invention has the above-described technical effects, in the present invention, the pore diameter of the honeycomb pores can be appropriately reduced, and the bonding force between the stainless steel substrate and the plastic material can be ensured. By reducing the pore size of the honeycomb pores, the corresponding pore forming process is also simplified, thereby resulting in simplification of the process flow and reduction in time cost. After the pore size of the honeycomb pores is lowered, the pores are more evenly distributed and the pore quality is higher. Figure 2 shows the morphology of the honeycomb pores on the surface of the stainless steel substrate after electrochemical passivation treatment, and the honeycomb pores are evenly distributed. 3 shows the oxide film 12 on the surface of the honeycomb pores 11 and the honeycomb pores 11.

Optionally, in one embodiment, the electrochemical passivation treatment uses a passivation solution having a volume fraction of 5-30% nitric acid, and the electrochemical passivation treatment uses a constant voltage of 0.6-3V. The electrochemical passivation treatment used in the present invention applies a voltage to a stainless steel substrate, and is made of a stainless steel substrate. The anode electrochemically reacts its surface with an oxidizing passivation medium to form a dense passivation film. Due to the forced driving of the applied potential, the chemical reaction on the surface of the stainless steel substrate is more efficient, and it is more compact and more effective than the ordinary acid-washed oxide film. The above is a specific manner of electrochemical passivation treatment provided by the present invention. The invention adopts constant potential electrochemical passivation, has simple equipment and process, has clear electrode state in the polarization process, has small influence factors, and is passivated. Can play a good passivation oxide film forming effect. At the same time, compared with the chemical passivation treatment using concentrated nitric acid, dichromic acid, etc., the oxide film prepared by the invention has higher reliability, and the pitting potential of the stainless steel substrate can reach 1000 mV (25 ° C, 3 wt.% NaCl). the above. Moreover, the concentration of the acid solution used is relatively low, the use is safe, and the impact on the human body and the environment is small, which is in line with the technological development trend of sustainable development.

Alternatively, the plastic material may be made of at least one of a polyphenylene sulfide resin, a polybutylene terephthalate resin, a polyamide, a polycarbonate, and a polyolefin. These materials can be combined to form a high-hardness crystalline resin composition in which the composition can be crystallized and solidified in the honeycomb pores after cooling.

Alternatively, the honeycomb pores may have an average pore diameter ranging from 10 to 150 nm, and the honeycomb pores may extend from the surface of the stainless steel substrate to an inner depth ranging from 10 to 200 nm. The above structural features can be adjusted by controlling the pore forming process. Alternatively, the honeycomb pores have an average pore size of 60 nm.

Alternatively, the oxide film may have a thickness ranging from 1 to 20 nm, and the thickness of the oxide film may be adjusted by adjusting the temperature of the passivation treatment, the time, the composition of the organic oxidizing solution, and the like.

In particular, the surface of the oxide film may further adsorb a pore-piercing agent, which is terephthalic acid, ethylenediaminetetraacetic acid, p-nitrobenzenesulfonic acid, water-soluble amino acid, ethylenediamine, and three At least one of ethanolamine, ammonia, ethyl chloride, and epichlorohydrin. The pore-penetrating agent can improve the surface characteristics of the oxide film, so that the plastic material can smoothly flow into the honeycomb pores during the injection molding process.

In particular, the plastic material may also be doped with a filler material, which is nylon fiber, carbon fiber, glass fiber, aramid fiber, calcium carbonate, magnesium carbonate, and second. At least one of silicon oxide and clay, the filler material occupies a mass percentage in the plastic material ranging from 5 to 40% by weight. The filler material may be doped in the plastic material prior to the injection molding process.

The coefficient of linear expansion of stainless steel is 1.5×10 ^-5 /°C, while the coefficient of linear expansion of plastic materials is 6-8×10 ^-5 /°C. The coefficient of linear expansion between stainless steel and plastic materials is not conducive to the curing of plastic materials. process. Therefore, it is necessary to modify the plastic material to reduce the coefficient of linear expansion of the plastic material. For example, the glass fiber material has a linear expansion coefficient of only 3.8 × 10 ^-5 / ° C, and a material such as glass fiber can be blended in the plastic material so that the linear expansion coefficient of the plastic material composition is as close as possible to the stainless steel.

The invention also provides a method for processing a combination of stainless steel and plastic, firstly, providing a stainless steel substrate, forming a honeycomb pore on the surface of the stainless steel substrate; and then electrochemically passivating the stainless steel substrate Forming an oxide film on the surface of the stainless steel substrate, the oxide film including at least two of iron oxide, chromium oxide or nickel oxide, and the processing condition of the electrochemical passivation treatment is 0.5-6V The voltage and the passivation time are 1-30 minutes. Finally, the plastic material is injection molded on the surface of the stainless steel substrate, and a partial structure of the plastic material is embedded in the honeycomb pores to form an integrated combination of stainless steel and plastic. . The combination of stainless steel and plastic provided by the present invention can be prepared by the processing method provided by the present invention.

The step of pretreatment may also be included prior to the hole forming process of the stainless steel substrate. Alternatively, the degreasing and degreasing treatment of the stainless steel substrate may be performed in advance. The stainless steel substrate was soaked in a stainless steel cleaning agent at 35-80 ° C for 60-600 s, and then washed in pure water having a conductivity of less than 20 us/cm for 60 s. The stainless steel cleaning agent is an acid, a base or an organic solvent of 100 to 300 g/L.

Alternatively, the surface layer of the stainless steel substrate can also be subjected to de-natural oxide treatment. The degreased stainless steel substrate is immersed in a 40-80 ° C removal solution for about 60 s, then placed in a neutralizing solution for about 60 s, and then washed in pure water. The membrane removing solution is an alkaline solution of 5-10 vol.% sodium hydroxide or potassium hydroxide, and the neutralizing liquid is 100-300 g/L of dilute nitric acid and sulfuric acid liquid and neutralizing alkali residue on the stainless steel substrate. Solution. Its main purpose is to remove the natural oxide film formed on the surface of the stainless steel substrate, and to eliminate the adverse effect of the uneven oxide film on the etching process.

In an optional embodiment of the present invention, the passivation solution used in the electrochemical passivation treatment is nitric acid having a volume fraction of 10-20%, and the electrochemical passivation treatment adopts a constant voltage of 0.8-1.5V. . An electrode is attached to the stainless steel substrate that acts as an anode in an electrochemical reaction. Preferably, the treatment temperature is 30 degrees Celsius and the treatment time is 15 minutes. The above is a specific manner of the electrochemical passivation treatment which is exemplified in the present invention, and can be used as the passivation liquid according to actual performance requirements of the product. Different voltages are used, and the invention does not limit this. Compared with the oxidation treatment using concentrated nitric acid, dichromic acid or the like, the oxide film obtained by the invention has higher reliability, and the pitting potential of the stainless steel substrate can reach 1000 mV or more. Moreover, the concentration of nitric acid used is relatively low, the use is safe, and the impact on the human body and the environment is small, which is in line with the technological development trend of sustainable development.

In particular, after the electrochemical passivation treatment, the stainless steel substrate may be subjected to a boring treatment, which can improve the surface characteristics of the oxide film, so that the plastic material can be better filled into the honeycomb in the subsequent injection molding process. In the pores, a form in which the plastic material is solidified and embedded in the honeycomb pores is formed. The hole-removing treatment may immerse the stainless steel substrate in a pore-treating agent, which is terephthalic acid, ethylenediaminetetraacetic acid, p-nitrobenzenesulfonic acid, water-soluble amino acid, ethylenediamine, triethanolamine. At least one of ammonia water, ethyl chloride, and epichlorohydrin. After the stainless steel substrate is taken out from the porogen, it can be dried naturally or washed. The pore-penetrating agent uniformly attached to the oxide layer can physically and chemically react with the plastic material in the injection molding process, so that the plastic material accelerates into the honeycomb-like pores, and the bonding force between the plastic and the stainless steel member is remarkably improved.

While the invention has been described in detail with reference to the preferred embodiments of the present invention, it is understood that It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims (10)

1. A joint member of stainless steel and plastic, characterized in that the joint member comprises a stainless steel substrate, and the surface of the stainless steel substrate is formed with honeycomb pores, which are electrochemically passivated, the honeycomb pores An oxide film is formed on the surface, the processing condition of the electrochemical passivation treatment is a voltage of 0.5-6 V, and the passivation time is 1-30 minutes, and the oxide film includes at least iron oxide, chromium oxide or nickel oxide. In the two types, the stainless steel substrate is injection molded with a plastic material embedded in the honeycomb pores.
2. The combination of stainless steel and plastic according to claim 1, wherein the electrochemical passivation treatment uses nitric acid, sulfuric acid, nitrous acid, hypochlorous acid, citric acid, phosphoric acid, chromic acid, and high manganese. At least one of an acid and a salt thereof.
3. A combination of stainless steel and plastic according to claim 1 or 2, wherein the plastic material is composed of polyphenylene sulfide resin, polybutylene terephthalate resin, polyamide, polycarbonate and polyolefin. Made of at least one material.
4. The combination of stainless steel and plastic according to any one of claims 1 to 3, wherein the honeycomb pores have an average pore diameter ranging from 10 to 150 nm, and the honeycomb pores are from the surface of the stainless steel substrate. The average depth extending to the inside ranges from 10 to 200 nm, and the thickness of the oxide film ranges from 1 to 20 nm.
5. The joint of stainless steel and plastic according to any one of claims 1 to 4, characterized in that the surface of the oxide film is adsorbed with a pore former, and the pore former is terephthalic acid or ethylenediamine. At least one of acetic acid, p-nitrobenzenesulfonic acid, water-soluble amino acid, ethylenediamine, triethanolamine, aqueous ammonia, ethyl chloride, and epichlorohydrin.
6. The combination of stainless steel and plastic according to any one of claims 1 to 5, characterized in that the plastic material is doped with a filler material, which is nylon fiber, carbon fiber, glass fiber, aromatic poly At least one of amide fibers, calcium carbonate, magnesium carbonate, silica, and clay, the filler material occupies a mass percentage in the plastic material ranging from 5 to 40% by weight.
7. A method for processing a combination of stainless steel and plastic, characterized in that stainless steel is provided a steel substrate; forming a honeycomb pore on a surface of the stainless steel substrate; performing an electrochemical passivation treatment on the stainless steel substrate to form an oxide film on a surface of the stainless steel substrate, and the electrochemical passivation treatment The condition is a voltage of 0.5-6 V, the passivation time is 1-30 minutes, and the oxide film includes two of iron oxide, chromium oxide or nickel oxide; plastic material is injection molded on the surface of the stainless steel substrate, A partial structure of the plastic material is embedded in the honeycomb pores to form an integrated combination of stainless steel and plastic.
8. The method according to claim 7, wherein the passivation solution used in the electrochemical passivation treatment is nitric acid having a volume fraction of 5-30%, and the electrochemical passivation treatment uses a constant voltage of 0.6-3V.
9. The method according to claim 7 or 8, wherein the electrochemical passivation solution has a temperature of 20-40 degrees Celsius and a passivation time of 10-20 minutes.
10. The method according to any one of claims 7 to 9, wherein after the electrochemical passivation, the stainless steel substrate is subjected to a boring treatment, and the stainless steel substrate is immersed in the porogen, and the boring agent is At least one of terephthalic acid, ethylenediaminetetraacetic acid, p-nitrobenzenesulfonic acid, water-soluble amino acid, ethylenediamine, triethanolamine, aqueous ammonia, ethyl chloride, and epichlorohydrin.

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