KR100856662B1 - method for forming metallic coating on plastic substrate - Google Patents

Abstract

The present invention relates to a method for forming a metal film on a plastic substrate, wherein the surface of the molded plastic substrate (1) is activated through embossing or blasting to form the uneven surface (5), and the copper has high thermal fatigue strength and wettability. The metal powder of Cu) alloy, aluminum (Al) alloy or nickel (Ni) alloy was sprayed on the base material 1 on which the uneven surface 5 was formed so that the metal powder was formed on the base 1 around the uneven surface 5. The metal coating layer 2 is formed while penetrating into the inside, and in some cases, the upper coating layer 4, or the metal coating layer 2 and the upper coating layer 4, depending on the use of plastic parts on the metal coating layer 2). It is characterized in that the bond coating layer 3 is additionally laminated therebetween.

According to the method for forming a metal film on the plastic substrate of the present invention, the metal film on the plastic substrate is not cracked or peeled off even by an external force, thereby providing excellent durability, and it is possible to produce a plastic part having a lighter weight and superior physical properties than a metal part.

Plastic parts, thermal spraying, metal coating, 龜 裂, 剝離

Description

Method for forming metallic coating on plastic substrate

1 is a cross-sectional view of a plastic member manufactured according to the first embodiment of the method for forming a metal film on a plastic substrate according to the present invention;

2 is a cross-sectional view of a plastic member manufactured according to the second embodiment of the method for forming a metal film on the plastic substrate according to the present invention;

3 is a cross-sectional view of a plastic member manufactured according to the third embodiment of the method for forming a metal film on the plastic substrate according to the present invention;

Figure 4 is a process chart showing the manufacturing process of the metal film forming method on a plastic substrate according to the present invention.

※ Explanation of symbols for main parts of drawing

DESCRIPTION OF SYMBOLS 1 Base material 2 Metal film layer

3: bond coating layer

4: upper coating layer 5: uneven surface

The present invention relates to a method of forming a metal film on a plastic substrate, and more particularly, to reinforce the physical properties of plastic parts that can be applied for automobile, shipbuilding or electronic parts and other various applications and building interior and exterior materials. It is about a method of forming a metal film in a.

Recently, with the development of high-performance plastics, many mechanical parts that have been made of existing metals have been replaced by low-weight plastic products. For example, in the case of a hybrid vehicle that has received a lot of attention around the world these days, the weight of the entire vehicle needs to be reduced, so that related parts such as the engine valve cover are mainly made of lightweight plastic parts, unlike general vehicles.

Plastic parts are lighter, more beautiful and cheaper than metal parts, but are still weaker than metal parts in mechanical strength, abrasion resistance, hardness, cold resistance and heat resistance, resulting in post-deformation due to changes over time. At least the physical properties equivalent to or surpassing those of the metal could not be obtained.

As a means for compensating the physical properties of plastic parts, a method of improving the quality and durability of a product by forming a metal film or ceramic film on the surface of the plastic molded body has been proposed.

As a surface treatment method of the plastic molded body developed so far, metal coating is applied by surface modification or surface functionalization methods such as plating, physical vacuum deposition, chemical vacuum deposition, ion implantation, and the like.

According to these methods, the weaknesses of plastic parts can be greatly strengthened. However, the metal film has a disadvantage in that the adhesion to the plastic surface is very low and easily peeled off by external force, and the choice of the deposit is narrow and the thickness of the film cannot be freely formed for various applications.

Therefore, in order to increase the adhesion of the metal film to the surface of the plastic substrate, the surface of the substrate is treated in advance by roughening, corroding, or activating the surface of the substrate, and then mixing the ceramic powder into the synthetic resin adhesive. A method of applying an material to form an intermediate layer and spraying metal powder thereon to form a coating layer has been proposed. In this method, adhesion between the substrate and the thermal spray coating is improved, but residual stress is generated in the thermal spray coating and an oxide layer exists in the coating, so that physical properties such as strength of the thermal spray coating itself are lowered, resulting in a decrease in surface modification effects such as wear resistance. In addition, when the intermediate layer is formed by applying the mixed material of the ceramic powder and the resin adhesive, the viscosity of the mixed material is very high, so that it is difficult to apply it uniformly and thinly on the surface of the substrate. In most cases, the coating work is dependent on manual work, so the error of the product is large and the work efficiency is low according to the skill of the operator. In addition, the resin adhesive is thermally decomposed in the mixed material due to the high temperature of the sprayed material. It was difficult to form the sprayed layer of the material.

In order to solve this problem, Japanese Patent Laid-Open No. 4-47932 discloses metals, copper, and metals having low melting point ductility on the surface of a synthetic resin molded article as a base material in order to increase the adhesion of the metal film and to obtain a uniform film layer. A method of forming a metal film by spraying iron, aluminum, or an alloy thereof first and then spraying the desired metal powder on it has been proposed.

However, even with this method, it is possible to modify the surface of plastic products, but the bonding strength between plastic and metal is very low, cracks occur during use, and thick coating layer cannot be formed. There was a problem that the formation process of is very complicated and the product cost is expensive.

The present invention is intended to provide a plastic film of a metal film that can replace the high-weight metal parts by exhibiting the inherent physical properties of the plastic parts inexpensive and lightweight, but reinforces the weak physical properties compared to the metal, In order to achieve this purpose, in order to achieve the above purpose, it is possible to strengthen the bonding force between the surface of the plastic substrate and the metal film layer and to melt the surface of the plastic substrate by using a special alloy that has a small surface tension at the time of melting so that it can be spread evenly on the surface of the substrate. By spraying at high speed, the metal powder collides with the plastic substrate to dig into the surface of the substrate to form a coating. Therefore, the adhesion is very good, so that a metal coating without peeling phenomenon can be formed in spite of the difference in shrinkage rate due to the difference between the metal and plastic materials. Can surpass the properties of metals Has been able to manufacture plastic parts.

Method for forming a metal film on a plastic substrate according to the present invention,

The surface of the molded plastic substrate is activated by embossing or blasting to form an uneven surface, and a copper alloy, aluminum alloy, or nickel (Ni) having high thermal fatigue strength and wettability. The alloy is sprayed on a substrate provided with the uneven surface to form a metal coating layer while the molten metal powder of the alloy penetrates into the substrate.

In addition, an upper coating layer may be further formed on the metal coating layer according to the use of the plastic part, and a bond coating layer of a material capable of improving the bonding strength between the metal coating layer and the upper coating layer may be additionally added.

The metal coating layer is a copper alloy having high thermal fatigue strength and high wettability under a gas heat source of 2500 to 3500K sprayed at a flow rate of 50 to 100 m / sec or a plasma heat source of 10000 to 15000K sprayed at a flow rate of 150 to 300 m / sec. After the nickel (Ni) alloy or aluminum (Al) alloy powder is formed by thermal spraying, and then subjected to a general annealing process (annealing) to a low temperature heat treatment is completed through a finish polishing process.

The blasting in the activation process is to form a concave-convex surface on the surface by colliding the fine particles of SiC or Al ₂ O ₃ to the substrate surface at high speed, the blasting effect is large if the particle diameter of the blasting material is less than # 60 The gap between the surface irregularities tends to be large and localized deeply, so that an effective stress cannot be imparted to the metal coating layer, and when it exceeds # 120, fine irregularities can be formed and a larger area per unit time can be obtained. Due to the non-uniformity and overall fine irregularities, the bonding force with the next metal-spray material is lowered and tends to peel off.

Cu-Zn, Cu-Sn, Cu-Zn-Sn, Cu-Zn-Ni, Cu-Mn-Sn, Cu-Ti, etc. may be used as the copper alloy having a high thermal fatigue strength and a large wettability. Ni-Cr as nickel (Ni) alloy, Al-Cu-Si, Al-Cr-Ti, Al-Si, Al-Mn-Zn, Al-Zr Can be. These alloy powders have a small surface tension at the time of melting, so that when they are mounted on a plastic substrate, they spread evenly to form a uniform coating, so there is no cracking of the coating after finishing.

That is, with reference to the accompanying drawings, a metal film forming method on a plastic substrate according to the present invention will be described.

1 and 4, the substrate 1 of the plastic part is molded (step a), and the surface of the molded substrate 1 is first embossed or SiC or Al ₂ O ₃ of # 60-120. Air is blown through the fine particles to form the uneven surface 5 having an average roughness of 2.5-13 μm through a blasting process of imparting unevenness (step b). By forming the uneven surface 5 with a plurality of irregularities through this activation process, they act as anchors to strengthen the binding force between the subsequent metal film layer 2 and the substrate 1. If the average roughness is less than 2.5 mu m, the unevenness is too fine, and the bonding strength with the metal film layer 2 falls, and if the average roughness exceeds 13 mu m, the unevenness is deeply formed locally, so that the stress on the substrate 1 cannot be effectively applied.

Then, the metal coating layer 2 is formed by thermally spraying copper alloy, aluminum alloy or nickel alloy having high thermal fatigue strength and wettability on the uneven surface 5 (step c). The metal film layer 2 has a high thermal fatigue strength and wettability under a gas heat source of 2500 to 3500K sprayed at a flow rate of 50 to 100m / sec or a plasma heat source of 10000 to 15000K sprayed at a flow rate of 150 to 300m / sec. By spraying a metal powder of a copper (Cu) alloy, a nickel (Ni) alloy or an aluminum (Al) alloy by an atmospheric plasma spray method or a flame spray method, the metal powder is laminated while being infiltrated around the uneven surface 5, and a thermal spray coating The thickness is formed to about 100-1000㎛.

In addition, according to the method for forming a metal film on a plastic substrate according to the present invention, as shown in FIG. 2, a material having a special performance, for example, a metal alloy or a ceramic powder, may be 100-1000 μm thick by atmospheric plasma spraying as shown in FIG. 2. The coating layer 4 is formed (step e), and in some cases, as shown in FIG. 3, the bonding strength is formed between the primary metal coating layer 2 in the step c and the upper coating layer 4 in the step e. Bond coating layer 3 to further increase may be formed before the formation of the upper coating layer 4 to a thickness of about 100-200㎛ (d process). The bond coating layer 3 is formed by thermally spraying a material having a large bonding strength therebetween in consideration of the metal coating layer 2 and the subsequent upper coating layer 4.

After that, the plastic substrate 1 having the metal coating layer 2 alone or the metal coating layer 2 and the upper coating layer 4, or both, together with the bond coating layer 3 formed thereon, is cooled through a low temperature heat treatment process and then a desired shape. It is completed by grinding | polishing by (f process).

The metal film on the plastic base material according to the present invention formed through such a process forms a metal film layer 2 by the metal powder in the state of flame collided and deposited around the uneven surface 5 on the surface of the plastic base material 1. There is no peeling or cracking of the metal film layer 2, and furthermore, since the upper film layer 4 is also firmly bound to the metal film layer 2, no peeling or cracking occurs even when an external force is applied.

In order to more easily understand the characteristics of the method for forming a metal film on the plastic substrate according to the present invention will be described by the following examples, these examples are only for the understanding of the present invention and the claims of the present invention It will be readily understood by those skilled in the art that modifications and variations are possible within the scope of the present invention.

Example 1

Automobile engine valve cover is molded from plastic, and the surface of this plastic part base is first formed with an uneven surface having an average roughness of 3.5 μm through an embossing process, and then mechanically alloyed Cu-Mn on the surface by a ball mill method. The -Sn alloy was thermally sprayed under a 3500 K gas heat source ejected at a flow rate of 50 m / sec to form an 800 µm thick metal film layer. It was then heat treated at low temperature to complete the required polishing treatment.

The automobile engine valve cover formed by such a treatment was lightweight and had excellent physical properties required for the parts such as surface hardness, strength and corrosion resistance, and excellent durability without cracking the metal coating layer on the surface even when external force was applied.

Example 2

A metal coating layer was formed on the surface of the substrate as in Example 1, and then ceramic powder was finely and uniformly mixed through a ball mill method to form an upper coating layer A having a thickness of 500 μm by atmospheric plasma spraying.

On the other hand, unlike the above, after forming the metal coating layer, prior to forming the upper coating layer, by coating the aluminum metal having a thickness of 200㎛ on the metal coating layer by a plasma spray method, a bond coating layer was first formed. Then, the same upper coating layer B as the upper coating layer A was formed.

The plastic substrate on which the upper coating layer A and the upper coating layer B were formed, respectively, was heat treated and polished in the same manner as in Example 1 to form an automobile engine valve cover.

The finished plastic parts of the upper coating layer A and the upper coating layer B were measured for physical properties under the same conditions as in Example 1, and as a result, they showed almost the same physical properties as in Example 1. The binding of the coating layer on the plastic substrate was both quite good, in particular better than that of the upper coating layer B. And both in strength and heat deformation showed better results than in Example 1.

In addition, in each of the plastic parts having the upper coating layer A and the upper coating layer B, although the upper coating layer was further laminated, unlike in Example 1, no cracking or peeling of the upper coating layer due to external force was observed.

According to the method for forming a metal film on a plastic substrate according to the present invention having the above-described configuration, the adhesion between the metal film and the substrate and the thickness of the metal film can be freely formed appropriately and the surface of the metal film itself is excellent. Modification effect can be exerted.

That is, according to the present invention, since the molten metal powder penetrates into the surface of the plastic substrate and spreads evenly to form a metal film, it is possible to form a metal film having excellent adhesion and no peeling phenomenon in spite of the difference between metal and plastic. Even investment facilities can produce plastic parts that have excellent mechanical strength, abrasion resistance, hardness, cold resistance and heat resistance, which surpass the properties of metals.

Therefore, according to the method for forming a metal film on the plastic substrate of the present invention, the product cost is low, the automation is possible, the quality is stable, and the work efficiency is excellent, thereby making it possible to manufacture a multipurpose plastic part.

Claims (8)

The surface of the molded plastic substrate 1 is activated by embossing or blasting to form the uneven surface 5 on the surface of the substrate 1, and has a high thermal fatigue strength and wettability. Metal powder of Al) alloy or nickel (Ni) alloy is sprayed on the base 1 having the uneven surface 5 to melt the metal powder and penetrate into the base 1 around the uneven surface 5. In the metal film forming method on a plastic substrate while forming a metal film layer (2) on the substrate 1, The large thermal fatigue strength and high wettability of copper (Cu), nickel (Ni) or aluminum (Al) alloys are Cu-Zn, Cu-Sn, Cu-Zn-Sn, Cu-Zn-Ni, Cu-Mn-Sn , Cu-Ti, Ni-Cr, Al-Cu-Si, Al-Cr-Ti, Al-Si, Al-Mn-Zn, or Al-Zr; The average roughness of the uneven surface 5 on the base material 1 is 2.5-13 µm; An upper coating layer 4 is further laminated on the metal coating layer 2 in accordance with the use of plastic parts; Blasting in the activation treatment of the substrate (1) is made of microparticles having a thickness of 60-120 of SiC or Al ₂ O ₃ ; A method of forming a metal film on a plastic substrate, characterized in that the metal powder of the alloy forming the metal film layer (2) is sprayed under a gas heat source of 2500 to 3500 K which is ejected at a flow rate of 50 to 100 m / sec. delete delete delete delete The surface of the molded plastic substrate 1 is activated by embossing or blasting to form the uneven surface 5 on the surface of the substrate 1, and has a high thermal fatigue strength and wettability. Metal powder of Al) alloy or nickel (Ni) alloy is sprayed on the base 1 having the uneven surface 5 to melt the metal powder and penetrate into the base 1 around the uneven surface 5. In the metal film forming method on a plastic substrate while forming a metal film layer (2) on the substrate 1, The large thermal fatigue strength and high wettability of copper (Cu), nickel (Ni) or aluminum (Al) alloys are Cu-Zn, Cu-Sn, Cu-Zn-Sn, Cu-Zn-Ni, Cu-Mn-Sn , Cu-Ti, Ni-Cr, Al-Cu-Si, Al-Cr-Ti, Al-Si, Al-Mn-Zn, or Al-Zr; The average roughness of the uneven surface 5 on the base material 1 is 2.5-13 µm; An upper coating layer 4 is further laminated on the metal coating layer 2 in accordance with the use of plastic parts; Blasting in the activation treatment of the substrate (1) is made of microparticles having a thickness of 60-120 of SiC or Al ₂ O ₃ ; A method of forming a metal film on a plastic substrate, characterized in that the metal powder of the alloy forming the metal film layer (2) is sprayed under a plasma heat source of 10000 to 15000 K which is ejected at a flow rate of 50 to 100 m / sec. delete delete

Images