JP6561302B2 - Method for forming superposed fine particle structure and method for joining metal and plastic member using the same - Google Patents

Description

  The present invention relates to direct bonding by mechanical bonding between metal and plastic.

  In making a composite member of metal and plastic, in order to directly join metal and plastic with sufficient mechanical bond strength without using an intermediate material such as an adhesive, a complicated microstructure is formed on the metal surface. Need to form.

  For example, Document 1 describes a method for forming a complicated uneven shape. The method uses an alloy composition (for example, a single crystal part and a eutectic part) by chemical etching with an acid aqueous solution in which a halogen compound is added to an Al—Si-based aluminum alloy plate, or by a combination of the etching and blasting. The shape is complicated by selectively dissolving using the difference in the distribution.

  Document 2 describes a method for forming a complicated uneven shape. The method scans and irradiates the surface of the metal member with a laser beam or the like to form grooves or depressions on the surface, and the molten metal splashes scattered by the heat of the laser beam based on the concave shape of the grooves or depressions. The shape is complicated by flowing or reattaching.

  In Document 3, as a method of forming a microstructure having a bridge shape or an overhang shape, which enhances the anchor effect in bonding, laser scanning is performed by a laser focused with a beam diameter of several hundreds of μm in a certain scanning direction. A technique is disclosed in which laser scanning is performed in another scanning direction crossing the scanning direction, and this is repeated to form the shape.

  However, since the etching process needs to be performed by an electrochemical reaction in a chemical solution, the masking process to the non-bonded part or the etching process is necessary for forming a local fine structure for local bonding. The waste liquid processing of the chemical | medical solution after that is needed, and an operation | work becomes a complicated and expensive construction method.

  Further, in the formation of a fine structure by laser scanning processing, it is necessary to reduce the number of scans in order to reduce the processing time, but in that case, there is a trade-off that the formation of the fine structure becomes difficult, and the bonding process It is difficult to improve efficiency.

  Therefore, according to the present applicant's invention, a metal joining planned surface coated with a mixed powder composed of a plurality of metal powders including carbon powder is raised by laser cladding with a spot diameter of several millimeters, and There is a technique for forming a superposed fine particle structure on the upper surface and using the structure to enable strong bonding between a metal-to-be-bonded surface and plastic. According to this technology, it is possible to join metal and plastic molded parts locally, for example, by local heating with a laser. In this case, since the ridge shape is the basis, it is easy and sufficient to press the bonding interfaces. Even when the fluidity of the plastic melted by heating is low, it is possible to sufficiently enter the inside of the microstructure.

  However, in the formation of the superposed fine particle structure in this technique, a suitable method is to use a method in which a mixed powder of a plurality of metals including carbon is uniformly kneaded and then adhered to the planned joining surface of the metal. Therefore, a separate manufacturing process for the mixed powder is required.

  Therefore, in order to simplify or omit this process and achieve cost reduction and productivity improvement of the joining method according to the technology, it is possible to use a powder feeding device when forming the laser cladding. Although it is conceivable, it is not always easy to handle the mixed powder used to form the superposed fine particle structure. For example, a mixed powder obtained by uniformly mixing aluminum, titanium and carbon powders continuously vibrates. When applied, the carbon powder is separated and re-agglomerated, the fluidity in the powder state is deteriorated, and the powder feeding device is clogged.

JP 2011-143539 A JP 2013-71312 A International Publication No. 2007/076023

  Therefore, the fluidity and uniform diffusibility of the mixed powder composed of a plurality of metal powders used for the formation of the superposed fine particle structure is improved, the formation of the superposed fine particle structure is simplified, and the composite of metal and plastic is formed. The purpose is to improve productivity.

A first invention is a method for forming a superposed fine particle structure on a metal substrate surface, wherein carbide powder and titanium having a particle size of 1 μm to 100 μm are formed on the metal substrate surface. And a process of attaching a mixed powder obtained by mixing these powders and a step of applying laser cladding to the surface to which the mixed powder is adhered while causing the surface to rise. This is a method for forming a particle structure.

  Here, the superimposed fine particle structure refers to a fine structure having a further fine irregular shape superimposed on a fine irregular shape surface exhibiting an anchor effect which is a mechanical coupling effect. FIG. 1 schematically shows the superposed fine particle structure. In this figure, a superimposed convex-concave shape 13 superimposed on the convex shape 11 and a superimposed convex-convex shape 14 formed in the same manner are schematically shown. Further, a superimposed concave-convex shape 15 formed so as to be superimposed on the concave shape 12 is shown. Further, the superimposed fine particle structure is formed on the raised shape 16 by the cladding. And the said structure includes the case where the alloy layer by any of a eutectic, a solid solution, or an intermetallic compound is formed.

  In addition, the step of attaching the metal powder on the surface of the metal base material is preferably sprayed by a cladding powder feeding device that can be used without selecting the shape of the object to be joined, However, it is not limited to these.

  The metal substrate includes, but is not limited to, a metal substrate made of other metals such as aluminum die cast other than aluminum alloy, stainless steel, and SPCC. In addition, the metal material includes a metal composed of a single metal element, an alloy containing two or more metal elements, and a base material obtained by plating or coating the surface of the metal base material.

As an example of the mixed powder having a particle diameter of 1 μm to 100 μm in FIG. 2, the particle diameter of a mixed powder of boron carbide, titanium and aluminum of F240 (JIS R6001 abrasive particle size). The data which measured distribution of are shown. (However, those that are atomized during mixing are included.)

  A second invention is the method for forming a superimposed fine particle structure according to the first invention, wherein the carbide is boron carbide.

  A third invention is the method of forming a superposed fine particle structure according to the first or second invention, wherein the mixed powder includes a powder made of the same metal as the metal substrate. .

  A fifth invention is a method for forming a superimposed fine particle structure according to any one of the first to fourth inventions, wherein the laser cladding is performed using an assist gas of nitrogen.

  The sixth invention includes a step of pressing the planned joining surface of the metal base material having the superimposed fine particle structure formed in any one of the first to fifth inventions, and the joining planned surface of the plastic, The step of applying energy for heating the pressed interface and the step of engaging the plastic by melting the plastic melted as a result of the heating into and enveloping the superposed fine particle structure, It is a method of joining.

  Here, the step of applying energy for heating the interface includes not only laser irradiation, but also hot press heating, ultrasonic vibration, and insert molding, and is not limited thereto. In the step of irradiating and heating the laser beam, a method in which the laser beam is incident from the plastic side is generally used. However, the laser beam absorbs the plastic, and the other metal substrate is the laser beam. In contrast to the general case, the contact interface with the plastic can be heated by the heat transfer of the metal by laser light irradiation from the metal substrate side.

  According to the present invention, it is possible to efficiently form a superposed fine particle structure at a low cost, and as a result, it is possible to reduce the cost and improve the productivity of a method for joining a metal base material and a plastic using this structure. it can.

It is the figure which showed the superposition fine particle structure in simulation It is measurement data of particle size distribution of mixed powder. It is the figure which showed the joining plan surface on a metal base material. It is a figure of the nozzle for laser cladding coaxial with the optical axis of a laser. It is the state of the metal substrate surface which gave laser cladding. It is an enlarged SEM photograph of a superposed fine particle structure. It is a figure which shows a mode that the metal base material and laser before laser joining were contact | abutted and pressed. It is the figure which showed the mode of laser joining. A composite material in which plastic is broken by twisting is shown. The shear test result of a composite member is shown. FIG. 6 is a diagram showing a cladding position by a laser spot in Example 2. An outline of a laser cladding method using side assist nitrogen gas is shown. It is a SEM photograph of a superposition fine particle structure. The photograph which expanded the magnification of the photograph shown in FIG. 13, and the analysis photograph of surface structure are shown. A state in which a part of the superposed fine particle structure observed with a scanning electron microscope is subjected to elemental analysis with an X-ray diffraction apparatus is shown. It is a figure which shows the state after peeling the composite member by which laser bonding was carried out. The relationship between the presence or absence of nitrogen assist gas and the bonding strength in laser cladding is shown. It is the schematic of the apparatus structure for joining by the hot press method of Example 3. FIG. The state of the aluminum base material and CFRTP joined by the hot press method is shown.

Hereinafter, a preferred embodiment of the present invention will be described in steps with reference to the drawings. Note that matters that are not particularly mentioned in the present specification and are necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

S1) Preparation of Metal Substrate In this example, as the metal substrate 1, a plate of aluminum alloy (A5052) having a width of 20 mm, a length of 50 mm, and a thickness of 1 mm was prepared. A part of this metal base material was provided with a planned joining surface 2 which is hatched in FIG.

  In addition, as a metal base material, the base material which consists of other metal materials, such as aluminum die-casting, stainless steel, SPCC other than an aluminum alloy, can be used. In addition, the metal material includes a metal composed of a single metal element, an alloy containing two or more metal elements, and a metal substrate surface plated or coated.

S2) Preparation of metal powder As the metal powder, the same aluminum metal powder, boron carbide powder and titanium metal powder as the metal substrate were prepared. Each metal powder is commercially available, and its particle size is in the range of 1 μm to 100 μm. In addition, although the molar ratio of each powder is a design matter, in this example, it is 1: 1: 3 in the order of aluminum metal powder, boron carbide, and titanium metal powder.

S3) Setting of Powder Feeder The same amount of each metal powder is put into two standard powder hoppers in a powder feeder of a powder feeder made by GTV, which is a powder feeder. Since this powder hopper is also equipped with a mixer for stirring as standard, it is not necessary to mix each powder in advance. In the next step, laser cladding, the mixed powder 31 is supplied to the surface of the metal substrate.

S4) Laser Cladding Laser cladding was performed on the planned joining surfaces of the metal substrates. At this time, the mixed powder 31 is supplied from the powder feeding device in step S3 through the powder feeding nozzle 42 coaxial with the cladding nozzle 41. As shown in FIG. 4, in this embodiment, semiconductor laser light having a wavelength of 970 nm shaped into a spot beam 4 having a diameter of 3 mm using an optical system was used. The scanning speed of the spot beam 4 was varied from 30 mm / s to 80 mm / s depending on the shape of the target superposed fine particle structure and the number of particles, and an optimum value as a combination with other cladding parameters was selected.

  In Table 1 below, combinations of parameters in Sample Nos. 0314-1, 0314-4, and 0314-6 that obtained good results from the samples that were attempted to form a superimposed fine particle structure in Example 1. Indicates.

  Based on the above results, the appearance of the superimposed fine particle structure 5 formed on the surface of the metal substrate is shown in FIG. In this surface photograph, it can be confirmed that the laser-irradiated site is discolored and an alloy region different from the metal substrate is formed. Moreover, in FIG. 6, it is the micrograph of those 5 times and 20 times. According to this photograph, formation of a superimposed fine particle structure can be further confirmed.

S5) Preparation of Plastic Member A sheet made of PA66 having a width of 20 mm, a length of 50 mm, and a thickness of 1 mm was prepared as the plastic member 71. In the present embodiment, the surface to be joined is not strictly defined on the plastic member 71. However, when the plastic member is a molded product, it is necessary to determine this.

S6) Abutment and pressing of metal base material and plastic member The superposed fine particle structure surface 5 formed on the planned joining surface of the metal base material in step S4 and the plastic member 71 are brought into contact with each other and pressed. did. As shown in FIG. 7, the pressing is supported by a metal backing plate 6 from the metal substrate side, the resin member is sandwiched between glass 81 (Tempax, thickness 5 mm), and on the display by a hydraulic pump. A pressure of 0.12 MPa was applied.

  In general, it is preferable to select an optimum condition for the degree of pressing in a pressure range of 0.1 to 3 MPa. When the selected pressure is appropriate and the initial pressure is maintained, the molten plastic described later uniformly enters the superposed fine particle structure formed on the metal substrate, and the joint strength between the two is sufficiently increased. . On the other hand, when pressure due to pressing is concentrated on a part of the raised shape, it is recommended to optimize the glass 81 with the point that the glass 81 is broken.

S7) Laser Joining Laser joining was performed by irradiating the laser spot 9 of the semiconductor laser shaped into a spot shape from the side of the plastic member 71 pressed against the joining surface of the metal base material in step S6. FIG. 8 shows this state. The irradiation conditions of the laser spot 9 were an average output of 100 W, a repetition frequency of 1000 Hz, a duty of 50%, and a scanning speed of 10 mm / s. The beam shaping is not limited to a circular spot shape, and can be optimized as appropriate depending on the shape and total area of the surface to be joined and the output of the laser to be used. Similar to laser cladding, the type of laser is not limited to a semiconductor laser.

  In this embodiment, the laser beam used for the cladding in step S4 is used. The wavelength 970 nm is a wavelength that transmits the plastic member 71. It should be noted that other lasers can be used as long as the wavelength is transparent to the plastic used. Specific parameters are shown in Table 2 below.

  Since the alloy layer having the superposed fine particle structure 5 formed by the cladding in step S4 is not transmissive to the wavelength of the laser beam, the laser beam that has passed through the plastic member 71 and has been irradiated onto the surface to be joined. It absorbs light and is converted into heat. The converted heat propagates to the joining surface of the pressed plastic member 71 and melts it. The molten plastic enters and wraps up the superposed fine particle structure 5, and as a result, the metal substrate 1 and the plastic member 71 are firmly bonded.

  FIG. 9 shows the shear tensile strength test result of the composite member composed of the metal base material and the plastic member 71 joined by the above steps. It can be seen that the joining force is strong and the plastic member 71 is broken. Similarly in FIG. 10, the measurement result of the shear tensile strength is shown.

  In Example 2, an attempt was made to form a superposed fine particle structure using a pre-kneaded mixed powder without using a powder feeder, and the formation region and the plastic member were combined by a laser welding technique. An attempt was made to create a composite material of metal and plastic.

S1) Preparation of Metal Base As in Example 1, a plate of aluminum alloy (A5052) having a width of 20 mm, a length of 50 mm, and a thickness of 1 mm was prepared as the metal base 1. And the joining plan surface 2 was set similarly.

S2) Preparation of metal powder The metal powder was prepared in the same manner as in Example 1 by preparing F240 boron carbide and titanium and aluminum metal powders having a particle size distribution equivalent to this. These were kneaded. The mixing ratio is 1: 1: 3 as the molar ratio in this order, but it is a design item that should be varied according to other parameters.

S3) Adhesion of mixed powder to metal base material The mixed powder 32 prepared in step S2 was attached to the surface to be bonded on the metal base material surface by a coating method so that the thickness was uniform. Although the coating thickness is generally 10 to 50 μm, this is also a numerical value that should be optimized in light of the parameters of laser cladding in the next step and the joint strength of the finally obtained component members. In the case where a superposed fine particle structure is to be formed on the joining surface of a metal base material that is difficult to apply due to a three-dimensional structure or low cost, a cladding powder feeding apparatus is used as in Example 1. It is preferable to use it.

S4) Laser Cladding Laser cladding was performed on the mixed powder 32 adhering to the joining surface of the metal substrate in step S3. As shown in FIG. 11, in Example 2, a semiconductor laser beam having a wavelength of 970 nm shaped into a spot beam 4 having a diameter of 1 mm using an optical system was used. The scanning speed of the spot beam 4 was varied from 30 mm / s to 100 mm / s depending on the shape of the superimposing fine particle structure and the number of particles. The spot beam 4 was scanned over a width of 20 mm, and an area of 40 mm ² or more was clad.

  Moreover, as shown in FIG. 12, nitrogen gas was also blown at 5 liters / minute. The arrow represents the scanning direction of the laser spot beam. In the second embodiment, nitrogen gas is supplied by the side nozzle method as shown in FIG. 12, but it may be supplied coaxially (concentrically) with the laser used in the first embodiment.

  The laser used for the laser cladding is not limited to the semiconductor laser used in this embodiment, a fiber laser, an Nd: YAG laser, a carbon dioxide gas laser, or any other laser capable of heating the mixed powder to be used. Table 3 below shows combinations of parameters in laser cladding.

A plurality of photographs of the superposed fine particle structure 5 obtained in step S4 are collectively shown in FIG. In this surface photograph, it can be confirmed that the laser-irradiated site is discolored and an alloy region different from the metal substrate is formed. Here, the four photographs show the case where the upper part is without assist gas and the lower part is when nitrogen assist gas is sprayed at 5 L / min, and the left column is a combination of the thickness of the applied mixed powder 32 and the laser scanning speed parameter. Is 50 μm coating thickness and 50 mm / s, and the right column is a combination of 10 μm coating thickness and 100 mm / s. The scale bars are all 500 μm.

  In FIG. 13, each of the upper and lower superposed fine particle structures 5 shown in the right column is enlarged about 30 times (scale bar: 10 μm) and shown in the center column of FIG. 14. The lower figure using nitrogen assist gas is further magnified 10 times (scale bar: 1 μm) and shown on the right side of the figure (lower right). On the other hand, for the superposed fine particle structure 5 without the nitrogen assist gas in the upper stage, the result of analyzing the eutectic state of the surface of the superposed fine particle structure with the same magnification is shown (upper right). The photo on the left shows that there is a lot of aluminum distribution in the circled area, and the photo on the right shows that the distribution of titanium is also high.

  FIG. 15 shows a state in which a part of the superposed fine particle structure observed with a scanning electron microscope is subjected to elemental analysis using an X-ray diffractometer. Magnesium (Mg) silicon (Si) was detected on the superposed microstructure surface by energy dispersive X-ray analysis. Since the mixed powder 32 contains neither magnesium nor silicon, it is a result of the magnesium and silicon contained in the aluminum metal substrate 1 being diffused and distributed in the alloy layer.

S5) Preparation of Plastic Member A sheet made of PA66 having a width of 20 mm, a length of 50 mm, and a thickness of 2 mm was prepared as the plastic member 72. In the second embodiment, the surface to be joined is not strictly defined on the plastic member 72. However, when the plastic member is a molded product, it is necessary to determine this.

S6) Abutting and pressing of metal base material and plastic member In step S4, the superposed fine particle structure surface 5 formed on the planned joining surface of the metal base material and the plastic member 72 are brought into contact with each other and pressed. did. The method is the same as in Example 1.

S7) Laser Joining Laser joining was performed by irradiating the laser spot 9 of the semiconductor laser shaped into a spot shape from the side of the plastic member 72 pressed against the planned joining surface of the metal base material in step S6. This method is also the same as in the first embodiment.

  Also in Example 2, the laser beam used for the cladding in step S4 was used. The wavelength 970 nm is a wavelength that transmits the plastic member 72. It should be noted that other lasers can be used as long as the wavelength is transparent to the plastic used. Specific parameters are shown in Table 1 below.

  Since the alloy layer having the superposed fine particle structure 5 formed by the cladding in step S4 is not transmissive with respect to the wavelength of the laser beam, the laser beam transmitted through the plastic member 72 and irradiated onto the surface to be joined. It absorbs light and is converted into heat. The converted heat propagates to the joining surface of the pressed plastic member 72 and melts it. The molten plastic member 72 enters and wraps up the superposed fine particle structure 5, and as a result, the metal substrate 1 and the plastic are firmly bonded.

  FIG. 16 shows the shear tensile strength test result of the composite member composed of the metal substrate 1 and the plastic member 72 joined by the above steps. As a result, a bonding strength exceeding 40 MPa was obtained. In addition, in the case where nitrogen gas is used as an assist gas and the case where it is not used, the result is that the unused one has higher bonding strength, but as seen in the error bar (± 3 sigma) in FIG. Variation in bonding strength was reduced.

  FIG. 17 shows a state after the composite member is peeled off. Part of the metal-side fine particles adhere to the surface of the plastic joint after peeling, but it is less likely to adhere using the assist gas, and the raised superposed microstructure forms an alloy layer that is in close contact with the metal substrate. I confirmed that.

In this third embodiment, the superposed fine particle structure 5 formed on the metal substrate by the same method, material and parameters as in the first embodiment, and CFRTP73 (a composite of carbon fiber and resin having no laser transparency). Carbon fiber reinforced plastic, which is a material, was joined by hot pressing instead of laser joining. FIG. 18 is a schematic configuration diagram of the apparatus. Table 4 below shows the parameters.

  In FIG. 19, the result of joining is shown. The wide sheet on the right in the photograph is a protective sheet for preventing the molten CFRTP 73 from adhering to the hot press. And it is the composite material which two sheets with which the left side overlapped were joined.

  The superposed fine particle structure can be formed efficiently at low cost, and by using this, it can be used for the production of a composite member of a metal substrate and plastic with low cost and high productivity.

DESCRIPTION OF SYMBOLS 1 Metal substrate 11 Convex shape 12 Concave shape 13 Superposition convex-concave shape 14 Superposition convex-convex shape 15 Superposition concave-convex shape 16 Raised shape 2 Surface to be joined 31 Mixed powder 32 Mixed powder (kneading type) )
4 Laser spot for cladding (spot beam 4)
41 Cladding nozzle 42 Powder feeding nozzle 5 Superposed fine particle structure 6 Backing plate 71 Plastic member (PA66, thickness 1 mm)
72 Plastic member (PA66, thickness 2mm)
73 CFRTP
81 Glass 82 Heater 83 Hydraulic press 9 Joining laser spot (spot beam 9)

Claims (5)

A method of forming a superimposed fine particle structure on a metal substrate surface,
Including a carbide powder and a titanium powder each having a particle size of 1 μm to 100 μm on the surface of the metal substrate, and attaching a mixed powder obtained by mixing them;
Applying a laser cladding to the surface to which the mixed powder is adhered while causing the surface to rise; and
A method for forming a superposed fine particle structure.   The method for forming a superimposed fine particle structure according to claim 1, wherein the carbide is boron carbide.   The method for forming a superimposed fine particle structure according to claim 1, wherein the mixed powder includes a powder made of the same metal as the metal substrate. The laser cladding method for forming a superimposed fine particle structure according to any one of claims 1 to 3, characterized in that applied by using an assist gas with nitrogen. Pressing a planned joining surface of the metal base material having a superimposed fine particle structure formed by using the method for forming a superimposed fine particle structure according to any one of claims 1 to 4 and a planned joining surface of a plastic And a process of
Applying energy for heating the pressed interface;
A method of joining the metal substrate and the plastic by a process in which the plastic melted as a result of the heating enters and wraps in the superposed fine particle structure to engage with each other.