KR102109127B1 - Method of joining metal and plastic using hot metal pressing - Google Patents

Abstract

The present invention provides a method of joining metal and plastic using a high temperature metal compression method that forms a strong, sturdy, and uniform joint between metal and plastic. A method of joining metal to plastic according to an embodiment of the present invention includes: placing a metal member on a plastic member to form an overlapping portion in contact with the metal member; Placing a metal block having a first temperature on the metal member corresponding to the overlapping portion; And forming a joint in which the metal member and the plastic member are joined in the overlapping portion by placing the weight member on the metal block and pressing the overlapping portion. It is characterized by preventing the formation of bubbles in the member.

Description

Method of joining metal and plastic using hot metal pressing

The technical idea of the present invention relates to a method of joining metal and plastic using a high temperature metal compression method.

With the rapid development of technology, it is necessary to form joints in which materials of different properties are bonded to each other to manufacture engineering structures and mechanical components. In most applications, it is difficult to use one type of material to meet the demands for unique properties such as high strength, high corrosion resistance, high conductivity, high toughness and light weight. Thus, by bonding different materials with different properties, it is possible to meet this need. In particular, in the technical field requiring high performance, such as automobile technology or aircraft technology, it is important in the field where materials need to be improved to have required special characteristics, and furthermore, it requires light weight to reduce fuel consumption. Polymeric plastics can meet the required properties such as high corrosion resistance, high formability and light weight [1]. In particular, polymer composites such as carbon fiber reinforced plastics can provide additional properties such as high fatigue strength, high corrosion resistance, and high weight to strength ratio [2-6]. On the other hand, metals such as magnesium can provide high thermal conductivity, good castability and easy recyclability [7,8]. Therefore, there is a need to develop a technology for forming a stronger, more robust, and more uniformly bonded metal-plastic joint.

[1] R.J. Crawford, Plastics Engineering, 3rd edition, Butterworth-Heinmann, Oxford, 1998, pp. 1-40. [2] L. Ye, Y. Lu, Z. Su, G. Meng, Functionalizedcomposite structures for new generation airframes, a review, Compos. Sci. Technol. 65 (2005) 1436-1446. [3] P. Beardmore, C.F. Johnson, The potential for composites in structural automotive applications, Compos. Sci. Technol. 26 (4) (1986) 251-281. [4] T. Roberts, Rapid growth forecast for carbon fiber market, Reinf. Plast. 51 (2007) 10-13. [5] K.L. Edwards, An overview of the technology of fiber-reinforced plastics for design purposes, Mater. Des. 19 (1998) 1-10. [6] H. Adam, Carbon fiber in automotive applications, Mater. Des. 18 (1997) 349-355. [7] K.U. Kainer, F. Von Buch, The currentstate of technology and potential for further development of magnesium applications, in: Magnesium Alloys and Technol., Wiley-VCH, Weinheim, 2003, pp. 1-22. [8] B.L. Mordike, T. Ebert, Magnesium: properties-applications-potential, Mater. Sci. Eng. A 302 (2001) 37-45. [9] R.W. Messler, Joining of Materials and Structures, Butterworth-Heinmann, Oxford, 2004, pp. 722-730. [10] S.T. Amancio Filho, Development and analysis of a new joining technique for polymer-metal multi-materialstructures, Weld. World 55 (2011) 13-24. [11] S.B. Kumar, I. Sridhar, S. Sivashanker, S.O. Osiyemi, A. Bag, Tensile failure of adhesively bonded CFRP composite scarf joints, Mater. Sci. Eng. B 11 (2006) 113-120. [12] J. Li, Y. Yan, T. Zhang, Z. Liang, Experimental study of adhesively bonded CFRP joints subjectedto tensile loads, Adhes. Adhes. 57 (2015) 95-104. [13] S. Katayama, Y. Kawahito, Laser direct joining of metal and plastic, Scr. Mater. 59 (2008) 1247-1250. [14] Y. Kawahito, Y. Niwa, T. Terajima, S. Katayama, Laser direct joining of glassy metal Zr55Al10Ni5Cu30 to engineering plastic polyethylene terephthalate, Mater. Trans. 51 (2010) 1433-1436. [15] M. Wahba, Y. Kawahito, S. Katayama, Laser direct joining of AZ91D thixomolded Mg alloy and amorphous polyethylene terephthalate, Mater. Process. Technol. 211 (2011) 1166-1174. [16] P. Mitschang, R. Velthuis, M. Didi, Induction spot welding of metal-CFRP hybrid joints, Adv. Eng. Mater. 15 (2013) 804-813. [17] F. Balle, G. Wagner, D. Eifler, Ultrasonic metal welding of aluminum sheets to carbon fiber reinforced thermoplastic composites, Adv. Eng. Mater. 11 (2009) 35-39. [18] C. Ageorges, L. Ye, Resistance welding of metal / thermoplastic composite joints, Thermoplast. Compos. Mater. 14 (2001) 449-475. [19] S.T. Amancio-Filho, C. Bueno, J.F. dos Santos, N. Huber, E. Hage, On the feasibility of friction spot joining in magnesium / fiber reinforced polymer composite hybrid structures, Mater. Sci. Eng. A 528 (2011) 3841-3848. [20] P.S. Ho, Chemistry and adhesion of metal polymer interfaces, Appl. Surf.Sci. 42 (1989) 559-566. [21] J.P. Kim, H.U. Lee, J.E. Yang, J.S. Bae, E.S. Park, J.H. Yoon, J.M. Kim, C.R. Cho, Effect of plasma treatment on chemical bonding states of porous TiO2 thin films prepared from polymer-blended solution, Thin Solid Films 519 (2011) 6916-6919. [22] A. Landragin, J.Y. Courtois, G. Labeyrie, N. Vansteenkiste, C.I. Westbrook, A. Aspect, Measurement of the Van der Waals force in an atomic mirror, Phys. Rev. Lett. 77 (1996) 1464-1467. [23] K. Pilakoutas, S. Hafeez, S. Dritsos, Residual bond strength of polymer adhesive anchored reinforcement subjectedto high temperatures, Mater. Struct. 27 (1994) 527-531. [24] K.W. Jung, Y. Kawahito, S. Katayama, Laser direct joining of carbon fiber reinforced plastic to stainless steel, Sci. Technol. Weld. Join. 16 (2011) 676-680. [25] H.W. Coleman, W.G. Steele, Experimentation, Validation, and Uncertainty Analysis for Engineers, John Wiley & Sons, United States, 2009, pp. 48-50. [26] K.W. Jung, Y. Kawahito, M. Takahashi, S. Katayama, Laser direct joining of carbon fiber reinforced plastic to zinc-coated steel, Mater. Des. 47 (2013) 179-188. [27] The materials project-reaction calculator. https://www.materialsproject.org/apps/reaction calculator /.

A technical problem to be achieved by the technical idea of the present invention is to provide a method of bonding metal and plastic using a high temperature metal compression method that forms a strong, sturdy, and uniform joint between metal and plastic.

However, these problems are exemplary, and the technical spirit of the present invention is not limited thereto.

The metal-plastic joining method using the high-temperature metal compression method according to the technical idea of the present invention for achieving the above technical problem is to place a metal member on a plastic member so that the metal member and the plastic member come into contact with each other. Forming; Placing a metal block having a first temperature on the metal member corresponding to the overlapping portion; And forming a joint in which the metal member and the plastic member are joined in the overlapping portion by placing the weight member on the metal block and pressing the overlapping portion. It is characterized by preventing the formation of bubbles in the member.

In some embodiments of the present invention, before the step of forming the overlapping portion, the method may further include forming an oxide layer on the surface of the metal member.

In some embodiments of the present invention, the oxide layer may be porous.

In some embodiments of the present invention, the step of forming the oxide layer may be annealing for more than 0 to 20 minutes at 400 to 600 ° C.

In some embodiments of the present invention, the oxide layer may have a thickness in the range of 0.1 to 5 μm.

In some embodiments of the present invention, the first temperature may range from 400 ° C to 600 ° C.

In some embodiments of the present invention, in the step of forming the junction, it may be to pressurize to 0.1 to 0.3 MPa.

In some embodiments of the present invention, the metal block may include at least one of copper alloy, aluminum alloy and carbon steel.

In some embodiments of the present invention, the metal member may include at least one of aluminum alloy, titanium alloy and magnesium alloy.

In some embodiments of the present invention, the metal member may include AZ31 magnesium alloy.

In some embodiments of the present invention, the plastic member may include a carbon fiber reinforced plastic containing a thermoplastic resin and carbon fiber.

In some embodiments of the present invention, the thermoplastic resin may be at least one selected from thermoplastic polyurethane and polyamide.

The metal-plastic bonding method using the high-temperature metal compression method according to the technical idea of the present invention is a high-temperature metal compression method as a method of bonding a new material. In order to bond the carbon fiber reinforced plastic (CFRP) sheet and the AZ31 magnesium alloy sheet, the performance, properties and mechanisms of the high temperature metal compression method were studied. In order to examine the effects of the present invention, two types of AZ31 magnesium alloy sheets were prepared. One is an AZ31 magnesium alloy sheet in which an oxide layer is not formed, and the other is an AZ31 magnesium alloy sheet in which an oxide layer is formed by annealing at different holding times. It can be seen that the oxide layer formed on the surface of the magnesium alloy by annealing has a significant effect on the bonding strength of the joint. In the results of the tensile shear test, when the oxide layer was included, the joint showed a high strength of approximately 5.1 kN. When the oxide layer was not formed, bubbles were formed and separated from the carbon fiber reinforced plastic adjacent to the bonding interface, but when the oxide layer was formed, no bubbles or separation were observed, which would contribute to the improvement of mechanical strength. Can be. In addition, in the case of annealing, it was analyzed that the oxide layer grew into the carbon fiber reinforced plastic adjacent to the bonding interface of the joint, thereby providing a possibility of a mechanical fixing effect that greatly increases the bonding strength.

The above-described effects of the present invention have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a flowchart illustrating a method of joining metal and plastic using a high temperature metal compression method according to an embodiment of the present invention.
2 is a scanning electron microscope photograph showing the microstructure of a metal member and a plastic member used in a method of joining metal and plastic using a high temperature metal compression method according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing an apparatus for performing a method of joining metal and plastic using the high-temperature metal compression method of FIG. 1 according to an embodiment of the present invention.
4 is a scanning electron microscope photograph of a junction of a metal-plastic assembly formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
5 is a photograph showing front and rear surfaces of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
FIG. 6 is a graph showing tensile shear load for annealing time of a metal-plastic joint formed using a metal-plastic joining method using a high-temperature metal compression method according to an embodiment of the present invention.
7 to 10 are scanning electron micrographs of a junction portion of a metal-plastic assembly formed by using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
FIG. 11 are photographs showing surfaces destroyed by a tensile shear test of a metal-plastic joint formed using a metal-to-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
FIG. 12 are scanning electron micrographs showing surfaces destroyed by a tensile shear test of a metal-plastic assembly formed using a metal-to-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
13 is a scanning electron micrograph and EDS mapping showing the fractured surfaces by a tensile shear test of a metal-plastic assembly formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. Is the result.
14 are graphs showing X-ray photoelectron spectroscopy analysis of a fractured surface of a metal-plastic assembly formed using a metal-to-plastic bonding method using a high temperature metal compression method according to an embodiment of the present invention.
15 is a transmission electron microscope photograph of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
FIG. 16 is a transmission electron micrograph and EDX element mapping of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
17 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
18 is a dark-field transmission electron micrograph and EDX analysis of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
19 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
20 is a transmission electron micrograph and EDX element mapping of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
21 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
22 is a dark-field transmission electron micrograph and EDX analysis of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.
23 is a schematic diagram illustrating a mechanism of a high-temperature metal compression bonding technique for a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more fully explain the technical spirit of the present invention to a person having ordinary knowledge in the art, and the following embodiments can be modified in various other forms. The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete, and to fully convey the technical spirit of the present invention to those skilled in the art. The same reference numerals in the present specification mean the same elements. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings. Note that, in this specification, “AZ31” is used as an abbreviation referring to the AZ31 magnesium alloy sheet, and “CFRP” is used as an abbreviation referring to the carbon fiber reinforced plastic sheet.

The technical idea of the present invention relates to a new material bonding technique known as hot metal pressing (HMP), and to a technique of bonding different materials, for example, metal and plastic.

As a technique for bonding materials, mechanical bonding techniques such as mechanical locking [9], staking, crimping, and friction riveting can be used [10]. In addition, as another technique for bonding materials, there is an adhesive bonding technique, and adhesives such as polyurethane, acrylic, and epoxy can be used [11,12]. However, the above-described mechanical bonding technology and adhesive bonding technology for bonding materials have limitations. For example, additional work may be required to form a hole by drilling or drilling in a mechanical joint, a long time may be required for joining, the strength of the joint may be non-uniform, it needs to be tightly controlled, and adhesive bonding is also required. You need to use expensive glue for.

In order to overcome the limitations of the conventional material bonding technology, efficient, effective, and reliable material bonding technologies have been developed. As a new joining technology, laser-assisted metal and plastic direct joining (LAMP), [13-15], induction spot welding technology [16], ultrasonic metal welding technology [17], Resistance welding technology [18] and friction point bonding technology [19]. Among them, the direct bonding technique of metal-plastic using the laser, such as using a continuous Nd: YAG laser having a Gaussian beam or using a continuous diode laser having a linear beam, is the most famous, because chemical bonding [20 -22], because stronger bonding can be formed by physical bonding [13,14,22] and mechanical bonding [23]. The conventional results using the direct bonding technique of metal-plastic using such a laser were to bond a carbon fiber reinforced plastic sheet and a 3 mm stainless steel sheet using a continuous wave disc laser, thereby overlapping the joint with a tensile shear load of 4.8 kN. Formed [24].

1 is a flowchart illustrating a method (S100) of joining metal and plastic using a high temperature metal compression method according to an embodiment of the present invention.

Referring to Figure 1, the method of bonding the metal and plastic (S100), forming an oxide layer on the surface of the metal member (S110); Placing the metal member on a plastic member to form an overlapping portion in contact with the oxide layer and the plastic member (S120); Positioning a metal block having a first temperature on the metal member corresponding to the overlapping portion (S130); And placing a weight member on the metal block and pressing the overlapping portion to form a junction in which the metal member and the plastic member are joined at the overlapping portion (S140).

In detail, in the step of forming the oxide layer (S110), the annealing temperature is 400 to 600 ° C, and the annealing time may be performed for more than 0 minutes to 20 minutes. When the annealing temperature and the annealing time are satisfied, the oxide layer may be formed to a thickness of 0.1 to 5 μm, more preferably 1 to 3 μm.

In the present invention, the oxide layer serves to prevent the heat having the first temperature from being rapidly transferred from the metal member to the plastic member. The oxide layer prevents bubbles from being formed, thereby preventing gaps, cracks, and the like at the junction interface.

In addition, the oxide layer may grow into the plastic member during the forming of the junction (S140). That is, the oxide layer may have branch portions having branch shapes grown inside the plastic member. The branch portion has an effect of fixing the plastic member and the metal member more strongly.

Meanwhile, the oxide layer according to the present invention may be a porous oxide layer. That is, when the oxide layer is porous, in the step of forming the junction, it may serve as a passage through which bubbles are discharged to the outside. Accordingly, the present invention can improve the bonding force between the metal member and the plastic member because the air bubbles can be removed by providing the oxide layer.

In detailing the present invention, the metal block may be a metal having good thermal conductivity and high temperature durability. As a specific example, the metal block may include at least one of copper alloy, aluminum alloy, and carbon steel.

In detailing the present invention, the metal member is sufficient as long as it is a metal or alloy capable of forming an oxide film having excellent corrosion resistance and rigidity. As a specific example, the metal member may include at least one of aluminum alloy, titanium alloy, and magnesium alloy.

In detailing the present invention, the plastic member may be melted by heat and have high strength while being able to bond with the metal member. The plastic member may include a carbon fiber reinforced plastic (CFRP) containing a thermoplastic resin and carbon fiber.

As a specific example, the thermoplastic resin may have a glass transition temperature of about 120 to 160 ° C, and a melting point of about 350 to 450 ° C. As a preferred example, the thermoplastic resin may include any one or two or more of a thermoplastic polyurethane, polyamide, PA6 material.

Experiment method

AZ31 magnesium alloy sheet was selected as the metal member. The AZ31 magnesium alloy was formed by rolling through a reversible warm mill after performing a double roll strip casting process, and the thickness was 2.0 mm. The chemical composition of the AZ31 magnesium alloy sheet was 2.9% Al, 0.75% Zn, 0.33% Mn, 0.03% Si, and the balance of Mg by weight ratio.

A carbon fiber reinforced plastic sheet was selected as the plastic member. The carbon fiber reinforced plastic sheet was composed of a plastic matrix comprising thermoplastic polyurethane (TPU) and long fiber pellets of finely chopped carbon fibers having a length of approximately 7 mm and a diameter of 15 μm. The carbon fiber reinforced plastic sheet was manufactured in an autoclave using a carbon fiber fabric having two layers. The glass transition temperature of the carbon fiber reinforced plastic sheet was approximately 143 ° C, and the melting temperature was 397 ° C.

After the mechanical polishing was completed, microstructures of the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet were observed using a scanning electron microscope. The AZ31 magnesium alloy sheet was etched for about 15 seconds using a solution containing 100 ml ethanol, 5 g picric acid, 5 ml acetic acid and 10 ml deionized water. After the etching was finished, the etched AZ31 magnesium alloy sheet was immersed in boiling ethanol to remove the etching solution layer formed on the surface after etching.

2 is a scanning electron microscope photograph showing the microstructure of a metal member and a plastic member used in a method of joining metal and plastic using a high temperature metal compression method according to an embodiment of the present invention.

In Fig. 2, (a) is an AZ31 magnesium alloy sheet, and (b) and (c) are carbon fiber reinforced plastic sheets.

Referring to FIG. 2, the AZ31 magnesium alloy sheet has a microstructure of a shape filled with recrystallized particles having twin structures, and has heterogeneous particles. The particles had an average particle size of approximately 18 μm. The carbon fiber reinforced plastic sheet exhibited a microstructure having carbon fibers arranged in a unique pattern within the plastic matrix.

FIG. 3 is a schematic diagram showing an apparatus for performing a metal-to-plastic bonding method (S100) using the high-temperature metal compression method of FIG. 1 according to an embodiment of the present invention. The device can perform a high temperature metal compression method.

3, the size of the base steel sheet is 150 mm x 90 mm x 10 mm. In addition, the two fixing plates have a size of 60 mm x 20 mm x 10 mm, and each has two through holes. After the AZ31 magnesium alloy sheet as the metal member and the carbon fiber reinforced plastic sheet as the plastic member were cleaned with alcohol, an AZ31 magnesium alloy sheet was laminated on the carbon fiber reinforced plastic sheet on the base steel sheet and 40 mm of Arranged to form overlapping portions to have overlapping portions. Subsequently, the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet are compressed using the fixing plate. The crimping may be performed by inserting bolts into the through holes of the fixing plate and applying a torque of 120 N cm to each bolt.

Next, a metal block made of copper having a size of 40 mm x 50 mm x 60 mm and a dead weight of 20 kg are prepared. The metal block is heated for about 15 minutes, for example 400 ° C., 500 ° C.? And a target temperature such as 600 ° C. Subsequently, the heated metal block is placed on the overlapping portion of the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. The pressure is then immediately applied to the metal block for about 5 minutes using a 20 kg load weight member. Additionally, an insulator may be interposed between the metal block and the weight member to prevent heat transfer from the metal block to the weight member. Accordingly, a metal-plastic joint in which the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet are joined is formed.

For reference, the AZ31 magnesium alloy sheet is prepared as an example in which an annealing treatment is performed to form an oxide layer in a separate process and a comparative example in which an oxide layer is not formed. In the following examples, annealing was performed in a general electric furnace and was performed in atmospheric pressure and air. In detail, the annealing was performed between 1 minute and 20 minutes while maintaining 500 ° C in an oxidizing atmosphere containing oxygen.

Table 1 is a table showing the experimental conditions in the case of forming a metal-plastic assembly using a metal-plastic bonding method according to an embodiment of the present invention.

Metal-plastic joint designations Metal block temperature (℃) Annealing time (minutes) HMP (A0, A1, A2, A3, A4) 400 0, 2, 5, 10, 20 HMP (B0, B1, B2, B3, B4) 500 0, 2, 5, 10, 20 HMP (C0, C1, C2, C3, C4) 600 0, 2, 5, 10, 20

Referring to Table 1, HMPA is a case where the metal block temperature is 400 ° C, HMPB is a case where the metal block temperature is 500 ° C, and HMPC is a case where the metal block temperature is 600 ° C. HMPA0, HMPB0, and HMPC0 are for unoxidized AZ31 magnesium alloy sheets, HMPA1, HMPB1, and HMPC1 are for AZ31 magnesium alloy sheets that have been annealed for 2 minutes to form an oxide layer, HMPA2, HMPB2, and HMPC2 Silver is the case of AZ31 magnesium alloy sheets that have been annealed for 5 minutes to form an oxide layer, HMPA3, HMPB3, and HMPC3 are the case of AZ31 magnesium alloy sheets that have been annealed for 10 minutes to form an oxide layer, HMPA4, HMPB4, And HMPC4 is the case of AZ31 magnesium alloy sheets that have been annealed for 20 minutes to form an oxide layer.

Ether, a tensile shear test was performed on a metal-plastic joint at room temperature using a universal tensile testing machine (Instron-5982, maximum load is 100 kN). For the tensile shear test, the AZ31 magnesium alloy had dimensions of 150 mm x 28 mm x 2 mm, and the carbon fiber reinforced plastic sheet had dimensions of 150 mm x 28 mm x 1 mm. The stroke was applied at 2 mm / min. The extensometer was attached to the metal part during the test.

The cross-sections of the bonding interfaces and the surfaces broken by the tensile test were analyzed for the metal-plastic joint using a JSM-7001F-scanning electron microscope. In addition, after the bonding interfaces were peeled off using a focused ion beam (FIB, FEI Helios Nano-Lab 600), a transmission electron microscope analysis of the cross sections of the bonding interfaces was performed.

X-ray photoelectron spectroscopy was performed on the metal-plastic conjugates by using an X-ray photoelectron spectroscopy (Mode 1 K-Alpha + Thermo) on the surfaces destroyed by the tensile test. As the X-ray source, a monochromatic aluminum source was used (Al Kα line: 486.6 eV). For a sample having a diameter of approximately 400 μm, the voltage was 12 kV and the current was 10 mA.

Experiment result

4 is a scanning electron microscope photograph of a junction of a metal-plastic assembly formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 4, (a) corresponds to HMPB1, (b) to HMPB2, (c) to HMPB3, and (d) to HMPB4.

4, it can be seen that the interfaces of the overlapping portion between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic are shown, and the oxide layers are formed on the interfaces. It is analyzed that the thickness of the oxide layer depends on the annealing time of the AZ31 magnesium alloy sheets. Specifically, HMPB1 has an oxide layer having a thickness of 180 nm, HMPB2 has an oxide layer having a thickness of 565 nm, HMPB3 has an oxide layer having a thickness of 820 nm, and HMPB4 has an oxide layer having a thickness of 1230 nm. Therefore, as the annealing time increases, the thickness of the oxide layer formed on the magnesium surface increases.

Figure 5 is a photograph showing the front (front side) and back (back side) of the metal-plastic assembly formed by using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 5, (a) corresponds to HMPA0, (b) to HMPA3, (c) to HMPB3, and (d) to HMPC3.

Referring to FIG. 5, the metal-plastic joint formed an excellent joint, and the average joint area was approximately 1120 mm ² . By the bonding process, small plastic aggregates were formed on the side surfaces of the bonding portion as indicated by the red arrows in FIGS. 5 (c) and 5 (d). The plastic aggregates were clearly seen in HMPB and HMPC, but not clearly in HMPA. In addition, the plastic aggregate showed a larger distribution and size in HMPC compared to HMPB. On the other hand, in HMPA, the distribution and size of the plastic aggregate was relatively small. It is analyzed that these plastic aggregates are formed at the bonding interfaces by melting and flowing the carbon fiber reinforced plastic during the bonding process. It is analyzed that a part of the molten carbon fiber reinforced plastic protrudes to the outside of the joint by pressing by the goods weight member. In addition, the reason why the size and dispersion of the plastic aggregates in the HMPA, HMPB and HMPC are different is analyzed to be due to the difference in the temperature of the metal block used in the bonding process. For example, since the temperature of the metal block of HMPC is 600 ° C, the melting of the carbon fiber reinforced plastic may be stronger than that of 400 ° C HMPA and 500 ° C HMPB.

FIG. 6 is a graph showing tensile shear load for annealing time of a metal-plastic joint formed using a metal-plastic joining method using a high-temperature metal compression method according to an embodiment of the present invention. For reference, in FIG. 6, HMPA has a metal block temperature of 400 ° C, HMPB is 500 ° C, and HMPC is 600 ° C.

Referring to Figure 6, tensile shear tests were performed to evaluate the bond strength of metal-plastic joints formed under different process conditions. The tensile shear test results show the tensile shear load versus annealing time at different metal block temperatures. The ratio of the maximum allowable deviation to the standard deviation (according to Chauvenet's standard) in the tensile shear load value was 1.38 [25].

In HMPA, the tensile shear load of the metal-plastic joint without the oxide layer (ie, the annealing time is 0 minutes) was 1.6 kN. In the case of an annealing time of 2 minutes, that is, when the metal-plastic joint has an oxide layer, the tensile shear load was reduced to show 1.3 kN, and then increased again, for an annealing time of 5 minutes, 1.9 kN, 10 minutes. The annealing time of 2.9 kN. For an annealing time of 10 minutes, the metal-plastic joint had a maximum tensile shear load. It was then reduced to show 1.8 kN for an annealing time of 20 minutes.

In HMPB, metal-plastic joints with an oxide layer had higher tensile shear loads than metal-plastic joints without an oxide layer. Specifically, the tensile shear load of the metal-plastic assembly without the oxide layer (ie, the annealing time is 0 minutes) was 1.9 kN. In the case of an annealing time of 2 minutes, the tensile shear load was increased to show 3.3 kN, and in the case of an annealing time of 5 minutes, the maximum value was 5.1 kN. Thereafter, as the annealing time was increased, the tensile shear load was decreased, in the case of an annealing time of 10 minutes, it was reduced to 4.3 kN, and in the case of an annealing time of 20 minutes, it was 3.8 kN. From these results, it is analyzed that the oxide layer formed on the surface of the magnesium alloy during annealing affects the strength of the joint formed in the bonding process. The oxide layer is analyzed to increase the tensile shear strength of the joint.

In HMPC, the tensile shear load increased linearly with increasing annealing time. The tensile shear load of the metal-plastic joint without the oxide layer (ie, the annealing time is 0 minutes) was 2.0 kN. The annealing time of 2 minutes was 2.2 kN, the annealing time of 5 minutes was 2.3 kN, the annealing time of 10 minutes was 2.6 kN, and the annealing time of 20 minutes was 3.6 kN. The maximum tensile shear load was seen at an annealing time of 20 minutes.

HMPB showed the highest bond strengths at all annealing times. In addition, the bonding strength of HMPC was higher than that of HMPA at annealing times of 0 minutes, 5 minutes, and 20 minutes. Through analysis of tensile shear strength, it is analyzed that the surface oxide layer affects the strength of the joint of the metal-plastic joint. In addition, the highest bonding strength was achieved when the magnesium alloy sheets were annealed between 5 minutes and 20 minutes, and a metal block at 500 ° C was used.

7 to 10 are scanning electron micrographs of a junction portion of a metal-plastic assembly formed by using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention.

Referring to FIG. 7, a cross-section of a junction to HMPB0 is shown as a metal-plastic junction without an oxide layer. In FIG. 7, (b) is an enlarged red square area of (a), and (c) is an enlarged red square area of (b). As shown by the white arrow in Fig. 7 (a), many bubbles formed adjacent to the bonding interface were observed. The size of these bubbles changed along the bonding interface, and exhibited a range of 130 nm to 850 nm. In a previous study by Jung et al. Using LAMP technology for bonding carbon fiber reinforced plastics and zinc coated steel, many bubbles with a size of less than millimeters are formed in the melting region of the carbon fiber reinforced plastic adjacent to the bonding interface. Reported. In addition, the formation of separate bubbles on the surface of the carbon fiber reinforced plastic adjacent to the bonding interface has been reported by Wahba et al [15]. Referring to (c) of FIG. 7, the carbon fiber reinforced plastic sheet is separated at the bonding interface, as indicated by the red arrow. In addition, as indicated by the blue arrow, debonding was observed along the bonding interface. As such, when bubbles are formed and the carbon fiber reinforced plastic is separated along the bonding interface, the bond between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet is lowered.

Referring to FIG. 8, a cross section of a junction to a metal-plastic junction having an oxide layer is shown. In FIG. 8, (a) and (b) correspond to HMPB1, (b) is an enlarged blue square region of (a), (c) and (d) correspond to HMPB2, and (d) is The blue square region of (c) is enlarged, (e) and (f) correspond to HMPB3, and (f) is a blue square region of (e).

Referring to (a) of FIG. 8, several bubbles were formed as indicated by white arrows, but no separation region of the carbon fiber reinforced plastic sheet such as HMPB0 in FIG. 7 was found. In addition, referring to (b) of FIG. 8, there was a close bond between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet, and no separation region was observed. From these results, it is analyzed that the oxide layer formed through annealing on the surface of the magnesium alloy has an important effect on the bonding mechanism.

8 (c), no bubbles were found at the bonding interface. In addition, referring to FIG. 8 (d), a very close bonding interface without a gap is shown between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. In addition, the separation region of the carbon fiber reinforced plastic sheet was not observed adjacent to the bonding interface.

8 (e), no bubbles were found at the bonding interface. In addition, referring to Fig. 8 (f), it shows a close bonding interface without a gap between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. In addition, the separation region of the carbon fiber reinforced plastic sheet was not observed adjacent to the bonding interface. As a result, the bond between the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet was very close, and no separation region was observed.

Referring to FIG. 9, a cross-section of a junction to HMPB3 as a metal-plastic junction having an oxide layer is shown, and an EDS mapping to the cross-section is shown. In the cross section, an oxide layer (MgO) is interposed between the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet. The oxide layer is approximately 820 nm thick and is uniformly distributed along the bonding interface. The oxide layer is analyzed to be composed of MgO from the EDS mapping results. The interface between the oxide layer and the carbon fiber reinforced plastic does not protrude and is formed smoothly. According to the carbon map, the carbon level is gradually changed along the interface of MgO and carbon fiber reinforced plastic, showing a more separated boundary between magnesium and oxygen between the two layers.

Referring to Figure 10, a cross-section of a junction to HMPB4 is shown as a metal-plastic junction having an oxide layer. In FIG. 10, (b) is an enlarged blue square area of (a). In this cross section, no bubbles were formed adjacent to the bonding interface. In addition, a bonding interface in close contact is formed between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. Therefore, it can be seen that when the oxide layer is formed on the surface of the AZ31 magnesium alloy sheet, a tight and uniform bond without a gap is formed between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. In addition, it is analyzed that the oxide layer formed on the surface of the AZ31 magnesium alloy sheet can prevent the formation of bubbles and also prevent the separation of the carbon fiber reinforced plastic sheet adjacent to the bonding interface.

FIG. 11 are photographs showing surfaces destroyed by a tensile shear test of a metal-plastic joint formed using a metal-to-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 11, (a) is HMPB0, (b) is HMPB1, (c) is HMPB2, (d) is HMPB3, and (e) is HMPB4.

Referring to FIG. 11, the fracture mode occurring on the broken surfaces was shown as interface failure. Also, a layer of carbon fiber reinforced plastic dissolved on magnesium alloy sheets can be observed. As shown in (a) of FIG. 11, it can be seen that in the case of HMPB0 in which the oxide layer is not formed, the bonding region between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet is not uniform. On the other hand, as shown in (b) to (e) of FIG. 11, in the case of HMPB1, HMPB2, HMPB3 and HMPB4 with oxide layers formed, a uniform bonding region was formed between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. As can be seen, the area of the junction region was also larger. In the case of HMPB1, HMPB2, HMPB3 and HMPB4, the molten carbon fiber reinforced plastic layer on the AZ31 magnesium alloy sheet appeared to be the same area as the melting region of the carbon fiber reinforced plastic sheet. On the other hand, in the case of HMPB0, the molten carbon fiber reinforced plastic layer on the AZ31 magnesium alloy sheet was not the same as the melting region of the carbon fiber reinforced plastic. Considering the shape of these fractured surfaces, it is analyzed that the oxide layer formed through annealing on the surface of the AZ31 magnesium alloy sheet forms a uniform and wide bonding region between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet.

FIG. 12 are scanning electron micrographs showing surfaces destroyed by a tensile shear test of a metal-plastic assembly formed using a metal-to-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In Fig. 12, (a) is the surface of the AZ31 magnesium alloy sheet of HMPB3, and (b) is the surface of the carbon fiber reinforced plastic sheet of HMPB3.

12 (a), it can be seen that the molten layer of the carbon fiber reinforced plastic sheet is attached to the surface of the AZ31 magnesium alloy sheet. Referring to (b) of FIG. 12, it can be seen that, as indicated by the dotted circle, the remainder of the molten carbon fiber reinforced plastic layer remains on the surface of the carbon fiber reinforced plastic sheet.

13 is a scanning electron micrograph and EDS mapping showing the fractured surfaces by a tensile shear test of a metal-plastic assembly formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. Is the result. In Fig. 13, (a) is the surface of the AZ31 magnesium alloy sheet of HMPB3, and (b) is the surface of the carbon fiber reinforced plastic sheet of HMPB3.

Referring to FIG. 13, a carbon peak is observed on the fractured surface of the AZ31 magnesium alloy sheet, indicating that the carbon fiber reinforced plastic is attached. On the other hand, no magnesium peak was observed on the surface of the carbon fiber reinforced plastic sheet.

X-ray photoelectron spectral spectrum analysis was performed to demonstrate that the oxide layer increases the bonding strength of the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet.

Table 2 is a table showing the formation energy of compounds that can be formed at the interface between the oxide layer and the carbon fiber reinforced plastic.

Chemical formula Space Energy of formation (eV) MgCO ₃ R3c -2.084 Mg (CO ₂ ) ₂ P21 / c -2.058 MgCO ₃ C2221 -2.084 Mg ₂ C ₃ Pmmm 0.169 Mg (OH) ₂ P3m1 -2.081 Mg ₄ H ₂ O ₅ P3m1 -2.607 Mg ₅ (HO ₃ ) ₂ P3m1 -2.675 Mg ₃ (HO ₂ ) ₂ P3m1 -2.503

Referring to Table 2, the space group and the formation energy of the compound formed on the surface of the AZ31 magnesium alloy sheet in the bonding process are shown. The formation energy was calculated using a DFT-based reaction calculator [27]. MgCO ₃ and Mg-HO compounds have very low formation energy. However, even if Mg-HO compounds show the lowest formation energy, X-ray photoelectron spectroscopy was not attempted because these compounds do not have reference data for X-ray photoelectron spectroscopy. Therefore, only for the MgO and MgCO ₃ compounds, X-ray photoelectron spectroscopy was performed and shown in FIG. 14 below.

14 are graphs showing X-ray photoelectron spectroscopy analysis of a fractured surface of a metal-plastic assembly formed using a metal-to-plastic bonding method using a high temperature metal compression method according to an embodiment of the present invention. In FIG. 14, (a) corresponds to HMPB0, and (b) corresponds to HMPB1.

Referring to FIG. 14, HMPB0 and HMPB1 showed different trends of X-ray photoelectron spectral spectra. The scanning electron microscope-EDX results of FIG. 9 have shown the possibility that a carbon-containing compound is formed at the interface between the oxide (MgO) and the carbon fiber reinforced plastic sheet. Specifically, in the case of HMPB0, the observed curve was in good agreement with the theoretical curve of MgO, whereas in the case of HMPB1, the observed curve was in good agreement with the theoretical curve of MgO and the theoretical curve of MgCO ₃ . Therefore, it is analyzed that the type of oxide layer present on the surface of the magnesium alloy sheet influences the properties of the observed spectral spectra. This contrasts with the spectra observed on the surface of the AZ31 magnesium alloy sheet where the oxide layer in HMPB0 was not formed. However, note that the binding energy of MgCO ₃ used in the above analysis is slightly different from the reference reference data. This means that the new phase observed may be a MgCO ₃ phase or another unknown phase. Therefore, at this stage, there is a limitation that it is not possible to clearly understand the characteristics of a new image possible.

15 is a transmission electron microscope photograph of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 15, (a) and (b) correspond to HMPB1, and (b) is an enlarged blue square area of (a).

15 (a), it can be seen that, as indicated by the black arrow, a branched structure is formed adjacent to the bonding interface. Referring to (b) of FIG. 15, a nanometer-sized thin oxide layer (Mg oxide) interposed between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet is observed.

FIG. 16 is a transmission electron micrograph and EDX element mapping of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In Fig. 16, it corresponds to HMPB1.

Referring to FIG. 16, the oxide layer is located in two parallel straight lines, and the oxide layer is analyzed as MgO by EDX element mapping. In addition, branched structures formed adjacent to the bonding interface are also analyzed as MgO. In addition, oxides grown in carbon fiber reinforced plastics are observed.

17 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 17, it corresponds to HMPB1, (b) is a photo in which the oxide layer is enlarged to the blue square region in (a), and (c) is a photo in which the branched structure is enlarged to the blue square region in (a).

Referring to FIG. 17, from the analysis results of the SAED pattern, it was analyzed that both the oxide layer and the branched structure consist of MgO, and is consistent with the results of FIG. 16. The oxide layer has a polycrystalline structure composed of high-angle crystal grain boundaries, as shown in the SAED pattern. On the other hand, the grain boundary of the branch-shaped structure does not appear clearly in the high-resolution transmission electron micrograph, and SAED pattern analysis shows a continuous ring pattern. Therefore, it is analyzed that the branched structure has a very fine nanoparticle structure or an almost amorphous oxide structure. However, at this stage, there is a limitation that the mechanism for forming a branched structure is not clearly understood.

18 is a dark-field transmission electron micrograph and EDX analysis of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 18, it corresponds to HMPB1, (a) is a dark field transmission electron micrograph, and (b) shows EDX analysis.

Referring to FIG. 18, the magnesium content gradually decreases from the left starting point (corresponding to area ①) and has a uniform flat portion at a portion 5 nm away from the boundary of the oxide layer (corresponding to area ②), followed by carbon fiber reinforced plastic It is rapidly reduced in the area where the sheet is located (corresponding to area ③). In the area where the carbon fiber reinforced plastics are located (corresponding to area ③), the magnesium content is significantly lower and the carbon content is higher. It is analyzed that it reacts with the thermoplastic polyurethane on the outside of the oxide layer, and the carbon-containing magnesium oxide is synthesized. This is in good agreement with the results of X-ray photoelectron spectroscopy in FIG. 14. However, the mechanism of this reaction occurs at a relatively low temperature, and there is a limitation that is not clearly understood at this stage.

19 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed by a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. FIG. 19 corresponds to HMPB3, (b) is an enlarged photograph of the blue square area of (a), and (c) shows a SAED pattern.

Referring to (a) of FIG. 19, branch-like structures formed adjacent to the bonding interface are indicated by black arrows. Referring to FIG. 19B, the MgO layer is shown as a very fine oxide layer interposed between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet. In addition, the inserted photographs show SAED patterns of magnesium alloy and oxide layer. Referring to (c) of FIG. 19, it can be seen that the oxide layer is MgO by SAED pattern analysis.

20 is a transmission electron micrograph and EDX element mapping of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In Fig. 20, it corresponds to HMPB3.

Referring to FIG. 20, the oxide layer is located in two parallel straight lines, and the oxide layer is analyzed as MgO by EDX element mapping. In addition, branched structures formed adjacent to the bonding interface are also analyzed as MgO. Similar to the results in Fig. 16, an oxide grown in the carbon fiber reinforced plastic is also observed.

21 is a transmission electron micrograph and a selective area electron diffraction pattern of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 21, it corresponds to HMPB3, and (b) is a selective region electron diffraction pattern of (a).

Referring to FIG. 21, when SAED patterns are analyzed, it is analyzed that the branched structure is composed of MgO. Similar to Fig. 17, the branched structure shows a ring pattern.

22 is a dark-field transmission electron micrograph and EDX analysis of a bonding interface of a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 22, it corresponds to HMPB3, (a) is a dark field transmission electron microscope photograph, and (b) shows EDX analysis.

Referring to FIG. 22, the magnesium content appears as a primary flat portion at a distance of approximately 100 nm from the left starting point (corresponding to region ①), and tends to decrease thereafter, before reaching the end of the portion covered with the oxide layer, approximately 100 nm At the distance, a second flat part appears (corresponding to area ②). In the area of carbon fiber reinforced plastics, the magnesium content is drastically reduced. This behavior is similar to the result of HMPB1 in FIG. 18. From these results, it can be seen that the outermost flat portion is a region that reacts with the thermoplastic polyurethane, and thus a carbon-containing magnesium oxide is synthesized.

In-depth analysis

From the results of the tensile shear test of FIG. 6, it is analyzed that an annealing layer formed on the AZ31 magnesium alloy sheet through annealing has a stronger joint. The annealing time affects the oxide layer formed on the surface of the AZ31 magnesium alloy sheet, and thus the tensile shear strength can be increased. Tensile shear strength was the best when the AZ31 magnesium alloy sheet was annealed in the range of 5 to 20 minutes. The junction formed using the high temperature metal compression bonding technique formed the strongest junction at a metal block temperature of 500 ° C. and an annealing time in the range of 5 minutes to 20 minutes. For reference, according to a study by Wabah et al., When LAMP technology was used to bond a polyethylene terephthalate (PET) and an AZ91D magnesium alloy sheet, when the plastic was laser irradiated, it exhibited a tensile shear load of 1.5 kN. When the metal was laser irradiated, it showed a tensile shear load of 2.9 kN [15]. According to a study by Jung et al., The maximum tensile shear load of 3.3 kN was shown when LAMP bonding technology was used for carbon fiber reinforced plastic and zinc coated sheets [26]. In addition, other studies have reported a maximum tensile shear load of 4.8 kN [24].

From the scanning electron microscope results, it was observed that bubbles were formed adjacent to the bonding interface. This bubble formation occurred more in the case of the AZ31 magnesium alloy sheet having no oxide layer than the annealed AZ31 magnesium alloy sheet. Therefore, it is analyzed that the oxide layer plays a major role in preventing the formation of such bubbles. Further, as shown in Fig. 7 (c), separation of the carbon fiber reinforced plastic was observed adjacent to the bonding interface of the bonding sample. The separation of the carbon fiber reinforced plastics adjacent to the bonding interface forms a separation region along the bonding interface. However, separation of the carbon fiber-reinforced plastic sheet was not observed in the AZ31 magnesium alloy sheet annealed and formed with an oxide layer as shown in FIGS. 8 and 10. Therefore, the separation of these carbon fiber reinforced plastics is analyzed as the reason that the tensile shear load is low when the oxide layer is not formed, such as HMPA0, HMPB0 and HMPC0. The oxide layer is analyzed to suppress the separation of the carbon fiber reinforced plastic sheet adjacent to the bonding interface, and is analyzed to strengthen the bond between the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet. This strengthening effect can be supported by tightly coupled bonding interfaces in HMPB1, HMPB2, HMPB3 and HMPB4 shown in FIGS. 8 (b), 8 (d), 8 (e) and 10 (b), respectively. . However, even in the unannealed AZ31 magnesium alloy sheet, the natural oxide layer is very thin in the bonded sample, but it is analyzed that it is not sufficiently thick to suppress the formation of bubbles or to prevent the separation of the carbon fiber reinforced plastic sheet adjacent to the bonded interface. . The thicker the oxide layer formed on the AZ31 magnesium alloy sheet by annealing, the more effectively the formation of bubbles can be suppressed, and the separation of the carbon fiber reinforced plastic sheet adjacent to the bonding interface can be more effectively prevented.

As shown in Fig. 11, the shape of the fractured surfaces of the metal-plastic assembly shows different effects of the oxide layer. Compared to the AZ31 magnesium alloy sheet in which the oxide layer is not formed, the annealed AZ31 magnesium alloy sheet includes a high uniformity bonding region. In addition, compared to the AZ31 magnesium alloy sheet without an oxide layer, the bonding region of the annealed AZ31 magnesium alloy sheet was formed to be wider.

As shown in Fig. 14, the results of the X-ray photoelectron spectral spectra show differences in the curves observed for the broken surfaces of HMPB0 and HMPB3. From these results, if an oxide layer is formed on the AZ31 magnesium alloy sheet, it may cause the formation of a chemical compound during bonding between the AZ31 magnesium alloy sheet and the carbon fiber reinforced plastic sheet, thereby increasing the strength of the joint. Further research is needed on these chemical reactions.

It can be seen from the results of the transmission electron microscope of FIGS. 15 and 19 and the results of the scanning electron microscope of FIG. 4 that a very fine MgO layer is interposed at the junction of the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet. The thickness of this MgO layer depends on the annealing time, and a thicker MgO oxide layer is formed at a longer annealing time. In addition, such an oxide layer may function as a sealing material between the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet.

The transmission electron micrographs of HMPB1 and HMPB3 show that branch shape structures are formed adjacent to the bonding interfaces, and SAED pattern analysis shows that these branch shape structures are formed of MgO. The MgO oxide layer also grows inside the carbon fiber reinforced plastic sheet. Further research is needed to further understand the mechanisms for this behavior. Branch shape structures can provide a mechanical fixation effect and can significantly increase the bond strength.

18 (b) and 22 (b), the transmission electron microscope-EDX results show other interesting results. The outermost thin MgO oxide layer closest to the interface of the carbon fiber reinforced plastic sheet has a slightly different composition of Mg, C and O. The mechanism of this behavior is still difficult to fully understand, but can be assumed to be due to a chemical reaction, as reported by Jung et al. [26], or the formation of an unknown structure. Further research is needed on this phenomenon.

23 is a schematic diagram illustrating a mechanism of a high-temperature metal compression bonding technique for a metal-plastic joint formed using a metal-plastic bonding method using a high-temperature metal compression method according to an embodiment of the present invention. In FIG. 23, (a) is a case where a carbon fiber reinforced plastic sheet and an AZ31 magnesium alloy without an oxide layer are bonded, and (b) is a case where an AZ31 magnesium alloy having an oxide layer formed by annealing with a carbon fiber reinforced plastic is bonded. .

Referring to FIG. 23, the mechanism can be configured based on the above-described results. In the case of bonding the AZ31 magnesium alloy sheet without an oxide layer, heat is rapidly transferred from the metal block to the magnesium alloy and then to the carbon fiber reinforced plastic sheet. The plastic matrix of the carbon fiber reinforced plastic sheet can be rapidly melted by the transferred heat, and a melt can be formed adjacent to the bonding interface. Subsequently, small bubbles can be generated from the melt adjacent to the bonding interface, resulting in separation of the plastic matrix and rapid transfer of heat to the reinforced carbon fibers [26]. After removing the metal block, the plastic matrix separated from the carbon fiber reinforced plastic sheet solidifies, separates from the surface of the magnesium alloy at the bonding interface, and consequently forms a gap at the bonding interface. Thus, separation of the carbon fiber reinforced plastic and bubble formation can be explained adjacent to the bonding interface.

When the oxide layer (MgO layer) is included on the surface of the magnesium alloy sheet, the oxide layer comes into direct contact with the carbon fiber reinforced plastic sheet, thereby preventing heat from being transferred from the metal block to the carbon fiber reinforced plastic sheet. Then, heat is transferred from the metal block to the AZ31 magnesium alloy sheet. However, since the oxide layer has lower thermal conductivity than the magnesium alloy, heat transfer from the AZ31 magnesium alloy sheet to the carbon fiber reinforced plastic sheet is slowed down. As a result, the melting of the carbon fiber reinforced plastic sheet gradually occurs adjacent to the bonding interface, and the melting portion of the carbon fiber reinforced plastic sheet at the bonding interface may be formed as a relatively thin layer. This thin molten layer adheres strongly to the surface of the AZ31 magnesium alloy sheet, and consequently solidifies at a slow rate when the metal block is removed, and the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet are very tightly bonded. Additionally, the oxide layer can grow into the carbon fiber reinforced plastic sheet, provide a mechanical fixation effect, and increase the bonding strength of the joint.

conclusion

A high temperature metal compression technique was used to bond the carbon fiber reinforced plastic sheet to the AZ31 magnesium alloy sheet. The bonding process was performed using an AZ31 magnesium alloy sheet in which an oxide layer was not formed and an AZ31 magnesium alloy sheet in which an oxide layer was formed by annealing at various times. Accordingly, the following conclusions were drawn.

1. Using high temperature metal compression bonding technology, bonding carbon fiber reinforced plastic sheet to AZ31 magnesium alloy sheet has been successfully performed.

2. A higher bonding strength was realized when the surface layer was oxidized on the surfaces of the AZ31 magnesium alloy sheets by annealing, compared to the junction using the AZ31 magnesium alloy sheets without an oxide layer.

3. In the AZ31 magnesium alloy sheet where the oxide layer was not formed, bubbles were formed and separation occurred in the carbon fiber reinforced plastic adjacent to the bonding interface, and a separation region was generated along the bonding interface.

4. When there were oxide layers formed by annealing on the surfaces of the AZ31 magnesium alloy sheets, the carbon fiber reinforced plastic sheet was not separated, and bubbles were not formed adjacent to the bonding interfaces. In this case, the carbon fiber reinforced plastic sheet and the AZ31 magnesium alloy sheet were tightly bonded.

5. The oxide layer formed on the surface of the AZ31 magnesium alloy sheets by annealing formed a joint having a uniform and wide bonding area between the magnesium alloy and the carbon fiber reinforced plastic sheets.

6. It has been observed that the oxide layer grows inside the carbon fiber reinforced plastic adjacent to the bonding interface of the annealed magnesium alloy sheet samples, thus providing a mechanical fixation effect that increases the bonding strength.

7. Optimal conditions for stronger joints using hot metal compression bonding techniques were realized by annealing the metal block temperature of 500 ° C. and magnesium alloy sheets between 5 and 20 minutes.

The technical spirit of the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

Claims (12)

Placing a metal member on the plastic member to form an overlapping portion in contact with the metal member;
Placing a metal block having a first temperature on the metal member corresponding to the overlapping portion; And
Including the step of forming a joint in which the metal member and the plastic member are joined in the overlapping portion by placing the weight member on the metal block and pressing the overlapping portion.
Before the step of forming the overlap portion, further comprising forming a porous oxide layer on the surface of the metal member,
The heat of the metal block is transferred from the metal block to the metal member, and then to the plastic member,
The oxide layer causes heat of the metal block to slow heat transfer from the metal member to the plastic member by the oxide layer, and the oxide layer discharges bubbles to the outside to generate bubbles in the plastic member corresponding to the junction. Characterized in that, to prevent the metal and plastic bonding method using a high-temperature metal compression method.
delete delete According to claim 2,
The step of forming the oxide layer,
A method of joining metal and plastic using a high temperature metal compression method, characterized by annealing at 400 to 600 ° C for more than 0 to 20 minutes.
According to claim 2,
The oxide layer has a thickness in the range of 0.1 to 5 ㎛, metal and plastic bonding method using a high-temperature metal compression method.
According to claim 1,
Wherein the first temperature is 400 ℃ to 600 ℃ range, a method of bonding metal and plastic using a high-temperature metal compression method.
According to claim 1,
In the step of forming the junction,
A method of joining metal and plastic using a high-temperature metal compression method, characterized in that it is pressurized to 0.1 to 0.3 MPa.
According to claim 1,
The metal block comprises at least one of copper alloy, aluminum alloy and carbon steel, a method of joining metal and plastic using a high-temperature metal compression method.
According to claim 1,
The metal member comprises at least one of an aluminum alloy, a titanium alloy and a magnesium alloy, a method of joining metal and plastic using a high-temperature metal compression method.
According to claim 1,
The metal member includes a AZ31 magnesium alloy, a method of joining metal and plastic using a high temperature metal compression method.
According to claim 1,
The plastic member comprises a thermoplastic resin and carbon fiber-reinforced plastic containing carbon fiber, a method of bonding metal and plastic using a high-temperature metal compression method.
The method of claim 11,
The thermoplastic resin is at least one selected from thermoplastic polyurethane and polyamide, a method of bonding metal and plastic using a high-temperature metal compression method.

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