KR101307634B1 - Method of bonding metal member and ceramic member - Google Patents

Abstract

The present invention relates to a method of joining a metal member and a ceramic member, and more particularly, to a method of joining a metal member and a ceramic member by a friction stir welding method.

Description

How to join metal and ceramic members {METHOD OF BONDING METAL MEMBER AND CERAMIC MEMBER}

The present invention relates to a method of joining a metal member and a ceramic member, and more particularly, to a method of joining a metal member and a ceramic member by a friction stir welding method.

Fine ceramics, which is a new material, uses refined synthetic powder compared to conventional ceramics, and is manufactured by molding sintering method that can precisely control chemical composition and microstructure, or high performance, high performance ceramics manufactured by processing method that can achieve densification Is defined as

Fine ceramics is roughly classified into structural ceramics mainly having functions related to mechanical, thermal, nuclear power, nuclear fusion, and the like, and functional ceramics mainly having electrical, magnetic, and optical functions. Functional ceramics account for two-thirds of the total demand for ceramics, but structural ceramics are also increasing in demand due to the diversified application field. Ceramics have been widely used as metal replacement materials utilizing their properties due to their heat resistance, low thermal expansion, low thermal conductivity, high temperature, high strength, high hardness, abrasion resistance, low specific gravity, chemical stability, and light weight, compared to metal materials. Moreover, although most of the elements used in special alloys face resource exhaustion, many of the elements that are used as raw materials for ceramics exist almost indefinitely, which is the driving force for the development of ceramics. However, although these ceramics are most excellent in fire resistance, high temperature strength and hardness, the low thermal shock resistance and fracture toughness are a big problem.

As mentioned above, ceramics are highly functional compared to metals, so they are expected to be applied to various fields. However, ceramics have the disadvantages of toughness (about 1/2 of cast iron) and difficulty in processing. This drawback is the biggest obstacle to the expansion of the use of ceramics. Since the low toughness of ceramics is due to the atomic bond mode, it is very difficult to improve the toughness. This drawback can be improved by complexation with the metal. As a method of complexing ceramics with a metal, a joining method is optimally known. Therefore, joining technology of metal and ceramics can be said to be an essential technology that can extend the application range of ceramics.

Ceramics are a typical material that is difficult to melt weld compared to metal materials due to the following problems. ① Weld crack is easy to occur because of low thermal shock resistance. (2) Because of the sintered body, pores are likely to occur in the molten portion. (3) High viscosity coefficient at melting point and various welding defects are likely to occur. (4) Low thermal conductivity, which is easily overheated and easily evaporated. (5) Crystals in the melt may grow abnormally depending on the material.

Therefore, joining methods are used more than melt welding. Since the ceramic / metal bonding method is similar to the ceramic surface coating method, many bonding methods using the surface coating method have been developed. Unlike the metal-to-metal bonding, the bonding between ceramics and metals is not only varied, but also the method of joining is different depending on the type, size, and shape of the ceramics.

Various methods of bonding ceramics and metals are currently applied in the industry, but each bonding method has its disadvantages. In the case of the mechanical fastening method, it is difficult to apply to the shape of the complex structure, the machining for the mechanical body diameter is required, and there is a problem that the damage is likely to occur due to the stress concentration of the fastening part by the bolt and nut fastening.

In addition, when the adhesive is used, the handling is simple and can be done quickly, but there is a problem in that the bonding strength is low overall. When the adhesive is used at a high temperature, the adhesive is suitable for its characteristics depending on the strength of the joint and the material. shall.

In the case of brazing, it is the most commonly used bonding method, but it requires an insert metal suitable for each material characteristic and an expensive brazing equipment that can maintain a gas atmosphere or a vacuum atmosphere at the same time as the optimum bonding conditions such as appropriate pressure and temperature. In the case of solid phase bonding, many researches are currently being conducted and applied in industry, but it is difficult to secure optimum bonding conditions, problems of shape constraints, and expensive expensive equipment.

Therefore, there has always been a demand for a method of easily bonding ceramics and metals that are difficult to join, but having excellent bonding strength.

The present invention provides a method capable of joining a ceramic and a metal which is not only insert metal or an adhesive but also capable of bonding in an air atmosphere by using a friction stir welding method, which is one of solid phase joining methods, and is more economical than the joining method.

According to an embodiment of the present invention, a method of joining a metal member and a ceramic member, comprising: placing the metal member and the ceramic member to overlap or engage; Positioning a tool of the milling machine over a portion where the metal member and the ceramic member overlap; And moving the tool of the milling machine along the overlapped portion.

According to a further embodiment of the present invention, in addition to the above steps, it may further comprise the step of removing the burr (burr) of the bonding surface.

In addition, in order to increase the strength of the joining, it is preferable to place a member having a relatively weak strength on the top and a member having a strong strength on the bottom.

In this case the metal comprises a nonferrous material and a steel material, and the ceramic comprises a carbonized, nitrided and oxidized ceramic.

Figure 1 shows a state in which the bonding in the form of overlap during friction stir welding of the ceramic-metal.
Figure 2 shows the state of bonding in the engagement form during friction stir welding of the ceramic-metal.
3 shows a front appearance of a friction stir welding portion of a ceramic-metal.
Figure 4 shows the rear appearance of the ceramic-metal friction stir welding portion.
5 shows a low magnification cross-sectional macro image of a friction stir welded portion of a ceramic-metal.
6 shows a high magnification cross-sectional macro image of a friction stir welded portion of a ceramic-metal.
7 shows an optical micro image of a friction stir welded portion of a ceramic-metal.
Figure 8 shows the fracture shape after the tensile shear test of the friction stir welding portion of the ceramic-metal.
Various embodiments are now described with reference to the drawings, wherein like reference numerals are used throughout the drawings to refer to like elements. For purposes of explanation, various descriptions are set forth herein to provide an understanding of the present invention. It is evident, however, that such embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments.

The following description provides a simplified description of one or more embodiments in order to provide a basic understanding of embodiments of the invention. This section is not intended to be a comprehensive overview of all possible embodiments, nor is it intended to identify key elements of all elements or to cover the scope of all embodiments. Its sole purpose is to present the concept of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

The present invention discloses a method of joining a metal member and a ceramic member, which method is performed by the following steps:

Placing the metal member and the ceramic member to overlap or engage (step 110); Positioning the tool of the milling machine over the portion where the metal member and the ceramic member overlap (step 120); Moving the tool of the milling machine along the overlap (step 130); And removing the burr of the joint surface (step 140).

1. Laying the metal member and the ceramic member to overlap or engage (step 110)

According to one embodiment of the present invention, the metal member and the ceramic member should be placed to overlap or engage. To this end, as shown in FIG. 1, the ceramic and metal members may be overlapped and placed up and down. Alternatively, as shown in FIG. 2, the ceramic member and the metal member may be processed in advance to engage with each other so as to be engaged. In this case, it is preferable to be processed into a "b" shape or a "b" shape to engage. If the ceramic member has been machined to the "a" shape, the metal member should be machined correspondingly to the "b" shape and vice versa.

On the other hand, the determination of the top and bottom in the overlapping or interlocking members is determined by the strength, it is preferable to place the relatively weak member on the top and the strong member below.

2. Milling on the overlapped part of the metal member and the ceramic member Machine  Positioning the Tool (Step 120)

After overlapping or interlocking the metal member and the ceramic member in step 110, the tool of the milling machine is positioned over the overlapped portion. This is for later friction stir joining the overlapped portions.

In the case of the present invention, the metal of the metal member includes a nonferrous material and a steel material, and the ceramic of the ceramic member includes a carbonized, nitrided, and oxidized ceramic.

In this case, when the metal is a low melting point alloy such as aluminum or magnesium, the tool may be a tool steel tool. When the metal is a high melting point material such as steel or titanium alloy, a tool made of a diamond material and ceramics-based material may be used. Joining is carried out using.

3. Mill along the overlap Machine  Moving the Tool (Step 130)

In step 130 the tool of the milling machine is moved along the overlapping portion, whereby friction stir welding occurs between the metal member and the ceramic member.

The actual coupling state using the present technology can be seen in Figures 3 to 8. 3 and 4 show the external appearance of the joint portion in which the 6061 aluminum alloy as the metal member and the WC-Co sheet member as the ceramic member are overlapped to form a friction stir weld.

As shown in FIG. 3, a metal member such as aluminum alloy having a relatively low strength was disposed on the top, and a ceramic plate such as WC-Co having a high strength was disposed below.

Bonding was performed under the conditions of tool rotation speed 1600rpm and tool feed speed 80mm / min, and the welding was performed in the atmosphere without any other gas atmosphere.

As can be seen in Figures 3 and 4, no cracks or defects were observed in the outer appearance of the junction, and it was confirmed that the junction was considerably firm.

Junction cross section macro images are shown in FIGS. 5 and 6. As can be seen from the cross-sectional macro image, no cracks or the like were observed in the joint, and the upper aluminum alloy and the lower WC-Co sheet were closely adhered to each other.

An optical micrograph of the enlarged junction is shown in FIG. 7. As shown in FIG. 7, it can be observed that there is a very fine interface between the two plates, and this reaction layer (interface) is formed by diffusion of aluminum and WC-Co due to heat and pressure during bonding. Becomes

In order to evaluate the strength of the joint, the tensile shear test (pulling test at 5mm / min) of the joint was conducted, and the shear test on three specimens resulted in an average load of about 3000 N (3 adult males weighing about 100 kg) High strength) was measured and fracture occurred at the interface between the two plates as shown in FIG. 8.

4. Joint Burr  Steps to Remove (Step 140)

When burrs are generated at the joint surface, the burrs are smoothed by removing the burrs with an end mill. This step is an optional step.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (3)

As a method of joining a metal member and a ceramic member,
Superimposing or engaging the metal member and the ceramic member;
Positioning a tool of the milling machine over a portion where the metal member and the ceramic member overlap; And
Moving the tool of the milling machine along the overlapping portion;
The step of overlapping or engaging the metal member and the ceramic member is made so as to place a member having a relatively weak strength on top and a member having a relatively strong strength below,
When the metal member is a low-melting alloy, a tool made of a tool steel material is used. When the metal member is a high melting point alloy, a diamond or ceramic material tool is used.
A method of joining a metal member and a ceramic member.
The method of claim 1,
Further comprising the removal of burrs at the joint surface,
A method of joining a metal member and a ceramic member.
3. The method according to claim 1 or 2,
The metal comprises a non-ferrous material and a steel material,
The ceramic includes carbonized, nitrided and oxidized ceramics,
A method of joining a metal member and a ceramic member.

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