Method for treating interface between resin-based composite material and aviation alloy

Abstract

The invention relates to a method for treating an interface between a resin-based composite material and an aviation alloy. The method comprises the following steps: firstly, processing a micro inverted taper hole in a to-be-bonded surface of an alloy, then carrying out surface treatment, then coating a thermoplastic elastic adhesive on the to-be-bonded surface, putting the to-be-bonded surface into a vacuum oven for treatment, taking out the to-be-bonded surface, and carrying out heating, pressurizing and co-curing with a composite material. The micro inverted cone hole can remarkably increase the bonding area of the resin-based composite material and the alloy, and the inverted cone structure can effectively prevent debonding caused by mismatching of thermal expansion coefficients of an adhesive and a metal interface in the temperature change process; the thermal expansion coefficient of the thermoplastic elastic adhesive is between the thermal expansion coefficient of the resin-based composite material and the thermal expansion coefficient of the alloy material, the thermoplastic elastic adhesive has certain flexibility, a buffer layer is formed between the fiber-reinforced resin-based composite material and an alloy interface through the adhesive, and the probability that in the cooling process of the fiber-reinforced resin-based composite material and the alloy, the thermal expansion coefficient of the fiber-reinforced resin-based composite material and the alloy is lowered can be effectively lowered. And the interface thermal residual stress is caused due to the large difference between the thermal expansion coefficients of the two.

Description

Technical Field

[0001] The invention relates to a method for processing the interface between a resin-based composite material and an aviation alloy. Background Art

[0002] Resin-based composite materials are widely used in the field of radomes as wave-transmitting functional materials and load-bearing structural materials due to their light weight, high strength and excellent dielectric properties. With the requirements of lightweight integration of modern weapons and equipment, integrating antennas / radomes to make conformal radome components has become a future trend. The functional structure of the conformal radome is typically represented by a wave-transmitting structure and a stealth structure, and the load-bearing structure is typically represented by an aluminum alloy, a titanium alloy, and a carbon fiber resin-based composite material structure. The composite performance between the two has become an important factor restricting the development of equipment. Among them, the interface bonding performance between quartz fiber resin-based composite materials as a typical wave-transmitting structure and the typical load-bearing structure aluminum / titanium alloy has become a key factor restricting the use of conformal radomes. The insufficient bonding strength between the resin-based composite material and the alloy itself, coupled with the difference in thermal expansion properties, often leads to debonding due to temperature changes during use.

[0003] After curing, the thermal expansion coefficient of the resin-based composite material and the alloy often differ by one order of magnitude. Therefore, during the cooling process after the co-curing of the resin-based composite material / alloy, due to the large difference in thermal expansion coefficient, a large thermal residual stress will be generated at the interface, resulting in a decrease in the bonding strength of the resin-based composite material / alloy interface, and causing deformation of the parts, affecting the product's service life and assembly accuracy. Therefore, it is necessary to find ways to reduce the thermal residual stress between the resin-based composite material / alloy interface and improve the bonding strength of the interface. Summary of the invention

[0004] The invention provides a method for processing the interface between a resin-based composite material and an aviation alloy, which solves the problem of insufficient bonding strength of the existing resin-based composite material / alloy interface.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A method for processing the interface between a resin-based composite material and an aviation alloy comprises the following steps: firstly processing a micro-conical hole on the surface of the alloy to be bonded, and then performing surface treatment on the surface to be bonded; then coating the surface to be bonded with a thermoplastic elastic adhesive, placing the surface in a vacuum oven for treatment, and taking the surface out for co-curing molding with the resin-based composite material under heating and pressurizing conditions.

[0007] In the above scheme, the cone angle range of the micro inverted cone hole on the surface of the alloy to be bonded is 5-15°, the hole surface area accounts for 30%-50% of the area of ​​the surface to be bonded, the spacing between adjacent holes is 1-3 times the side length or diameter of the hole, and the hole depth is 1%-20% of the thickness of the alloy to be bonded.

[0008] In the above scheme, the thermoplastic elastic adhesive includes but is not limited to one of fluorinated polyimide glue, polybenzimidazole glue, nylon epoxy resin glue, nylon phenolic resin glue, etc. The overall coating thickness is 0.1-0.2 mm, and the local coating thickness is 0.1-0.2 mm plus the depth of the inverted cone hole.

[0009] In the above scheme, the treatment time of the thermoplastic elastic adhesive in the vacuum oven on the alloy surface to be bonded is controlled to be 30 to 60 minutes, and the treatment temperature is controlled below the gel point of the adhesive.

[0010] In the above scheme, the composition of the thermoplastic adhesive is adjusted so that its thermal expansion coefficient is between that of the resin-based composite material and the alloy, forming a gradient change in the thermal expansion coefficient among the three.

[0011] In the above scheme, the resin-based composite material specifically refers to a thermosetting resin-based composite material, including but not limited to a wave-transmitting composite material, such as a quartz / glass fiber reinforced cyanate ester / epoxy resin / phenolic resin / polyimide resin composite material; the aviation alloy includes but is not limited to aluminum alloy and titanium alloy.

[0012] In the above solution, the micro inverted cone holes are array-type regular hexagonal or circular inverted cone holes.

[0013] In the above scheme, the surface to be bonded is subjected to surface treatment, wherein the surface treatment is phosphoric acid anodizing treatment or sandblasting treatment.

[0014] The beneficial effects of the present invention are:

[0015] 1. Use the inverted cone holes on the alloy surface to allow the adhesive to penetrate into the holes, forming an effect of the adhesive and the alloy interlocking, and improving the bonding strength between the composite material and the alloy from the physical structure. The micro inverted cone holes involved in the present invention can significantly increase the bonding area between the resin-based composite material and the alloy, and the inverted cone structure can effectively prevent the debonding caused by the mismatch of the thermal expansion coefficient between the adhesive and the metal interface during temperature changes.

[0016] 2. By adjusting the components of thermoplastic adhesives, the thermal expansion coefficient is between that of resin-based composite materials and alloy metals, especially aluminum alloys, forming a gradient change in the thermal expansion coefficient among the three. Thermoplastic adhesives are highly flexible and will produce large deformations under stress. They can absorb part of the stress as a stress buffer, thereby effectively reducing the interfacial thermal residual stress caused by the difference in thermal expansion coefficients during the cooling process of resin-based composite materials / alloys, thereby improving the interfacial bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the resin-based composite material / alloy interface treatment of Example 1 and Example 2.

[0018] Figure 2 Schematic diagram of machining micro inverted cone holes on the alloy surface in Example 1 and Example 2.

[0019] Figure 3 Schematic diagram of the side length of the regular hexagonal micro inverted cone hole in Example 1.

[0020] In the figure: 1-resin-based composite material; 2-adhesive layer, 3-alloy, 3-1-micro inverted cone hole, 3-1-1-hole side length; 3-1-2-inverted cone angle, 3-1-3-hole depth, 3-1-4-hole spacing. DETAILED DESCRIPTION

[0021] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the drawings and embodiments, but the content of the present invention is not limited to the following embodiments.

[0022] Example 1

[0023] Step 1: If Figure 1 , Figure 2 , Figure 3 As shown, firstly, a regular hexagonal micro inverted cone hole 3-1 (or inverted cone microhole) is processed on the surface to be bonded of the aluminum alloy 3, the inverted cone angle 3-1-2 of the micro inverted cone hole 3-1 is 15°, the hole spacing 3-1-4 is 2.5 times the hole side length 3-1-1, the hole depth 3-1-3 is 20% of the total thickness of the alloy and 80% of the hole side length 3-1-1, and the hole surface area is 30% of the total bonding surface area;

[0024] Step 2: performing phosphoric acid anodizing treatment on the surface to be bonded with the array-type micropores to increase the reaction activity of the surface to be bonded;

[0025] Step 3: Apply nylon epoxy resin adhesive to the surface to be bonded treated in step 2, with a coating thickness of 0.15 mm, and vacuum treat at 60° C. for 40 min to allow the adhesive to fully penetrate into the micropores 3-1;

[0026] Step 4: Lay quartz fiber reinforced epoxy resin prepreg on the adhesive layer 2 formed in step 3, and cure at 120° C. and 0.1 MPa pressure for 3 hours.

[0027] In this embodiment, the corresponding components of the nylon epoxy resin adhesive are adjusted according to the thermal expansion coefficients of the quartz fiber reinforced epoxy resin composite material and the aluminum alloy material, and the size of the inverted cone micropores is designed. After the corresponding material combination is processed and subjected to an extreme use temperature of 130°C, there are no cracks or debonding at the interface between the adhesive layer and the alloy layer, and the bonding strength retention rate reaches 90%.

[0028] Example 2

[0029] Step 1: First, a circular micro-conical hole 3-1 is processed on the surface to be bonded of the titanium alloy 3, the inverted cone angle 3-1-2 of the micro-conical hole 3-1 is 10°, the hole spacing 3-1-4 is twice the hole side length 3-1-1, the hole depth 3-1-3 is 10% of the total thickness of the alloy and 50% of the hole diameter 3-1-1, and the hole surface area is 50% of the total bonding surface area;

[0030] Step 2: sandblasting the surface 3 to be bonded with the array-type micropores to increase the reactivity of the surface to be bonded;

[0031] Step 3: Apply the fluorinated polyimide adhesive to the surface to be bonded treated in step 2, with a coating thickness of 0.2 mm, and vacuum treat at 150° C. for 60 min to allow the adhesive to fully penetrate into the micropores 3-1;

[0032] Step 4: Lay a layer of quartz fiber fabric on the adhesive layer 2 formed in step 3, apply polyimide resin by brushing, repeat the laying and brushing process until the required thickness is reached, let it air-dry, and cure it at 380°C and 1MPa pressure for 5h.

[0033] The thermal expansion performance of the fluorinated polyimide adhesive in this embodiment is close to that of titanium alloy. At a use temperature of 400° C., the thermal expansion coefficients of the two are almost consistent. In addition, the undercut effect formed by the conical micropores allows the bonding strength retention rate to be close to 100%.

[0034] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and implement it accordingly. It can be understood by those skilled in the art that various replacements, changes and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the contents disclosed in the embodiments of this specification, and the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A method for treating the interface between a resin-based composite material and an aviation alloy, characterized in that: First, micro inverted cone holes are machined on the surface of the alloy to be bonded, and then the surface to be bonded is surface treated; then a thermoplastic elastic adhesive is coated on the surface to be bonded, and the surface is placed in a vacuum oven for treatment. After being taken out, the surface is co-cured with the resin-based composite material under heating and pressure conditions.

2. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The cone angle of the micro inverted cone hole on the alloy surface to be bonded is in the range of 5 to 15 degrees, the hole surface area accounts for 30% to 50% of the surface area to be bonded, the spacing between adjacent holes is 1 to 3 times the side length or diameter of the hole, and the hole depth is 1% to 20% of the thickness of the alloy to be bonded.

3. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The thermoplastic elastic adhesive includes one of fluorinated polyimide adhesive, polybenzimidazole adhesive, nylon epoxy resin adhesive, nylon phenolic resin adhesive and the like.

4. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The overall coating thickness of the thermoplastic elastic adhesive is 0.1-0.2 mm, and the local coating thickness is 0.1-0.2 mm plus the depth of the inverted cone hole.

5. The method for treating the interface between the resin-based composite material and the aviation alloy according to claim 1, characterized in that: The vacuum oven treatment time of the thermoplastic elastic adhesive on the alloy surface to be bonded is controlled to be 30 to 60 minutes, and the treatment temperature is controlled to be below the gel point of the adhesive.

6. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The components of the thermoplastic adhesive are adjusted so that its thermal expansion coefficient is between that of the resin-based composite material and the alloy, forming a gradient change in the thermal expansion coefficient among the three.

7. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The resin-based composite material is a thermosetting resin-based composite material, including one of the following: quartz / glass fiber reinforced cyanate ester composite material, quartz / glass fiber reinforced epoxy resin composite material, quartz / glass fiber reinforced phenolic resin composite material, quartz / glass fiber reinforced polyimide resin composite material.

8. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The aviation alloy is an aluminum alloy or a titanium alloy.

9. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The micro inverted cone holes are array-type regular hexagonal or circular inverted cone holes.

10. The method for treating the interface between a resin-based composite material and an aviation alloy according to claim 1, characterized in that: The surface to be bonded is subjected to surface treatment, wherein the surface treatment is phosphoric acid anodizing treatment or sandblasting treatment.

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