RU2775662C1 - Metal fiber laminate based on unidirectional glass fiber and polypropylene prepreg, biaxially oriented polypropylene film and surface treated aluminum alloy sheets - Google Patents

Abstract

FIELD: composite materials.

SUBSTANCE: invention relates to the field of layered hybrid composite materials and relates to a fiber-metal laminate. The laminate is obtained by hot pressing, which consists of alternating layers of unidirectional fibrous prepreg based on glass fibers and polypropylene, biaxially oriented polypropylene film and aluminum alloy sheets with anodized surface treatment in a solution of H₂SO₄ 60 ml/l and Al₂(SO₄)₃ 200 g /l at a temperature of 20°C and a current density of 1.5 A/dm² for 20 minutes.

EFFECT: invention provides for laminate tensile strength of 320 MPa, flexural strength of 475 MPa and impact strength of 350 kJ/m².

1 cl, 1 dwg, 2 tbl

Description

The present invention relates to laminated hybrid composite materials consisting of interleaved metal sheets, layers of unidirectional fiber prepreg, based on unidirectional glass fiber and polypropylene prepreg, biaxially oriented polypropylene film, and surface treated aluminum alloy sheets. The invention can be used in the automotive, aviation, construction, shipbuilding or space industries.

Several basic types of fiber-metal composite materials are known from the current state of the art.

Known Russian fiber-metal laminates (patents RU 2185964, RU 2565215, RU 2641744), consisting of layers of high-strength aluminum alloy Al-Li (up to 1.5% Li) and prepreg layers based on glass fibers and thermally cured epoxy resins. The disadvantage of which is the use of thermosetting polymers.

Known fibrous metal laminate (patent RU 2238850), consisting of alternating sheets of aluminum alloy and layers of fiberglass based on a thermosetting binder, additionally containing elastic polymer layers located between the sheet of aluminum alloy and fiberglass, based on phenolic resins of the resole type and high molecular weight rubber, thickness 20-100 microns. The disadvantage of this material is the use of thermosetting polymers.

Known fibrous metal laminate (patent DE 102006051989 A1), which contains at least 2 layers of metal, less than 1.5 mm thick, and a polymer layer, both from thermoplastic and thermosetting binder, having in its composition basalt fibers in the amount from 35% to 75%. The disadvantage of this patent is the use of basalt fibers.

Known laminate of metal and polymer based on polypropylene filled with long glass fibers (patent EP 1118451B1). The material is made of polypropylene filled with long fibers, not less than 1 mm and not more than 50 mm in length, and having the same coefficient of thermal expansion as that used with it to make the composite, metal. The strength of the composite material exceeds the strength of structures made from pure metal. The disadvantage of this material is the use of long fibers, the strength of which is lower than that of continuous ones.

The closest of the known analogues is patent US 20110052910 A1, describing a high-strength fiber-metal laminate containing a fiber-reinforced layer and a layer of thin sheets of metal, with a reinforcing layer content of 0% to 47%. As reinforcing fibers, fibers such as carbon, glass, metal and thermoplastic polymer and natural fibers can be used. As a polymer material, thermoplastic polymers are used such as: polyamides, polyimides, polyethersulfones, polyphenylene sulfides, polyamide-imides, ABS, thermoplastic polyesters, preferably having an amorphous structure and a glass transition temperature of more than 140°C. Alloys such as steels, titanium and aluminum alloys are used as the metal layer. The disadvantage of this material is the use of epoxy resins as a matrix, which reduces the manufacturability.

Thus, the technical problem to be solved by the claimed technical solution is the development of a fiber-metal laminate based on a unidirectional prepreg of glass fiber and polypropylene, biaxially oriented polypropylene film and aluminum alloy sheets with surface treatment.

The solution to this technical problem is achieved due to the fact that the surface of the sheets of aluminum alloy was subjected to electrochemical treatment under specified conditions.

The technical result of the proposed technical solution is that the surface of aluminum alloy sheets is processed by the method of sulfuric anodizing in a solution of H ₂ SO ₄ 60 ml/l and Al ₂ (SO ₄ ) ₃ 200 g/l at a temperature of 20°C and a current density of 1, 5 A / dm ² for 20 minutes, which provides for the laminate ultimate tensile strength of 320 MPa, bending 475 MPa and impact strength of 350 kJ/m ² .

The technical solution is illustrated by the following figures.

Fig. 1 - a diagram of a fiber-metal laminate consisting of sheets of aluminum alloy with a surface treated (1), a biaxially oriented polypropylene film (2) and 2 layers of a unidirectional prepreg based on glass fiber and polypropylene oriented at 0° and 90° (3 ).

To improve the properties of the fiber-metal laminate, electrochemical processing of aluminum alloy sheets is carried out. Before surface treatment, the sheets are pre-cleaned by washing in soapy water; washing in acetone; etching in 10% NaOH solution for 10 seconds. After each step, the sheets are washed with distilled water. Electrochemical processing of aluminum alloy sheets is carried out according to the modes indicated in table 1. The deviation from the parameters should not be ± 3% from those indicated in table 1.

Table 1. Modes of metal surface treatment

Processing type Water solution Temperature Time current density Electrochemical Al ₂ (SO ₄ ) ₃ 200 g/l
H ₂ SO ₄ 60 ml/l 20°C 20 minutes 1.5 A / dm ²

Before assembling the layers, each layer is wiped with a lint-free cloth soaked in alcohol. The fiber-metal laminate is assembled from the same type of bags as shown in Fig. 1. Each package consists of AlMg6 aluminum alloy sheets with surface treatment, 0.5mm thick; polymer films made of polypropylene, 40 microns thick, adjoin aluminum alloy sheets; in the middle of the bag are placed 2 layers of prepreg, based on glass fiber and polypropylene, with a laying of 0° / 90°. After preparing and laying all the components in the mold, the fiber-metal laminate is produced by hot pressing under the following process parameters: pressure - 2 MPa; temperature - 190 °C; holding time at a given temperature - 20 min.

Table 2 shows an example implementation. The characteristics of the material are shown in comparison with the known. The resulting material was tested for tensile and bending strength, impact strength. The data obtained illustrates the improvement in characteristics relative to the material obtained without additional processing.

Table 2. Mechanical properties of the resulting fiber-metal laminates

Surface treatment Tensile strength, MPa Bending strength, MPa Impact strength, kJ/m ² No processing 280 420 320 Electrochemical processing 320 475 350

Claims (1)

Hot-pressed metal fiber laminate consisting of alternating layers of unidirectional prepreg based on glass fibers and polypropylene, biaxially oriented polypropylene film and aluminum alloy sheets, characterized in that the surface of the aluminum alloy sheets is treated by sulfuric anodizing in a solution of H ₂ SO ₄ 60 ml/l and Al ₂ (SO ₄ ) ₃ 200 g/l at a temperature of 20°C and a current density of 1.5 A/dm ² for 20 minutes.

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