CS205402B1 - Method of composite half-made product preparation for compositive materials reinforced by continuous fibres - Google Patents

Description

The present invention provides a process for preparing a composite blank for production of continuous reinforced fiber reinforced composites with metallic or ceramic matrices, by powder metallurgy processes, and is within the field of physical metallurgy.

The development of current technology requires high-strength construction materials with functional characteristics that are markedly improved over a wide temperature range. Composite materials consisting of metallic or ceramic matrices reinforced with metal or ceramic continuous or discrete, directionally arranged reinforcement fibers can meet these requirements.

Composites with reinforcing fibers in metal matrices are now manufactured by infiltrating the molten matrix metal between the assembly in one direction arranged reinforcing fibers, or by hot pressing stacked monolayer precomposites prepared by plasma spraying the matrix metal onto a reinforcing fiber laminate wound in a single film a matrix metal, or by hot pressing, a set of directionally arranged, electrolytically or chemically metallized reinforcing fibers.

Composites are also prepared by powder metallurgy processes, i. by hot pressing, assembly, mechanically crimped, matrix reinforced fiber reinforcement fibers, after prior sintering, or a method of this method, wherein the matrix powder in the form of a suspension in a suitable liquid is introduced between the mechanically fractionated reinforcing fibers by filtering the melt under vacuum, and subsequent drying and sintering as in the previous method. This also includes a method of making a composite by extruding a discrete fiber matrix powder composition.

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Said composite manufacturing processes exhibit several drawbacks, such as: the cross-reacting of the reinforcing fiber with the matrix, which can lead to complete degradation of the reinforcing fiber, in the production by matrix metal infiltration; no or imperfect wettability of the surface of the ceramic reinforcement fibers by the molten matrix metal; a limited volume percent of reinforcing fibers that can be incorporated into the matrix by means of mechanical collimation preparations; uneven distribution of discrete reinforcing fibers, their mutual contact and imperfect directional arrangement in the matrix, in the method of production of composites by extrusion, difficulty of production of difficult parts, etc.

The above drawbacks overcome the process of preparing a composite blank for continuous fiber-reinforced composite materials, the principle of which is that the reinforcing fiber itself or, in the case of extremely small diameters, respectively. of low strength, together with fine polymeric monofilament fibers, is passed at least once through an organic binder environment, for example an aqueous solution of polyvinyl alcohol and a sweeping pass through an environment in which the matrix powder is in fluid form, or at least once it passes through the suspension of matrix powder the binder, and the fiber thus wrapped with a concentric and continuous layer of binder and matrix powder are further dried at the cure temperature of the binder used.

The advantages of the present invention are that it allows the continuous, economically advantageous production of a composite blank into a stock from which it can be produced by powder metallurgy processes, by sintering and subsequent hot pressing, including isostatic hot pressing, finally composites of high technical parameters. The invention makes it possible to incorporate even high volume percentages of reinforcing fibers into the dies and to produce shaped and dimensionally demanding parts. The invention makes it possible to further manufacture composites with a combined, multi-component matrix as well as a combined reinforcement reinforcement.

The attached drawing shows a schematic of the application of a binder film, respectively. a suspension of a binder and a matrix powder, on a reinforcing fiber, or on a fiber where the matrix powder layers are already applied.

This is accomplished by pulling the filament through the die according to the schematic drawing in the appendix, comprising: a central flange 1 with a central, conically tapering channel 2 of circular cross-section, with a hole diameter at the narrowest point slightly greater than the diameter of the reinforcing filament ; from a sleeve 3 of a screw-in flange of the guide cone χ, provided with a central opening on the end wall 4 with a small distance from the opening of the guide cone mouth 1, the opening 4 having a diameter greater than the mouth of the channel 2. respectively. suspension, filled with binder, respectively. a suspension of satisfactory viscosity. The binder solution can also be applied to the fiber by dusting.

As binders, an aqueous solution of polivinyl alcohol, an acetone solution of polivinyl acetate, a chloroform, toluene or benzene solution of polistyrene and the like can be used.

If multiple layers are required, this is achieved by drawing through the die assembly and gradually increasing the opening primers, with the inclusion of drying ovens between the individual die.

The process for preparing continuous fiber reinforced composite materials according to this method is carried out as follows: The fiber reinforcement is covered with a continuous binder film and passed through a matrix powder fluidized bed chamber wrapped with a thick layer of matrix powder and after drying constitutes a composite blank.

Another preferred method is that the reinforcing fibers can be coated with a suspension of matrix powder in an organic binder solution and, after drying, are a composite blank.

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It is also possible to apply two or more layers of matrix powder of different but mutually compatible composition to one reinforcing fiber by drawing through the coating dies.

In cases of wrapping of extremely thin and brittle reinforcing fibers, these are passed through the wrapping die together with the auxiliary fine polymeric monofilament fibers, which are then decomposed by heat.

In the manufacture of the final composites, reinforcing fibers coated with mutually compatible matrix powders of different composition may be combined or the reinforcing fibers of different composition coated with matrix powder may be combined.

Execution example

As a particular example, the preparation of a composite blank for a composite material with a tungsten reinforced nickel mattress continuous fiber. The tungsten continuously filament is passed through a suspension of aqueous polivinyl alcohol and nickel powder, thereby wrapping it with a concentric uniform layer of nickel matrix powder. Subsequent drying of the coated fiber with said suspension at 80 ° C cures the coating on the fiber to give a composite blank for the nickel-tungsten composite material.

After suitable placement of the fibers to form the composite material, the coated tungsten fibers are annealed in a reducing atmosphere at a temperature of up to 1000 ° C, for 1 hour. During annealing, the organic binder is disintegrated and removed, and at the same time the matrix powder is sintered on the surface of the fibers, respectively. between individual threads. The annealing is followed by the final compression of the coated tungsten fibers with the nickel matrix powder to 100% density of the composite material. The final compression can be realized e.g. by hot isostatic pressing at a temperature of 1000 ° C, a pressure of 150 MPa and a time of 1 h.

The present invention can find wide application in fields where high refractory construction materials and low density high-strength materials are required, i. in aeronautics, energy, nuclear technology, transport and construction.

Claims (1)

Also, two or more layers of matrix powder of different but compatible composition may be applied to one reinforcing fiber by dragging through the wrapping dies. In the case of coating extremely thin and brittle reinforcing fibers, they are stretched through the wrapper together with the auxiliary fine polymeric fibers, which are then thermally decomposed. In the preparation of the final composites, it is possible to combine reinforcing fibers coated with mutually compatible matrix powders of different composition, or combining fibers of different composition coated with matrix powder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As a particular case, the preparation of a composite blank for a composite material with a tungsten continuous fiber reinforced nickel mattress can be mentioned. The tungsten-discontinuous fiber is elongated through a suspension of aqueous polivinylalcohol and nickel-powder, thereby wrapping it with a concentric uniform layer of nickel matrix powder. Subsequent drying of the coated fiber with said suspension at 80 ° C results in curing of the package on the fiber to obtain a composite blank for nickel composite material tungsten. After suitable laying of the fibers to form a composite material, the coated tungsten fibers are annealed to a reducing atmosphere at a temperature of up to 1000 ° C for 1 hour. The ironing breaks down and the organic binder is removed and the matrix powder is sintered at the fiber surface, respectively. between individual fibers. After annealing, the final compression of the coated tungsten fibers with nickel matrix powder follows 100% density of the composite material. The final compression can be carried out, for example, by isostatic hot pressing at a temperature of 1000 ° C, a pressure of 150, MPa and a time of 1 h. The present invention can be widely used in fields where high-temperature structural materials and high-strength materials are required low density, i. in aviation, energy, nuclear, transport and construction. BEFORE THE INVENTION A method for preparing a composite blank for composite fiber reinforced materials, characterized in that the fiber reinforcement is continuously reinforced by itself or, in the case of an extremely small diameter and / or diameter. of a low strength together with the fine polymeric monofilament fibers, it is drawn through the organic binder medium at least once, for example an aqueous solution of polivinylalcohol, followed by elongation through the medium in which the matrix powder is located in fluidized bed, or at least once drawn through the matrix suspension medium The powder in the organic binder, and the thus coated concentric and continuous layer of binder and matrix powder are further dried at the curing temperature of the binder used. 1 drawing