RU2755353C1 - Composite material based on aluminium or aluminium alloy and method for production thereof - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to production of a cast composite material based on aluminium or aluminium alloy reinforced with discrete Al₂O ₃ fibres of a nanoscale diameter, and can be used as a construction material in various fields of technology. The cast composite material comprises a matrix of aluminium or aluminium alloy and a reinforcer made in the form of a conglomerate of discrete aluminium oxide fibres with a diameter of 10 to 20 nm and transport copper powders with a size of 10 to 20 mcm, wherein the total content of aluminium oxide and copper is 1% wt. The method for producing a cast composite material includes mixing discrete aluminium oxide fibres with a diameter of 10 to 20 nm and copper powders with a size of 10 to 20 mcm for 30 to 40 minutesthe introducing the resulting conglomerates into the melt of aluminium or aluminium alloy at a temperature of 750 to 800°C, mixing at a rate of 600 rpm with sustaining for 10 to 15 min for the development of processes of distribution of the discrete fibres throughout the volume of the melt, followed by mixing with controlled lowering of the temperature to 740 to 750°C and casting into moulds.

EFFECT: invention is aimed at increasing the hardness and microhardness of a composite material based on aluminium or an aluminium alloy while maintaining the density thereof.

2 cl, 2 dwg, 2 tbl

Description

The invention relates to the field of metallurgy, in particular to the production of a composite material based on aluminum or an aluminum alloy, reinforced with discrete fibers of Al ₂ O _{3 with a} diameter of the nano-range, which can be used in various fields of technology as a structural material with increased hardness without increasing density. The areas of priority application include: space systems, aircraft construction, mechanical engineering, instrument making, shipbuilding, railway and other types of transport.

A known method of manufacturing a powder composite material, which contains a matrix of aluminum or magnesium alloy, and 20-80 vol.% Of the hardener, made in the form of reinforcing nanofibers of aluminum oxide, covered with a film of amorphous carbon (RF Patent No. 2374355 from 27.11.2009). The disadvantage of the proposed invention is the complexity of the technology, the need to use specialized equipment, the difficulty of making samples, the danger of powder burning and explosion during production.

There is also known a method of producing an aluminum-based alloy (RF patent No. 2516679, dated 20.05.2014), which is obtained by mechanical mixing of discrete ceramic particles of the carbon-containing boride phase C ₂ Al ₃ B _{48 with a} size of 1-2 microns into the melt in an amount of 0.1-0 , 6% by weight. The proposed method of mechanical mixing is practically difficult to implement due to the agglomeration of particles and loss of fluidity of the melt, moreover, the method does not provide a uniform distribution of particles in the matrix and, therefore, a stable level of properties of paintwork materials.

As a prototype, a cast composite material based on an aluminum alloy and a method for its production were chosen (RF Patent No. 2353475 dated 04/27/2009), which consists in mixing powders of a matrix component from an aluminum alloy Al + 3% Mg and reinforcing discrete ceramic silicon carbide particles with a grain size of 30-50 microns in an amount of 3-5 wt.% or 9-15 wt.%, briquetting the mixture under a pressure of 28-35 MPa, introducing briquettes into the Al + 3% Mg alloy melt, mixing the melt and casting. The disadvantage of the proposed invention is the large size of the filler, the ineffectiveness of manufacturing composite materials reinforced with nanosized fillers due to the problem of introducing a nanosized reinforcing phase into the melt.

The problem to be solved by the claimed invention is to develop a composition and a method for producing a cast composite material based on aluminum or an aluminum alloy reinforced with discrete Al ₂ O ₃ fibers with a nanoscale diameter.

The essence of the invention lies in the fact that the proposed cast composite material based on aluminum or aluminum alloy is filled with discrete Al ₂ O ₃ fibers with a nanoscale diameter. It is proposed to use copper as an effective component, which, on the one hand, can act as an alloying element for the matrix material, and on the other hand, as an element providing transport functions when introducing nanofibers. The transporting copper powder is preliminarily ground with a filler, forming a certain conglomerate.

The method is illustrated by graphic materials: Fig. 1, Fig. 2. Figure 1 shows a diagram of obtaining a composite material based on aluminum or aluminum alloy, reinforced with discrete fibers of Al ₂ O _{3 with a} diameter of the nanoscale. Figure 2 shows a scheme for obtaining a conglomerate.

The proposed method for producing a cast composite material consists in mixing reinforcing phases containing discrete fibers of aluminum oxide with a diameter of the nanoscale (10-20 nm) and micron-sized copper powders (10-20 microns), followed by mechanical kneading of the conglomerate into the matrix melt.

The reinforcing phases are mixed in a ceramic mortar at room temperature. Mixing time 30-40 minutes at a speed of 60 rpm. The resulting conglomerate is introduced into the matrix melt, heated to 800 ± 10 ° C, under the condition of constant stirring at a speed of 600 rpm. In the course of research, the optimal melt temperature was established empirically to ensure proper assimilation of the filling component. At 750-800 ° C, the melt was kept for 10-15 minutes to distribute the filler in volume, then it was stirred at a controlled temperature decrease to 740-750 ° C and poured. The subsequent crystallization of the melt took place spontaneously.

Using the above technology, samples were made to measure the physical and mechanical properties. The characteristics of the tested materials are given in table. 1 and 2.

Thus, the proposed cast composite material differs from the original matrix materials in a better set of properties: an increase in hardness by 41%, microhardness by 22%. While maintaining the density at the level of precision of the second decimal place. The hardening effect with the introduction of nanofibers is shown in Table 2 in terms of impact work. Impact work is reduced by 53%.

Table 1 Material Density
(g / cm ³ ) Hardness
(HB) Microhardness (HV0.1) Initial matrix material Al 2.6917 19.07 ± 1.36 26.1 ± 2.91 Raw material
Al + 1% Cu material 2.6736 22.42 ± 1.64 29.94 ± 2.26 Al + 1% (nanoAl ₂ O ₃ + Cu)
composite material 2.6739 26.87 ± 1.54 31.86 ± 3.16

table 2 Material Impact work (J) Initial matrix material
Al 67.4 ± 5.9 Raw material
Al + 1% Cu material 22.5 ± 2.2 Al + 1% (nanoAl ₂ O ₃ + Cu)
composite material 31.3 ± 1.1

Claims (2)

1. Cast composite material based on aluminum or aluminum alloy, containing a matrix of aluminum alloy and a hardener made in the form of a conglomerate of discrete fibers of aluminum oxide with a diameter of 10-20 nm and transport copper powders with a size of 10-20 microns, while the total content of aluminum oxide and copper is 1 wt.%. 2. A method of producing a cast composite material based on aluminum or an aluminum alloy, characterized in that it includes mixing discrete fibers of aluminum oxide with a diameter of 10-20 microns and copper powders with a size of 10-20 microns for 30-40 minutes, introducing the obtained conglomerates into the melt aluminum or aluminum alloy at a temperature of 750-800 ° C, stirring at a speed of 600 rpm for 10-15 minutes for the processes of distribution of discrete fibers in the volume of an aluminum or aluminum alloy melt, then stirring is carried out at a controlled temperature decrease to 740-750 ° C and casting into molds to obtain cast composite materials.

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