BR-102024017669-A2 - High Electrical and Thermal Conductivity Aluminum-Graphene Nanocomposites and Methods for Obtaining Them via Microstructural Control

Abstract

This patent application relates to "HIGH ELECTRICAL AND THERMAL CONDUCTIVITY ALUMINUM-GRAPHENE NANOCOMPOSITES AND METHODS OF OBTAINING THEM VIA MICROSTRUCTURAL CONTROL", more specifically to the incorporation of multilayer graphene nanoplatelets (NGM - or few-layer nanoplatelets), in up to 10 layers, in pure commercial aluminum or aluminum alloys, using electric furnaces. The nanocomposites obtained consist of an aluminum matrix with dispersed graphene as a reinforcing phase, in proportions ranging from 0.1% to 3% by weight. To obtain the nanocomposites, gravity casting techniques in resistive furnaces and induction casting were employed, with adaptations to prevent oxidation through the use of an inert gas atmosphere. The methodology employed allowed for a significant increase in electrical conductivity, ranging from 45% to 95% compared to the commercial material as received, depending on the amount of graphene added. The thermal diffusivity of the nanocomposites also showed an increase of 15% to 50%, with a possible maximum around 0.5 to 1 wt% of graphene. Similarly, the overall physical properties exhibited significant gains, although the rate of improvement decreased for nanocomposites with more than 2 wt% of graphene.

Inventors

• SIDNEY NICODEMOS DA SILVA

Assignees

• DELPHYS PARTNERS S/A

Dates

Publication Date

20260310

Application Date

20240828

Claims (6)

1. 1. HIGH ELECTRICAL AND THERMAL CONDUCTIVITY ALUMINUM-GRAPHENE NANOCOMPOSITES, characterized by comprising an aluminum (Al) matrix reinforced with graphenic materials that establish - preferably - a spatial distribution with dispersions around the alpha (α) grain boundaries - in unary microstructure - or (α) and beta (β) grains when there are intermetallic phases, forming peritectic-type microstructures with uniform stereoscopic dispersion of graphene nanoplatelets forming an interconnected nanostructured network, with a graphene proportion varying between 0.1% and 3.0% by weight, the nanocomposite exhibiting an electrical conductivity greater than 70% IACS.
2. 2. HIGH ELECTRICAL AND THERMAL CONDUCTIVITY ALUMINUM-GRAPHENE NANOCOMPOSITES, according to claim 1, characterized in that the aluminum matrix is preferably derived from aluminum alloys of the 1000 series - such as 1350 (commercially pure) - or typical casting alloys such as SAE 323 or 6201 for the production of electrical cables.
3. 3. HIGH ELECTRICAL AND THERMAL CONDUCTIVITY ALUMINUM-GRAPHENE NANOCOMPOSITES, according to claim 1, characterized by graphenic materials, in the form of multilayer graphene nanoplatelets (MGNs), used in the processing of (Al) nanocomposites, with the number of layers varying from one to ten, and having an average surface area equal to or greater than 60 m2/g.
4. 4. HIGH ELECTRICAL AND THERMAL CONDUCTIVITY ALUMINUM-GRAPHENE NANOCOMPOSITES, according to the preceding claims, characterized by having an increased thermal diffusivity of 15 to 50% compared to the aluminum alloy used for the synthesis of the nanocomposites, this diffusivity being obtained through the formation of an interconnected nanostructured graphene network that promotes efficient heat transfer along the metallic matrix, resulting in a significant reduction in thermal resistance and an improvement in heat dissipation.
5. 5. METHOD FOR OBTAINING ALUMINUM-GRAPHENE NANOCOMPOSITES WITH HIGH ELECTRICAL AND THERMAL CONDUCTIVITY, characterized by encompassing the following steps: • Preparation of aluminum and graphene in crucibles heated to 850°C under an inert atmosphere; • Gradual addition of 2/3 of the graphene to the molten aluminum in the first crucible, followed by the incorporation of the molten aluminum from the second crucible and manual stirring for homogenization; • Addition of the remaining graphene and solid aluminum to the system, with subsequent manual stirring and holding in a furnace for microstructural stabilization; • Molding of the alloy in a sand box after verifying that the temperature is above 740°C, to ensure dimensional accuracy and structural quality.
6. 6. METHOD FOR OBTAINING ALUMINUM-GRAPHENE NANOCOMPOSITES WITH HIGH ELECTRICAL AND THERMAL CONDUCTIVITY, according to claim 5, characterized by using resistive furnaces and/or electromagnetic induction furnaces, where eddy currents and the magnetic blast generated by the induced currents assist in the agitation and homogeneous dispersion of graphene in the molten aluminum matrix.

Description

[001] This invention patent refers to a technology for the synthesis of graphene-reinforced aluminum (Al) metal matrix nanocomposites, which exhibit enhanced electrical, thermal, and mechanical properties through microstructural control of the products obtained – a solid (graphene nanoplatelets) and a liquid (aluminum or molten aluminum alloy) transforming into a solid through a peritectic reaction (involving 3 phases: δ + L θ Y) where the optimization of the dispersion and quantities of dispersed phases (graphene) in the aluminum matrix were processed in more effective electric furnaces to improve the physical properties. The technique stands out for the gradual and controlled addition of high-quality graphene materials in resistive furnaces and/or in an electromagnetic induction furnace, operating in an inert atmosphere. Nanocomposites can be formed from various aluminum alloys, especially alloys from the 1000 series - such as 1350 (commercially pure) - or typical casting alloys like SAE 323. [002] Based on the technique developed and employed here, it was possible to create nanocomposites with unprecedented properties. This was made possible by understanding and applying quantum concepts to ideally control the proportion and homogeneous dispersion of graphene in the metallic matrix, inducing a uniform spatial (3D) distribution of graphene in the microstructure, especially with dispersions around the alpha (α) grain boundaries – unary microstructure – or (α) and beta (β) grains, forming peritectic-type microstructures with uniform stereoscopic dispersion of graphene nanoplatelets. This distribution and dispersion generate a nanostructured and interconnected network that facilitates electron flow with the appearance of Cooper pairs – consequently bosons caused by electron-phonon interaction, significantly improving the electrical and/or thermal conductivity of the material, in addition to increasing other mechanical and/or physical properties through mechanisms that increase toughness. Scientific Context and Description of the State of the Art: [003] The need to mitigate the effects of climate change drives the search for disruptive technological solutions in the energy transition. The demand for materials with enhanced properties for electrification, energy storage, and energy efficiency catalyzes the development of new materials. Aluminum and copper alloys, widely used in industrial applications, stand out for their lightness, electrical and thermal conductivity, and corrosion resistance. However, their intrinsic properties limit their performance in modern applications that require superior physical and chemical characteristics. [004] Recent research in the fields of engineering and materials science—especially with the advent of nanotechnology—aims to overcome these technological barriers through the development of new materials and manufacturing routes. This scientific field has proven crucial in solving contemporary social and environmental problems, particularly in the context of climate change and environmental degradation. The creation of new materials, especially nanocomposites, offers unprecedented opportunities to improve quality of life and protect the environment. [005] Nanotechnology is an area of science and engineering dedicated to the study, manipulation, and control of matter at nanometric scales, generally below 100 nanometers. The origin of this technology dates back to the famous speech given by Richard Feynman in 1959, entitled "There's Plenty of Room at the Bottom," in which he discussed the possibilities of manipulating atoms and molecules individually. This speech is widely recognized as the initial milestone that sparked scientific interest in manipulation at the nanometric scale. [006] The evolution of nanotechnology occurred significantly in the following decades, with the development of techniques and tools that allowed the visualization and manipulation of matter at this scale. In 1981, the invention of the scanning tunneling microscope (STM) by Gerd Binnig and Heinrich Rohrer, who later received the Nobel Prize in Physics in 1986, was a crucial advance. This device allowed the direct observation of atoms on surfaces, providing a means to explore and manipulate sub-nanometric structures. [007] In the 1980s and 1990s, nanotechnology began to gain momentum as an interdisciplinary research field, encompassing physics, chemistry, biology, materials science, and engineering. During this period, the discovery of fullerenes (allotropic forms of carbon in closed structures, such as C60) by Harold Kroto, Richard Smalley, and Robert Curl in 1985, which also earned them the Nobel Prize in Chemistry in 1996, and the subsequent discovery of carbon nanotubes by Sumio Iijima in 1991, opened new frontiers in materials science due to the unique properties of these structures, such as high mechanical strength, electrical and thermal conductivity. [008] One of the most remarkable advances in na