Integrating Graphene in Aluminum Composites to Reduce Friction and Wear

13.05.2024

Introduction

An investigation into the combination of graphene and aluminum shows how graphene improves the friction properties of the metal in powder form. There has been a considerable amount of research into alloys and composites that increase the lifespan and durability of metals while at the same time reducing the occurrence of abrasive wear. Graphene consists of a single plane of carbon with unique physical and mechanical properties and, in its liquid form, it is an innovative and efficient lubricant that can be applied to form a strong protective barrier and shield surfaces from abrasion. Graphene powder also combines well with aluminum, adding fatigue strength as well as reducing the composite’s friction coefficient. Several studies have now looked deeper into the methods used to combine aluminum and graphene to find ways of optimizing the form and function of this unique and highly useful composite.

Enhancing the Friction Coefficient of Aluminum

As a pure metal, aluminum’s excellent strength-to-weight ratio makes it suitable for a range of lightweight applications in industry. High-quality aluminum sheets can be cut into identification tags to track merchandise and equipment, or formed into larger components used in construction such as roofing and cladding panels. The tribological qualities of aluminum are of little consequence in these cases, but, in other applications such as machinery or car parts, the metal may experience damage and wear due to repeated sliding and abrasion.  By integrating a solid lubricant with aluminum, the resulting composite can become self-lubricating. This is because a thin film is formed between the surface of the material and other parts joining forces with it. As graphene only occurs in a single layer it is not the most suitable addition, however, the composite structure can be modified by using multilayer graphene (MLG). With the addition of between 10% vol and 15% vol of MLG to aluminum matrix composites, the wear rate, friction coefficients, and overall tribological properties of the composite are improved.

Determining the Optimum Graphene Content in Aluminum Composites

Adding too much graphene to an aluminum composite can also result in a deterioration of friction and wear resistance. The aluminum alloy B319 (a mix of aluminum, silicon, and copper) is commonly used in the car industry to manufacture powertrain components including the engine, cylinder heads, transmission, and drive shaft as it performs well mechanically even in high temperatures. However, its wear resistance is poor which limits its use. Recently, reinforcement of B319 with graphene has shown promising results in the improvement of both mechanical and lubrication properties.  In aluminum alloy-graphene composites created through the process of stir casting, those with a 0.3 weight percentage of graphene showed the optimum tribological results.

Overcoming the Limitations of Graphene To Improve Wear Resistance

Graphene can have a significant effect on the properties of a range of both metal and nonmetallic substances and has therefore been the subject of much interest in materials research. It does, however, have some limitations due to its tendency to agglomerate. When mixing graphene and aluminum composites in powder form, an unwanted clustering of particles, or agglomeration, may occur.  One experiment has reduced this risk by preparing the composite with high-energy ball milling where materials are ground and mixed together by steel or ceramic balls in a rotating cylindrical blender.  The properties of the composite, including strength, microstructure and tribological corrosion qualities, can then be then analyzed. Compared with pure aluminum, the addition of graphene improves the hardness in composite form and, with an average friction coefficient of 0.027, the composite has the potential for good resistance against wear and corrosion. This leads to an overall improvement in the performance and lifespan of aluminum components.

Although aluminum in its purest form already has relatively low friction coefficients, when it is combined with graphene, the resulting composites are more durable and have increased protection against friction and wear.  Scientific research into the methods used to mix graphene with aluminum, whether in pure, alloy or powder form, is helping to optimize the tribological properties of the metal so that it meets the requirements of a wide range of mechanical applications.

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Author: Briana Hilton ([email protected])

Administration of the project

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