In today’s modern world, composite materials, which have a low cost along with excellent mechanical properties, are extensively used. Great advantages are obtained when incorporating low density aluminum alloy with the extraordinary mechanical properties of carbon nanotubes (CNTs). Nevertheless, many obstacles were found to combining carbon nanotubes with aluminum alloy and maintaining this combination without reducing the basic properties. In this article, multiwalled carbon nanotubes (MWNTs) with diameters of 30–50 nm and lengths of 0.5–2 μm were incorporated into the matrix of aluminum silicon alloy (Al-11 wt.% Si) with an average particle size 15–75 μm using air plasma spray (APS) coating. These coatings were deposited on wrought aluminum alloy AA6082-T6 and have applications in the low temperature section of the rotary parts of turbine engines, which are exposed to a high wear rate.

The outstanding mechanical properties of CNTs and light weight with a high aspect ratio led to their use as a reinforcement agent in composite materials. The use of CNTs as a reinforcement material was found to have many advantages, and they can be combined very well with base materials (matrix) such as metals, ceramics and polymers by filling the holes inside the structures as a nanomaterial. These composites use CNTs to reinforce and support the matrix. Therefore, it maintains its strength and other mechanical properties on a microscopic scale.

Aluminum composites with various reinforcement materials have been under development for many years with different degrees of success. There are certain techniques to produce nanocomposite coatings or bulk nanocomposite materials. The nanoparticles or nanotubes are susceptible to heat during fabrication, which leads to the production of the final nanocomposite material. Heating, such as sintering or heat treatment, causes diffusion or sublimation of the nanoparticles. Therefore, the heating could result in the elimination of the nanoparticles or change their properties. There are several methods to fabricate Al-Si-MWNTs nanocomposite coating such as plasma spray coating, cold spray coating, and laser cladding, and for bulk nanocomposite materials it is preferable to use spark plasma sintering, as the rapid cooling maintains the nanomaterials within the matrix without causing disorder to their shape or damaging the structure.

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