This paper focuses on reporting results obtained by the spark plasma sintering (SPS) consolidation and characterization of aluminum-based nanocomposites reinforced with concentrations of 0.5 wt%, 1 wt% and 2 wt% of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Experimental characterization performed by SEM shows uniform carbon nanotube (CNT) dispersion as well as carbon clusters located in the grain boundary of the Al matrix. The structural analysis and crystallite size calculation were performed by X-ray diffraction tests, detecting the characteristic CNT diffraction peak only for the composites reinforced with MWCNTs. Furthermore, a considerable increment in the crystallite size value for those Al samples reinforced and sintered with 1 wt% of CNTs was observed. Hardness tests show an improvement in the composite surface hardness of about 11% and 18% for those samples reinforced with 2 wt% of SWNCTs and MWCNTs, respectively. Conductivity measurements show that the Al samples reinforced with 2 wt% of MWCNTs and with 0.5 wt% SWCNTs reach the highest IACS values of 50% and 34%, respectively.

This article focuses on exploring how the electrical conductivity and densification properties of metallic samples made from aluminum (Al) powders reinforced with 0.5 wt % concentration of multi-walled carbon nanotubes (MWCNTs) and consolidated through spark plasma sintering (SPS) process are affected by the carbon nanotubes dispersion and the Al particles morphology. Experimental characterization tests performed by scanning electron microscopy (SEM) and by energy dispersive spectroscopy (EDS) show that the MWCNTs were uniformly ball-milled and dispersed in the Al surface particles, and undesirable phases were not observed in X-ray diffraction measurements. Furthermore, high densification parts and an improvement of about 40% in the electrical conductivity values were confirmed via experimental tests performed on the produced sintered samples. These results elucidate that modifying the powder morphology using the ball-milling technique to bond carbon nanotubes into the Al surface particles aids the ability to obtain highly dense parts with increasing electrical conductivity properties.

Novel copper-nickel matrix composites reinforced with silicon carbide (SiC) micro particles for metal contact applications were manufactured by powder metallurgy technology and were experimentally characterized. Cu and Cu alloys are commonly used as metal contact for either vacuum, oil, or SF6 in low-voltage circuit breaker devices, but their application in environments with the presence of oxygen is limited due to their tendency to form high-resistance copper oxides. Thus, the addition of Ni as an alloying element provides resistance to both humidity and several corrosive environments and increases the composites' hardness, mechanical strength, and wear resistance. Moreover, SiC was chosen due to its contribution to mechanical strength, mouldability, low production cost, and non-reactive nature at ordinary temperatures. Here, three SiC particle size distributions were considered, and it was found that the composites' physical properties are also dependent on the ceramic loading. After evaluating these properties, two specific SiC concentrations were potentially considered for electrode applications: 10 wt% and 20 wt%. The obtained hardness values are in the range of 55–65 HR30T which guarantees the necessary strength without detriment of the contact area whereas the welding is minimized. In addition to a homogeneous particle distribution in the solid material, specific wear resistance of ∼10⁻⁵ mm³N⁻¹m⁻¹ and electrical conductivities of ∼20 %IACS were obtained. Considering these parameters, Cu-Ni/SiC composites' performance is not compromised compared to commercial Ag/WC materials commonly used in metal contact applications.

The synthesis and characterization of bimetallic catalysts with Pt and W as active phases, supported on carbon, were carried out. A synthesis method based on the thermolysis of metal precursors was developed with systems in which an aqueous phase, an organic one and solid carbon are present. The Pt loading in the synthesized catalysts was kept constant and the amounts of W and carbon changed. It was found that the Pt phase forms hemispherical particles with average diameter of 3 nm. The W is predominantly in the form of hexagonal WO₃ crystals with average dimensions 35 by 15 nm. No evidence of alloy formation is found. The electrochemical characterization of ethanol oxidation includes cyclic voltammetry and current–sampled voltammetry techniques. Tungsten exerts a promoting role in the activity of the catalysts, revealed by considerably increased current densities with respect to carbon–supported Pt. Details of this enhanced activity are revealed by cyclic voltammetry with different operating conditions and electrolyte formulations. These experiments allowed to identify the oxidation of adsorbed organic intermediates influenced by the tungsten phase. WO₃ appears as well to cause the decrease in the rate at which Pt oxides reduce, leading to higher surface coverage of OH• species.

The aim of this paper focuses on presenting a recent study that describes the fundamental steps needed to effectively scale-up from lab to mass production parts produced from Al powders reinforced with 0.5 wt% of industrial multiwalled carbon nanotubes (MWCNTs), with mechanical and electrical conductivity properties higher that those measured at the lab scale. The produced material samples were produced via a Spark Plasma Sintering (SPS) process using nanocomposite aluminum powders elaborated with a planetary ball-mill at the lab scale, and high-volume attrition milling equipment in combination with controlled atmosphere sinter hardening furnace equipment, which were used to consolidate the material at the industrial level. Surprisingly, the electrical conductivity and mechanical properties of the samples produced with the reinforced nanocomposite Al powders were made with mass production equipment and were similar or higher than those samples fabricated using metallic powders prepared with ball-mill lab equipment. Experimental measurements show that the hardness and the electrical conductivity properties of the samples fabricated with the mass production Al powders are 48% and 7.5% higher than those of the produced lab samples. This paper elucidates the steps that one needs to follow during the mass production process of reinforced aluminum powders to improve the physical properties of metallic samples consolidated via the SPS process.

This article explores the industrial application of an Al-based nanocomposite reinforced with 0.5 wt.% of multiwalled carbon nanotubes with a Zn mechanical plating applied to fulfill the field requirements of electrical devices. The performance of electric devices made from this nanocomposite material and with a Zn plating was compared with that of MCCB devices using a normal Cu compound. MCCB devices with the Al-based nanocomposites compound showed a better performance, with less heat generated due to a flow of electrical charge passing through the device. The presence of MWCNTs in the Al nanocomposite dissipates heat, maintaining a stable electrical resistance in the MCCB, in contrast to what happens with Cu compound, which increases its electrical resistance as the temperature in the device increases.