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The aim of this paper is to study both the mechanical and chemical properties of a new material composed of B4C doped with 3% volume of CoCrFeNiMo HEA by the spark plasma sintering technique. Scanning electron microscopy and microhardness were used to characterize the composite microstructure and hardness. Corrosion behavior was studied by corrosion potential, corrosion rate and electrochemical impedance spectroscopy, where the equivalent circuit was obtained, characterized by the presence of the Warburg element. The addition of HEA resulted in a more compact microstructure, filling pores and inhibiting ceramic grain growth. A microhardness statistical analysis revealed that the sample followed a normal distribution, which suggests that the sample has a homogeneous structure. The doped material exhibits excellent corrosion resistance in artificial seawater, where its chemical interaction occurs in two steps, with an important diffusional component. This study highlights the potential for use in environments where both corrosion resistance and mechanical strength are critical factors. [ABSTRACT FROM AUTHOR]

Monolithic NbB2, NbB2-SiC, and NbB2-SiC-GNP samples were produced by spark plasma sintering (SPS), and the effects of additives on the mechanical and thermal properties, microstructures, and oxidation behavior of the samples were investigated. The addition of SiC up to 30 vol% decreased the Vickers hardness of the binary composites due to microcrack formation. The fracture toughness and oxidation resistance of NbB2 were improved with the incorporation of SiC. Fracture toughness was higher for all the composites in comparison to monolithic NbB2, moreover the highest value of ~5.2 MPa·m1/2 exhibited by 3 vol% GNP-containing composite. A strong interface and homogeneous distribution of GNPs enhanced the thermal transfer properties and improved the oxidation resistance of selected NbB2-SiC ceramics in oxidation studies at 1200°C. A combination of high mechanical properties, high thermal conductivity, and low mass gain was achieved for the NbB2-SiC-GNP samples with 1 and 3 vol% GNPs. [ABSTRACT FROM AUTHOR]