J. P. Cardoso

University of Aveiro | UA · Division of Materials Engineering

The annealing behavior of (1-x)BiMg0.5Ti0.5O3–xBiZn0.5Ti0.5O3 [(1-x)BMT–xBZT] perovskite solid solutions synthesized under high pressure was studied in situ via X-ray diffraction and piezoresponse force microscopy. The as prepared ceramics show a morphotropic phase boundary (MPB) between the non-polar orthorhombic and ferroelectric tetragonal state...

Layered double hydroxides (LDHs) are regarded as potential adsorbents for water treatment from a wide range of pollutants. However, there are only a few studies concerning application of LDHs for elimination of microorganisms from aquatic systems. In this work, experiments were conducted to investigate the efficiency of commercial synthetic hydrota...

(1–x)BiMg0.5Ti0.5O3−xBiZn0.5Ti0.5O3 [(1−x)BMT–xBZT] ceramics of perovskite solid solutions, in which BMT and BZT are lead-free structural analogs of PbZrO3 and PbTiO3, respectively, have been synthesized under high pressure. It was found that the as-prepared compositions with a relative BZT content of <75 mol% are orthorhombic (space group Pnnm), w...

The phase content and sequence, the crystal structure, and the magnetic properties of perovskite solid solutions of the (1−y)BiFeO3–yBiZn0.5Ti0.5O3 series (0.05 ≤ y ≤ 0.90) synthesized under high pressure have been studied. Two perovskite phases, namely the rhombohedral R3c and the tetragonal P4mm, which correspond to the structural types of the en...

The (1-x)BiFeO3-xBiZn0.5Ti0.5O3 solid solutions (0.05 ≤ x ≤ 0.25) were prepared using high-pressure synthesis. Up to 25 at.% substitutions of Fe by the combination of [Mg0.5Ti0.5] were found to increase the unit cell volume of the primitive perovskite cell, while the crystal structure remains the rhombohedral perovskite, as that in the parent BiFeO...

Precipitation of nanocrystallites of cobalt-aluminium layered double hydroxides in a magnetic field has been studied. In a magnetic field perpendicular to the substrate, dense and homogeneous films have been obtained....

Ni-Cr-Mo is a candidate to substitute Co binders in WC-based composites, where high corrosion resistance is required. This work focused on the effect of Cr on the corrosion susceptibility of WC-Ni-Cr-Mo composites, in acid media. Specimens were produced by powder metallurgy followed by microstructural, chemical and mechanical characterization. Open...

The temperature behavior of the crystal structure as well as dielectric and magnetic properties of the perovskite bismuth chromate ceramics with the 10 mol % Cr3+-to-Sc3+ substitution were studied and compared with those of the unmodified compound. Using a high-pressure synthesis, BiCrO3 and BiCr0.9Sc0.1O3 were obtained as metastable perovskite pha...

WC-Ni-Cr-Mo are good candidates for replacing WC-Co for its better corrosion performance. This work investigated the effect of different Mo content on the mechanical properties and corrosion susceptibility of WC-Ni-Cr-Mo composites in chloride and sulphate acidic media. Chemical, microstructural, and electrochemical analysis were performed. Results...

Alternative binders to cobalt, based on stainless steel (SS, AISI304) and copper were investigated for tungsten carbide (WC) based cemented carbides. The binder content was fixed at 12 wt%, and the Cu:SS ratio varied in proportions of 0:1, 1:5, 1:2, 1:1, 1:0. High energy ball milling was applied to ensure high homogenization, nanometric particle si...

Cobalt is the standard binder in tungsten carbide (WC) hardmetals due to its compatibility with the WC phase, resulting in composites with exceptional hardness and wear resistance. However, their corrosion resistance is not satisfactory in many applications, leading to the early deterioration and failure of tools and equipment. In this work, the co...

WC-AISI304 (SS) composites with the phase composition controlled by adequate carbon addition are being developed as potential alternatives to the established WC-Co hardmetals, following the REACH regulation relatively to the elimination of toxic and critical elements and the actual market demands of lower cost production and enlarged range of prope...