This study carried out the microstructural characterization, by light microscopy, of sintered SiC in the presence of liquid phase at temperatures of 1800, 1850 and 1900 ºC, added with Al₂O₃ and Y₂O₃ as well with Al₂O₃-YAG composite in the proportions of 5, 10 and 15% by weight. It was possible to observe the formation of microstructural patterns resulting from the heterogeneous segregation of the additives, such observation is associated to the pulling of additives during the initial stage of ceramography. Two ceramographic paths were followed: method I - surface grinding followed by manual polishing and method II - automatic grinding and polishing. In order to compare the two techniques the analysis of 3D roughness by light interferometry and the Vickers microhardness test were used. It was concluded by the analysis of variance with 95% confidence that the degree of finishing obtained by both methods allowed the adequate microstructural characterization, as well as, to meet the requirements established by the ASTM C1327-15 standard for hardness test.

Additive manufacturing (AM) plays a crucial role in the development of NiTi alloys, enabling the creation of complex and customized structures while optimizing properties for various biomedical and industrial applications. The aim of this paper was to investigate the influence of laser scanning speed on laser-assisted reactive sintering of a mixture of No and Ti powders. The samples were sintered at two different beam speeds, 4 and 5 4 mm/s and their morphological and microstructural characteristics were investigated. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD) analyses revealed the presence of intermetallic compounds rich in Ni and Ti for both scanning speeds; however, the scanning speed of 5 mm/s produced a microstructure with greater porosity, leading to a sintered body with poorer consolidation. Thus, employing a slower beam scanning of 4 mm/s seems to be a better alternative in the laser-assisted reactive sintering of NiTi alloys.

This work investigated the sintering of silicon carbide (SiC) with alumina (Al2O3) and yttria (Y2O3) additives by hot pressing. Mixtures of SiC with 1% and 5% Al2O3 and Y2O3 were used, pressed at 1800 °C and 1850 °C, resulting in specimens that were characterized in terms of density, microstructure, Vickers hardness and fracture toughness. The addition of 5% oxide additives provided greater densification and better mechanical properties. The temperature of 1800 °C proved to be the most effective for sintering due to the microstructure presented. The analysis revealed a homogeneous distribution of additives and grains, concluding that the 5% additive is considerably superior for increasing the densification and mechanical strength of SiC.

Tecnol. Metal. Mater. Min., vol.22, e3147, 2025

In this study, nanometric powders of silicon carbide (SiC), micrometric alumina (Al₂O₃) and yttria (Y₂O₃), with specific characteristics provided by the manufacturers, were used to investigate the compaction behavior and the resulting properties after sintering. The SiC used has a purity of over 99% and a particle size distribution with a d50 of 40 nm, while Al₂O₃ and Y₂O₃ have purities of 99.8% and 99.995%, respectively. The morphological evaluation of the powders was carried out using scanning electron microscopy (SEM), while the apparent density analysis was conducted using gas pycnometry. SiC mixtures with 1% and 5% Al₂O₃ and Y₂O₃ were prepared and subjected to uniaxial compaction tests to determine densification behavior under different pressures. The results of this study are relevant to the development of ceramic materials with optimized properties for a wide range of industrial applications. The addition of small amounts of oxides to SiC does not compromise its compaction properties, maintaining the effectiveness of the sintering process and resulting in materials with high density and improved mechanical properties.