Hydroxyapatite is an essential material for bone and dental composition, widely used in biomaterials due to its biocompatibility and bioactivity. Its crystalline structure, similar to human bone, facilitates integration with biological tissues, promoting bone and dental regeneration. Applications include implants, orthopedic coatings, and bone grafts. The aim of this work was to synthesize hydroxyapatite with different percentages of lithium fluoride by aqueous precipitation. The produced powders were sintered at 1100 °C, and their properties were characterized by XRD, FTIR, and SEM. The results indicated the presence of fluorapatite and calcium oxide phases in the hydroxyapatite with lithium fluoride, with ion substitution occurring, while samples without LiF addition revealed the presence of hydroxyapatite and calcium oxide phases. SEM images showed that the samples with LiF addition exhibited morphological anisotropy, while pure hydroxyapatite samples showed equiaxed grains. The addition of LiF reduced the porosity of the samples after sintering. FTIR results indicated that fluoride ions replaced the hydroxyl groups originally present in the pure hydroxyapatite structure.

Additive manufacturing using laser powder bed fusion (LPBF) has been widely used to produce nickel-based superalloy components with complex shapes for high-temperature applications requiring creep resistance. In this research, the creep behavior of LPBF Inconel 718 under solution and double-aging heat treatments, performed at 590–650 °C under stresses of 450–550 MPa, is studied. The characterization included optical microscopy, scanning electron microscopy (SEM), porosity analysis, Vickers microhardness tests, and fracture surface examination. The findings revealed that even after heat treatment, the material maintained a mainly directional, columnar microstructure, with an average porosity below 1%, which was unevenly distributed and contained critical defects related to lack-of-fusion (LOF) and trapped powder. Fracture after creep presents regions of ductile failure alongside facets indicative of quasi-cleavage. Kinetic analysis revealed a high stress exponent (n = 18.26) and an activation energy (Qc = 410–538 kJ/mol), indicating that the deformation operates within the power-law breakdown (PLB) regime, where dislocation–precipitate interactions govern the creep rate in this precipitation-strengthened superalloy. Overall, the results highlight that the directional microstructure and residual defects typical of LPBF can reduce the creep resistance of Inconel 718, underscoring the importance of post-processing methods and internal defect control specifically tailored for additively manufactured materials.

This article analyzes a failure of a disc brake used in the Stock Car Pro Series. It focuses on a phase transformation in the pearlitic gray cast iron, commonly occurring during heat treatment. Telemetry data from the racing team, along with samples of brake discs, were utilized for this study. The aim was to explore the potential causes leading to catastrophic wear and failure of the component under real racing conditions. The analyzed brake disc exhibited catastrophic wear due to abrasion, adherence, and material transfer between the disc and brake pads. Through metallographic investigation using optical and scanning electron microscopy, a phase transformation was identified in the outer layer of the brake disc, which may have contributed to its reduced lifespan. Surface hardness was evaluated using a Vickers microhardness tester, revealing that rapid temperature increases induced tensile and compressive stresses, resulting in austenitization and eutectoid transformation in the cooling process.

O setor de cerâmica no Brasil vivencia uma grande expansão, tendo uma participação no PIB nacional de quase 1,0%, em virtude principalmente dos materiais cerâmicos serem os mais utilizados na construção civil. Diante disto, as elevadas perdas de produtos manufaturados gera grande quantidade de resíduos, causando transtornos as imediações vizinhas. Baseado nisso, este trabalho teve como finalidade avaliar a viabilidade de incorporar o resíduo gerado por uma indústria de cerâmica vermelha em uma massa cerâmica argilosa para produção de tijolos e incentivar o reaproveitamento de tal resíduo. Foi realizada caracterização química das amostras e três misturas cerâmicas foram formuladas, utilizando uma argila plástica e o resíduo, onde posteriormente confeccionou-se corpos-de-prova. Os corpos de prova foram sinterizados e passaram para análise físico-mecânica. A adição do resíduo na massa em substituição a argila sem plasticidade, se mostrou favorável em relação as propridedaes físicas, sendo que a propriedade mecânica deverá ser reavaliada.