RESUMO
The pollution of heavy metal ions in water seriously affects the ecosystem and human health. Here, an efficient synergetic photocatalytic-photothermal system is designed by combining a mildly oxidized Ti3C2 (mo-Ti3C2) with a super hydrophilic bamboo fiber (BF) membrane. The mo-Ti3C2 heterojunction promotes the transfer and separation of photoinduced charges and thus enhances the photocatalytic reduction of heavy metal ions (Co2+, Pb2+, Zn2+, Mn2+ and Cu2+). The photoreduced metal nanoparticles with high conductivity and LSPR effect further accelerate the transfer and separation of photoinduced charges, and improve photothermal and evaporative performance. The mo-Ti3C2-2.4 @BF membrane in Co(NO3)2 solution can achieve an excellent evaporation rate of 4.6 kg·m-2·h-1 and a high solar-vapor efficiency of up to 97.5% under the light intensity of 2.44 kW·m-2, which are 27.8% and 19.6% higher than those in H2O, respectively, demonstrating the reuse of photoreduced Co nanoparticles. No heavy metal ions are detected in any of the condensed water, and the Co2+ removal rate in the concentrated Co(NO3)2 solution is up to 80.4%. The synergetic photocatalytic-photothermal approach on the mo-Ti3C2 @BF membrane provides a new scope for the continuous removal and reuse of heavy metal ions, as well as for obtaining clean water.
RESUMO
Mo-Si-B alloys have attracted considerable research interest during the last several decades due to their high melting points, excellent high-temperature strength and relatively good oxidation resistance. However, insufficient room-temperature fracture toughness and high-temperature oxidation resistance restrain their further application. Generally, a sufficient volume fraction of BCC-Mo solid-solution phase, providing the ductility, and a high Si content, responsible for the formation of passive oxide scales, is difficult to achieve simultaneously in this ternary system. Recently, macroalloying of Ti has been proposed to establish a novel phase equilibrium with a combination of enough BCC phase and intermetallic compounds that contain a large amount of Si. In this article, the development history from the ternary Mo-Si-B to the quaternary Mo-Ti-Si-B system was reviewed. It was found that the constitution phases could be easily tailored by changing the Ti content. In this regard, better performance of mechanical properties and oxidation resistance can be obtained through proper alloy design. In-depth understanding of the advantages of the quaternary alloys over their ternary ancestors may contribute to bringing about a new concept in designing novel ultra-high-temperature structural materials.
RESUMO
This paper investigated the improvement of mechanical properties for one of the most used biomaterials, titanium-based alloy. To improve its mechanical properties, molybdenum was chosen to be added to Ti and Ti-Zr alloys through a mechanical blending process. After homogenization of Ti (12, 15) Mo and Ti (12, 15) Mo-6 Zr, the compaction pressure and sintering temperature were varied to create pellets. Characterization has been done using scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers's hardness, Archimedes test and ultrasonic method, and 3-point bending test. Micrograph of each pellet revealed the influence of Mo content that plays a prominent role in the variation of microstructure in the alloys Ti-Mo and Ti-Zr-Mo. The porosity and density were also influenced by changing the ß-phase. EBSD analysis shows the increase in ß-phase with the addition of Zr. The overall results indicated that the percentage of ß-phase greatly affects the mechanical properties for the specimens.
RESUMO
Purpose: Titanium alloys are commonly used for prosthetic abutments fabrication, but these alloys present high cost and difficult handling. Alternative Ni-Cr alloys with Mo and Ti combination have been proposed. This study compared the alloys Ti-6Al-4V and Ni-Cr-Ti-Mo by analyzing their surface properties such as hardness, morphology and microstructural characterization. Methods: Five discs (5 x 2 mm) of commercially Ti-6Al-4V and Ni-Cr-Ti-Mo alloys were used to evaluate Vickers hardness by hardness micro indentation test. The same specimens were analyzed by scanning electron microscopy (SEM) regarding surface morphology and subjected to a metallographic analysis of the microstructure by optical microscopy. Data on surface hardness were analyzed using one-way ANOVA followed by Tukey test (α = 0.05). Results: The Ni-Cr-Mo-Ti alloy showed significantly higher Vickers hardness (kg/mm2) values (452.2 ± 3.9) than the Ti-6Al-4V alloy (375.7 ± 15.2). The surface morphology evaluated by SEM revealed differences between the alloys. Metallographic analyses, for both alloys, showed a two-phase equilibrium microstructure, with the presence of e α + ß phase for Ti-6Al-4V; and gamma (γ) primary phase and gamma-prime (γ´) as a second phase for Ni-Cr-Mo-Ti. Conclusion: It can be concluded that both alloys present the requirements to be used in prosthetic abutments.
Objetivo: As ligas de titânio são comumente usadas para a fabricação de componentes protéticos, entretanto apresentam alto custo e dificuldade de manuseio laboratorial. Ligas alternativas a base de Ni-Cr combinadas com Mo e Ti também tem sido propostas com o mesmo objeto. Este estudo comparou as ligas Ti-6Al-4V e Ni-Cr-Ti-Mo pela análise de suas propriedades de superfície como dureza, morfologia e caracterização da microestrutura.Metodologia: Cinco discos (5 × 2 mm) das ligas Ti-6Al-4V e Ni-Cr-Ti-Mo foram utilizados para a avaliação da dureza Vickers, análise de morfologia de superfície por meio da microscopia eletrônica de varredura (MEV) e análise da microestrutura pela análise metalográfica. Os dados da dureza de superfície foram analisados pela Análise de Variância a um nível seguida do teste de Tukey (α = 0,05). Resultados: A liga Ni-Cr-Mo-Ti apresentou os maiores valores de dureza Vickers (kg/mm2) (452,2 ± 3,9) comparada a liga Ti-6Al-4V (375,7 ± 15,2) A morfologia de superfície avaliada por MEV revelou características distintas entre as ligas. A análise metalográfica para ambas as ligas mostrou uma microestrutura com equilíbrio de duas fases, com a presença de fase α + ß para Ti-6Al-4V; e fase gamma primária (γ) e fase gamma-prime (γ') como secundária para Ni-Cr-Mo-Ti. Conclusão: Ambas as ligas podem ser utilizadas para fabricação de pilares protéticos.