https://ri.ufs.br/jspui/handle/riufs/2492 Fri, 24 Apr 2026 20:46:51 GMT 2026-04-24T20:46:51Z http://ri.ufs.br:80/retrieve/6be76712-b7a8-42c8-80eb-d0072a226548/P2cem.png https://ri.ufs.br/jspui/handle/riufs/2492 https://ri.ufs.br/jspui/handle/riufs/24418 Título: Avaliação do duplo ataque ácido em ligas de titânio para uso em implantes dentários Autor(es): Silva, Myllena Vieira Abstract: Double acid etching is a well-established method of surface modification for implants, although there are few studies on its application in newly developed alloys. The topography and surface composition influence the long-term success of dental implants, favoring fixation and osseointegration. Titanium alloys β emerge as an alternative with low modulus of elasticity, high resistance to corrosion and better mechanical properties, in addition to being composed of biocompatible elements, if compared to the most commonly used alloys today, Ti (cp-grade 2) and Ti-6Al-4V. Promising new alloys based on niobium and tin have been researched. In the present research, the influence of the double acid etching process on Ti-xNb-ySn alloys (x= 35 and 42 and y= 0 and 2) only cold-deformed, cold-deformed and aged was studied. The samples were subjected to surface acid attack in two steps of different acids HCl, HNO3 and H2SO4). The surface roughness parameters were quantified by roughness meter, while topography was studied by scanning electron microscopy, and wettability was determined by the sessile drop method. The results revealed that the two-step acid treatment altered the topography, increasing the surface area and consequently the potential for osseointegration. Attack A (HCl and HNO3) was more efficient for alloys with lower niobium content, while attack B (HCl and H2SO4) stood out as the most balanced in terms of roughness, surface energy and topography. Attack D (HCl, HNO3 and H2SO4) proved to be less efficient. Fri, 22 Aug 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/24418 2025-08-22T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/23484 Título: Desenvolvimento e avaliação do desempenho de filme compósito anticorrosivo reforçado de forma sustentável com resíduo de casca de arroz Autor(es): Batista, Joana Sueveny Barbosa Abstract: This study investigated the incorporation of rice husk ash (CCA) ranging from 5 to 40% into a poly(vinyl alcohol) (PVA) matrix for the development of composite films aimed at improving the corrosion resistance of SAE 1020 carbon steel. The results indicated that films with 40% CCA exhibited the best protective performance, with no visible corrosion on the substrate after 72 hours of exposure in a 3.5% NaCl solution. Scanning electron microscopy (SEM), confocal microscopy, and atomic force microscopy (AFM) analyses revealed that films with 40% CCA presented better surface uniformity with two distinct micro-regions. Fourier-transform infrared spectroscopy (FTIR) demonstrated interactions between the PVA matrix and CCA particles, with shifts in the hydroxyl group peak and changes in bands related to particle-polymer matrix interactions. Differential thermal analysis (DTA) and thermogravimetry (TG) showed that CCA is thermally stable, with mass loss associated with free water evaporation and organic compound decomposition. Electrochemical tests confirmed that films with 40% CCA exhibited superior corrosion resistance compared to both pure PVA and uncoated steel substrates. Wettability tests demonstrated a decrease in hydrophilicity as CCA concentration increased, and adhesion tests confirmed excellent adhesion at all tested concentrations. Additionally, the films were able to reduce mass loss by 20.7% compared to the uncoated substrate and by 8.5% compared to PVA without additives after 15 days of exposure, suggesting that PVA-CCA composite films are promising for corrosion protection of metallic substrates. https://ri.ufs.br/jspui/handle/riufs/23484 https://ri.ufs.br/jspui/handle/riufs/23477 Título: Estudo da influência da incorporação de resíduo de gesso nas características do tijolo solo-cimento Autor(es): Nascimento, Elvia Soraya Santos Nascimento Abstract: This dissertation investigated the use of recycled gypsum waste as a partial replacement for cement in the production of soil-cement composites, focusing on the evaluation of physical-mechanical performance and the environmental feasibility of the proposed solution. The soil used was characterized in terms of particle size distribution, chemical composition, and consistency limits. Portland cement CP V-ARI was selected for its high early strength, suitable for the experimental schedule. Improper disposal of gypsum waste poses a growing environmental concern, particularly due to the potential release of sulfates into soil and water bodies. This study aimed to mitigate such impacts by reusing this waste in soil-cement formulations. The gypsum was dried, ground, and sieved prior to incorporation in varying proportions. The materials were characterized using XRF, XRD, FTIR, and SEM/EDS. Cylindrical specimens were molded with 0%, 10%, 20%, and 40% gypsum replacing cement, and were tested for compressive strength and water absorption after 7 and 28 days of curing. Composites with up to 20% gypsum showed compressive strength of up to 3.87 MPa at 28 days and water absorption below 18%, meeting performance requirements for non-structural applications. In contrast, the 40% gypsum formulation exhibited significant strength reduction and microstructural degradation, with excessive ettringite formation confirmed by XRD and SEM. These findings highlight the need for careful control of gypsum content to ensure composite stability. It is concluded that incorporating up to 20% recycled gypsum is a technically viable, environmentally strategic, and economically feasible solution, capable of converting an environmental liability into a sustainable input for civil construction. Thu, 17 Jul 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/23477 2025-07-17T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/23043 Título: Estudo da intercalação de sulfadiazina de prata em hidróxido duplo lamelar de níquel e ferro Autor(es): Santos, Elenilson Rivando dos Abstract: Layered double hydroxides (LDH) are clayey materials of the hydrotalcite class and have a structure made up of layers formed by mixed hydroxides of two metal cations, structured in a two-dimensional stacking form. In recent years, it has been gaining greater prominence mainly due to its reconstruction and anion exchange properties, which allow the incorporation of biologically active substances that are negatively charged in the interlayer region. This property neutralizes positive charges, which generates not only the possibility of adsorbing positively charged materials on the HDL surface, but also of intercalating chemical species. The present work aimed to prepare and characterize NiFeLDH by coprecipitation route, evaluating the modification of its pH during synthesis and verifying its possible application as a carrier of the drug silver sulfadiazine (SDZ-Ag). The prepared materials were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Thus, it was possible to observe that the synthesis of NiFe-HDL by the selected method presents greater crystallinity and yield when the precursor solution is prepared with pH 9,0 and that this same HDL can be used in the anion exchange intercalation process. The intercalation of SDZ-Ag was confirmed by XRD, since there was a shift of the peak related to the basal plane (0 0 3) from 0.775 nm to 1.06 nm when aged in a 1000 ppm solution of the drug, and a decrease in the band at 1834 cm-1 that can be attributed to anion exchange. In the release test, the hybrid obtained an excellent response, since within 4 h it was able to stabilize the release rate of SDZ-Ag in aqueous medium and in PBS solution with pH set at 7,4, which demonstrates the potential for application of the material as a drug carrier. Wed, 16 Jul 2025 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/23043 2025-07-16T00:00:00Z