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Water repellency has significant potential in applications like self-cleaning coatings, anti-staining textiles, and electronics. This study introduces a novel nanocomposite system incorporating functionalized Al2O3 and CeO2 nanoparticles within a polyurethane matrix to achieve hydrophobic and UV-blocking properties. The nanoparticles were functionalized using an octadecyl phosphonic acid solution and characterized by FTIR and XPS, confirming non-covalent functionalization. Spin-coated polyurethane coatings with functionalized and non-functionalized Al2O3, CeO2, and binary Al2O3-CeO2 nanoparticles were analyzed. The three-layered Al2O3-CeO2-ODPA binary system achieved a contact angle of 166.4° and 85% transmittance in the visible range. Incorporating this binary functionalized system into a 0.4% w/v polyurethane solution resulted in a nanocomposite with 75% visible transmittance, 60% at 365 nm UV, and a 147.7° contact angle after three layers. These findings suggest that ODPA-functionalized nanoparticles, when combined with a polymer matrix, offer a promising approach to developing advanced hydrophobic and UV-protective coatings with potential applications across various industrial sectors.

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This study aimed to identify the potential use of the ceramic composite ZrO2(CeO2)-Al2O3 as a dental implant due to its intrinsic geometry and different masticatory loads based on finite element simulations. Ceramic samples were sintered at 1500 °C-2h, and characterized: The mechanical properties of the ceramic composite (hardness, fracture toughness, flexural strength, Young's Modulus, and Poisson ratio) were determined, in addition to the relative density and its structural characteristics. Commercial dental implant designs (incisal and third-molar) on CAD models were used in this study as an initial implant geometry applied in a typical simulated mandible anatomy. Finite element models were generated for implant geometries using CAD and CAE techniques. Loading cases were considered based on different intensities (100-500 N) and orientation angles to the implant axis (0° and 45°) to reproduce human masticatory conditions. For comparison purposes, the numerical predictions were compared with finite element simulations of gold-standard titanium implants. Ce-TZP/Al2O3 sintered ceramics showed flexural strength of 952.6 ± 88 MPa, hardness and fracture toughness of 1427 ± 46 HV and 11.3 ± 0.4 MPa m1/2, respectively, beside Young's modulus of 228.3 ± 65 GPa and Poisson ratio of 0.28. For both Ce-TZP/Al2O3 dental implant geometries, the implant prototypes showed adequate mechanical behavior regardless of the masticatory load value or the orientation angle applied in the simulations: All finite element predictions are lower than the values established by Mohr Coulomb's failure criterion, allowing the feasibility, preliminarily, of the proposed ceramics for dental implant applications without fracture risk.

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This work deals with the durability of a Pinus elliotti wood impregnated with alumina (Al2O3) particles. The samples were impregnated at three different Al2O3 weight fractions (c.a. 0.1%, 0.3% and 0.5%) and were then exposed to two wood-rot fungi, namely white-rot fungus (Trametes versicolor) and brown-rot fungus (Gloeophyllum trabeum). Thermal and chemical characteristics were evaluated by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG) analyses. The wood which incorporated 0.3 wt% of Al2O3 presented a weight loss 91.5% smaller than the untreated wood after being exposed to the white-rot fungus. On the other hand, the highest effectiveness against the brown-rot fungus was reached by the wood treated with 5 wt% of Al2O3, which presented a mass loss 91.6% smaller than that of the untreated pine wood. The Al2O3-treated woods presented higher antifungal resistances than the untreated ones in a way that: the higher the Al2O3 content, the higher the thermal stability. In general, the impregnation of the Al2O3 particles seems to be a promising treatment for wood protection against both studied wood-rot fungi. Additionally, both FT-IR and TG results were valuable tools to ascertain chemical changes ascribed to fungal decay.

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The search for adsorbent materials with a certain chemical inertness, mechanical resistance, and high adsorption capacity, as is the case with alumina, is carried out with structural or surface modifications with the addition of additives or metallic salts. This research shows the synthesis, characterization, phase evolution and Cd(II) adsorbent capacity of α-Al2O3/Ba-ß-Al2O3 spheres obtained from α-Al2O3 nanopowders by the ion encapsulation method. The formation of the Ba-ß-Al2O3 phase is manifested at 1500 °C according to the infrared spectrum by the appearance of bands corresponding to AlO4 bonds and the appearance of peaks corresponding to Ba-O bonds in Raman spectroscopy. XRD determined the presence of BaO·Al2O3 at 1000 °C and the formation of Ba-ß-Al2O3 at 1600 °C. Scanning electron microscopy revealed the presence of spherical grains corresponding to α-Al2O3 and hexagonal plates corresponding to ß-Al2O3 in the spheres treated at 1600 °C. The spheres obtained have dimensions of 4.65 ± 0.30 mm in diameter, weight of 43 ± 2 mg and a surface area of 0.66 m2/g. According to the curve of pH vs. zeta potential, the spheres have an acid character and a negative surface charge of -30 mV at pH 5. Through adsorption studies, an adsorbent capacity of Cd(II) of 59.97 mg/g (87 ppm Cd(II)) was determined at pH 5, and the data were fitted to the pseudo first order, pseudo second order and Freundlich models, with correlation factors of 0.993, 0.987 and 0.998, respectively.

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We evaluated the influence of the open porosity of alumina (Al2O3) substrates on the phase formation of calcium phosphates deposited onto it surface. The Al2O3 substrates were prepared with different porosities by the foam-gelcasting method associated with different amounts of polyethylene beads. The substrates were coated biomimetically for 14 and 21 days of incubation in a simulated body fluid (SBF). Scanning electron microscopy characterisation and X-ray computed microtomography showed that the increase in the number of beads provided an increase in the open porosity. The X-ray diffraction and infrared spectroscopy showed that the biomimetic method was able to form different phases of calcium phosphates. It was observed that the increase in the porosity favoured the formation of ß-tricalcium phosphate for both incubation periods. The incubation period and the porosity of the substrates can influence the phases and the amount of calcium phosphates formed. Thus, it is possible to target the best application for the biomaterial produced.

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The present work highlights the versatility of a TiO2-Al2O3 mixed oxide bearing highly dispersed gold nanoparticles that was applied in the CO oxidation reaction at room temperature. The TiO2, Al2O3, and TiO2-Al2O3 supports were synthesized by the sol-gel method, while gold nanoparticles were added by the deposition-precipitation with urea method using a theoretical Au loading of 2 wt.%. A promotional effect of the TiO2-Al2O3 support on the activity of gold catalysts with respect to TiO2 and Al2O3 was observed; Au/TiO2-Al2O3 showed outstanding CO oxidation, being active from 0 °C and stable throughout a 24-h test. As for the alumina content (5, 10, and 15 wt.%) in TiO2, it improved the textural properties by retarding the crystal growth and anatase-rutile phase transformation of TiO2, suppressing the deposition of carbon on the catalyst surface and stabilizing the Au nanoparticles even at high temperatures. Gold was highly dispersed with nanoparticle sizes ranging from 1 to 2 nm when H2 was used to treat thermally the Au/TiO2-Al2O3, Au/TiO2, and Au/Al2O3 materials. In addition, the XPS technique helped elicit that Au0 and Au1+ boosted their interaction with the TiO2, Al2O3, and TiO2-Al2O3 supports by means of charge transfer, which resulted in outstanding CO oxidation activity from 0 °C. Likewise, the key factors that control the peculiar catalytic performance in the CO oxidation reaction are discussed, which represents a step forward in the versatility behavior of gold catalysts supported on mixed oxide catalysts.

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OBJECTIVES: This study investigates the simulation of the mechanical behavior of a bioceramic composite based on (Ce,Y)-TZP reinforced with equiaxed Al2O3 and platelet-shaped hexaaluminate (H6A) grains using Finit Element Method (FEM). METHODS: A commercial (Ce, Y)-TZP/Al2O3 ceramic powder was compacted into disc-shaped specimens that were sintered at 1500 °C for 2 h. The sintered samples were further subjected to hydrothermal degradation in an autoclave at 134 °C, 0.2 MPa, for 10 h and characterized according to their phase composition, microstructure, and relative density. Their flexural strength values were determined by the piston-on-three-ball test, and Weibull statistics was used to evaluate the results. Their hardness, fracture toughness and elastic parameters were also measured. Numerical simulations of the biaxial strength test were performed using the ABAQUS finite element code. RESULTS: The sintered ceramic composite material presented relative density >99%, high resistance to hydrothermal degradation, average hardness of 1435 ± 35 HV, fracture toughness KIC of 9.7 ± 0.5 MPa m1/2, and average biaxial flexural strength of 952.6 ± 88 MPa. The numerical predictions of the biaxial flexural strength showed a consistently lower average biaxial flexural strength value of 880.9 MPa, ∼10% lower than the average experimental results. CONCLUSIONS: The differences observed are attributed to the complex coupled toughness mechanisms of this material, not included in the finite element simulations.

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Diffusion bonding of Ti6Al4V to Al2O3 using Ni/Ti reactive nanomultilayers as interlayer material was investigated. For this purpose, Ni/Ti multilayer thin films with 12, 25, and 60 nm modulation periods (bilayer thickness) were deposited by d.c. magnetron sputtering onto the base materials' surface. The joints were processed at 750 and 800 °C with a dwell time of 60 min and under a pressure of 5 MPa. Microstructural characterization of the interfaces was conducted by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). The mechanical characterization of the joints was performed by nanoindentation, and hardness and reduced Young's modulus distribution maps were obtained across the interfaces. The joints processed at 800 °C using the three modulation periods were successful, showing the feasibility of using these nanolayered films to improve the diffusion bonding of dissimilar materials. Using modulation periods of 25 and 60 nm, it was also possible to reduce the bonding temperature to 750 °C and obtain a sound interface. The interfaces are mainly composed of NiTi and NiTi2 phases. The nanoindentation experiments revealed that the hardness and reduced Young's modulus at the interfaces reflect the observed microstructure.

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Catalysts prepared on ZrO2, Al2O3 and ZrO2-Al2O3 (ZrAl-10) supported with Anderson heteropolyanion (RhMo6) as active phase were investigated for the elimination of NO3- from water. Raman characterization of pure and supported RhMo6 phase showed the presence of polymolybdic species of different degrees of complexity when RhMo6 was supported. The temperature-programmed reduction study revealed the synergic effect between Rh and Mo species, through which the reducibility of Mo was promoted by Rh, and different phase/support interactions were verified. Among the supports, ZrAl-10 presented the highest acidity due to the presence of ZrO2 in the tetragonal modification and high specific surface area (due to Al2O3), favouring rhodium-molybdenum active phase/support interaction and high dispersion. All catalysts prepared were active in removing NO3-, the one prepared with the RhMo6 phase on the ZrAl-10 support being the most active. These results point to the formation of an active surface with a high dispersion of Rh and Mo. The highest selectivity to N2 (99.3) exhibited by the RhMo6/ZrAl-10 catalyst is proposed to be related to the high Rh dispersion (0.755) and to the presence of Lewis acid sites (oxygen vacancies) of the tetragonal ZrO2 modification that favour NO3- adsorption through electrostatic interactions.

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The atomic layer deposition (ALD) of Al2O3 between perovskite and the hole transporting material (HTM) PEDOT:PSS has previously been shown to improve the efficiency of perovskite solar cells. However, the costs associated with this technique make it unaffordable. In this work, the deposition of an organic-inorganic PEDOT:PSS-Cl-Al2O3 bilayer is performed by a simple electrochemical technique with a final annealing step, and the performance of this material as HTM in inverted perovskite solar cells is studied. It was found that this material (PEDOT:PSS-Al2O3) improves the solar cell performance by the same mechanisms as Al2O3 obtained by ALD: formation of an additional energy barrier, perovskite passivation, and increase in the open-circuit voltage (Voc) due to suppressed recombination. As a result, the incorporation of the electrochemical Al2O3 increased the cell efficiency from 12.1% to 14.3%. Remarkably, this material led to higher steady-state power conversion efficiency, improving a recurring problem in solar cells.

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Aluminum oxide (Al2O3) nanoparticles (NPs) are among the nanoparticles most used industrially, but their impacts on living organisms are widely unknown. We evaluated the effects of 50-1000 mg L-1 Al2O3 NPs on the growth, metabolism of lignin and its monomeric composition in soybean plants. Al2O3 NPs did not affect the length of roots and stems. However, at the microscopic level, Al2O3 NPs altered the root surface inducing the formation of cracks near to root apexes and damage to the root cap. The results suggest that Al2O3 NPs were internalized and accumulated into the cytosol and cell wall of roots, probably interacting with organelles such as mitochondria. At the metabolic level, Al2O3 NPs increased soluble and cell wall-bound peroxidase activities in roots and stems but reduced phenylalanine ammonia-lyase activity in stems. Increased lignin contents were also detected in roots and stems. The Al2O3 NPs increased the p-hydroxyphenyl monomer levels in stems but reduced them in roots. The total phenolic content increased in roots and stems; cell wall-esterified p-coumaric and ferulic acids increased in roots, while the content of p-coumaric acid decreased in stems. In roots, the content of ionic aluminum (Al+3) was extremely low, corresponding to 0.0000252% of the aluminum applied in the nanoparticulate form. This finding suggests that all adverse effects observed were due to the Al2O3 NPs only. Altogether, these findings suggest that the structure and properties of the soybean cell wall were altered by the Al2O3 NPs, probably to reduce its uptake and phytotoxicity.

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This paper reports the sol-gel synthesis of Al2O3-Nd2O3 (Al-Nd-x; x = 5%, 10%, 15% and 25% of Nd2O3) binary oxides and the photodegradation of diclofenac activated by UV light. Al-Nd-based catalysts were analyzed by N2 physisorption, XRD, TEM, SEM, UV-Vis and PL spectroscopies. The inclusion of Nd2O3 in the aluminum oxide matrix in the 10-25% range reduced the band gap energies from 3.35 eV for the γ-Al2O3 to values as low as 3.13-3.20 eV, which are typical of semiconductor materials absorbing in the UV region. γ-Al2O3 and Al-Nd-x binary oxides reached more than 92.0% of photoconverted diclofenac after 40 min of reaction. However, the photocatalytic activity in the diclofenac degradation using Al-Nd-x with Nd2O3 contents in the range 10-25% was improved with respect to that of γ-Al2O3 at short reaction times. The diclofenac photoconversion using γ-Al2O3 was 63.0% at 10 min of UV light exposure, whereas Al-Nd-15 binary oxide reached 82.0% at this reaction time. The rate constants determined from the kinetic experiments revealed that the highest activities in the aqueous medium were reached with the catalysts with 15% and 25% of Nd2O3, and these compounds presented the lowest band gap energies. The experimental results also demonstrated that Nd2O3 acts as a separator of charges favoring the decrease in the recombination rate of electron-hole pairs.

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The effect of α-Al2O3 nanoparticles (up to 5 wt.%) on the physical, mechanical, and thermal properties, as well as on the microstructural evolution of a dense magnesia refractory is studied. Sintering temperatures at 1300, 1500, and 1600 °C are used. The physical properties of interest were bulk density and apparent porosity, which were evaluated by the Archimedes method. Thermal properties were examined by differential scanning calorimetry. The mechanical behavior was studied by cold crushing strength and microhardness tests. Finally, the microstructure and mineralogical qualitative characteristics were studied by scanning electron microscopy and X-ray diffraction, respectively. Increasing the sintering temperature resulted in improved density and reduced apparent porosity. However, as the α-Al2O3 nanoparticle content increased, the density and microhardness decreased. Microstructural observations showed that the presence of α-Al2O3 nanoparticles in the magnesia matrix induced the magnesium-aluminate spinel formation (MgAl2O4), which improved the mechanical resistance most significantly at 1500 °C.

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Objetivo: Este estudo teve como objetivo avaliar a resistência ao desgaste de dentes em acrílico para próteses contendo nanopartículas de dióxido de silício (nano-SiO2 ) e dióxido de alumínio (nanoAl2 O3 ). Material e Métodos: O material em polimetilmetacrilato (PMMA) foi utilizado para fabricar 84 amostras (n=10) contendo nano-SiO2 e nano-Al2 O3 nas concentrações 0,1% em peso, 0,3% em peso e 0,5% em peso de pó acrílico. Uma máquina de teste de desgaste de dois corpos e um microscópio digital foram usados para medir as mudanças na perda de peso e rugosidade da superfície, respectivamente. Testes de ANOVA a um fator e testes de comparações múltiplas de Tukey foram utilizados para análise dos dados (α = 0,05). Resultados: O material modificado com nano-SiO2 demonstrou um aumento significativo na perda de peso em comparação com o material acrílico artificial convencional (p ˂ 0,05) enquanto o material modificado com nano-Al2 O3 demonstrou aumento não significativo na perda de peso, exceto no subgrupo 0,5% (p < 0,05). Não há diferenças significativas em relação à alteração da rugosidade após a simulação de desgaste entre todos os grupos testados (p > 0,05). Conclusão: As nanopartículas de nano-Al2 O3 exibem menos efeito negativo que o nanoSiO2 , podendo ser usado com cautela, se necessário. (AU)

Objective: This study aimed to evaluate the wear resistance of acrylic denture teeth containing silicon dioxide (nano-SiO2 ) and aluminum dioxide (nano-Al2 O3 ) nanoparticles. Material and Methods: Poly methyl methacrylate (PMMA) denture tooth material was used to denture tooth material was used to fabricate 84 specimens (n=10) containing nano-SiO2 and nano-Al2 O3 in concentrations 0.1wt%, 0.3wt%, and 0.5wt% of acrylic powder. A two-body wear testing machine and digital microscope were used to measure the changes in weight loss and surface roughness respectively. One-way ANOVA and pair-wise Tukey's post-hoc tests were used for data analysis (α = 0.05). Results: Nano-SiO2 modified teeth material demonstrated a significant increase in weight loss in comparison conventional artificial acrylic teeth material (p ˂ 0.05) while nanoAl2 O3 modified teeth material demonstrated non-significant increase in weight loss except for 0.5% subgroup (p ˂ 0.05). There is no significant differences regarding roughness change after wear simulation among all tested groups (p > 0.05). Conclusion: Nano-Al2 O3 nanoparticles exhibit less negative effect than nano-SiO2 so; it could be used with caution if necessary. (AU)

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Modern concrete infrastructure requires structural components with higher mechanical strength and greater durability. A solution is the addition of nanomaterials to cement-based materials, which can enhance their mechanical properties. Some such nanomaterials include nano-silica (nano-SiO2), nano-alumina (nano-Al2O3), nano-ferric oxide (nano-Fe2O3), nano-titanium oxide (nano-TiO2), carbon nanotubes (CNTs), graphene and graphene oxide. These nanomaterials can be added to cement with other reinforcement materials such as steel fibers, glass, rice hull powder and fly ash. Optimal dosages of these materials can improve the compressive, tensile and flexural strength of cement-based materials, as well as their water absorption and workability. The use of these nanomaterials can enhance the performance and life cycle of concrete infrastructures. This review presents recent researches about the main effects on performance of cement-based composites caused by the incorporation of nanomaterials. The nanomaterials could decrease the cement porosity, generating a denser interfacial transition zone. In addition, nanomaterials reinforced cement can allow the construction of high-strength concrete structures with greater durability, which will decrease the maintenance requirements or early replacement. Also, the incorporation of nano-TiO2 and CNTs in cementitious matrices can provide concrete structures with self-cleaning and self-sensing abilities. These advantages could help in the photocatalytic decomposition of pollutants and structural health monitoring of the concrete structures. The nanomaterials have a great potential for applications in smart infrastructure based on high-strength concrete structures.

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Acetone is an important solvent and widely used in the synthesis of drugs and polymers. Currently, acetone is mainly generated by the Cumene Process, which employs benzene and propylene as fossil raw materials. Phenol is a co-product of this synthesis. However, this ketone can be generated from ethanol (a renewable feedstock) in one-step. The aim of this work is to describe the influence of physical-chemical properties of three different catalysts on each step of this reaction. Furthermore, contribute to improve the description of the mechanism of this synthesis. The acetone synthesis from ethanol was studied employing Cu/ZnO/Al2O3, Ce0.75Zr0.25O2 and ZrO2. It was verified that the acidity of the catalysts needs fine-tuning in order to promote the oxygenate species adsorption and avoid the dehydration of ethanol. The higher the reducibility and the H2O dissociation activity of the catalysts are, the higher the selectivity to acetone is. In relation to the oxides, these properties are associated with the presence of O vacancies. The H2 generation, which occurs during the TPSR, indicates the redox character of this synthesis. The main steps of the acetone synthesis from ethanol are the generation of acetaldehyde, the oxidation of this aldehyde to acetate species (which reduces the catalyst), the H2O dissociation, the oxidation of the catalyst producing H2, and, finally, the ketonization reaction. These pieces of information will support the development of active catalysts for not only the acetone synthesis from ethanol, but also the isobutene and propylene syntheses in which this ketone is an intermediate. Graphical abstract Acetone from ethanol.

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In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

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Ni- and Cu/alumina powders were prepared and characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), and N2 physisorption isotherms were also determined. The Ni/Al2O3 sample reveled agglomerated (1 µm) of nanoparticles of Ni (30-80 nm) however, NiO particles were also identified, probably for the low temperature during the H2 reduction treatment (350 °C), the Cu/Al2O3 sample presented agglomerates (1-1.5 µm) of nanoparticles (70-150 nm), but only of pure copper. Both surface morphologies were different, but resulted in mesoporous material, with a higher specificity for the Ni sample. The surfaces were used in a new proposal for producing copper and nickel phthalocyanines using a parallel-plate reactor. Phthalonitrile was used and metallic particles were deposited on alumina in ethanol solution with CH3ONa at low temperatures; ≤60 °C. The mass-transfer was evaluated in reaction testing with a recent three-resistance model. The kinetics were studied with a Langmuir-Hinshelwood model. The activation energy and Thiele modulus revealed a slow surface reaction. The nickel sample was the most active, influenced by the NiO morphology and phthalonitrile adsorption.

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As cerâmicas à base de zircônia (Y-TZP) apresentam propriedades mecânicas superiores às das demais cerâmicas odontológicas. Entretanto, o aumento do conteúdo cristalino modificou suas características de adesão a cimentos resinosos, tornando necessário o desenvolvimento de métodos mais efetivos de união a estes materiais. Este trabalho in vitro pretende, portanto, avaliar a influência de diferentes tratamentos de superfície e de diferentes agentes de união na resistência ao cisalhamento entre uma zircônia estabilizada por ítrio e um agente cimentante autoadesivo (RelyX U100®/3M ESPE). Para tal, cilindros de PROCERA® Allzircon receberam como tratamento de superfície jateamento com óxido de alumínio (Al2O3 - 50 µm) ou jateamento com o sistema Rocatec. Sobre a superfície tratada dos cilindros foram aplicados, de acordo com os diferentes grupos experimentais, o sistema adesivo Clearfil SE Bond® (Kuraray Co.), e os primers Metal Zirconia Primer (Ivoclar Vivadent) e Alloy Primer (Kuraray Co.) e, finalmente, o cimento resinoso adotado. Cada espécime foi, então, submetido ao teste de cisalhamento (0,05 mm/min), por meio da ação de uma alça de fio ortodôntico passando o mais próximo possível da interface adesiva. A análise de variância a um critérios (ANOVA) e o teste de Tukey (p < 0,05) mostraram que a realização do tratamento de superfície aumentou os valores de resistência de união entre a cerâmica e o cimento resinoso.

O jateamento com o sistema Rocatec (15,33 MPa) apresentou valores significantemente maiores que o jateamento com Al2O3 (11,93 MPa). A aplicação dos agentes de união resultou em uma maior resistência adesiva, sendo que o sistema adesivo Clearfill SE Bond (17,07 MPa) teve um comportamento estatisticamente superior aos demais materiais. Entre os primers, o Metal Zircônia Primer (11,26 MPa) apresentou maior valor de resistência de união que o Alloy Primer (10,01 MPa). Portanto, a associação de um tratamento superficial com um agente de união é valida, já que promoveu os maiores valores de resistência adesiva.

Yttrium-stabilized tetragonal zircon polycrystal (Y-TZP) ceramics show better mechanical properties than other dental ceramics. However, the high crystalline content modified their adhesiveness to resin cements, making it extremely necessary to develop a more effective adhesive strategy between them. This in vitro study intends to evaluate the influence of different surface treatments and different bond agents on the shear bond strength between a Y-TZP and self-adhesive resin cement. PROCERA® Allzircon cylinders (3.5 mm in diameter) received a surface airborne abrasion treatment with 50 µm aluminum-oxide (Al2O3) particles or with the Rocatec system. According to the experimental groups, the adhesive system Clearfil SE Bond® (Kuraray Co.), and the primers Metal Zirconia Primer (Ivoclar Vivadent) and Alloy Primer (Kuraray Co.) were applied on the treated surface of the cylinders, before the application of the adopted resin cement (RelyX U100®/3M ESPE). Each specimen was submitted to the shear bond strength test (0.5 mm/min), by the action of an orthodontic stainless steel ligature wire (0.5 mm in diameter) loop, wrapped around the resin cement, as close as possible to the adhesive interface. One way- ANOVA and Tukey´s post hoc tests (p < 0.05) revealed that surface treatment increased bond strength between the ceramic and the resin cement. Silica coating with the Rocatec system (15.33 MPa) showed significantly higher values than airborne abrasion with Al2O3 (11.93 MPa). Application of all bond agents improved shear bond strength: adhesive system Clearfil SE Bond (17.07 MPa) showed better performance than the other evaluated materials, and Metal Zirconia Primer (11.26 MPa) showed higher bond strength values than Alloy Primer (10.01 MPa). Therefore, the association of a surface treatment with a bond agent is suitable, once it resulted in higher values of adhesive strength.

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