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Electrocatalytic nitrate reduction reaction presents a promising avenue for environmentally friendly ammonia (NH3) synthesis and wastewater treatment. An essential aspect to consider is the meticulous design of electrocatalysts. This study explores the utilization of a Ni-Co alloy nanosheet-decorated three-dimensional titanium dioxide (3D-TiO2) nanobelts electrodeposited on titanium meshes (NixCoy@TiO2/TM) for efficient electrocatalytic NH3 production. The optimized Ni1Co3@TiO2/TM electrode achieves a significant NH3 yield of 676.3 ± 27.1 umol h-1 cm-2 with an impressive Faradaic efficiency (FE) of 95.1 % ± 2.1 % in a 0.1 M KOH solution containing 0.1 M NO3- at -0.4 V versus the reversible hydrogen electrode. Additionally, the electrode demonstrates exceptional electrochemical activity for NH3 synthesis in simulated wastewater, delivering an outstanding NH3 yield of 751.6 ± 44.3 umol h-1 cm-2 with a FE of 96.8 % ± 0.4 % at the same potential of -0.4 V. Moreover, the electrode exhibits minimal variation in current density, NH3 yields and FEs throughout the 24-h stability test and the 20-cycle test, demonstrating its excellent stability and durability. This study offers a straightforward electrodeposited approach for the development of 3D-nanostructured alloys as catalysts for NH3 electrosynthesis from nitrates at room temperature.
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The rational design of efficient, stable, low-cost non-precious metal-based electrocatalysts with enhanced oxygen reduction reaction (ORR) activity has attracted widespread attention. In this study, a novel electrocatalyst, Fe/Co-N-MWCNT, was prepared by in-situ growth of ZIF-8 and Fe/Co-Phen on multi-walled carbon nanotubes (MWCNTs), then pyrolysis under different temperature to obtain optimal one. During the pyrolysis process, the incorporation of Fe and Co facilitated the formation of metal active sites and Fe-Co alloy, thereby promoting electron transfer and enhancing the ORR activity. Compared to Pt/C (E1/2 = 0.854V, JL = 4.90 mA cm-2), Fe/Co-N-MWCNT demonstrated a comparable half-wave potential (E1/2 = 0.812V) and an enhanced limiting current density (JL = 5.37 mA cm-2). Furthermore, Fe/Co-N-MWCNT was stable and showed no significant change after 2000 cycles, with only a negative shift of 7 mV in E1/2. Ampere response testing revealed that the current decay of Fe/Co-N-MWCNT after 10000 s was only about 7.8%, while that of Pt/C was about 18.4%. Due to its excellent catalytic stability, Fe/Co-N-MWCNT was demonstrated to be an excellent candidate for rechargeable zinc-air batteries. The outstanding electrocatalytic performance of Fe/Co-N-MWCNT can be attributed to its high pyridinic nitrogen content, the unique structure and abundant metal active sites.
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This study investigated how process parameters of laser cladding affect the microstructure and mechanical properties of WC-12Co composite coating for use as a protective layer of continuous caster rolls. WC-Co powders, WC-Ni powders, and Ni-Cr alloy powder with various wear resistance characteristics were evaluated in order to determine their applicability for use as cladding materials for continuous caster roll coating. The cladding process was conducted with various parameters, including laser powers, cladding speeds, and powder feeding rates, then the phases, microstructure, and micro-hardness of the cladding layer were analyzed in each specimen. Results indicate that, to increase the hardness of the cladding layer in WC-Co composite coating, the dilution of the cladding layer by dissolution of Fe from the substrate should be minimized, and the formation of the Fe-Co alloy phase should be prevented. The mechanical properties and wear resistance of each powder with the same process parameters were compared and analyzed. The microstructure and mechanical properties of the laser cladding layer depend not only on the process parameters, but also on the powder characteristics, such as WC particle size and the type of binder material. Additionally, depending on the degree of thermal decomposition of WC particles and evolution of W distribution within the cladding layer, the hardness of each powder can differ significantly, and the wear mechanism can change.
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Carbon nanotube (CNT) is an excellent field emission material. However, uniformity and stability are the key issues hampering its device application. In this work, a bimetallic W-Co alloy was adopted as the catalyst of CNT in chemical vapor deposition process. The high melting point and stable crystal structure of W-Co helps to increase the grown CNT diameter uniformity and homogeneous crystal structure. High-crystallinity CNTs were grown on the W-Co bimetallic catalyst. Its field emission characteristics demonstrated a low turn-on field, high current density, stable current stability, and uniform emission distribution. The Fowler-Nordheim (FN) and Seppen-Katamuki (SK) analyses revealed that the CNT grown on the W-Co catalyst has a relatively low work function and high field enhancement factor. The high crystallinity and homogeneous crystal structure of CNT also reduce the body resistance and increase the emission current stability and maximum current. The result provides a way to synthesis a high-quality CNT field emitter, which will accelerate the development of cold cathode vacuum electronic device application.
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Selective laser melting (SLM) technologies are becoming increasingly popular. The aim of the work is to compare the metallographic structure, hardness, and selected strength properties of alloys obtained by casting and by SLM, with a particular emphasis on fatigue strength. Twenty Cr/Co alloy bars were made by casting or SLM, and samples of appropriate dimensions were prepared for individual tests. The microstructures of the samples were tested by metallography, and then tested for hardness, impact strength, tensile strength, bending strength, and fatigue strength; they were also subjected to fracture after bending, tensile, fatigue, and impact tests, with the resulting fractures examined by scanning electron microscopy (SEM). Primary dendrites and small amounts of gas bubbles were present in the cast samples ground lengthwise. The SEM samples were more finer grained and uniform. Compared to the casting samples, the SLM samples demonstrated higher hardness, lower mean impact strength and higher tensile strength. The casting samples also displayed lower mean elongation values. The casting samples demonstrated slightly higher fatigue strength. The fractures of the casting samples showed an interdendritic character with clearly visible dendrites at the fracture, while those of the SLM samples were also intergranular, but finer grained. SLM generally results in better strength properties, while casting obtains slightly greater fatigue strength.
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Hydrodeoxygenation of furfural over non-noble metal catalyst is an effective route to synthesis 2-methylfuran, but the reaction is often hampered by the low activity and selectivity of the catalyst. Herein, a bimetallic catalyst with CuCo alloy encapsulated in a hollow nitrogen-doped carbon cages (CuCo/NC) are fabricated by using ZIF-67 as a sacrificial template, which exhibited superior catalytic performance and a full conversion of furfural with a 95.7 % selectivity towards 2-methylfuran was achieved at an under relatively mild reaction conditions (150 â, 1.5 MPa H2 and 4.0 h). The characterizations and density functional theory calculations clearly evidenced that the introduced Cu species acts as a switch to regulate the activity and selectivity of the catalyst via two aspects. On the one hand, the Cu species perturb the Co electronic structure leading to adsorption configuration of furfural change from flat to vertical on the catalyst surface, which successfully hindered the hydrogenation of furan ring, resulting high selectivity towards 2-methylfuran. On the other hand, the formed CuCo (111) sites promotes the dissociation of hydrogen, cleavage of the CO bond and reduces the diffusion barrier of hydrogen so as to advance the formation of 2-methylfuran. This work may provide a feasible strategy for the design of nanoalloy catalyst for the hydrodeoxygenation of biomass platforms to value-added chemicals.
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Proton-exchange membrane fuel cell technology is a key component in the future zero-carbon energy system, generating power from carbon-free fuels, such as green hydrogen. However, the high Pt loading in conventional fuel cell electrodes to maintain electrocatalytic activity and durability, especially on the cathode for oxygen reduction, is the Achilles heel for the worldwide deployment of fuel cell technologies. To minimize Pt consumption for oxygen reduction, we synthesized Pt-Co-based electrocatalysts with meticulous structuring from micrometer to the atomic scale based on reaction pathways. The resulting Pt-Co-based electrocatalysts contain only 1.9 wt% Pt, which is 20 times lower than the conventional Pt-C catalysts for fuel cells. By utilizing electrospinning and in situ synthesis, we anchored three-dimensionally structured zeolitic imidazolate frameworks on continuously connected nanofibrous electrospun mats. The Pt-Co@Pt-free nanowire (PC@PFN) electrocatalysts contain Pt-Co nanoparticles (NPs) and non-Pt elements, Co-containing sites comprising NPs, nanoclusters, and N-coordinated Co single atoms. Despite the ultralow Pt loading in PC@PFN, the mass activity exceeds the U.S. Department of Energy 2025 target by 2.8 times and retains 85.5% of the initial activity after 80,000 durability test cycles, possibly owing to synergistic reaction pathways between Pt and non-Pt sites.
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Fe-Co alloy nanoparticles with different sizes, supported by carbon derived from several polymers, namely polyacrylonitrile, polyvinyl alcohol and chitosan, have been synthesized by a one-pot method involving simultaneous metal nanoparticle formation and polymer carbonization. The method involves the joint dissolution of metal salts and a polymer, followed by annealing of the resulting dried film. Detailed XRD analysis confirmed the formation of Fe-Co alloy nanoparticles in each sample, regardless of the initial polymer used. Transmission electron microscopy images showed that the Fe-Co nanoparticles were all spherical, were homogeneously distributed within the carbon support and varied by size depending on the initial polymer nature and synthesis temperature. Fe-Co nanoparticles supported by polyacrylonitrile-derived carbon exhibited the smallest size (6-12 nm), whereas nanoparticles on chitosan-derived carbon support were characterized by the largest particle size (13-38 nm). The size dependence of magnetic properties were studied by a vibrating sample magnetometer at room temperature. For the first time, the critical particle size of Fe-Co alloy nanoparticles with equiatomic composition has been experimentally determined as 13 nm, indicating the transition of magnetic properties from ferromagnetic to superparamagnetic.
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At present, the V-Ti-Co phase diagram is not established, which seriously hinders the subsequent development of this potential hydrogen permeation alloy system. To this end, this article constructed the first phase diagram of the V-Ti-Co system by using the CALculation of PHAse Diagrams (CALPHAD) approach as well as relevant validation experiments. On this basis, hydrogen-permeable VxTi50Co50-x (x = 17.5, 20.5, , 32.5) alloys were designed, and their microstructure characteristics and hydrogen transport behaviour were further studied by XRD, SEM, EDS, and so on. It was found that six ternary invariant reactions are located in the liquidus projection, and the phase diagram is divided into eight phase regions by their connecting lines. Among them, some alloys in the TiCo phase region were proven to be promising candidate materials for hydrogen permeation. Typically, VxTi50Co50-x (x = 17.5-23.5) alloys, which consist of the primary TiCo and the eutectic {bcc-(V, Ti) and TiCo} structure, show a high hydrogen permeability without hydrogen embrittlement. In particular, V23.5Ti50Co26.5 exhibit the highest permeability of 4.05 × 10-8 mol H2 m-1s-1Pa-0.5, which is the highest value known heretofore in the V-Ti-Co system. The high permeability of these alloys is due in large part to the simultaneous increment of hydrogen solubility and diffusivity, and is closely related to the composition of hydrogen permeable alloys, especially the Ti content in the (V, Ti) phase. The permeability of this alloy system is much higher than those of Nb-TiCo and/or Nb-TiNi alloys.
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BACKGROUND: Is abrasive blasting accompanied by the phenomenon of driving abrasive particles into the conditioned material? METHODS: Three hundred and fifteen cylindrical disks of three types of metal alloy (chromium/cobalt, chromium/nickel, titanium, and sintered zirconium dioxide) were divided into four groups (n = 35) and sandblasted at pressures of 0.2, 0.4, or 0.6 MPa with aluminum oxide (Al2O3), grain size 50, 110, or 250 µm. Then, the surface topography was examined using a scanning microscope, and the amount of embedded grain was measured using quantitative metallography. For each group, five samples were randomly selected and subjected to Vickers hardness testing. In the statistical analyses, a three-factor analysis of variance was carried out, considering the type of material, the size of gradation of the abrasive, and the amount of pressure. RESULTS: The smallest amounts of embedded abrasive (2.62) were observed in the ZrO2 treatment, and the largest (38.19) occurred in the treatment of the Ti alloy. An increase in the gradation and the pressure were a systematic increase in the amount of embedded grain. CONCLUSIONS: After abrasive blasting, abrasive particles were found on the surface of the materials. The amount of driven abrasive depends on the hardness of the processed material.
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To improve the oxygen reduction reaction (ORR) performance in a proton-exchange membrane fuel cell (PEMFC) cathode with respect to mass activity and durability, a suitable electrocatalyst design strategy is essentially needed. Here, we have prepared a sub-three nm-sized platinum (Pt)-cobalt (Co) alloy (Pt3Co)-supported N-doped microporous 3D graphene (Pt3Co/pNEGF) by using the polyol synthesis method. A microwave-assisted synthesis method was employed to prepare the catalyst based on the 3D porous carbon support with a large pore volume and dense micro-/mesoporous surfaces. The ORR performance of Pt3Co/pNEGF closely matches with the state-of-the-art commercial Pt/C catalyst in 0.1 M HClO4, with a small overpotential of 10 mV. The 3D microporous structure of the N-doped graphene significantly improves the mass transport of the reactant and thus the overall ORR performance. As a result of the lower loading of Pt in Pt3Co/pNEGF as compared to that in Pt/C, the alloy catalyst achieved 1.5 times higher mass activity than Pt/C. After 10,000 cycles, the difference in the electrochemically active surface area (ECSA) and half-wave potential (E1/2) of Pt3Co/pNEGF is found to be 5 m2 gPt-1 (ΔECSA) and 24 mV (ΔE1/2), whereas, for Pt/C, these values are 9 m2 gPt-1 and 32 mV, respectively. Finally, in a realistic perspective, single-cell testing of a membrane electrode assembly (MEA) was made by sandwiching the Pt3Co/pNEGF-coated gas diffusion layers as the cathode displayed a maximum power density of 800 mW cm-2 under H2-O2 feed conditions with a clear indication of helping the system in the mass-transfer region (i.e., the high current dragging condition). The nature of the I-V polarization shows a progressively lower slope in this region of the polarization plot compared to a similar system made from its Pt/C counterpart and a significantly improved performance throughout the polarization region in the case of the system made from the Pt3Co/NEGF catalyst (without the microwave treatment) counterpart. These results validate the better process friendliness of Pt3Co/pNEGF as a PEMFC electrode-specific catalyst owing to its unique texture with 3D architecture and well-defined porosity with better structural endurance.
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The low cycle performance and low Coulomb efficiency of tin-based materials confine their large-scale commercial application for lithium-ion batteries. To overcome the shortage of volume expansion of pristine tin, Sn-Co alloy/rGO composites have been successfully synthesized by chemical reduction and sintering methods. The effects of sintering temperature on the composition, structure and electrochemical properties of Sn-Co alloy/rGO composites were investigated by experimental study and first-principles calculation. The results show that Sn-Co alloys are composed of a large number of CoSn and trace CoSn2 intermetallics, which are uniformly anchored on graphene nanosheets. The sintering treatment effectively improves the electrochemical performance, especially for the first Coulomb efficiency. The first charge capacity of Sn-Co alloy/rGO composites sintered at 450 °C is 675 mAh·g-1, and the corresponding Coulomb efficiency reaches 80.4%. This strategy provides a convenient approach to synthesizing tin-based materials for high-performance lithium-ion batteries.
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Hydrogen reduction is becoming a promising method for recycling lithium-ion battery cathode materials. However, the reaction mechanism and kinetics during hydrogen reduction are unclear, requiring further investigation. Therefore, non-isothermal and isothermal reduction experiments were conducted to evaluate the temperature dependence of the hydrogen reduction kinetics using simultaneous thermogravimetric and differential thermal analysis equipped with mass spectrometry. XRD and SEM were used to characterize the reduction products to understand the underlying reduction mechanisms. The hydrogen reduction profile could be divided into three main stages: decomposition of cathode materials, reduction of the resultant nickel and cobalt oxides, and reduction of LiMnO2 and residual nickel and cobalt oxides. The hydrogen reduction rate increased with increasing temperature, and 800°C was the optimum temperature for separating the magnetic Ni-Co alloy from the non-magnetic manganese oxide particles. The apparent activation energy for the isothermal tests in the range of 500-700°C was 84.86 kJ/mol, and the rate-controlling step was the inward diffusion of H2(g) within each particle. There was an downward progression of the reduction through the material bed for the isothermal tests in the range of 700-900°C, with an apparent activation energy of 51.82 kJ/mol.
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(1) Background: This paper aims to determine the influence of hardness on the number of abrasive material grains (SiC) embedded on the surface metal alloys and ZrO2 during abrasion. (2) Methods: Cylindrical samples were created: 315 made of Cr/Co, Ni/Cr or Ti, and 315 made of sintered ZrO2- 3TPZ-Y. These were divided into four groups (each n = 35 samples), and were treated with SiC grain sizes 50, 110, and 250 µm at pressures 0.2, 0.4, or 0.6 MPa. The samples were then observed in SEM to study SE and BSE. The surface coverage of abrasive material particles was determined by quantitative metallography. Five samples from each group were subjected to hardness measurements. The results were compared with three-factor variance analysis with using the post hoc Tukey test. (3) Results: The highest amount (40.06) of embedded abrasive was obtained for Ti alloy with a gradation of 250µm at a pressure of 0.6 MPa. The smallest amount of embedded grain (2.66) was obtained for ZrO2 for the same treatment parameters. (4) Conclusions: The amount of embedded abrasive particles depends on the type of treated material, gradation particles, and the amount of applied pressure. Harder treated materials are more resistant to grains of abrasive becoming embedded on surface.
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Herein, we introduce a facile approach to synthesize a unique class of Pt-M (M = Ni, Co) catalysts with a nanoflower structure for boosting both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). By controlling the surface-active agents, we modified the functional groups surrounding the Pt atoms, tuned the alloying of Pt and the transition metals Ni and Co, and prepared two different kinds of nanodendrites. Their successful synthesis depends on the selection and amount of surfactants (hexadecyltrimethylammonium bromide (CTAB), Polyvinylpyrrolidone (PVP)). Besides, by controlling reaction time, we also explored the forming procedures for Pt-Co globularia nanodendrite (Pt-Co GND) and Pt-Ni petalody nanodendrite (Pt-Ni PND). Our investigation highlights the importance of complex nanoarchitecture, which enables surface and interface modification to achieve excellent catalytic performance in fuel cell electrocatalysis. The characterization of the as-prepared catalysts reveals a high electrochemical surface area and mass activity (2041 mAmgPt-1and 950 mAmgPt-1 for Pt-Co GND and Pt-Ni PND, respectively, for ORR). Furthermore, Pt-Co GND showed a high MOR activity, with a mass activity value recorded at 1615 mAmgPt-1 which is far superior to that for Pt/C. Moreover, both catalysts retain high activity after accelerated durability tests (ADTs). The electron transfer number was calculated by performing the rotating ring-disk electrode (RRDE) measurements. Due to abundant active sites of Pt, both Pt-Co GND and Pt-Ni PND exhibit a 4e- pathway for ORR with electron transfer number of >3.95.
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Different methods of producing nanostructured materials at the laboratory scale have been studied using a variety of physical and chemical techniques, though the challenge here is the homogeneous distribution of the elements which also depends on the precursor elements. This work thus focused on the micro-analytical characterization of Cu-Ni-Co metallic nanoparticles produced by an alternative chemical route aiming to produce solid solution nanoparticles. This method was based on two steps: the co-formation of oxides by nitrates' decomposition followed by their hydrogen reduction. Based on the initial composition of precursor nitrates, three homogeneous ternaries of the Ni, Cu and Co final alloy products were pre-established. Thus, the compositions in %wt of the synthesized alloy particles studied in this work are 24Cu-64Ni-12Co, 12Cu-64Ni-24Co and 10Cu-80Ni-10Co. Both precursor oxides and metallic powders were characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM/EDS) and transmission electron microscopy (TEM). The results show that the synthesis procedure was successful since it produced a homogeneous material distributed in different particle sizes depending on the temperature applied in the reducing process. The final composition of the metallic product was consistent with what was theoretically expected. Resulting from reduction at the lower temperature of 300 °C, the main powder product consisted of particles with a spheroidal and eventually facetted morphology of 50 nm on average, which shared the same FCC crystal structure. Particles smaller than 100 nm in the Cu-Ni-Co alloy agglomerates were also observed. At a higher reduction temperature, the ternary powder developed robust particles of 1 micron in size, which are, in fact, the result of the coarsening of several nanoparticles.
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In this research work, the nanostructured Fe-Mn (BM0), Fe-Mn-Cu (BM1), Fe-Mn-W (BM2), and Fe-Mn-Co (BM3) biodegradable alloys were successfully synthesized using mechanical alloying. The microstructure of the synthesized alloys was examined using XRD, SEM equipped with EDS, and HRTEM techniques. The results obtained based on these techniques confirmed the development of nanostructured BM0, BM1, BM2, and BM3 alloys and homogenous solid solutions with an even elemental dispersion. The compressibility of the synthesized alloys was investigated experimentally and empirically in the as-milled conditions and after applying a stress relief treatment (150 °C for 1 h). The load applied for compaction experiments ranged from 25-1100 MPa with a rate of 1 mm/min. According to the experimentation performed in the current study, the relative density of the as-milled BM0, BM1, BM2, and BM3 alloys was 72.90% and 71.64%, 72.32%, and 72.03%, respectively. After applying the stress relief treatment, the density was observed to increase to 75.23%, 77.10%, 72.65%, and 72.86% for BM0-S, BM1-S, BM2-S and BM3-S samples, respectively. A number of compaction models were tested to identify the optimum models for predicting the compressibility behavior of nanostructured Fe-Mn, Fe-Mn-Cu, Fe-Mn-W, and Fe-Mn-Co alloys in the as-milled and stress-relieved conditions.
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Development of bifunctional catalysts with low platinum (Pt) content for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is highly desirable, yet challenging. Herein, we present structural engineering of a series of two-dimensional/three-dimensional (2D/3D) hierarchical N-doped graphene-supported nanosized Pt3Co alloys and Co clusters (PtCo@N-GNSs) via a hydrolysis-pyrolysis route. For the ORR, the optimal PtCo@N-GNS exhibits a high mass activity of 3.01 A mgPt-1, which is comparable to the best Pt-based catalyst obtained through sophisticated synthesis. It also possesses excellent stability with minor decay after 50â¯000 cyclic voltammograms (CV) cycles in acidic medium. For the EOR, PtCo@N-GNS achieves the highest mass-specific and area-specific activities of 1.96 A mgPt-1 and 5.75 mA cm-2, respectively, among all of the reported EOR catalysts to date. The unique 2D/3D hierarchy, high Pt utilization, and valid encapsulation of nanosized Pt3Co/Co synergistically contribute to the robust ORR and EOR activities of the present PtCo@N-GNS. A direct ethanol fuel cell based on PtCo@N-GNS delivers a high open-circuit potential of 0.9 V, a stable power density of 10.5 mW cm-2, and an excellent rate performance, implying the feasibility of the bifunctional PtCo@N-GNS. This work offers a new strategy for designing an ultralow Pt loading yet highly active and durable catalyst for ethanol fuel cell application.
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In this work, the high temperature oxidation behavior of Al71Co29 and Al76Co24 alloys (concentration in at.%) is presented. The alloys were prepared by controlled arc-melting of Co and Al granules in high purity argon. The as-solidified alloys were found to consist of several different phases, including structurally complex m-Al13Co4 and Z-Al3Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773-1173 K. A protective Al2O3 scale was formed on the sample surface. A parabolic rate law was observed. The rate constants of the alloys have been found between 1.63 × 10-14 and 8.83 × 10-12 g cm-4 s-1. The experimental activation energies of oxidation are 90 and 123 kJ mol-1 for the Al71Co29 and Al76Co24 alloys, respectively. The oxidation mechanism of the Al-Co alloys is discussed and implications towards practical applications of these alloys at high temperatures are provided.
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The aim of this study was to compare the quality of different computer-assisted-design and computer assisted manufacturing systems (CAD-CAM) generated by only one scanner, focusing on vertical fit discrepancies and the mechanical properties. A master model was obtained from a real clinical situation: the replacement of an absent (pontic) tooth, with the construction of a fixed partial denture on natural abutments with three elements. Nine scans were performed by each tested and 36 copies were designed using a dental CAD-CAM software (Exocad). The frameworks were manufactured using three-axis and five-axis, with the same batch of the chrome-cobalt (CrCo) alloy. The frameworks were not cemented. A focus ion beam-high resolution scanning electron microscope (FIB-HRSEM) allowed us to obtain the vertical gap measurements in five points for each specimen. Roughness parameters were measured using white light interferometry (WLI). The samples were mechanically characterized by means of flexural tests. A servo-hydraulic testing machine was used with a cross-head rate of 1 mm/min. One-way ANOVA statistical analysis was performed to determine whether the vertical discrepancies and mechanical properties were significantly different between each group (significance level p < 0.05). The overall mean marginal gap values ranged: from 92.38 ± 19.24 µm to 19.46 ± 10.20 µm, for the samples produced by three-axis and five-axis machines, respectively. Roughness was lower in the five-axis machine than the three-axis one, and as a consequence, the surface quality was better when the five-axis machine was used. These results revealed a statistically significant difference (p < 0.005) in the mean marginal gap between the CAD-CAM systems studied. The flexural strength for these restorations range from 6500 to 7000 N, and does not present any statistical differences' significance between two CAD-CAM systems studied. This contribution suggests that the number of axes improves vertical fit and surface quality due to the lower roughness. These claims show some discrepancies with other studies.