Residual Amorphous Phase Research Articles

Evaluation of in-plane and out-of-plane crystallinities with residual amorphous phases for MgB2 superconductor

We focus on in-plane and out-of-plane crystallinities of the MgB2 superconductor. These two structural properties were evaluated in terms of peak broadening at lower angles in the X-ray diffraction. The angular behavior of the in-plane and out-of-plane peaks was used to compare it with the corresponding behavior estimated in the case of several crystallite sizes (that affect the in-field superconductivity of MgB2). We propose that this comparison allows a simple evaluation to provide insight into the individual influences of in-plane and out-of-plane crystallinities on the in-field critical current density (without needing to calculate numerical values of crystallite sizes and lattice strains of fabricated MgB2 materials). For this study, we used MgB2 samples sintered at different temperatures. The sintering conditions affected not only the crystallinities but also the phase compositions. The behavior of the compositions, including amorphous phases, was also evaluated by using a quantitative analysis for X-ray diffraction results.

Nanocrystalline Fe(Co)ZrMoBCu soft magnetic alloys: A transmission electron microscopy study of the microstructures

Nanocrystalline Fe81Zr7Mo2B9Cu1 and Fe40.5Co40.5Zr7Mo2B9Cu1 alloy ribbons were prepared by annealing the as-quenched amorphous alloys at their first exothermic peak temperature. The primary crystallization phases of Fe81Zr7Mo2B9Cu1 and Fe40.5Co40.5Zr7Mo2B9Cu1 consisted of nanoscale body-centered cubic α-Fe and α-FeCo grains, respectively. The microstructures and compositions were analyzed via transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), and area maps were obtained through energy-dispersive spectroscopy (EDS). The addition of Co decreased the mean grain size (D) and broadened the grain-size distribution (σ). The effect of the addition of Co on the Cu clusters and element distribution was studied in detail. Scanning transmission electron spectroscopy combined with energy-dispersive spectroscopy revealed that both alloys contained Cu clusters; the Fe40.5Co40.5Zr7Mo2B9Cu1 alloy exhibited a Cu-cluster density similar to that of the Fe81Zr7Mo2B9Cu1 alloy. Both alloys contained relatively less Fe in their residual amorphous phases than in their nanocrystals, with the nanocrystals in Fe40.5Co40.5Zr7Mo2B9Cu1 containing less Co than in the residual amorphous phase. Fe40.5Co40.5Zr7Mo2B9Cu1 exhibited higher specific saturation magnetization (Ms), specific remanent magnetization (Mr) and larger coercivity (Hc) than Fe81Zr7Mo2B9Cu1.

Imparting high elastocaloric cooling potential to NiTi alloy by two-step enhancements

The large adiabatic temperature change during the stress-induced phase transformation in the superelastic NiTi alloy makes it a leading candidate material for solid-state elastocaloric cooling applications. However, NiTi with a uniform grain structure generally offers either large cooling capacity or low energy dissipation, but not both. In an earlier study, we demonstrated that the alloy with graded grain sizes, obtained using differential annealing of heavily cold-worked sheets, can overcome this intrinsic limitation. However, non-transformable components (residual martensite and amorphous phases), which are introduced into the microstructure during cold rolling, impair the full exploitation of the cooling potential of the graded NiTi. Here, we introduce an intermediate processing step, namely post-deformation annealing, which eliminates the undesirable phases while maintaining nanocrystallinity, before imparting a microstructural gradient. Results show that the synergy between various microstructural elements results in a significant enhancement in the cooling capacity while keeping the energy dissipation low. Moreover, the functional fatigue performance of the graded alloy is also preferable to that of the conventional coarse-grained NiTi. The micromechanical reasons behind these improvements are elucidated by recourse to detailed experiments.

Uncovering White Light Emission in Pressure‐Treated Sb‐Doped Double Perovskite by Coherent Optical Phonon

AbstractSingle‐component white‐light emitters are ideal for solid‐state lighting applications. Here, the dual‐emission white light in the 3D Cs2NaInCl6:0.1 Sb3+ crystal is successfully achieved by the high‐pressure treatment strategy. Upon compression, the remarkable self‐trapped exciton (STE) emission enhancement is observed at 20.6 GPa due to the tilting and twisting of inorganic octahedron caused by the phase transition of Cs2NaInCl6:0.1 Sb3+ crystal. Intriguingly, after undergoing the high‐pressure treatment, in addition to the blue high‐energy emission from the STEs, [SbCl6]3− exhibits the orange low‐energy emission from STEs, which is ascribed to the remaining local distortion of inorganic octahedron resulting from the presence of residual amorphous phase in the local region upon decompression. Furthermore, coherent phonon generation and density functional theory calculations indicate that the electrons exhibit a strong coupling to A1g stretch mode and T2gIn bending mode in Cs2NaInCl6:0.1 Sb3+. After high‐pressure treatment, the coupling between the electrons and the T2gIn bending mode disappears, suggesting local octahedral symmetry disruption due to residual amorphous structures induced by high‐pressure treatment. This work unveils the relationship between the electron‐phonon coupling and the STE emission and offers a new strategy to design and synthesize the new single‐component white‐light metal halide perovskites.

Effect of annealing at Tg on the crystallization behaviors of Au49Ag5.5Pd2.3Cu26.9Si16.3 metallic glass revealed by nanocalorimetry

Crystallization of metallic glass is not only affected by undercooling but also influenced by microstructure. However, the role of structure in the crystallization is still ambiguous. In this study, nanocalorimetry with a rapid quenching rate was used to obtain the critical cooling rates suppressing nucleation and crystal growth, realizing the in-situ preparation of the amorphous phase. Based on the nuclei-free metallic glass, annealing at Tg was performed to tune the microstructure. With a reheating analysis, the consecutive occurrence of relaxation, nucleation, and crystal growth during annealing was distinguished based on the evolution of crystallization heat. Moreover, the effect of annealing and the resulting microstructure evolution on the reheating crystallization was demonstrated. With the formation of nuclei, the stability of the undercooled melt deteriorated, causing the reduction of activation energy (Ea). When crystals formed during annealing, the confined residual amorphous phase was dominant for crystallization, and a higher Ea was observed.

Novel composition of Nd-Fe-B gas atomized powder to produce compression bonded magnets

New compositions of Nd-Fe-B powders were produced via gas atomization. Helium and argon were used as atomizing gases. For the same process parameters, helium resulted in a powder that is 6 times finer than the powder produced with argon. In both cases, the atomization conditions were set to achieve fine powders and, therefore, fine microstructures, since this is critical to obtain a suitable coercivity. The powders were sieved to separate the fraction below 20 μm (∼90 % of powder atomized with He). The microstructure is formed by a mix of elongated and equiaxial grains with random crystallographic orientation and an average grain size of ∼ 1 μm, which was measured by Electron Backscattered Diffraction. This kind of measurements and images were taken for the first time for fine helium atomized Nd-Fe-B powders. The embedding of the powder in copper was found to be useful, as the conventional mounting in metallographic conductive resin produced charging of the sample. Annealing up to 1000 °C did not cause any significant grain growth that could deteriorate the magnetic properties. Annealing at 700 °C for 15 min improved the magnetic properties due to the crystallization of residual amorphous phase. Warm compaction was used to produce magnets with a high volume fraction of magnetic powder (>70 %) and low real porosity (∼5 %). These magnets exhibit a high remanence (∼0.5 T) and maximum energy product (∼35 kJ/m3), combined with a suitable intrinsic coercivity (>500 kA/m). The new compositions and processing route could cover a market niche. The thoroughly analyzed powders could be also suitable for some additive manufacturing technologies that require spherical powders with very specific particle size distributions.

Recent advances on innovative bioactive glass-hydroxyapatite composites for bone tissue applications: Processing, mechanical properties, and biological performance

New Hydroxyapatite-Bioactive Glass composites, xHA-(1-x)BG (x = 25, 50, and 75 wt %), are developed using HA and BGMS10 glass powders co-milled up to 2 h prior to Spark Plasma Sintering (SPS). Ball milling (BM) promoted the consolidation of HA-rich powders, whereas hindered the densification of 25HA-75BG samples. HA crystallite size is reduced from > 200 nm (unmilled) to 60 (x = 25 %) or 88 nm (x = 75 %) when using 2 h milled mixtures. Glass crystallization occurred in 75HA-25BG samples processed by SPS at 950 °C: a negligeable effect in the amount of the residual amorphous phase (12.3–13.3 wt %) is produced by BM, while changes are observed in the relative content of crystalline phases, with SiO2 increases from 8.5 to 13.1 wt %, whereas α- and β-CaSiO3 correspondingly decrease. Superior Young’s modulus and Vickers hardness (130 GPa and 726, respectively) are obtained in HA rich products. Biological tests evidenced that the milling treatment does not determine negative consequences on cells viability.

Effect of Chemical Composition on Molecular Mobility and Phase Coupling in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Different Comonomer Contents

Two series of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) with different amounts of hydroxyvalerate (HV) and hydroxyhexanoate (HHx) units are compared. The influence of chemical composition on the molecular mobility in quenched samples is discussed, as well as the consequences on the aptitude to crystallize and the microstructures developed during cold-crystallization. In both quenched PHBHV and PHBHHx, $$T_g$$ decreases as the content of comonomer unit increases. The HHx units (propyl side-groups) are better molecular spacers and produce a stronger $$T_g$$ shift as compared to the HV units (ethyl side-groups). Copolymerization has no striking effect on the width of the glass transition and the cooperativity length in quenched samples, but in cold-crystallized samples the glass transition is dramatically broadened. When the fully amorphous copolymers are heated from the glassy state to room temperature, crystallization occurs but is largely disrupted, suggesting that the molecular environment in the amorphous phase is significantly changed. The HHx units, which are excluded from the host crystals, delay and slow down the crystallization kinetics in a stronger way as compared to the HV units, which can partially co-crystallize. The obtained crystalline phases are prone to reorganization and the residual amorphous phases appear to have strong differences in composition and large density fluctuations. A practical consequence is that microstructures with different coupling between phases, and thus different properties and stability over time, can be obtained by controlling the nature and content of the comonomer units.

High thermal stability of residual amorphous regions in metallic glasses

As a thermodynamic non-equilibrium material, metallic glasses have a spontaneous tendency to crystallize, commonly accompanied by a degradation of mechanical properties. In this work, the thermal stability of a composition Zr60Co27Al13 under both a monolithic amorphous state and symbiotic primary crystal-glass state was intensively analyzed to uncover the origination of the thermal stability. It shows that the symbiotic metallic glass is much more stable than that of the monolithic metallic glass, which can be attributed to the consumption of short-range order clusters, the relaxation in atomic dimensions, and the more homogenous elemental distribution in the residual amorphous regions. Revealing the effect of the primary crystal on the residual amorphous phase in the symbiotic state may be beneficial for developing metallic glasses with high thermal stability.

Microstructural evolution and superelastic properties of ultrafine-grained NiTi-based shape memory alloy via sintering of amorphous ribbon precursor

NiTi-based shape memory alloys (SMAs) are considered as cutting-edge intelligent functional materials. However, it remains a great challenge to obtain ultrafine-grained (UFGed) bulk materials with mm-scale size as well as outstanding superelastic properties. Here, UFGed bulk Ti35Zr15Ni35Cu15 NiTi-based SMA is successfully prepared via spark plasma sintering of amorphous ribbon precursor at different sintering temperatures, and microstructural evolution and superelastic properties are symmetrically investigated. It is found that its grain size ranges from UFG to micro-grain with increased sintering temperature regardless of the predominant B2 matrix in all bulk samples. Interestingly, the orientation relationships between B2 matrix and nano-scale fcc (Ti,Zr)2Ni precipitate evolve from coherent to incoherent. Consequently, the UFGed samples exhibit perfect superelasticity with the high recoverable strain of ∼5.8%, the stable recovery rate above 99%, and the great critical stress inducing martensitic transformation higher than 1 GPa, far superior to the corresponding ones of suction-cast micro-grained TiZrNiCu SMAs. Fundamentally, the perfect superelasticity is attributed to the good resistance to dislocation slip or grain boundary slip by residual nano-scale amorphous phase or secondary phase of coherent and semi-coherent fcc (Ti,Zr)2Ni precipitate. In addition, the gentle superelastic plateau is associated to the favorable transfer stress and the strong ability to accommodate dislocation movement, which is generated by the coherent interface between nano-scale fcc (Ti,Zr)2Ni and UFGed B2 matrix. These results suggest that spark plasma sintering of amorphous alloy precursor is a feasible route to obtaining excellent superelasticity in NiTi-based SMAs.

5 - Effect of Roughness on Flexural Strength of Dental Lithium-Disilicate

A common process in dental clinics is to perform small fitting adjustments of dentures after testing in the patient's mouth using the micro-grinding tool. This procedure promotes a local roughness increase and can lead to the formation of microcracks on the prosthesis surface. The aim of this work was to investigate the benefits of a post-finishing heat treatment on the surface roughness smoothing and crack healing of lithium disilicate dental glass ceramics, and its effect on the flexural strength. Commercially available lithium metasilicate, Li 2 SiO 3 (IPS e-maxCAD), samples were heat treated at 840C-7min. The material was characterized by X-ray diffraction, Scanning Electron Microscopy, Vickers hardness, Youngs modulus and fracture toughness. One of the surfaces of the samples was machined, aiming to simulate the fitting procedure of dentures in the dentist's laboratory, generating a rough surface. Half of the samples were tested by biaxial flexural testing (3B-P) and the other half were submitted to a rapid heat treatment (840C-3min) and later tested by biaxial strength, with statistical analysis by Weibull. The Roughness parameters (Ra, PV and Rz) were measured using Zygo New View 7100 Optical Profiler. After the crystallization heat-treatment protocol suggested by the manufacturer, the formation of elongated lithium disilicate crystals, Li 2 Si 2 O 5 , with 36% residual amorphous phase was observed. In addition, the Vickers hardness of 6.1±0.3 GPa, fracture toughness of 1.90± 0.2 MPa.m1/2 and modulus of elasticity values of 91 ±2 GPa were obtained. The samples from the group without rapid heat-treatment showed bending strength of 203.5 ±33 MPa, with roughness values of Ra=0.6 ±0.2 μm, Rz=22 ±6 μm and PV=28 ±7 μm. After the rapid heat treatment, the roughness parameters Ra, Rz and PV were 0.3 ±0.2 μm, 9 ±6 μm and 5 ±4 μm, respectively. With this reduction in roughness, the flexural strength increased by 65%, with mean values of 336.6 ±32 MPa. Weibull modulus values were in the order of 5 for both groups. In the need for finishing machining of lithium disilicate-based glass-ceramic dental prostheses, the use of a rapid heat treatment at 840 C allows considerable gains in flexural strength. Increasing the service life of the prosthesis, due to a reduction on the surface roughness, promoted by the softening of the remaining amorphous phase in the glass-ceramic.

High Bs Fe-B-P-C-Cu nanocrystalline alloy with longtime annealing stability and low heating rate sensitivity

To solve the sensitivity of soft magnetic properties of Fe-B-P-C-Cu alloy system without transition metal addition on heat treatment process parameters, the effect of P content on the heat treatment process parameters and soft magnetic properties of Fe83B12-xPxC4Cu1 (x = 3, 5 and 7) alloys have been investigated. It is found that increasing P can effectively reduce the sensitivity of microstructure and soft magnetic properties on the annealing holding time (th). The th of Fe83B7P5C4Cu1 and Fe83B5P7C4Cu1 alloys can be extended to 60 min compared to the th of 6 min for Fe83B9P3C4Cu1 alloy to obtain a low coercivity (Hc) below 8.5 A/m. However, too high P content will reduce the stability of residual amorphous phase and shorten the optimal th. The results indicate that increase of P can also reduce the sensitivity of microstructure and soft magnetic properties on the heating rate (β). The β of Fe83B7P5C4Cu1 and Fe83B5P7C4Cu1 alloys can be as low as 40 K/min and 20 K/min to obtain high saturation magnetic flux density (Bs) of 1.80 T and 1.73 T, and low Hc of 8.4 A/m and 8.1 A/m, respectively.

AlCoCrFeNi high entropy alloy fabricated via selective laser melting reinforced by Fe-based metallic glass

The 5% Fe-based amorphous reinforced AlCoCrFeNi high-entropy alloy (HEA) specimens were prepared by selective laser melting (SLM) technique. The mixed of Fe-based amorphous reduces the grain diameter and eliminates the presence of texture. Meanwhile, the anisotropy of the specimen was reduced. The addition of Fe-based amorphous causes the precipitation of FCC phase in the body-centered cubic (BCC) matrix, and the face-centered cubic (FCC) phase is uniformly distributed at the grain boundaries. The presence of FCC phase significantly reduces the internal stress of the specimen. The elements in the amorphous alloy solidly dissolve into the BCC matrix during the printing process, further strengthening the BCC matrix. The residual amorphous and nanocrystalline phases also result in a significant improvement in the performance of the specimen.

Formation of L10-FeNi hard magnetic material from FeNi-based amorphous alloys

L10-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe42Ni41.3Si8B4P4Cu0.7 amorphous alloy, and the L10-FeNi formation mechanism has been studied. It is found the L10-FeNi in annealed samples at 400 °C mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 60 °C lower than the measured onset temperature of the second stage with a 5 °C/min heating rate. Annealing at 400 °C after fully crystallization still caused a slight increase of coercivity, which was probably contributed by the limited transformation from other high temperature crystalline phases towards L10 phase, or the removal of B from L10 lattice and improvement of the ordering quality of L10 phase due to the reduced temperature from 520 °C to 400 °C. The first stage of crystallization has hardly direct contribution to L10-FeNi formation. Ab initio simulations show that the addition of Si or Co in L10-FeNi has the effect of enhancing the thermal stability of L10 phase without seriously deteriorating its magnetic hardness. The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects. The approaches of synthesizing L10-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.

Effect of type and volume fraction of crystallization products on the variations of electrical resistivity in Cu47Ti34Zr11Ni8 and Ti40Zr25Cu12Ni3Be20 metallic glasses

The variation of electrical resistivity can be an indicative of the crystallization path for metallic glass (MG). The primary phases of Cu47Ti34Zr11Ni8 and Ti40Zr25Cu12Ni3Be20 MGs are Cu3Ti and quasicrystal, respectively, which further influences change of electrical resistivity at the onset crystallization temperature (Tx1). The former shows a rapidly drop in the electrical resistivity curve along with apparent change in curve slope at Tx1, while the latter exhibits a long and continuous decrement of electrical resistivity from Tg to Tx2 without obvious change of curve slope at Tx1. The nanoscale quasicrystal with slower growth rate indicates that the icosahedral short-range orders might exist during sample preparation, which could easily overcome crystallization obstacle and transform into the quasicrystalline phase continuously, inducing the special change of the Ti40Zr25Cu12Ni3Be20 MG. Meanwhile, the TCR of the crystalline/glass composite materials depends on the volume fraction of crystalline phase. When the volume fraction of crystalline phases is small, the TCR is still determined by the residual amorphous phase.

Non-additive sintering of Si2N2O ceramic with enhanced high-temperature strength, oxidation resistance, and dielectric properties

The high-temperature mechanical and dielectric properties of Si2N2O ceramics are often limited by the introduction of a sintering aid. Herein, dense Si2N2O was prepared at 1700 °C by hot-pressing oxidized amorphous Si3N4 powder without sintering additives. A homogeneous network with short-range order and a SiN3O structure was formed in the oxidized amorphous Si3N4 powder during the hot-pressing process. Si2N2O crystals preferentially nucleated at positions within the SiN3O structure and grew into rod-like and plate-like grains. Fully dense ceramics with mainly crystalline Si2N2O and some residual amorphous phases were obtained. The as-prepared Si2N2O possessed a good flexural strength of 311 ± 14.9 MPa at 1400 °C, oxidation resistance at 1500 °C, and a low dielectric loss tangent of less than 5 × 10−3 at 1000 °C.

Origin of the separated α-Al nanocrystallization with Si added to Al86Ni9La5 amorphous alloy

An understanding of nanocrystallization is an important precondition for controlling the microstructure and properties of nanocrystal-reinforced amorphous alloys. In the present work, the microstructures of Al86Ni9La5 and (Al86Ni9La5)98Si2 amorphous alloys and their annealed products were investigated systematically to reveal why the nanocrystallization behavior of primary α-Al was considerably changed with Si addition. Upon heating, α-Al nucleates in the Al-rich regions of two amorphous alloys. The addition of Si significantly shrinks the size of single Al-rich region in the as-quenched amorphous sample, but raises the local maximum Al concentration and slows down the rate of diffusion of solute atoms. As a result, the primary crystallization of α-Al first takes place at a higher nucleation rate in the Al-rich regions at lower temperatures. However, the residual amorphous phase enriched with solute elements does not crystallize until the alloy is heated to a high enough temperature for massive atomic diffusion to occur, with further crystallization of α-Al occurring through epitaxial growth of the existing α-Al crystals. The high bonding strength between Si with Ni, and especially La, is responsible for the splitting of α-Al nanocrystallization into two stages.

Influences of Si addition on the thermal stability and crystallization behavior of Al-Y binary amorphous alloys

In the present study, the crystallization behavior of (Al90Y10)100−xSix (x = 0, 1, 2, 2.5 and 3 at%) amorphous alloys were characterized by differential scanning calorimetry, X-ray diffraction and transmission electron microscopy. As Si is added to the Al90Y10 base amorphous alloy, the primary crystallization of α-Al is advanced to lower temperature, the precipitation of Al4Y in the residual amorphous phase is depressed but the crystallization of Al3Y is promoted. The Si addition stabilizes the α-Al3Y phase significantly, due to which both the as-cast ingot and the fully crystallized ribbon of (Al90Y10)98Si2 alloy consist of α-Al and α-Al3Y, whereas the corresponding products in Al90Y10 alloy are α-Al and β-Al3Y. The addition of 2.5 at% Si makes the crystallization of α-Al split into two stages with a temperature interval of 140 K between the two peaks. The reason is thought to be related with the enhanced concentration fluctuation in amorphous alloy and the slower diffusion of Y atoms in crystallization after the Si addition.

Evaluation and control of residual amorphous phases in carbon-doped MgB2 superconductors

Evaluation and control of amorphous phases in materials are very important for optimizing their properties. Herein, we focus on polycrystalline MgB2 materials prepared with hydrocarbon doping and study the effects of residual amorphous impurities on the superconducting performance. Carbon is known to be an effective element for enhancing the transport critical current under an external magnetic field. The doped samples were prepared under two different nominal conditions, MgB2(C16H10)x/16 and MgB2−x(C16H10)x/16, which respectively correspond to additional and substitutional type doping of the MgB2 composition. Regardless of the doping type, both fabrication methods retarded the formation of the MgB2 phase due to the dopant, leading to an increase in amorphous impurities. However, the apparent phenomena that arise from the additional and substitutional types are still elusive. Ultimately, the structural differences due to the impurity effects caused significant changes in the transport critical current performance. The present quantitative analysis of the amorphous impurities thus paves the way to further optimize the doping methodology for MgB2 superconducting materials.

Shear Bond Strength of Lithium Disilicate to Resin Cement After Treatment with Hydrofluoric Acid and a Self-etching Ceramic Primer

The aim of this work was to analyze the properties and shear bond strength (SBS) of lithium disilicate to resin cement before and after etching the glass-ceramic surfaces. Lithium-metasilicate samples were heat treated and characterized by Scanning Electron Microscopy, X-ray diffraction and roughness measurement. For the analysis of the shear bonding strength (SBS) of lithium disilicate to dental resin cement, three groups (n = 12) of Li2Si2O5 were prepared: 1°)without treatment (NT); 2°)surface etching with hydrofluoric acid(HF), followed by silane agent and adhesive treatment; 3°) surface treatment with a self-etching ceramic primer (SECP). After the heat-treatment, the samples had Li2Si2O5 crystalline phase dispersed in a residual amorphous phase. Roughness of the NT and SECP samples was smaller that of the HF samples. Samples without surface treatment (NT) had the lowest SBS (5.5MPa). HF(24.2MPa) and SECP(24.8MPa) samples has similar SBS. Weibull statistics showed that HF-samples are more reliable than NT and SECP. The SBS was significantly increased by either HF etching and SECP surface treatment. While the chemical characteristics of the surface submitted to SECP treatment are considered to be responsible for the SBS increase, the main adhesion mechanism after HF etching is the increase in surface roughness.