Unpolished Surfaces Research Articles

Roughness Reduction of Additively Manufactured Steel by Electropolishing

Improving surface finishing is the critical step in the application of an additively manufactured (AM) component in high fatigue and corrosion-sensitive fields. This paper provides insights into surface properties of electropolished AM component made up of 316 stainless steel with > 6% carbon. We performed surface analysis with profilometer, scanning electron microscope, and AFM to investigate the electropolished and unpolished AM components. The first major discovery of the present work is that our optical profilometry study provided an estimate of the amount of material to be removed to achieve a shiny and smooth surface on 316 stainless steel AM part. One needs to remove more than 200 μm thick layer from the surface to make a mirror-smooth surface. Such estimation can enable researchers to incorporate requisite tolerance during the design stage itself. The second important finding of our work is that ultrasmooth microstructure on the AM surface appeared when preferential material removal occurred along the boundary of the hexagonal microscopic features. Additionally, our optical profilometry studies provided an analysis of several roughness parameters on the electropolished surface. Electropolishing was effective in reducing the surface roughness below ~ 0.1 μm RMS over microscopic regions. Observation of sub-μm RMS roughness was consistently observed with the optical profilometer, SEM, and AFM. SEM study revealed a significant change in the microstructure of the electropolished samples in a medium and highly smooth state. We also conducted a water contact angle study and spectroscopic reflectance study on electropolished and unpolished AM component surfaces. Our study revealed that electropolishing is a highly promising route for improving the surface finishing of AM components.

Topographic characterization of canine teeth using atomic force microscopy images in nano-scale

The purpose of the present study was to investigate a new method to evaluate micro topography and micro morphology of hard tissue of canine teeth using an atomic force microscope (AFM). For this aim, three extracted human canine teeth were applied. The unpolished surfaces were analyzed with AFM images with 15 µm × 5 µm area and their information obtained by power spectral density (PSD) method and fast Fourier transform algorithm. It was observed that PSD analyses extract suitable information about surface morphological variations so that by moving from enamel to cementum, the fractal dimension and surface complexity were increased.

About the Microstructure of the Graptolite Periderm - Examples from the Holy Cross Mountains (Poland)

Graptolite reflectance is one of the main parameters for assessing thermal maturity of pre-Devonian rocks in which vitrinite does not occur. However, microstructure of the graptolite periderm has been known only recently, and still little is known about low-reflectance graptolites. The purpose of the work was to determine microstructural features of the graptolite periderm in the oil window shales and compare them to those known from the previous studies, in which more matured organic matter was investigated. Four samples were collected in the Holy Cross Mountains (Central Poland), in two localities (Bardo Stawy and Prągowiec ravine). Reflectance (Rr) measurements as well as micro-Raman analysis were carried out on the sections parallel to the bedding. Micro-Raman analysis was performed on unpolished surfaces to exclude influence of polishing on microstructure. The obtained spectra were curve-fitted using four Lorentzian (G, D1, D2 and D4 band) and one (D3 band) Gaussian lines. Graptolites (Rr=0.70-0.77%; Vitrinite Reflectance Equivalent VRE=0.67-0.72%) occur in the Silurian dark grey clay shales of the Llandovery (Bardo Stawy) and Wenlock - Lower Ludlow (the Prągowiec ravine) age. Graptolite periderm represents poorly organized carbonaceous material, which is inferred from the occurrence of the D3 and D4 bands, and overlapping D2 and G bands. Microstructure does not vary significantly between the samples from the two considered localities (the exception being the D1 band FWHM), which corresponds to the narrow range of graptolite reflectance. Compared to the Raman spectra obtained from graptolites with higher reflectance, the G peak is significantly moved to the lower and the D1 peak to the higher wavenumbers. The FWHM of the G band is higher, while the ID1/IG ratio usually smaller. Taking into account the results from the previous study, it can be concluded that in the reflectance range of 0.7-1.8% the G band position first moves to the higher, and at Rr>1.2% to the lower wavenumbers, while the D1 peak gradually shifts to the lower wavenumbers. The G band FWHM decreases with increasing graptolite reflectance, which reflects improvement in structural ordering, while the ID1/IG ratio starts to increase at Rr≈1.5%, indicating the growth of the coherent domains within the graptolite periderm.

Effect of Nanoscale Defect Structure on Magnetic Properties of Tb–Co Films with Perpendicular Magnetic Anisotropy

Magnetization reversal is studied for Ta/Tb29Co71/Ta thin films with different types of nanostructure. The films are deposited onto structuring substrates of anodized aluminum with unpolished surfaces, polished surfaces, and barrier layers. Nanoholes are found to triple the coercivity, due likely to the pinning of domain walls. Continuous and antidot films reveal the strong effect nanoconvexities have on the slope of the hysteresis loops. Such surface features could be one of the main reasons for the attenuation of perpendicular anisotropy in films deposited onto porous substrates.

EFFECT OF FINISHING AND POLISHING ON SURFACE ROUGHNESS OF CUBIC ZIRCONIA

Aim: The purpose of this invitro study was to evaluate the effect of finishing and polishing on surface roughness of BruxZir Anterior Cubic zirconia before and after hydrothermal aging. Materials and methods: Twenty samples of BruxZir Anterior Cubic zirconia were divided into two groups, group (1): Polished BruxZir Anterior Cubic zirconia (n=10), group (2): Unpolished BruxZir Anterior Cubic zirconia (n=10). All samples were fabricated out of CAD CAM blocks and evaluated for surface roughness before and after hydrothermal aging. Results: Before aging, there was a significant difference in the surface roughness (Ra) of the polished (M=125.28, SD=1.27) and unpolished (M=128.97, SD=2.61) surfaces. Similarly after ag­ing, there was a significant difference in the surface roughness (Ra) of the polished (M=125.89, SD=1.35) and unpolished (M=130.09, SD=2.97) surfaces. Conclusions: Finishing and polishing of cubic zirconia considerably lowered the surface roughness before and after hydrothermal aging.

Effects of Polishing Bur Application Force and Reuse on Sintered Zirconia Surface Topography.

Limited information is available on how to polish and finish zirconia surfaces following computer-aided design/computer-aided manufacturing (CAD/CAM), specifically, how differing application forces and reuse of zirconia polishing systems affect zirconia topography. To determine the effect of differing, clinically relevant, polishing application forces and multiple usages of polishing burs on the surface topography of CAD/CAM zirconia. One hundred twenty 220-grit carbide finished zirconia disks were sintered according to manufacturer's directions and divided into two groups for the study of two coarse polishing bur types. Each group was divided into subgroups for polishing (15,000 rpm) at 15 seconds for 1.0 N, 4.5 N, or 11 N of force using a purpose-built fixture. Subgroups were further divided to study the effects of polishing for the first, fifth, 15th, and 30th bur use, simulating clinical procedures. Unpolished surfaces served as a control group. Surfaces were imaged with noncontact optical profilometry (OP) and atomic force microscopy (AFM) to measure average roughness values (Ra). Polishing burs were optically examined for wear. Scanning electron microscopy (SEM) was performed on burs and zirconia surfaces. One-way ANOVA with post hoc Tukey HSD (honest significant difference) tests (α=0.05) were used for statistical analyses. AFM and OP Ra values of all polished surfaces were significantly lower than those of the unpolished control. Different polishing forces and bur reuse showed no significant differences in AFM Ra. However, significant differences in OP Ra were found due to differing application forces and bur reuse between the first and subsequent uses. SEM and optical micrographs revealed notable bur wear, increasing with increasing reuse. SEM and AFM micrographs clearly showed polished, periodic zirconia surfaces. Nanoscale topography, as analyzed with kurtosis and average groove depth, was found dependent on the specific polishing bur type. These in vitro results suggest changes in OP Ra due to bur reuse and polishing application force. Within the parameters of this study, the resultant topography of zirconia polishing is force-dependent and the reuse of coarse polishing burs is possible without statistically significant differences in Ra values after initial use. Nanoscale and microscale topography were shown to depend on specific polishing bur type.

Petrogenesis and thermal overprint of S-type granites in Helanshan region, North China Craton: Constraints on the 1.90 Ga khondalites decompression melting and 1.32 Ga tectono-thermal event

Widespread Paleoproterozoic S-type granites and khondalites (high-grade sillimanite-garnet gneisses) are exposed in the Khondalite Belt of the North China Craton (NCC). Porphyritic biotite granites in the Helanshan region from the western Khondalite Belt exhibit a gradual contact relationship with the neighboring khondalites. In order to constrain the petrogenesis of these granites and their genetic relationship with the khondalites, detailed geochronological data, as well as geochemical and whole-rock Sm-Nd and zircon Lu-Hf isotope compositions of these granites are reported. LA-ICP-MS zircon U-Pb dating on magmatic zircon cores yields an emplacement age of 1902±22Ma, whereas metamorphic rims define a metamorphic age of 1356±57Ma. The unpolished surfaces of zircon crystals selected based on the presence of rims visible in cathodoluminescence were further analyzed by SIMS depth profiling, which gave a more precise metamorphic age of 1317±18Ma. The Helanshan granites display typical S-type geochemical characteristics, e.g., high A/CNK (1.16–1.29) and K2O (5.09–5.86wt%) contents, but low FeOt/MgO (2.39–4.88) and P2O5 (0.15–0.23wt%) contents. Similar trace and rare earth element patterns, and consistent zircon Hf model ages (2366–2483Ma) and whole rock Nd model ages (2407–2499Ma) between the porphyritic biotite granites and the khondalites, suggest that they were derived from partial melting of khondalites. The geochemical character of the porphyritic biotite granites, including significant negative Eu anomalies, high Rb/Ba and Rb/Sr ratios, and variable HREE contents and (La/Yb)N ratios, suggest that they are probably related to the post-peak decompression stage that was characterized by biotite breakdown and the progressive replacement of garnet with the presence of K-feldspar and plagioclase in the residues. Homogeneous zircon εHf(t) values (mostly from −0.5 to +1.7), combined with low bulk-rock Fe2O3T content and CaO/Na2O ratios, preclude the contribution from mafic magma. Following the continental collision, the emplacement of the porphyritic biotite granites at ca.1.90Ga provides the latest limit on the timing of post-peak decompression metamorphism of the khondalites, and their formation supports a post-collisional mantle upwelling model to account for the 1.92–1.90Ga regional metamorphic/magmatic events. On the other hand, the metamorphic zircon rims indicate that S-type granites were overprinted by a 1.32Ga tectono-thermal event, which was probably related to the breakup of the Columbia supercontinent.

Evaluation of the effect of denture adhesives on surface roughness of two chemically different denture base resins.

Objective:To evaluate the effect of four commercially available denture adhesives (DAs) on surface roughness of two chemically different denture base materials.Materials and Methods:Fifty specimens of heat-cured polymethyl methacrylate, and another fifty specimens of light-cured urethane dimethacrylate were divided into five groups (n = 10), each was immersed in four prepared DAs (Corega Super Cream, Corega Ultra Powder, Olivafix Cream, Protefix Cream) as well as distilled water (control group). The mean surface roughness (Ra) of the polished and unpolished surfaces of the specimens was recorded using profilometer device. T-test for paired observation was used to indicate any changes in surface roughness between the baseline and after 30 days of immersion in the DA.Results:Almost all the tested DAs had no significant effect on the roughness of polished and unpolished surfaces of both denture base materials. The Corega super cream DA produced significant increase in the roughness of the polished surfaces of both types of acrylic specimens (P < 0.05).Conclusion:The majority of the investigated DAs appears not to affect the surface roughness of denture base materials. Only Corega super cream DA produced detectable increase in the roughness of polished surfaces of denture base specimens.

Effect of substrate polishing on the growth of graphene on 3C–SiC(111)/Si(111) by high temperature annealing

We analyse the effects of substrate polishing and of the epilayer thickness on the quality of graphene layers grown by high temperature annealing on 3C–SiC(111)/Si(111) by scanning tunnelling microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, low energy electron diffraction and high resolution angle resolved photoemission spectroscopy. The results provide a comprehensive set of data confirming the superior quality of the graphene layers obtained on polished substrates, and the limitations of the growth obtained on unpolished surfaces.

In Vitro Analysis of Surface Roughness of Acrylic Resin Exposed to the Combined Hygiene Method of Brushing and Immersion in Ricinus communis and Sodium Hypochlorite.

To evaluate a solution based on Ricinus communis (Castor oil) for denture cleansing, comparing it to sodium hypochlorite (NaOCl) for the surface roughness of heat-polymerized acrylic resin. Forty polished and unpolished resin specimens (90 × 30 × 4 mm) were evaluated before and after their exposure to protocol hygiene: brushing the specimens with a specific denture brush and mild soap for 3 minutes, three times a day, and immersing them in hygiene solutions (0.25% NaOCl-S1 and 0.5% NaOCl-S2; 10% R. communis-S3; saline-S4: control) for 20 minutes. Surface roughness was evaluated by rugosimeter and scanning electron microscopy (SEM) before and after the protocol. For evaluation of surface roughness, polished and unpolished surfaces were used. The roughness of the polished surface was not affected by time (p = 0.062), but was affected by solutions (p < 0.0001) and the interaction between factors (p = 0.005). For S1 and S4, the period did not influence the roughness. For S2, there was a change after 7 days, remaining stable after 14 days. For S3, there were changes, and stabilization occurred after 14 days. After 7 and 14 days, S2 and S3 promoted major changes, but after 21 days, there were no differences among solutions, except saline. The unpolished surface was not influenced by factors: period (p = 0.115), solution (p = 0.120), and their interaction (p = 0.382). SEM analysis showed similar results on the evaluation of surface roughness. The polished surface of the prosthesis was more susceptible to changes when exposed to hygiene solutions, and although the 0.5% NaOCl solution promoted an increase in the surface roughness compared with the same solution at 0.25% and R. communis at 10%, the values are clinically acceptable.

The eruptive and magmatic history of the youngest pulse of volcanism at the Valles caldera: Implications for successfully dating late Quaternary eruptions

New 40Ar/39Ar and U/Th ages provide insight into the youngest eruptions at the Valles caldera and also reveal previously unknown pulses of magmatism. The youngest eruptive units, collectively termed the East Fork Member of the Valles Rhyolite, include the El Cajete pyroclastic beds and co-erupted Battleship Rock ignimbrite, and the disconformably overlying Banco Bonito lava flow. Previous attempts to date these units using a variety of techniques yielded ages ranging from <40ka to >1Ma. New 40Ar/39Ar ages were generated using the high-sensitivity, multi-collector ARGUS VI mass spectrometer, which provides more than an order of magnitude increase in precision compared to most single-detector mass spectrometers. 40Ar/39Ar dating of single crystals yields a range of ages, of which the youngest populations are interpreted to represent the eruption age. Sanidine ages indicate that the El Cajete pyroclastic beds and Battleship Rock ignimbrite erupted at 74.4±1.3ka, whereas the Banco Bonito lava erupted at 68.3±1.5ka. Populations of older crystals represent variably degassed xenocrysts, explaining why previous 40Ar/39Ar bulk step-heating analyses yielded spuriously old and irreproducible results. U/Th dating of unpolished zircon surfaces also yield multiple age populations, which range from the eruption age to >350ka, indicating protracted magmatism during the 453-ka-long eruptive hiatus prior to the eruption of the East Fork Member. 40Ar/39Ar and U/Th ages indicate that the East Fork Member represents a short (6.1±2.8ka) eruptive cycle, from a longer-lived magmatic system beneath the southern caldera. Equally short repose periods, similar to the interval between the El Cajete–Battleship Rock and Banco Bonito eruptions, are possible during future volcanism at the Valles caldera. Results demonstrate that detailed geochronology using single-crystal and in-situ techniques is necessary for understanding the eruptive history and magmatic evolution at some young volcanic systems.

Comparison of Fungal Biofilm Formation on Three Contemporary Denture Base Materials

ABSTRACTStatement of problem: Modern polyamide ‘flexible’ denture base materials have increased in popularity for use in removable partial dentures in the last several years. The introduction of these newer products warrants investigation of their relative potential to develop fungal biofilms.PurposeThe purpose of this study was to investigate the potential of three denture base materials to support fungal biofilm formation.Materials and methodsSpecimens of two ‘flexible’ nylon type materials and one traditional heat processed, methyl methacrylate resin material were studied (both polished and unpolished surfaces). The specimens were coated with saliva and evaluated for fungal (Candida albicans) biofilm formation. The fungal biofilm mass formed on denture substrates were evaluated by dry weight analysis and by determining the number of viable fungal cells in the biofilm by MTT viability assay. Alteration in fungal metabolic function following the treatment of the biofilmC. albicanswith nystatin and fluconazole was determined by XTT assay.ResultsIn general, the unpolished surfaces of the denture disks favored the fungal biofilm, the most being on polyamide specimen, Valplast. Significantly, less biofilm was formed on Duraflex and Lucitone surfaces. Biofim on C. albicans was also found to be resistant to antifungal agents. As compared to freshly incubated (grown) planktonic cells, biofilm fungal cells required significantly higher concentrations of nystatin and fluconazole in order to obtain 50% reduction in metabolic activity.ConclusionThis study demonstrated the differences in denture materials to support fungal biofilm formation, and also difference between polished and unpolished denture material surfaces. The results demonstrated that one of the polyamide materials (duraflex) had lesser potential to biofilm formation than the others.Clinical significanceUnfavorable tissue responses can ensue from the presence of fungal biofilms on dental prosthetics. Resistance to biofilm formation is a factor for dental materials in their selection and usage. This study helps to quantify, evaluate and compare biofilm formation on polished and unpolished surfaces of three commonly used denture base materials. The results of this study helped to identify materials, which may, therefore, be better indicated in clinical applications. Evaluations for the newer denture base materials, specific to these testing methods, appear to be novel in the scientific literature.How to cite this articleJain V, Babu J, Ahuja S, Wicks R, Garcia-Godoy F. Comparison of Fungal Biofilm Formation on Three Contemporary Denture Base Materials. Int J Experiment Dent Sci 2015;4(2):104-108.

Effect of polishing systems on stain susceptibility and surface roughness of nanocomposite resin material

Different polishing systems vary in their effect on reducing surface roughness and stain susceptibility of dental composite resin materials. The purpose of this study was to compare the effect of 3 polishing systems on the stain susceptibility and surface roughness of 2 nanocomposite resins and a microhybrid composite resin. Forty-five disks (2×10 mm) each were fabricated of 2 nanocomposite resins (Filtek Supreme XT and Tetric EvoCeram) and 1 microhybrid composite resin (Z250). Both sides of the disks were wet finished, and 1 side was polished with PoGo, Astropol, or Hi-Shine (n=5). Unpolished surfaces served as controls. The average roughness (Ra, μm) was measured with a profilometer, and the baseline color was recorded with a spectrophotometer. All specimens were incubated while soaking in a staining solution of coffee, green tea, and berry juice for 3 weeks. The color was recorded again, and the data were analyzed with 2-way ANOVA at α=.05 and Tukey multiple comparison tests. All polishing systems improved the staining resistance of Filtek Supreme XT and Z250 but did not affect that of Tetric EvoCeram. The surface color of Filtek Supreme XT was changed significantly and was the smoothest after polishing with PoGo, whereas Hi-Shine produced significantly rougher surfaces but with the lowest color change. Hi-Shine produced the highest color change in Z250. The surface roughness did not differ significantly between the other polishing systems. Tetric EvoCeram showed no significant differences in color change or surface roughness. Staining susceptibility and surface roughness depend mainly on material composition and on the polishing procedures. Polishing improves the staining resistance of composite resins. Nanocomposite resins did not exhibit better staining resistance or surface roughness than microhybrid composite resin.

Photovoltaic properties of n-type SnS contact on the unpolished p-type Si surfaces with and without sulfide treatment

• The SnS/Si device with sulfide treatment for 40 s showed a good rectifying behavior. • Sulfide treatment led to reductions in an ideality factor and series resistance. • Sulfide treatment led to enhanced power conversion efficiency (PCE) of solar cells. • The enhanced PCE is due to the rectifying performance and interface passivation. • A suitable sulfide treatment time is also an important issue for enhancing PCE. The fabrication and detailed electrical properties of heterojunction diodes based on n-type SnS (n-SnS) and p-type Si (p-Si) were reported. The effect of sulfide treatment of p-Si on the power conversion efficiency (PCE) of the n-SnS/unpolished p-Si solar cell was investigated. The n-SnS/unpolished p-Si device without sulfide treatment showed a rectifying behavior with an ideality factor ( η ) of 1.6 and high series resistance ( R s ). However, the n-SnS/unpolished p-Si diode with sulfide treatment for 40 s showed a good rectifying behavior with η of 1.4 and low R s . Therefore, the enhanced PCE can be interpreted by the device rectifying performance and interface passivation. In addition, note that a suitable sulfide treatment time is an important issue for producing high-efficiency solar cells.

Measurement of Flat Samples With Rough Surfaces by Magnetic Adaptive Testing

Magnetic nondestructive tests of structural degradation of ferromagnetic construction materials must be often carried out on flat samples whose magnetic circuit is artificially closed by an attached soft magnetic yoke. Quality of magnetic contact between the sample surface and faces of the yoke has a strong influence on the measured signal, and especially with unpolished surfaces, it is difficult to be re- produced. The presented experiment suggests a partial solution of the problem via application of nonmagnetic spacers inserted between the sample and the yoke. The spacers distort and decrease the signal, but they also decrease fluctuation of the magnetic contact quality and smooth scatter of the measured data. As the goal of the nondestructive test is not absolute measurement of magnetic parameters of the material, but relative comparison of some convenient magnetic features, which relate to degradation of microstructure of the sample, application of the spacers proves to be not only acceptable, but it is very helpful.

Conceptual design of stacked-layer detectors to increase the sensitivity of Fast Neutron Gamma-ray Radiography (FNGR)

This study is focused on the structure and other possible factors related to scintillators used in the Fast Neutron and Gamma-ray Radiography (FNGR) system to increase its sensitivity. The CsI(Tl) crystal scintillator (Co-60 gamma-ray detection) and the BC430 plastic scintillator (14 MeV fast neutron detection) were analyzed with the Monte Carlo simulation (MCNPX and DETEC97 codes). Each scintillator was investigated with regard to the optimum thickness (1 cm × 1 cm), reconfiguration of detector modules (a stacked-layer structure), the optimum surface treatment, and the spectral matching with customized PIN-type photodiodes. As a result, the optimum thickness of the CsI(Tl) was found to be 4.5 cm; the optimum value was 5.5 cm for the BC430. When the detector modules were stacked in a sandwich structure rather than the existing single detector structure, the light photon transmission to the surface of the photodiode was enhanced by 40% and 58% for CsI(Tl) and BC430, respectively. In the matter of scintillator surface treatment, both scintillators were simulated with unpolished and polished condition before coating. The polished condition of the scintillator surfaces showed a higher performance, more than doubling that of the unpolished condition surfaces. Then, the performance improvement of the scintillator with the paint coating was compared to the scintillator with the metal coating conditions. For CsI(Tl), the metal coating showed a 10 % higher performance than that of the paint coating, and the metal coating of BC430 showed a 6% higher performance than that of the paint coating. As a result of spectral matching between the scintillators and the customized PIN-photodiodes, PS100-6b of Silicon AG, SD445-14-21-305 of API, and FSD1010-CAL of THOLABS were compared. The spectral matching factor of PS100-6b was 0.39 with CsI(Tl) and was 0.42 with BC430; the spectral matching factors of the other samples were relatively lower (SD445-14-21-305 with CsI(Tl): 0.29; SD445-14-21-305 with BC430: 0.33; FSD1010-CAL with CsI(Tl): 0.26; FSD1010-CAL with BC430: 0.29).

Ferromagnetism on the unpolished surfaces of single crystal metal oxide substrates

It is shown that a variety of single crystal substrates (Al2O3, LaAlO3, SrTiO3, TiO2, and ZnO), purchased from commercial suppliers, contain a ferromagnetic component to the magnetization in addition to the expected linear magnetic response. This ferromagnetic contribution is only observed on the unpolished surfaces and can be eliminated by either polishing or annealing at 600 °C in air, but not by annealing at 600 °C in a vacuum of 5 × 10−6 Torr. Particle induced x-ray emission spectra demonstrate that there is excess Fe on the unpolished surfaces of these single crystal substrates. While defect related ferromagnetic signals have been reported in some of these substrates, and while our results do not exclude this origin of ferromagnetism, we clearly show that the ferromagnetic signals observed in our samples are largely due to excess iron on the unpolished surfaces, possibly in the form of a mixture of Fe, Fe3O4, and or γ-Fe2O3.

Mechanical Study of Copper Bonded at Low Temperature Using Spark Plasma Sintering Process

Bonding of high purity polished copper was investigated using the Spark Plasma Sintering technique (SPS) showing the effect of SPS parameters (surface roughness, time, temperature and pressure) on the bonding strength behaviour. Mechanical characterization of the bonded samples was performed at room temperature using tensile test. Two surfaces roughnesses were studied (un-polished and polished samples). It was found that the bonding strength varied from 50 MPa to 233 MPa for un-polished and polished surfaces respectively The tensile strength of the used bulk copper-rod was found to be 365 MPa, while most results are over 122 MPa (a third of the bulk value).

Performances of 800 nm femtosecond laser ablation on natural and synthetic quartz

A commercial femtosecond laser system operating at its fundamental wavelength (λ = 800 nm, near Infra-Red) was used to ablate both synthetic and natural quartz on polished and unpolished surfaces. Ablation rates and maximum depths were determined using two distinct optical setups: a 25 mm focal length Cassegrain reflecting objective, and a 50 mm focal length convergent coated lens. All samples were ablated with the same laser beam at E = 1 mJ, τ = 60 fs, f = 5 Hz and N = 10–8000 shots. The depth of ablation craters obtained with the lens shows a linear increase with shot number N up to N = 2000 shots. Then the depth increases much less with N and reaches a plateau above N = 3000 shots. Maximum depth was close to 1300 μm for N = 3000 shots. Using the reflecting objective, ablation rate starts from 0.42 μm/shot and decreases rapidly to 0.02 μm/shot at a maximum depth of 350 μm for N =1500 shots. Ablation thresholds ( F th) were calculated for 1 and 10 consecutive shots with energy increasing from E = 0.1–2 mJ/pulse. Threshold values varies from F th=0.1 J.cm−2 (unpolished, 10 shots) to F th = 2.9 J.cm−2 (polished, single shot). The energy penetration of IR-femtosecond laser pulses in quartz has been calculated at l = 271 nm. The low absorption of IR wavelengths in quartz affects the ablation efficiency in the first shots. The associated non-linear effects are visible on a crater FIB foil observed with TEM as progressive high-pressure photomechanical damage developing under the ablation pit. The present study emphasizes the potential of IR-femtosecond laser for ablation of highly transparent material, and provides reliable data for LA-ICP-MS applications in earth sciences.

Current–voltage characteristics of AlCdO Schottky contact on the polished and unpolished p-type Si surfaces with and without light illumination

In this study, the current–voltage characteristics of the AlCdO/unpolished p-type Si and AlCdO/polished p-type Si Schottky diodes with and without light illumination were examined. It is found that the Schottky barrier height (the series resistance) of the AlCdO/unpolished p-type Si Schottky diode is higher (lower) than that of the AlCdO/polished p-type Si Schottky diode. The power conversion efficiency of the AlCdO/p-type Si devices in the light (AM 1.5 G, 100 mW/cm 2) was improved by increasing built-in potential at the AlCdO/p-type Si interfaces and reducing the device series resistance and surface reflectivity. It is shown that the device surface roughness plays an essential role in improving the device performance.