Increase In Roughness Values Research Articles

Electrochemical deposition of bilayer PPy/PPy-HA coating on AZ31 Mg alloy: Effect of HA content on characteristics and corrosion protection

This study aimed to examine the impact of naturally derived hydroxyapatite (HA) particles on the surface characteristics and corrosion behavior of polypyrrole (PPy)/polypyrrole-HA bilayer coatings. The coatings were applied onto AZ31 Mg alloy substrates using the potentiostatic electrodeposition method. Varying concentrations of HA particles (1, 3, and 5 wt%) were incorporated into the electrodeposition baths to create the top composite layers. Morphological analysis using FESEM revealed that the presence of HA particles led to PPy coatings with reduced porosity and more compact structures. EDS analysis and elemental mapping confirmed the presence of HA particles within the PPy matrix. AFM topography parameters indicated a slight increase in roughness values as the concentration of HA particles increased, with the average roughness rising from 46 nm for pure PPy coating to 53 nm for the coating with the highest HA content. Wettability results showed that the water contact angle (WCA) decreased from 56.6° for unreinforced PPy to 35.6° for the bilayer PPy/PPy-5 wt%HA coating. The corrosion behavior of the samples was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. It was observed that HA particles effectively reduced the corrosion current density (icorr), with the icorr of the optimal bilayer coating containing 3 wt% HA being 3.7 × 10−7 A cm−2, approximately two times lower than that of unreinforced PPy coating. Furthermore, the adhesion strength of the coatings was not affected by the inclusion of HA particles.

Roughness assessment of colored compomers: Results after an erosive-abrasive in vitro cycling test.

The present in vitro study aimed to evaluate and compare the surface roughness of a colored compomer and a composite resin, after 15 days of erosive-abrasive cycling. The sample included ninety circular specimens, randomly divided (n = 10): G1 Berry, G2 Gold, G3 Pink, G4 Lemon, G5 Blue, G6 Silver, G7 Orange and G8 Green, referring to the different colors of compomer (Twinky Star®, VOCO, Germany) and G9 for composite resin (Z250®, 3M ESPE). The specimens were submerged in artificial saliva and stored at 37°C for 24 hours. After polishing and finishing, the specimens were submitted to initial roughness (R1). Then, the specimens were submerged in an acidic cola-based drink for 1 minute and then exposed to electric toothbrushing for 2 minutes for 15 days. After this period, the final roughness (R2) and the ΔRa were performed. Data were submitted to ANOVA and Tukey's test for intergroup comparison and paired T-test for intragroup comparison (p<0.05). Among compomers, the green color presented the higher/lower initial and final roughness values (0.94 ± 0.44, 1.35 ± 0.55) with lemon color presenting the most prominent real roughness increase (ΔRa = 0,74) whereas composite resin showed the lower values (0,17 ± 0.06, 0,31 ± 0.15; ΔRa = 0,14). All compomers, after the erosive-abrasive challenge, presented an increase in roughness values when compared to composite resin with a highlight to green tones. Key words:Compomers, composite resins, surface properties.

Experimental investigation of pool boiling heat transfer performance of refrigerant R-134a on differently roughened copper surfaces

Pool boiling heat transfer of refrigerant R-134a at saturation temperature of 5 °C was investigated experimentally on copper. The effect of surface roughness was studied at various average roughness (Ra) values ranging from 0.130 to 0.274 µm. All experimental samples were vertically oriented, and experiments were carried out at varying heat flux ranges between 10 and 70 kW/m2. The investigations are carried out to calculate the boiling heat transfer coefficient (h), wall superheat (ΔT) and heat flux (q) for different roughness of heat transfer surfaces. The obtained results revealed that the Cu surface with Ra = 0.274 µm showed outstanding heat transfer performance compared to other Cu surfaces. The overall boiling performances enhanced with an increase in roughness value of the heat transfer surface owing to the increased number of cavities.

In-vitro evaluation of remineralization efficiency of chicken eggshell slurry on eroded deciduous enamel

OBJECTIVES: The present study evaluated the re-mineralizing efficiency of CESP on experimentally eroded deciduous tooth enamel by Claritin syrup. MATERIALS AND METHODS: 20 extracted deciduous teeth had been selected and stored in normal saline. Each tooth was cut in a labiolingual direction into 2 halves, one half used as a control and the other used as study. Demineralization of all specimens were done by twice daily immersion in Claritin syrup for ½ an hour for 12 days to form enamel erosion. Remineralization of the study group was done by using CESP slurry twice daily application for 3min. for 10 days. Surface roughness of the specimens was measured by surface profile gauge and microhardness evaluation was done using Vickers tester. Resulted data were tabulated and ana1yzed statistically by t-test with 5% significance 1evel RESULTS: There was statistically significant increase in roughness values after erosion with Claritin syrup (P<0.001). however, it was significantly decreased after remineralization (P=0.01). There was statistically significant decreased mean value of microhardness after erosion with Claritin syrup (P<0.001). however, it was significantly increased after remineralization (P=0.01). CONCLUSION: CESP slurry is a valuable topical treatment in deciduous teeth erosion since it decreased the roughness and increased the microhardness of the enamel surface in-vitro

Synergistic reinforcement of glass-ionomer dental cements with silanized glass fibres

ABSTRACT The purpose of this study is to evaluate the general function and properties of a new class of reinforced glass-ionomer cements (GICs). In this regard, GIC powders based on a molar composition of 4.5SiO2.3Al2O3.1.5P2O5.3CaO.2CaF2 were synthesised via a melt-quenching method. The cement reinforced with silanized fibers (CSFs) were made by adding silanized E-glass fibers to the glass powder, before mixing with FUJI II LC, and then cured. The CSFs achieved maximum values of mechanical properties and showed a lower increase in roughness value compare to the other tested groups. Additionally, the CSFs demonstrated acceptable biocompatibility to fibroblast cells. Reinforcing the GICs with silanized glass fibers could improve the mechanical properties and toughening behavior of the final products, making them a promising biomaterial for dental restorative applications.

Effect of Er:YAG laser irradiation on deciduous enamel roughness and bacterial adhesion: An in vitro study.

Laser irradiation has been proposed as a preventive method against dental caries since it is capable to inhibit enamel demineralization by reducing carbonate and modifying organic matter, yet it can produce significant morphological changes. The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on superficial roughness of deciduous dental enamel and bacterial adhesion. Fifty-four samples of deciduous enamel were divided into three groups (n = 18 each). G1_control (nonirradiated); G2_100 (7.5 J/cm2 ) and G3_100 (12.7 J/cm2 ) were irradiated with Er:YAG laser at 7.5 and 12.7 J/cm2 , respectively, under water irrigation. Surface roughness was measured before and after irradiation using a profilometer. Afterwards, six samples per group were used to measure bacterial growth by XTT cell viability assay. Adhered bacteria were observed using confocal laser scanning microscopy (CLSM) and a scanning electron microscopy (SEM). Paired t-, one-way analysis of variance (ANOVA), Kruskal-Wallis and pairwise Mann-Whitney U tests were performed to analyze statistical differences (p < .05). Before treatment, samples showed homogenous surface roughness, and after Er:YAG laser irradiation, the surfaces showed a significant increase in roughness values (p < .05). G3_100 (12.7 J/cm2 ) showed the highest amount of Streptococcus mutans adhered (p < .05). The increase in the roughness of the tooth enamel surfaces was proportional to the energy density used; the increase in surface roughness caused by laser irradiation did not augment the adhesion of Streptococcus sanguinis; only the use of the energy density of 12.7 J/cm2 favored significantly the adhesion of S. mutans.

Wear of Silicon Carbide Wheel During Grinding of Intermetallic Titanium Aluminide

An experimental investigation is reported on the wear of silicon carbide wheel and its influence on the wheel topography and grinding behaviour during the surface grinding of high performance intermetallic gamma titianium aluminide. The radial wear of the wheel was characterised by initial transient state followed by a steady state wear regime and finally a steel rise in wear rate. The initial transient region progressed up to a radial wear of 40 μm. The normal and tangential forces remained approximately constant up to about 25 μm wheel wear and subsequently progressively increased to a maximum at 60 μm wear. The specific energy began approximately at about u = 140 J/mm3 and started progressing beyond radial wear of 25 μm and increased up to 600 J/mm3 at wear of 60 μm. There was high initial roughness value with the fresh wheel with a progressive decrease with continued grinding. There was noticeable increase in roughness value after a radial wear of 60 μm. With the progress of wear there was presence of surface burns, chatter marks and cracking. The presence of blue oxide discoloration was observed during the visual inspection signifying the generation of reasonably high temperature.

Preparation of antifouling polyvinylpyrrolidone (PVP 40K) modified polyethersulfone (PES) ultrafiltration (UF) membrane for water purification

This study reports the fabrication of polyethersulfone (PES) membrane using the phase inversion method in the presence of polyvinylpyrrolidone (PVP, 40K) as pore-forming agent. The membranes were made from two PES concentration types, i.e. 16 and 18wt.%. The effect of high molecular weight PVP concentration (2–10%) was examined in order to obtain a membrane with good performance, i.e. high water flux and reasonable Bovine Serum Albumin (BSA, protein model solution) rejection. The optimised membranes were characterised by ATR-FTIR, AFM, SEM, contact angle and dead-end membrane filtration tests. It was found that PVP moieties have positive influence in the prepared PES membranes. SEM surface and cross-sectional images were used to observed morphological changes as PVP content was varied. The pore sizes increased with PVP content for membranes prepared from 16wt.% PES polymer, whereas at the higher PVP content in 18wt.% PES membrane, pore sizes tend to decrease or completely disappear. The CA decreased gradually for the 16wt.% PES with increasing PVP content whereas in the 18wt.% PES the CA decreased initially before tapering off or increasing slightly. The rejection of BSA solution by both neat PES and PVP-containing PES membrane was above 85%. AFM surface topography exhibited increase in roughness value with PVP content. FTIR/ATR spectra corroborated the functional composition of neat PES and PVP molecule dispersed on PES membrane backbone. The results attained confirmed the potential industrial application of PVP molecule to minimise fouling tendencies.

Effect of bleaching agents and whitening dentifrices on the surface roughness of human teeth enamel

Objective. The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 10% carbamide peroxide or 10% hydrogen peroxide bleaching agents at different times and also subjected to different superficial cleaning treatments. Materials and methods. One hundred and forty flat enamel samples were divided into 14 groups, Group 1–Group 14 (G1–G14). G1–G7 were treated with 10% carbamide peroxide and different dentifrices, G8–G14 were treated with 10% hydrogen peroxide and different dentifrices (G1 and G8: not brushed as control groups; G2 and G9: brushed with Ipana® toothpaste; G3 and G10: brushed with Clinomyn® toothpaste; G4 and G11: brushed with Moos Dent® toothpaste; G5 and G12: brushed with Signal® toothpaste; G6 and G13: brushed with Colgate® toothpaste; G7 and G14: brushed without dentifrice). A profilometer was used to measure average roughness values of the initial surface roughness and at each 7-day-interval. The bleaching was performed for 6 h a day and the surface cleaning treatment was performed 3-times a day, 2 min each time, for 4 weeks. The samples were stored in distilled water during the test period. Results. Statistical analysis revealed significant differences in surface roughness values over time for all groups except G1 and G8 (not brushed). The results of the surface roughness of all groups were nearly the same. Conclusions. The bleaching with 10% hydrogen peroxide and 10% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with abrasive dentifrices, a significant increase in roughness values was observed.

Enhancing the adhesive wear performance of polyetherimide composites through nano-particle treatment of the carbon fabric

Rare earth compound Ytterbium fluoride (YbF3) in nano-size (40–80 nm) was employed for surface treatment of carbon fabric (CF) to improve its wettability with polyetherimide matrix. Composites were developed based on untreated and surface-treated CF with three doses, 0.1, 0.3, and 0.5 wt%, of YbF3 in ethyl alcohol suspension. The composites were analyzed for interlaminar shear strength (ILSS). Improvement in ILSS was observed for treated fabric reinforced composites and it was maximum (61%) for 0.3 wt% dose of YbF3. The adhesive wear performance of composites was evaluated by sliding a pin of composite against mild steel disc under varying loads (200–600 N). The treated fabric composites exhibited lower coefficient of friction (μ) and higher wear resistance (W R). ILSS and W R showed good linear correlation. Both properties were highest for 0.3% YbF3 dosing. Increased roughness of fiber surface and adhesion of nano-particles on the fiber surface was observed in scanning electron microscopic (SEM) studies. SEM studies of worn surfaces of composites were performed to understand wear mechanisms. Atomic force microscopic studies indicated substantial increase in roughness value of CF.

Optimization of surface treatment to enhance fiber–matrix interface and performance of composites

Oxidation treatment with concentrated HNO3 was employed to the carbon fabric (CF) for various time intervals (30–180min) to observe the effect of treatment on two simultaneous processes involved viz. improvement in its adhesion with the matrix and reduction of fiber strength which in turn is responsible for change in the performance properties of composites. Seven composites with untreated and acid treated CF were developed based on the polyetherimide (PEI) matrix and evaluated for adhesive wear properties under various loads (200–600N) against mild steel disc. 90min treated CF composite indicated the best tribological properties and showed 30% reduction in specific wear rate (K0) and 23% in coefficient of friction (μ) respectively at 600N load. Treatment beyond this time proved detrimental for improvement in properties. Field emission scanning electron microscopy (FE-SEM) showed increase in roughness with treatment time, while atomic force microscopy (AFM) studies indicated substantial increase in roughness value. Scanning electron microscopy (SEM) of worn surfaces supported the wear mechanisms and improvement in adhesion between fiber and matrix.

Surface roughness resulting from wear of lithia-disilicate-based posterior crowns

The objective of this study was to determine the surface roughness that occurred as a result of wear of all-ceramic crowns after 2 years of intraoral service. The ceramic material used in this study was a lithia-disilicate-based all-ceramic core ceramic and a glass-phase veneer ceramic. Posterior bilayer crowns were made for 30 subjects, who were recalled annually. At each recall time, the quality of crowns and adjacent gingival tissues were examined for acceptability, and impressions were made for replica models. The occlusal contacts of each ceramic crown were identified and surface roughness ( R a) measurement was performed on the replica model using a contact profilometer. Mean surface roughness values were analyzed using a repeated measure ANOVA. The wear patterns of contact surfaces were also characterized using a scanning electron microscope. From 30 ceramic crowns, 12 premolars and 13 molars were used for surface roughness measurements. For molar crowns, the surface roughness ( R a) at baseline was 1.76 ± 0.43 μm and the roughness significantly increased after 1 year and 2 years ( p < 0.05). For premolar crowns, the increase in roughness values was significantly different only after 2 years from 1.49 ± 0.22 to 1.9 ± 0.44 μm ( p < 0.05). Roughening of ceramic surfaces was observed over the entire occlusal area, especially in the contact zones. Loss of superficial ceramic material as a result of microfracture was the reason for surface roughening. In conclusion, the surface roughness of ceramic crowns was significantly increased after 2 years. The increase in surface roughness indicated the degradation of the ceramic crown surfaces over time that resulted from the wear process.

Effect of selected mouthwashes on the surface roughness of resin modified glass-ionomer restorative materials

Objectives It is known that the use of mouthwashes and toothbrushing can affect some restorative dental materials. The purpose of this laboratory study was to investigate the effect of four commercially available mouthwashes on the surface roughness of a number of resin modified glass-ionomer restorative materials when used with and without tooth brushing. Methods Specimens of the restorative materials in the study (Vitremer, Compoglass and Dyract) were prepared. Half of the specimens were only exposed to a mouthwash (Plax, Macleans, Listerine, Corsodyl or deionised water as control). The remaining specimens were exposed to one of the mouthwashes in conjunction with tooth brushing. The initial surface roughness and the subsequent changes in surface roughness were assessed by scanning electron microscopy (SEM) and profilometry. The assessment times were: baseline, 4, 12 and 24 weeks. Results Initial SEM observations of the surface morphology of the specimens revealed a rougher surface for Vitremer in comparison to the other two materials. Assessments at increasing time intervals showed that specimens exposed to a mouthwash only appeared to become rougher. The appearance of specimens exposed to mouthwash and brushing seemed to become even rougher with increasing time. The results of the profilometric assessment showed that at 24 weeks, specimens exposed to mouthwash only, had an overall increase in the surface roughness values for all three materials investigated. The differences between groups allocated to different mouthwashes were not however statistically significant ( P > 0.05). Exposure to mouthwash and toothbrushing over the same time period resulted in an increase in roughness values in all groups. The differences between mouthwash groups were not statistically significant at this stage ( P > 0.05). Significance Exposure of the materials investigated to the mouthwashes included in the study had adverse effects on surface roughness. The adverse effects were more pronounced with tooth brushing.

In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing

The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra) values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.