Evaluation Of Surface Characteristics Research Articles

Evaluation of Surface Characteristics with Pre-treatment Polishing Process in Pulsed Laser Polishing AISI 4140 Mold Steel

Evaluation of Surface Characteristics with Pre-treatment Polishing Process in Pulsed Laser Polishing AISI 4140 Mold Steel

Evaluation of Surface Characteristics and Weight Variation of Different Composite Resins after Simulated Toothbrushing

Abstract Objective: To evaluate the surface characteristics of restorations performed after simulated toothbrushing and to compare the results between the composites. Materials and Methods: In total, 80 samples were made (7 mm × 4 mm) from the composites: Bulk Fill One, Bulk Fill Flow, Z350 XT, and Z350 XT flow (3M/ESPE, St. Paul, MN, USA). Half of the specimens was submitted to 60,000 cycles of simulated toothbrushing, while the other half was the control group (n = 10). The surface was evaluated through Scanning electronic microscopy (SEM), surface roughness (Ra), and weight loss, before and after the simulated toothbrushing. To evaluate the statistical analysis, a two-factors variance test and the Tukey's posttest were performed. Results: In the analysis performed by SEM, it was observed the presence of both small and medium protruding particles in all groups after simulated toothbrushing, with the exception of the group which used Z350 flow composite. All materials presented increasing on Ra after simulated toothbrushing. Regarding weight variation, there was not any significant statistical difference in all materials. Conclusions: The abrasive process occasioned by toothbrushing leads to changes on the particles' disposition, which causes changes on the surface and increase on the Ra. On the other hand, there was not any difference regarding to weight variation.

Evaluation of Surface Characteristics and Cytotoxicity of Dental Composites

The purpose of this study was to evaluate the surface and in vitro cytotoxicity on human dysplastic oral keratinocytes (DOK) of four commercial resins-based dental composites commonly used in prosthodontics dental therapies: two indirect composites for crown and bridges—SR Adoro (IvoclarVivadent GmbH) and Solidex (Shofu Dental GmbH); and two dual-curing luting resin cements—RelyxUnicem (3M ESPE Dental Products) and Variolink Esthetic DC (IvoclarVivadentGmbH). A complex assessment of surface characteristics of the four materials was conducted before and after the exposure to artificial saliva through various analyses, such as Scanning Electron Microscopy, Atomic Force Microscopy and Cross Polarized Light Microscopy (PLM). The results showed that DOK viability was not severely affected by exposure to any of these materials; however, Variolink expressed higher values but still above the toxicity level of the rest of the composites. The analysis of the surface structure between initial and artificial saliva exposed specimens returned a compact aspect in both categories and although Variolink and Relyx were subjected to increased roughness after saliva exposure, no damage of the internal compactness was recorded, demonstrating a fair behavior of the luting cements in contact with the saliva.

Evaluation of Surface Characteristics and Hemocompatibility on the Oxygen Plasma-Modified Biomedical Titanium

Oxygen plasma with different treatment powers and durations was utilized to modify the biomedical pure titanium (Ti) surface in the present study. The superficial, microstructural and biological properties of the plasma-oxidized samples were investigated using the electron microscopy, X-ray photoemission spectroscopy, grazing incidence X-ray diffractometer, contact angle goniometer and blood clotting time assay. During different treatment powers and durations, the island-like nanostructural rutile-TiO2 layer and dimple-like nanostructural rutile-TiO2 layer were generated on the surfaces of the plasma-oxidized samples, respectively. It was also found that the plasma-oxidized sample with a rough oxide layer resulted in the formation of a higher wettability. Moreover, the blood clotting time assay indicated that the plasma-oxidized samples exhibited the adhesion behaviors of red blood cells. As the Ti surface underwent plasma oxidation at 280 W for 30 min, it not only generates a rough nanostructural rutile-TiO2 layer, but also presents an excellent hemocompatibility. Therefore, these findings demonstrate that oxygen plasma modification is a potential approach to promote the hemocompatibility of biomedical pure Ti surface.

Evaluation of Surface Characteristics and Physical Properties on Biodegradable Magnesium-Calcium Alloys by Anodic Oxidation

of calcium (Ca) on the surface characteristics and physical properties of magnesium-calcium alloys after anodization. A novel binary alloy Mg-xCa (in which x = 0:5, 1, or 5 wt.%) was cast by combining magnesium (99.9%) and calcium (99.9%) in an argon gas (99.99%) atmosphere. A magnesium alloy rod having a diameter of 15 mm was cut into discs, each 2 mm thick. The specimens were subjected to anodic oxidation at 120 V for 15 minutes at room temperature in an electrolyte solution consisting of calcium gluconate, sodium hexametaphosphate, and sodium hydroxide. Surface and cross-sectional morphological changes were observed using scanning electron microscopy, and the microstructures and phases were detected by means of X-ray diraction. Hardness and surface roughness were assessed by means of a Vickers hardness tester and a surface roughness meter, respectively. The results show that the physical properties of these magnesiumcalcium alloys have been improved, because it was possible to control the dissolution rate according to the amount of calcium added. DOI: 10.12693/APhysPolA.129.736 PACS/topics: 87.85.jj, 87.85.jc

Surface medication of Ti–15Mo alloy by thermal oxidation: Evaluation of surface characteristics and corrosion resistance in Ringer's solution

Ti–15Mo alloy has received considerable attention for biomedical applications (currently listed by ASTM) due to its non-toxic nature, good mechanical properties and better corrosion resistance. Thermal oxidation is an effective method to form a thicker oxide layer on Ti and its alloys. In the present study, thermal oxidation of Ti–15Mo alloy is explored for the first time. The objective of the study is to ascertain the surface, structural and morphological characteristics of Ti–15Mo alloy subjected to thermal oxidation at different temperatures (500, 650 and 800°C), for various periods of time (8, 16, 24 and 48h). It is also aimed at to evaluate their corrosion behavior in Ringer's solution in order to assess their suitability for biomedical applications. Thermal oxidation increased the average surface roughness (Ra) and microhardness, while decreasing the water contact angle of the Ti–15Mo alloy. The phase contents of the oxide layer show a strong dependence on treatment conditions with a predominance of the rutile phase over the anatase phase at temperatures >650°C and for time periods >16h. A more positive Ecorr and a lower ipass are observed for the thermally oxidized Ti–15Mo alloys when compared with the untreated alloy. For the experimental conditions employed in the present study, it is clear that Ti–15Mo alloy subjected to thermal oxidation at 650°C for 8–48h offers a better corrosion resistance than those treated at 800°C for 8h.

Contemporary Dental Polymer Nanocomposites Light-Cured Under Polyester Strip: Evaluation of Surface Characteristics Using SEM and AFM

The aim of this investigation was the evaluation of both the morphology/surface roughness and the texture/phase distribution of four contemporary dental light-cured nanocomposites using scanning electron microscopy and atomic force microscopy. The materials evaluated were a nanofill composite and three nanohybrids. Scanning electron microscopy coupled with EDS analysis was able to see and identify the large filler particles of the materials. Atomic force microscopy in the tapping mode provided topography of the nanocomposites while the tapping mode coupled with phase imaging information on the surface texture. The differences observed are attributed to differences in the shape, size distribution, amount, and surface coverage of filler particles.

Evaluation of Surface Characteristics and Shear Bond Strength of Metal Brackets Bonded to Two Different Porcelain Systems (Feldspathic/IPS-Empress-2) treated with Different Surface Conditioning Methods

Evaluation of Surface Characteristics and Shear Bond Strength of Metal Brackets Bonded to Two Different Porcelain Systems (Feldspathic/IPS-Empress-2) treated with Different Surface Conditioning Methods

Evaluation of Surface Characteristics and Shear Bond Strength of Metal Brackets Bonded to Two Different Porcelain Systems (Feldspathic/IPS-Empress-2) treated with Different Surface Conditioning Methods

Objective: To evaluate the surface roughness of the ceramic samples subsequent to various surface conditioning methods using scanning electron microscopy (SEM) and to find out the best surface conditioning methods in feldspathic and IPS-Empress-2. Materials and methods: A total of 120 disk samples were prepared for the present study. Samples were divided into namely Group A: Feldspathic (60) and Group B IPS-Empress 2 (60). They were further subdivided into six groups each containing nine samples each based on different surface conditioning. After each surface conditioning method, the surface roughness of one sample from the surface conditioning groups and the control group were subjected to SEM for determining the surface roughness in the two groups. These samples were not used for the shear bond test because the measurements destroyed the surfaces. Results: The shear bond strength of metal brackets bonded to feldspathic ceramic surface when sandblasting with aluminum oxide yielded the highest (14.64 ± 2.14 MPa) and least among the control groups (0 MPa). The shear bond strength of metal brackets bonded to IPS-Empress-2 ceramic surface when sandblasting with aluminum oxide with silane yielded the highest (10.19 ± 0.56 MPa) and least among the control groups (0 MPa). Conclusion: Surface conditioning with Co-Jet sand which produced silicatization resulted in a favorable bond strength in both feldspathic and IPS-Empress-2 ceramic surfaces. It was shown that it produced the least surface roughness among all the other surface conditioning groups.

Evaluation of surface characteristics of inner layer fabrics suitable for structural firefighters’ clothing

Effective firefighters’ clothing design requires great consideration of physiological comfort factors including sensorial or tactile comfort. The friction between the fabric surface and the skin, and the fabric surface roughness are the two important components in the evaluation of the sensorial comfort of fabrics and materials. The objective of this study is to investigate and compare the material surface characteristics of fabrics suitable for the inner layer of structural clothing for firefighters. We quantitatively examine and evaluate the effects of the fabrics’ composition, construction and their physical parameters on the surface characteristics, as relevant to the practical wear and maintenance of the garments. In addition, the influence of the presence of moisture in the fabrics due to the sweat absorption during strenuous physical activity on the fabrics surface characteristics is addressed.

Evaluation of surface characteristics under fretting of electrical contacts: Removal behaviour of hot dipped tin coating

The fretting corrosion behaviour of hot dipped tin coating is investigated at low fretting cycles at ±25 μm displacement amplitude, 0.5N normal load, 3 Hz frequency, 45–50% relative humidity, and 25 ± 1 °C temperature. The typical characteristics of the change in contact resistance with fretting cycles are explained. The fretted surface is examined using laser scanning microscope, scanning electron microscope and energy dispersive X-ray analysis to assess the surface profile, extent of fretting damage, extent of oxidation and elemental distribution across the contact zone. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behaviour of tin coating. The variation of contact resistance clearly revealed the fretting of tin coating from 50 to 1200 cycles and the fretting of the substrate above 1200 cycles. The observed low and stable contact resistance region and the fluctuating resistance region at various fretting cycles are explained and substantiated with Scanning electron microscopy (SEM), laser scanning microscope (LSM) and energy dispersive analysis of X-rays (EDAX) analysis results of the fretted surface.

Fretting corrosion of tin-plated contacts: Evaluation of surface characteristics

The surface characteristics of the contact zone of tin-plated copper alloy contacts subjected to fretting motion for 8000, 16,800 and 48,000 cycles under unlubricated conditions are presented. The nature of the contact zone, at the verge of wearing out of the tin coating as well as upon the coating is completely worn out, is assessed using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and X-ray dot mapping, and the influence of these changes on the contact resistance is correlated. The study reveals that under unlubricated conditions, fretting caused significant damage at the contact zone. Occurrence of adhesive wear failure is observed at early stages whereas at latter stages, delamination wear is the predominant mode of failure. As the fretting cycle increases, the concentration of copper increases whereas the concentration of tin decreases; oxygen concentration though not appreciable at the early stages, starts to build with increase in fretting cycles, attributing to the increase in contact resistance due to the formation of oxides of copper and tin at the contact zone.

Evaluation of Surface Characteristics of ZnS and Zn2SiO4 Powders by SFM

Evaluation of Surface Characteristics of ZnS and Zn2SiO4 Powders by SFM