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دسترسی آزاد مقاله
1 - Study of an argon dielectric barrier discharge reactor with atmospheric pressure for material treatment
Maryam Hosseinpour Akbar ZendehnamAbstractIn this study, effects of the variation in the dielectric barrier discharge’s (DBD) gap distance and the nature of dielectric layers which cover both of the reactor electrodes on the electron density, mass fraction of excited argon atoms across the discharge gap چکیده کاملAbstractIn this study, effects of the variation in the dielectric barrier discharge’s (DBD) gap distance and the nature of dielectric layers which cover both of the reactor electrodes on the electron density, mass fraction of excited argon atoms across the discharge gap, mean electron energy, ion and electron current density, and electron temperature are investigated at atmospheric pressure. In order to find the optimal reactor gap, the DBD’s average power consumption is studied. The achievements show that when the value of dielectric constant is increased from 7.6 to 10, discharge gap of 1 mm still demonstrates the maximum power consumption, which can be considered as the optimum discharge gap. To optimize the characteristics of one-dimensional modeling of DBD system for material treatment, various types of materials with different values of the permittivity [aluminum, glass (quartz) and silicon] are embedded in the discharge gap between the two electrodes. In this case, the reactor gap is changed from 0.5 mm to 2 mm, while the dielectric constant of the dielectric layers which cover both of the metallic electrodes is assumed to be 10. Compared to the other examined materials, our numerical results illustrate that the treated material with higher value of the relative permittivity (silicon) has greater influences on the variations in the electron density, argon ion density and also total plasma current density than in the values of excited argon atom density, mass fraction of excited argon atoms and also average power consumption. پرونده مقاله -
دسترسی آزاد مقاله
2 - Effect of Surface Treatment and Heat Treatment on the Microstructure and Mechanical Properties of Ti6Al4V Alloy Manufactured by Selective Laser Melting
Q Salim Shaher M Razazi Boroujeni S NosohiyanOne of the most attractive and widely used alloys in the industry and field of implants is titanium and titanium alloys, including Ti6Al4V. The outstanding properties and application of this with the attractive capabilities of additive manufacturing technology have incr چکیده کاملOne of the most attractive and widely used alloys in the industry and field of implants is titanium and titanium alloys, including Ti6Al4V. The outstanding properties and application of this with the attractive capabilities of additive manufacturing technology have increased the inclination towards additive manufacturing of titanium parts. In this research, the effect of surface treatment and heat treatment on the microstructure and mechanical properties of Ti6Al4V alloy manufactured by selective laser melting was investigated. For this purpose, Ti6Al4V alloy produced by selective laser melting was subjected to annealing heat treatment at 1050 degrees Celsius and surface treatment of surface ultrasonic mechanical stimulation. Then, the microstructure and phases of Ti6Al4V alloy, which included α and β phases, were investigated with optical microscopy and X-ray diffraction analysis. The mechanical properties of the samples were also checked by Vickers hardness, tensile and uniaxial compression tests. The results showed that annealing heat treatment and then aging decreases the strength properties but increases the flexibility and toughness. By performing surface treatment, the hardness of Ti6Al4V alloy increases. In general, it can be said that the desired properties of this alloy, produced by selective laser melting, can be obtained by performing suitable surface and thermal treatments. پرونده مقاله -
دسترسی آزاد مقاله
3 - Investigation of Dental Implant’s Titanium Surface Hydrophilicity Effect on Biocompatibility and Osseointegration
B Mohammadi A. G Dezfuli E Anbarzadeh A. A Malek AltejariWith the expansion of studies and research to recognize the mouth's biocompatibility properties, the components and types of implants have been examined in terms of different surfaces with respect to one another. The bone around the implant plays a crucial role in suppo چکیده کاملWith the expansion of studies and research to recognize the mouth's biocompatibility properties, the components and types of implants have been examined in terms of different surfaces with respect to one another. The bone around the implant plays a crucial role in supporting and maintaining the stability of the implant after implantation in the gums, and its gradual loss will reduce the biocompatibility and, ultimately, the strength of the bond between the implant fixture surface and the gingival bone. In this study, the 3A implant characteristics have been investigated from the perspective of hydrophilicity, biocompatibility, and osseointegration of this implant's surface. So that the viability of the noted fixture’s titanium surface, when the hydrophilicity has been established in it, should be examined with the time when it lacks the hydrophilicity. Finally, it was found that the adsorption rate of the implant’s titanium surface to the gingival bone decreased from about 8 weeks to about 4 weeks, when the implant surface was hydrophilic compared to the time it lacked this property. The results also show that with the increase of hydrophilicity in the implant surface treatment method, the improvement of surface treatment in the first 2 to 4 weeks after implant placement has grown and gained more speed. This result indicates an acceleration in the process of adaptation of the 3A implant’s titanium surface when it has biocompatibility. The SLActive surface treatment method's high success rate has led to a success rate of 96.8%. پرونده مقاله -
دسترسی آزاد مقاله
4 - A Review on Biocompatibility Characteristics of Dental Implant’s Titanium Surface Treatment Methods, Focusing on SLA and SLActive Procedures
Mohammadi B Anbarzadeh EThe implant's metal base is not considered a foreign body when placed inside the jawbone and is compatible with the patient's jaw environment. This is due to its non-magnetic properties and high resistance to oxygen, acidic compounds, and salt. The implant’s struc چکیده کاملThe implant's metal base is not considered a foreign body when placed inside the jawbone and is compatible with the patient's jaw environment. This is due to its non-magnetic properties and high resistance to oxygen, acidic compounds, and salt. The implant’s structure and the surface will also affect the interaction between the metal and living tissues. One of the main reasons for the implant’s surface changes is the reduction of coalescing time and their integration with the jawbone. Since strong bone formation is crucial in dental implants treatment, with this operation, the bone formation in the pores of the fixture is done better, and the fixture fuses more to the bone. Implant surface coating increases bone deposition on the implant, which includes: mechanical changes (machining or sandblasting), chemical changes (acid pickling), electrochemical changes (anodic oxidation), vacuum changes, and heat or laser treatments. These changes control the growth and metabolic activities of bone cells. In this study, a review of various implant treatment methods, including sandblasting (SLA) and sandblasting with acid washing (SLActive), has been performed. Finally, it was concluded that SLA, SLActive, and HA surface treatment methods bind to the patient's jawbone faster than other methods in post-surgery weeks. In the meantime, the adsorption rate of the implant to the bone in the SLActive process compared to the SLA method increases by about 20 to 22% in the period of two to eight weeks after surgery, which is due to the integration speed of this method. پرونده مقاله -
دسترسی آزاد مقاله
5 - CORROSION BEHAVIOR OF BIOACTIVATED TITANIUM DENTAL IMPLANT USING DIFFERENT CHEMICAL METHODS
Mohammad Khodaei Ehsan Khoda Bande Dastjerdi Hamid Nazemi Alireza Valanezhad Ikuya WatanabeAt the past, damaged tissue was removed from the body of patients. But now tissue regeneration using scaffolds and implants are used to repair the damaged tissue and organs. Besides of the mechanical properties of metallic biomaterials, they suffer from bioinertness. Us چکیده کاملAt the past, damaged tissue was removed from the body of patients. But now tissue regeneration using scaffolds and implants are used to repair the damaged tissue and organs. Besides of the mechanical properties of metallic biomaterials, they suffer from bioinertness. Using some surface treatment techniques, the bioactivity and also corrosion resistance of titanium implants could be improved. In this study the effect of H2O2 and alkali treatments on the corrosion behavior of titanium implant in the artificial saliva, surface morphology and phases formed on the surface, were investigated using electrochemical corrosion test, scanning electron microscopy (SEM) and thin film x-ray diffractometery (TF-XRD) respectively. Results indicated that on the surface of H2O2 and alkali treated titanium samples, fine particles of anatase and fine wire of rutile was formed respectively. The results indicated that the corrosion resistance of alkali treated titanium in the artificial saliva was higher than H2O2 treated titanium sample. The corrosion current density for untreated, H2O2 and alkali treated titanium samples were about 0.6×10-8, 5×10-8, 3×10-8 A/cm2respectively. پرونده مقاله -
دسترسی آزاد مقاله
6 - Mechanical Characterization of Hemp Cotton Hybrid Composites: Effect of Surface Treatment
Hiral Parikh Shrey PatelOver a past few decade there have been extensive research noted on fiber reinforce polymer matrix composites, moreover in recent years there has been remarkable study on natural fiber polymer matrix composites due to its capability to sustain against the synthetic fiber چکیده کاملOver a past few decade there have been extensive research noted on fiber reinforce polymer matrix composites, moreover in recent years there has been remarkable study on natural fiber polymer matrix composites due to its capability to sustain against the synthetic fibers and conventional materials. This helps in achieving more desirable material properties for an existing application. In line with this in the present study the composite with the treated and untreated hemp – cotton hybrid mat and epoxy resin prepared with hand layup compression moulding technique. The prepared composites were tested for the tensile strength, flexural strength, impact strength and hardness using American society of testing and materials (ASTM) standards. The test results reveals that the treated fiber composites exhibits significant increase in the tensile strength and hardness while there was a reduction in flexural strength. The focus of the study was to compare the mechanical properties of these composites with the various materials to identify which materials could completely or partially replaced. پرونده مقاله -
دسترسی آزاد مقاله
7 - Effect of Fluoride Coating on the Degradation of Mg-Based Alloy Containing Calcium for Biomedical Applications
Abouzar Rezaei-Baravati Masoud Kasiri-Asgarani Hamid Reza Bakhsheshi-Rad Mahdi Omidi Ebrahim KaramianThe effect of hydrofluoric acid (HF) treatment on the corrosion performance of the Mg–Zn–Al–0.5Ca alloy was studied by immersing a specimen in HF solutions for varying lengths of time at room temperature. X-ray diffraction (XRD), scanning electron micr چکیده کاملThe effect of hydrofluoric acid (HF) treatment on the corrosion performance of the Mg–Zn–Al–0.5Ca alloy was studied by immersing a specimen in HF solutions for varying lengths of time at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the evolution of microstructures. In vitro corrosion resistance was assessed using potentiodynamic polarization and a room-temperature immersion test in Kokubo solution. The fluoride-treated Mg–Zn–Al–0.5Ca alloy formed by 24h immersion in HF exhibited a more homogeneous, compact, and thicker (2.1 μm) coating layer compared to the other HF treated specimens in 6, 12 and 18 hours. The corrosion resistance performance of the Mg–Zn–Al–0.5Ca alloy formed by 24h immersion in HF was the best, with a corrosion rate of 2.87 mm/y according to the electrochemical experiment. The mean weight loss of the untreated samples was more considerably higher (up to 2 times) than that of the fluoride-treated alloys, according to in vitro degradation assessments. According to the findings because of its low degradation kinetics and apatite formation ability, the fluoride-treated Mg–Zn–Al–0.5Ca alloy is a promising candidate for biodegradable implants. پرونده مقاله
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