Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000463
Merabet N, R. Rabah, Abdiche A
In this present work, we perform first-principles calculations of the structural, electronic, mechanical and mechanical properties of Cobalt sub-hydrides (Co2H and Co3H) based on the density functional theory with local spin density (LSDA), and generalized gradient (GGA) approximations. The optimized structural parameters, densities of states, elastic constants (Cij) and mechanical properties (Young’s modulus Y, Shear modulus G, Poisson’s ratio ν) were obtained for the first time and analyzed. Our calculation shows that the insertion of hydrogen in low-concentration into cobalt leads to the expansion of unit cell volume and the bulk modulus as a function of this concentration. A resulting strong reduction of magnetization characterizes these subs-hydrides.
{"title":"First-Principle Calculation of Structural, Mechanical, Electronic and Magnetic Properties of Cobalt Sub Hydrides Co2H and Co3H","authors":"Merabet N, R. Rabah, Abdiche A","doi":"10.4172/2169-0022.1000463","DOIUrl":"https://doi.org/10.4172/2169-0022.1000463","url":null,"abstract":"In this present work, we perform first-principles calculations of the structural, electronic, mechanical and mechanical properties of Cobalt sub-hydrides (Co2H and Co3H) based on the density functional theory with local spin density (LSDA), and generalized gradient (GGA) approximations. The optimized structural parameters, densities of states, elastic constants (Cij) and mechanical properties (Young’s modulus Y, Shear modulus G, Poisson’s ratio ν) were obtained for the first time and analyzed. Our calculation shows that the insertion of hydrogen in low-concentration into cobalt leads to the expansion of unit cell volume and the bulk modulus as a function of this concentration. A resulting strong reduction of magnetization characterizes these subs-hydrides.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"87 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88867712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000472
Suoware To, Edelugo So
Various oil palm fibre reinforced polyester composite (OPFPC) panels has been fabricated with different FR formulations at increasing percentage loading using hand lay-up compression moulding technique. The effects of aluminium hydroxide (ATH), ammonium polyphosphate (APP), their hybridization and synergism with carbon black (CB) on the mechanical and thermal properties have been investigated. The results obtained showed that 12% ATH inclusion in the OPFC enhanced the tensile strength (TS), tensile modulus (TM) and flexural strength (FS) relative to 0%OPFC panel by 16.2%, 5.9% and 71.2%, respectively. The inclusion of 15%APP-GAP/CB decreased in TS and FS by 18.8% and 20.8% respectively while 18%ATH/APP-GAP/CB hybrid formulation decreased the most by 28.1% in TM showing poor performance in the presence of CB. TGA results reveals that the inclusion of 12%ATH and 15%APP-GAP/CB improved the thermal degradation relative to the 0%OPFC by 5.1°C and 20.48°C respectively while other FR formulations exhibited a decrease. Char residue at 900°C which signifies the end of the test increased significantly for all the FR formulations with 15%APP-GAP/CB observed as the highest at 17.47% and 12%APP-GAP as the least at 10.53%. The inclusion of 12%ATH in the OPFC panel suggest a better mechanical and thermal stability while the inclusion of 15%APP-GAP/CB suggest a better flame retardancy owing to the highest char formation.
各种油棕纤维增强聚酯复合材料(OPFPC)板已制造不同的FR配方在增加百分比的负载使用手工铺层压缩成型技术。研究了氢氧化铝(ATH)、聚磷酸铵(APP)及其与炭黑(CB)的杂化和增效作用对复合材料力学性能和热性能的影响。结果表明，与0%OPFC相比，12% ATH包埋OPFC的拉伸强度(TS)、拉伸模量(TM)和抗弯强度(FS)分别提高了16.2%、5.9%和71.2%。15%APP-GAP/CB在TS和FS中分别下降18.8%和20.8%，而18%ATH/APP-GAP/CB混合配方在TM中下降最多，下降28.1%，表明在CB存在下表现不佳。TGA结果表明，相对于0%的opfc，加入12%的ath和15%的app - gap /CB的热降解率分别提高了5.1℃和20.48℃，而其他FR配方的热降解率则有所下降。在900°C时，所有FR配方的焦渣残留量显著增加，其中15%APP-GAP/CB最高，为17.47%，12%APP-GAP最低，为10.53%。在OPFC面板中包含12%的ath表明有更好的机械和热稳定性，而包含15%的app - gap /CB由于最高的炭形成而表明有更好的阻燃性。
{"title":"Fabrication of Oil Palm Fibre Polymer Composite Panel: Impact of Hybridized Flame Retardant Formulations on Thermo-Mechanical Properties","authors":"Suoware To, Edelugo So","doi":"10.4172/2169-0022.1000472","DOIUrl":"https://doi.org/10.4172/2169-0022.1000472","url":null,"abstract":"Various oil palm fibre reinforced polyester composite (OPFPC) panels has been fabricated with different FR formulations at increasing percentage loading using hand lay-up compression moulding technique. The effects of aluminium hydroxide (ATH), ammonium polyphosphate (APP), their hybridization and synergism with carbon black (CB) on the mechanical and thermal properties have been investigated. The results obtained showed that 12% ATH inclusion in the OPFC enhanced the tensile strength (TS), tensile modulus (TM) and flexural strength (FS) relative to 0%OPFC panel by 16.2%, 5.9% and 71.2%, respectively. The inclusion of 15%APP-GAP/CB decreased in TS and FS by 18.8% and 20.8% respectively while 18%ATH/APP-GAP/CB hybrid formulation decreased the most by 28.1% in TM showing poor performance in the presence of CB. TGA results reveals that the inclusion of 12%ATH and 15%APP-GAP/CB improved the thermal degradation relative to the 0%OPFC by 5.1°C and 20.48°C respectively while other FR formulations exhibited a decrease. Char residue at 900°C which signifies the end of the test increased significantly for all the FR formulations with 15%APP-GAP/CB observed as the highest at 17.47% and 12%APP-GAP as the least at 10.53%. The inclusion of 12%ATH in the OPFC panel suggest a better mechanical and thermal stability while the inclusion of 15%APP-GAP/CB suggest a better flame retardancy owing to the highest char formation.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"43 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84548437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000444
Melilli G, Gorse D, G. A., Oral O, Balanzat E, D. O., T. M., Bechelany M, Lairez D, Wegrowe Je, M. Clochard
Poly(vinylidene fluoride) (PVDF) composites have recently emerged as excellent candidates to fabricate flexible and small piezoelectric generators for portable devices. Among various techniques used to nanostructure polarized PVDF, the track-etching represents a new route for manufacturing nanostructured composite thin films. The moderate influence of irradiation on the piezoelectric response of polarized PVDF makes possible the use of this technique. In this way, a nanostructured composite based on polarized thin PVDF films comprising embedded nickel nanowires (Ni NWs) was fabricated. The nanostructured PVDF/Ni NWs composites were tested under bending conditions using a homemade pressure cell. Due to the presence of NWs, an increase of five-fold the initial dielectric permittivity, in the low-frequency range, was observed. It suggested the presence of an interfacial polarization at the PVDF/Ni interface. With respect to the etched PVDF, the nanostructured PVDF/Ni NWs composites exhibited a non-negligible enhancement by 2.5 times the piezoelectric efficiency. This result was attributed to the increased Au/Ni NWs electrode surface.
{"title":"Enhanced Piezoelectric Response in Nanostructured Ni/PVDF Films","authors":"Melilli G, Gorse D, G. A., Oral O, Balanzat E, D. O., T. M., Bechelany M, Lairez D, Wegrowe Je, M. Clochard","doi":"10.4172/2169-0022.1000444","DOIUrl":"https://doi.org/10.4172/2169-0022.1000444","url":null,"abstract":"Poly(vinylidene fluoride) (PVDF) composites have recently emerged as excellent candidates to fabricate flexible and small piezoelectric generators for portable devices. Among various techniques used to nanostructure polarized PVDF, the track-etching represents a new route for manufacturing nanostructured composite thin films. The moderate influence of irradiation on the piezoelectric response of polarized PVDF makes possible the use of this technique. In this way, a nanostructured composite based on polarized thin PVDF films comprising embedded nickel nanowires (Ni NWs) was fabricated. The nanostructured PVDF/Ni NWs composites were tested under bending conditions using a homemade pressure cell. Due to the presence of NWs, an increase of five-fold the initial dielectric permittivity, in the low-frequency range, was observed. It suggested the presence of an interfacial polarization at the PVDF/Ni interface. With respect to the etched PVDF, the nanostructured PVDF/Ni NWs composites exhibited a non-negligible enhancement by 2.5 times the piezoelectric efficiency. This result was attributed to the increased Au/Ni NWs electrode surface.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"28 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79662939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000431
S. Fashu
Metal casting is the mother of Zimbabwean industries since their performance is mainly hinged upon cast components. An overview of the Zimbabwean foundry industry showing its state of the art including annual production, number of employees, technology, material, quality and diversity of castings, and common markets is presented. The Zimbabwean foundries were then compared with global leading countries in performance. Challenges faced by the Zimbabwean foundries were identified and potential development strategies were suggested.
{"title":"Foundry Industry of Zimbabwe - The Present and Future","authors":"S. Fashu","doi":"10.4172/2169-0022.1000431","DOIUrl":"https://doi.org/10.4172/2169-0022.1000431","url":null,"abstract":"Metal casting is the mother of Zimbabwean industries since their performance is mainly hinged upon cast components. An overview of the Zimbabwean foundry industry showing its state of the art including annual production, number of employees, technology, material, quality and diversity of castings, and common markets is presented. The Zimbabwean foundries were then compared with global leading countries in performance. Challenges faced by the Zimbabwean foundries were identified and potential development strategies were suggested.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"31 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72732119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000410
Charaf Lazrak, B. Kabouchi, M. Hammi, A. Famiri, Naseem Abbas
In this paper, we have investigated the stability, mechanical properties, and the microstructure of wood–plastic composites, which were fabricated using recycled high-density polyethylene (HDPE) with pine wood flour used as fillers. Composite panels were obtained using hot-press molding. The tensile and flexural properties of the composites based on recycled HDPE revealed the strength properties of the composites can be improved by increasing the polymer content, also the composite formulation significantly improved the morphology and the stability. Scanning Electron Microscope (SEM) was used to characterize the morphology of the wood particulate/HDPE interface. It was clearly proved from the results that wood-plastic composite (WPC) based on recycled high density polyethylene (HDPE) can be successfully utilized to fabricate stable and strong WPCs.
{"title":"Physico-Mechanical Behavior and Recovery of Wood-Plastic Composite (WPC) Based on Recycled High Density Polyethylene (HDPE)","authors":"Charaf Lazrak, B. Kabouchi, M. Hammi, A. Famiri, Naseem Abbas","doi":"10.4172/2169-0022.1000410","DOIUrl":"https://doi.org/10.4172/2169-0022.1000410","url":null,"abstract":"In this paper, we have investigated the stability, mechanical properties, and the microstructure of wood–plastic composites, which were fabricated using recycled high-density polyethylene (HDPE) with pine wood flour used as fillers. Composite panels were obtained using hot-press molding. The tensile and flexural properties of the composites based on recycled HDPE revealed the strength properties of the composites can be improved by increasing the polymer content, also the composite formulation significantly improved the morphology and the stability. Scanning Electron Microscope (SEM) was used to characterize the morphology of the wood particulate/HDPE interface. It was clearly proved from the results that wood-plastic composite (WPC) based on recycled high density polyethylene (HDPE) can be successfully utilized to fabricate stable and strong WPCs.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"98 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77917298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000443
S. Kouidri
Based on the full-potential linearized augmented plane waves method (FL-LAPW) with local density approximation (LDA), the partials and totals densities of state of Tl3SbS3 and SbT eI are calculated in order to find the semiconductor character via direct or indirect gap. Tl3SbS3 and SbTeI present the most important candidates of the antimony chalcogenides family. Their densities of states curves bring out characteristic features in the valence band a core like peak, at environ 13.00 eV below the valence band maximum, originating mainly from S 3s and I 5s states respectively, and a three-peak structure at the top of the valence band from S 3p and I 5p states hybridized with Sb 5p and Te 5p states. Our results give a good agreement with other theoretical calculations and experimental data.
{"title":"Density of State Calculations for Tl3SbS3 and SbTeI","authors":"S. Kouidri","doi":"10.4172/2169-0022.1000443","DOIUrl":"https://doi.org/10.4172/2169-0022.1000443","url":null,"abstract":"Based on the full-potential linearized augmented plane waves method (FL-LAPW) with local density approximation (LDA), the partials and totals densities of state of Tl3SbS3 and SbT eI are calculated in order to find the semiconductor character via direct or indirect gap. Tl3SbS3 and SbTeI present the most important candidates of the antimony chalcogenides family. Their densities of states curves bring out characteristic features in the valence band a core like peak, at environ 13.00 eV below the valence band maximum, originating mainly from S 3s and I 5s states respectively, and a three-peak structure at the top of the valence band from S 3p and I 5p states hybridized with Sb 5p and Te 5p states. Our results give a good agreement with other theoretical calculations and experimental data.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"102 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78067515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000462
Aouad Razika, A. Idriss
The stability of a cutting process directly influences the quality of a final surface. The control of the cutting process is an important problem for machining technology. Instabilities usually manifest as harmful chatter vibrations generated during cutting. Modal testing is a form of vibration testing which is able to determine the Frequency Response Function (FRF) of the mechanical test structures. In this context, we realized a study of vibration and of deformation between a tool without defect and a tool with two cases of defects. These defects have a random shape (any form), and the contact length tool-work piece, is considered the length of defects Lc=1 mm and the height of wear has been studied for two cases: VB=0.1 and 0.2 mm. In this paper, the main focus is creating a predictive model based on vibrations of body mass. The body mass mean the amount of material that constituting the cutting tool. The loss of a part of this mass makes the tool lighter; it increases the vibration of the tool. In addition to that, the Finite Element Method (FEM) modal analysis was used to obtain the natural frequencies. In this analysis we use ANSYS software based on (FEM), it is known for its high performance, quality and ability to solve all kinds of challenging simulations. The main idea is to create defects (wear) on the flank surface in order to create a model prediction. After the creation of defects, we start the modal analysis to study the deformation and the frequency of the tool. The results indicate that the frequency response and harmonic response analysis simulated by ANSYS with various defects created. First analysis is frequency response; we find the natural frequencies vary depending on the defect. When the tool is not defective we find the natural frequencies equal 337.77 Hz but in a tool with defects (VB=0.1-0.2 and 0.3 mm) we find the natural frequencies equal 340.36 Hz, 340.69 Hz and 341.11 Hz, this shows that the quality of the surface of the defect and its shape have an impact on the vibration of the tool. Then we based on a mathematical model to compare the results of the FEM where it shows a satisfactory correlation. In addition, the results of second analysis indicate that the deformation simulation by ANSYS with varying defects created. It increases with these defects: when VB=0.1 mm, we find that the maximum normal elastic deformation equal 0.16344 mm/mm and for VB=0.2 mm, we find that the maximum normal elastic deformation equal 0.16863 mm/mm, but for a new tool we find that the maximum normal elastic deformation equal 0.014976 mm/mm. This paper is designed to be beneficial for researcher’s engineers in manufacturing area In order to provide an advance vision about the vibration and the deformation evolution of the cutting tools when there are defects (wear) at tool tip.
{"title":"Frequency Analysis of the Tool with and without Wear during Turning by Modal Analysis","authors":"Aouad Razika, A. Idriss","doi":"10.4172/2169-0022.1000462","DOIUrl":"https://doi.org/10.4172/2169-0022.1000462","url":null,"abstract":"The stability of a cutting process directly influences the quality of a final surface. The control of the cutting process is an important problem for machining technology. Instabilities usually manifest as harmful chatter vibrations generated during cutting. Modal testing is a form of vibration testing which is able to determine the Frequency Response Function (FRF) of the mechanical test structures. In this context, we realized a study of vibration and of deformation between a tool without defect and a tool with two cases of defects. These defects have a random shape (any form), and the contact length tool-work piece, is considered the length of defects Lc=1 mm and the height of wear has been studied for two cases: VB=0.1 and 0.2 mm. In this paper, the main focus is creating a predictive model based on vibrations of body mass. The body mass mean the amount of material that constituting the cutting tool. The loss of a part of this mass makes the tool lighter; it increases the vibration of the tool. In addition to that, the Finite Element Method (FEM) modal analysis was used to obtain the natural frequencies. In this analysis we use ANSYS software based on (FEM), it is known for its high performance, quality and ability to solve all kinds of challenging simulations. The main idea is to create defects (wear) on the flank surface in order to create a model prediction. After the creation of defects, we start the modal analysis to study the deformation and the frequency of the tool. The results indicate that the frequency response and harmonic response analysis simulated by ANSYS with various defects created. First analysis is frequency response; we find the natural frequencies vary depending on the defect. When the tool is not defective we find the natural frequencies equal 337.77 Hz but in a tool with defects (VB=0.1-0.2 and 0.3 mm) we find the natural frequencies equal 340.36 Hz, 340.69 Hz and 341.11 Hz, this shows that the quality of the surface of the defect and its shape have an impact on the vibration of the tool. Then we based on a mathematical model to compare the results of the FEM where it shows a satisfactory correlation. In addition, the results of second analysis indicate that the deformation simulation by ANSYS with varying defects created. It increases with these defects: when VB=0.1 mm, we find that the maximum normal elastic deformation equal 0.16344 mm/mm and for VB=0.2 mm, we find that the maximum normal elastic deformation equal 0.16863 mm/mm, but for a new tool we find that the maximum normal elastic deformation equal 0.014976 mm/mm. This paper is designed to be beneficial for researcher’s engineers in manufacturing area In order to provide an advance vision about the vibration and the deformation evolution of the cutting tools when there are defects (wear) at tool tip.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"38 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75912191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000430
E. O. Nasakina, S. V. Konushkin, M. I. Baskakova, I. Fedyuk, K. V. Sergienko, A. S. Baikin, M. Kaplan, M. Sevost’yanov, A. Kolmakov
Alloys possessing a shape memory effect and mechanical characteristics similar to the behavior of living tissues have been already used for years as the material for production of medical devices, including implants, for example stents, without the need for additional devices except catheter-carrier. However, most of these alloys contain elements (including on its surface) which is toxic for organism. To satisfy the requirements of biochemical compatibility, the alloy should contain only safe elements as alloy components, which include: Ti, Nb, Ta, Zr. The possibility of obtaining of Ti-Nb-Ta-Zr thin wire was investigated. The structure was determined with the use of the optical microscope, X-ray diffractometer, scanning electron microscope (SEM) and Auger spectrometer. Optimal conditions for smelting were chosen. It was noted that a uniform structure was obtained for all compositions, before and after homogenizing annealing. The ingots have a dendritic structure. Niobium and zirconium were uniformly distributed throughout the sample, tantalum was concentrated in the dendrites themselves, titanium was predominantly in the regions between the dendritic axes, but is also found in it. X-ray diffractometry indicates that the elements of the alloy were not distributed in it by separate fragments, but were united in a single structure. The optimal annealing temperature of Ti-(20-30)Nb- (10-13)Ta-5Zr alloys was noted in the range from 600 to 900°C. The grain boundaries after plastic deformation and heat treatment were not identified in a microstructural analysis, which indicates that there was no recrystallization. It is possible that nanostructure was formed. The morphology of wires of any composition after drawing shows a high heterogeneity, two types of surfaces of different composition alternate - areas with a high content of carbon and with a high content of oxygen were observed. After mechanical treatment the surface, its uniformity increases.
{"title":"The Production of a Thin Wire of Ti-Nb-Ta-Zr Shape Memory Alloy for Medical Devices","authors":"E. O. Nasakina, S. V. Konushkin, M. I. Baskakova, I. Fedyuk, K. V. Sergienko, A. S. Baikin, M. Kaplan, M. Sevost’yanov, A. Kolmakov","doi":"10.4172/2169-0022.1000430","DOIUrl":"https://doi.org/10.4172/2169-0022.1000430","url":null,"abstract":"Alloys possessing a shape memory effect and mechanical characteristics similar to the behavior of living tissues have been already used for years as the material for production of medical devices, including implants, for example stents, without the need for additional devices except catheter-carrier. However, most of these alloys contain elements (including on its surface) which is toxic for organism. To satisfy the requirements of biochemical compatibility, the alloy should contain only safe elements as alloy components, which include: Ti, Nb, Ta, Zr. The possibility of obtaining of Ti-Nb-Ta-Zr thin wire was investigated. The structure was determined with the use of the optical microscope, X-ray diffractometer, scanning electron microscope (SEM) and Auger spectrometer. Optimal conditions for smelting were chosen. It was noted that a uniform structure was obtained for all compositions, before and after homogenizing annealing. The ingots have a dendritic structure. Niobium and zirconium were uniformly distributed throughout the sample, tantalum was concentrated in the dendrites themselves, titanium was predominantly in the regions between the dendritic axes, but is also found in it. X-ray diffractometry indicates that the elements of the alloy were not distributed in it by separate fragments, but were united in a single structure. The optimal annealing temperature of Ti-(20-30)Nb- (10-13)Ta-5Zr alloys was noted in the range from 600 to 900°C. The grain boundaries after plastic deformation and heat treatment were not identified in a microstructural analysis, which indicates that there was no recrystallization. It is possible that nanostructure was formed. The morphology of wires of any composition after drawing shows a high heterogeneity, two types of surfaces of different composition alternate - areas with a high content of carbon and with a high content of oxygen were observed. After mechanical treatment the surface, its uniformity increases.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"393 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79645292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000432
Yash Abhang
This paper is a brief review of different tactile sensors based on piezo-resistive mechanism developed in recent times. The topics which are briefly covered are crystalline silicon-based sensors, flexible graphene based sensors, Carbon Nano Tubes (CNT) based flexible sensors, patterned PDMS thin film and self-healing materials for sensors.
{"title":"Review of Different Tactile Sensors Using Piezoresistivity Mechanism","authors":"Yash Abhang","doi":"10.4172/2169-0022.1000432","DOIUrl":"https://doi.org/10.4172/2169-0022.1000432","url":null,"abstract":"This paper is a brief review of different tactile sensors based on piezo-resistive mechanism developed in recent times. The topics which are briefly covered are crystalline silicon-based sensors, flexible graphene based sensors, Carbon Nano Tubes (CNT) based flexible sensors, patterned PDMS thin film and self-healing materials for sensors.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"9 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78544731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.4172/2169-0022.1000466
M. Dn, A. Sarakinis, D. Mavrilas
Background: Soft tissues are characterized by strong mechanical anisotropy, as a result of internal fiber architecture, matching the needs of mechanical function in each body part. Polymeric grafts, used for diseased tissues replacement, suffer from mechanical mismatch with the tissues replaced and the remaining healthy tissues to be connected. Electrospinning is an attractive technique by which we can produce biodegradable polymeric scaffolds for tissue engineering applications. Fiber characteristics and structural architecture has to be tuned to match mechanically the tissues to be replaced. Furthermore, for the design of fibrous scaffolds, other characteristics, like fiber diameter, porosity and hydrophilicity play an important role as far as cell atraction, function and tissue regeneration are concerned.Objective: In the present work, we aimed to produce polymeric membranous scaffolds with specific architecture, giving attention to fibers’ orientation and hence, controlling the final mechanical behavior to match that of the physiological tissues to be replaced.Methods: To this end, we used a specifically designed drum collector, with accurate velocity control, and tested different electrospinning parameters (polymeric solution concentrations, transfer rates, rotational speed, etc) to obtain design optimization.Results: Scanning Electron Microscopy on scaffolds showed a good morphology quality. Fiber orientation was directly related to the drum speed. Tensile testing showed mechanical anisotropy in higher speeds. Young’s modulus and Ultimate tensile strength demonstrated strong anisotropy (one order of magnitude larger) in parallel to transverse direction, with regard to drum speed, similar to that of physiologic soft cardiovascular tissues. Scaffold hydrophilicity, expressed by contact angle measurements remained high, although a relation to fiber architecture has been recorded. Conclusion: Enhancement of membranous anisotropy was attained, one order of magnitude greater for the parallel fibers’ direction compared to the transverse one. A similar anisotropy can be found in cardiovascular soft tissues, like human and porcine aortic heart valve leaflets.
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