Pub Date : 2017-11-29DOI: 10.4172/2169-0022.1000397
M. Richetta
The peculiar properties of layered Double Hydroxides (LDH) have progressively drawn the attention of the scientific community. The main characteristic of LDH is the ability to capture anionic species (organic and inorganic) to build different composites. This is made possible by the sandwich structure of the LDH, similar to the brucite architecture, made up of positive charged lamellas interspersed by anions. Several distant fields, ranging from medicine to physics and engineering, exhibit interest in LDH applications. To satisfy all those requirements, energy was spent to sculpt LDHs physical and chemical properties and for designing layered double hydroxides “ad hoc” for different needs and employments. Notably, among the many applications, those related to metallurgical processes and products are of particular interest. This paper presents the characteristics, the main preparation routes and reviews the applications of LDH to metallurgy with some examples taken from the experimental research of the author.
{"title":"Characteristics, Preparation Routes and Metallurgical Applications of LDHs: An Overview","authors":"M. Richetta","doi":"10.4172/2169-0022.1000397","DOIUrl":"https://doi.org/10.4172/2169-0022.1000397","url":null,"abstract":"The peculiar properties of layered Double Hydroxides (LDH) have progressively drawn the attention of the scientific community. The main characteristic of LDH is the ability to capture anionic species (organic and inorganic) to build different composites. This is made possible by the sandwich structure of the LDH, similar to the brucite architecture, made up of positive charged lamellas interspersed by anions. Several distant fields, ranging from medicine to physics and engineering, exhibit interest in LDH applications. To satisfy all those requirements, energy was spent to sculpt LDHs physical and chemical properties and for designing layered double hydroxides “ad hoc” for different needs and employments. Notably, among the many applications, those related to metallurgical processes and products are of particular interest. This paper presents the characteristics, the main preparation routes and reviews the applications of LDH to metallurgy with some examples taken from the experimental research of the author.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"36 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2017-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80565488","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 : 2017-11-24DOI: 10.4172/2169-0022.1000393
Gang Zhang, Changwoo Nam, Mike Chung Tc
Polypropylene (PP) represents about a quarter of commercial plastics produced around the world. Despite its huge commercial success, PP polymer is not suitable for the applications that require long-term exposure to high temperatures (>80°C), due to its chemical and physical stability. The PP chain is prone to the oxidative chaindegradation and exhibits a relatively low material softening temperature. This paper discusses a new research approach by developing the PP-bonded hindered phenol (PP-HP) antioxidants to address this scientifically challenging issue. We have investigated two PP-HP structures, one with two methylene units adjacent to the hindered phenol group (HP-L) and one without this spacer (HP-S). In general, PP-HP polymers are advantaged with the ability to incorporate a suitable concentration of HP antioxidant groups with homogeneous distribution along the polymer chain, which provide effective protection to the PP chains from oxidative degradation. In addition, the specific PP-HP-L structure can also engage in a facile crosslinking reaction to form a 3-D network during the oxidation reaction. In one accelerated oxidation test in air at 190-210°C, the regular commercial PP polymer (containing common antioxidants and stabilizers) degrades within a few minutes; a PP-HP-L copolymer with about 1 mol% HP-L group shows almost no detectable weight loss after 24 hrs. In an ASTM endurance test at 140°C in air, the commercial PP shows 1% weight loss within about 10 days. On the other hand, the PP-HP-L polymer lasts for more than 30 years. Overall, the experiment results present the potential of expanding PP applications into a much higher temperature range (>140°C) under oxygen oxidative environments
{"title":"Developing Polypropylene Bonded Hindered Phenol Antioxidants for Expanding Polypropylene Applications in High Temperature Conditions","authors":"Gang Zhang, Changwoo Nam, Mike Chung Tc","doi":"10.4172/2169-0022.1000393","DOIUrl":"https://doi.org/10.4172/2169-0022.1000393","url":null,"abstract":"Polypropylene (PP) represents about a quarter of commercial plastics produced around the world. Despite its huge commercial success, PP polymer is not suitable for the applications that require long-term exposure to high temperatures (>80°C), due to its chemical and physical stability. The PP chain is prone to the oxidative chaindegradation and exhibits a relatively low material softening temperature. This paper discusses a new research approach by developing the PP-bonded hindered phenol (PP-HP) antioxidants to address this scientifically challenging issue. We have investigated two PP-HP structures, one with two methylene units adjacent to the hindered phenol group (HP-L) and one without this spacer (HP-S). In general, PP-HP polymers are advantaged with the ability to incorporate a suitable concentration of HP antioxidant groups with homogeneous distribution along the polymer chain, which provide effective protection to the PP chains from oxidative degradation. In addition, the specific PP-HP-L structure can also engage in a facile crosslinking reaction to form a 3-D network during the oxidation reaction. In one accelerated oxidation test in air at 190-210°C, the regular commercial PP polymer (containing common antioxidants and stabilizers) degrades within a few minutes; a PP-HP-L copolymer with about 1 mol% HP-L group shows almost no detectable weight loss after 24 hrs. In an ASTM endurance test at 140°C in air, the commercial PP shows 1% weight loss within about 10 days. On the other hand, the PP-HP-L polymer lasts for more than 30 years. Overall, the experiment results present the potential of expanding PP applications into a much higher temperature range (>140°C) under oxygen oxidative environments","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"59 10","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2017-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91402671","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 : 2017-11-24DOI: 10.4172/2169-0022.1000395
H. Haddad, I. Sbarski
This study investigates the effect of unsaturated polyester resin chemical composition on the coefficient of thermal expansion, damping properties, flexural strength, tensile strength and hardness. The resin is used as binder in polymer concrete for manufacturing the bases of precision tool machines in previous work published by the authors. Resins of various ratios of styrene-ARAPOL and methyl methacrylate (MMA)-ARAPOL were made and their curing kinetics was studied using viscosity measurements and exothermic reaction temperature profiles. The resins were studied using dynamic mechanical analysis and in-house thermal expansion measuring devices. It was found that ARAPOL–MMA (60:40) has the highest damping factor of 5.46%, and the thermal expansion coefficient of 7.98 × 10- 5/°C. This composition also has the optimum flexural and tensile strengths at 128 MPa and 58.6 MPa
{"title":"Optimization of Thermal and Mechanical Properties of Unsaturated Polyester Resin as a Binder in Polymer Concrete for Manufacturing Precision Tool Machine Bases","authors":"H. Haddad, I. Sbarski","doi":"10.4172/2169-0022.1000395","DOIUrl":"https://doi.org/10.4172/2169-0022.1000395","url":null,"abstract":"This study investigates the effect of unsaturated polyester resin chemical composition on the coefficient of thermal expansion, damping properties, flexural strength, tensile strength and hardness. The resin is used as binder in polymer concrete for manufacturing the bases of precision tool machines in previous work published by the authors. Resins of various ratios of styrene-ARAPOL and methyl methacrylate (MMA)-ARAPOL were made and their curing kinetics was studied using viscosity measurements and exothermic reaction temperature profiles. The resins were studied using dynamic mechanical analysis and in-house thermal expansion measuring devices. It was found that ARAPOL–MMA (60:40) has the highest damping factor of 5.46%, and the thermal expansion coefficient of 7.98 × 10- 5/°C. This composition also has the optimum flexural and tensile strengths at 128 MPa and 58.6 MPa","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"23 2 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2017-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77311616","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 : 2017-11-23DOI: 10.4172/2169-0022.1000392
Z. Ahmad, F. Al-Sagheer, A. Bumajdad, Jessy Shiju
In situ polymerization technique was used to link chemically the amine-terminated high molecular weight aramid chains with acid-functionalized MWCNTs. The The X-ray photoelectron spectroscopy (XPS) was used to study the chemical linkage between aramid chains and MWCNTs and the composite morphology was investigated by scanning electron microscopy. Dynamic mechanical analysis (DMA) showed a higher increase in the storage modulus. The temperature involving α-relaxations on MWCNTs loading was found higher in comparison to the system where pristine MWCNTs were used. Iinterfacial interactions between the matrix and MWCNTs including hydrogen bonding, π–π stacking and chemical bonding are considered the key parameters responsible and the chemical bonding of the MWCNTs with the matrix resulted in better dispersion of CNTs and the higher visco-elastic properties. The maximum glass transition and the thermal decomposition temperature of these composites respectively were observed around 346°C and 533°C. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 1.67 vol.%. Such mechanically strong and thermally stable aramid composites are suitable for many applications including high performance materials for electromagnetic shielding and radar absorption.
{"title":"In situ Preparation of Aramid-MWCNT Nano-composites: Morphology, Thermal Mechanical and Dielectric Properties","authors":"Z. Ahmad, F. Al-Sagheer, A. Bumajdad, Jessy Shiju","doi":"10.4172/2169-0022.1000392","DOIUrl":"https://doi.org/10.4172/2169-0022.1000392","url":null,"abstract":"In situ polymerization technique was used to link chemically the amine-terminated high molecular weight aramid chains with acid-functionalized MWCNTs. The The X-ray photoelectron spectroscopy (XPS) was used to study the chemical linkage between aramid chains and MWCNTs and the composite morphology was investigated by scanning electron microscopy. Dynamic mechanical analysis (DMA) showed a higher increase in the storage modulus. The temperature involving α-relaxations on MWCNTs loading was found higher in comparison to the system where pristine MWCNTs were used. Iinterfacial interactions between the matrix and MWCNTs including hydrogen bonding, π–π stacking and chemical bonding are considered the key parameters responsible and the chemical bonding of the MWCNTs with the matrix resulted in better dispersion of CNTs and the higher visco-elastic properties. The maximum glass transition and the thermal decomposition temperature of these composites respectively were observed around 346°C and 533°C. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 1.67 vol.%. Such mechanically strong and thermally stable aramid composites are suitable for many applications including high performance materials for electromagnetic shielding and radar absorption.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"120 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2017-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80614205","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 : 2017-11-16DOI: 10.4172/2169-0022.1000394
U. Waware, N. Wasekar
Present study deals with electrodeposition of binary Ni-B and ternary Ni-B-Fe2O3 alloy coatings using DMAB as a source of boron. The coatings were characterized for elemental composition, phase composition and surface topography using FE-SEM, XRD and Atomic Force Microscopy (AFM). The phase stability of coatings was studied using differential scanning colorimetry (DSC). Subsequently, the mechanical and electrochemical corrosion studies were carried out using nano indentation and potentiodynamic polarization studies respectively. The results indicate that addition of Fe2O3 in Ni-B alloy coatings results in 52% improvement in hardness and 3 times improvement in corrosion protection efficiency over Ni-B coatings. Ni-B-Fe2O3 coatings can be suitable economical option towards conventional electroless Ni-B alloy.
{"title":"Manufacture and Properties of Ni-B-Fe 2 O 3 Composite Nano-coatings by Electrodeposition","authors":"U. Waware, N. Wasekar","doi":"10.4172/2169-0022.1000394","DOIUrl":"https://doi.org/10.4172/2169-0022.1000394","url":null,"abstract":"Present study deals with electrodeposition of binary Ni-B and ternary Ni-B-Fe2O3 alloy coatings using DMAB as a source of boron. The coatings were characterized for elemental composition, phase composition and surface topography using FE-SEM, XRD and Atomic Force Microscopy (AFM). The phase stability of coatings was studied using differential scanning colorimetry (DSC). Subsequently, the mechanical and electrochemical corrosion studies were carried out using nano indentation and potentiodynamic polarization studies respectively. The results indicate that addition of Fe2O3 in Ni-B alloy coatings results in 52% improvement in hardness and 3 times improvement in corrosion protection efficiency over Ni-B coatings. Ni-B-Fe2O3 coatings can be suitable economical option towards conventional electroless Ni-B alloy.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84889385","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 : 2017-11-16DOI: 10.4172/2169-0022.1000390
Bolandhemat Najmeh, R. Mahmudur, H. Zainuddin, Chang Kt, A. Shuaibu
This paper is presented a theoretical study of electronic, magnetic and chemical bonding properties of spinel CdCr2O4 with a general formula of AB2X4 (A, B=transition- metal, X=oxides, chalcogenides) using density functional calculation method combined with spin- polarized theory within generalized gradient approximation. Density functional calculation is performed to observe the effects of magnetic ordering on the electronic and chemical bonding properties of spinel CdCr2O4 with both cubic and tetragonal structure from a pyrochlore lattice, using Quantum ESPRESSO package. Consequently, in order to investigate the magnetic properties in paramagnetic, ferromagnetic and antiferromagnetic orderings of spinel CdCr2O4, a first-principles study of the electronic structure as well as chemical bonding properties of spinel CdCr2O4 compound in two different structural form is performed: the cubic structure in order to investigate the desired properties in paramagnetic and ferromagnetic orderings, and tetragonal structure to calculate the same properties in antiferromagnetic ordering
{"title":"Density Functional Study of Electronic, Magnetic and Chemical Bonding Properties of Spinel CdCr2O4","authors":"Bolandhemat Najmeh, R. Mahmudur, H. Zainuddin, Chang Kt, A. Shuaibu","doi":"10.4172/2169-0022.1000390","DOIUrl":"https://doi.org/10.4172/2169-0022.1000390","url":null,"abstract":"This paper is presented a theoretical study of electronic, magnetic and chemical bonding properties of spinel CdCr2O4 with a general formula of AB2X4 (A, B=transition- metal, X=oxides, chalcogenides) using density functional calculation method combined with spin- polarized theory within generalized gradient approximation. Density functional calculation is performed to observe the effects of magnetic ordering on the electronic and chemical bonding properties of spinel CdCr2O4 with both cubic and tetragonal structure from a pyrochlore lattice, using Quantum ESPRESSO package. Consequently, in order to investigate the magnetic properties in paramagnetic, ferromagnetic and antiferromagnetic orderings of spinel CdCr2O4, a first-principles study of the electronic structure as well as chemical bonding properties of spinel CdCr2O4 compound in two different structural form is performed: the cubic structure in order to investigate the desired properties in paramagnetic and ferromagnetic orderings, and tetragonal structure to calculate the same properties in antiferromagnetic ordering","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"17 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2017-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78758155","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 : 2017-10-31DOI: 10.4172/2169-0022.1000386
H. Sugi
In 1971, Harrington et al. put forward a hypothesis, in which helix-coil transition in the hinge region of myosin subfragment-2 (S-2) contributes to muscle contraction. The helix-coil transition hypothesis has been, however, ignored by muscle investigators over many years. In 1992, we worked with him to examine the effect of polyclonal antibody to myosin subfragment-2 (anti-S-2 antibody), and found that the antibody eliminated Ca2+-activated isometric force generation of skinned vertebrate muscle fibers without affecting MgATPase activity. Further studies using the same antibody indicated functional communication between myosin head and myosin S-2, including regulation of binding strength between myosin head and actin filament during Ca2+-activated contraction in vertebrate muscle fibers. These findings indicate that the swinging lever arm hypothesis, in which muscle contraction results from active rotation of myosin head converter domain, is incomplete because it ignores of the role of myosin S-2. Much more experimental work is necessary to reach full understanding of muscle contraction mechanism at the molecular level.
{"title":"Evidence for the Essential Role of Myosin Subfragment-2 in Muscle Contraction: Functional Communication between Myosin Head and Subfragment-2","authors":"H. Sugi","doi":"10.4172/2169-0022.1000386","DOIUrl":"https://doi.org/10.4172/2169-0022.1000386","url":null,"abstract":"In 1971, Harrington et al. put forward a hypothesis, in which helix-coil transition in the hinge region of myosin subfragment-2 (S-2) contributes to muscle contraction. The helix-coil transition hypothesis has been, however, ignored by muscle investigators over many years. In 1992, we worked with him to examine the effect of polyclonal antibody to myosin subfragment-2 (anti-S-2 antibody), and found that the antibody eliminated Ca2+-activated isometric force generation of skinned vertebrate muscle fibers without affecting MgATPase activity. Further studies using the same antibody indicated functional communication between myosin head and myosin S-2, including regulation of binding strength between myosin head and actin filament during Ca2+-activated contraction in vertebrate muscle fibers. These findings indicate that the swinging lever arm hypothesis, in which muscle contraction results from active rotation of myosin head converter domain, is incomplete because it ignores of the role of myosin S-2. Much more experimental work is necessary to reach full understanding of muscle contraction mechanism at the molecular level.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"1 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2017-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83194263","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 : 2017-10-31DOI: 10.4172/2169-0022.1000383
S. Abdalla, A. Obaid, F. Al-Marzouki, F. Bahabri
Spider silk (SS) is naturally tough; however, it turns soft when wet by water. Spiders produce high-quality silk threads by adjusting the molecular assemblage of SS-proteins and the arrangements structure of threads and recombinant spider dragline silk (RSDS). The general wet spinning techniques for producing recombinant spidroins results in uncorrected explanation to the natural spinning technique. In this study, we use tailored-SS with relative low molecular weight of 47 kD to produce a water-soluble RSDS protein. We built a microfluidic ship and used it to spun SS using aqueous solutions-micro-technique (wet spinning). This was done in order to mimic the spider-spinning processes using a steady post-spin drawing process. We succeeded to produce assemblies of spidroins with fibril structure. Then, compact constituting of micro-threads followed these wet spinning processes. Wet spinning was followed by improving the orientation, crystalline structure, and fibril melting of the hierarchical structure. The initial mechanical characterization (tensile strength) of the RSDSs attained about 510 MPa with respective extension 44%.
{"title":"Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques","authors":"S. Abdalla, A. Obaid, F. Al-Marzouki, F. Bahabri","doi":"10.4172/2169-0022.1000383","DOIUrl":"https://doi.org/10.4172/2169-0022.1000383","url":null,"abstract":"Spider silk (SS) is naturally tough; however, it turns soft when wet by water. Spiders produce high-quality silk threads by adjusting the molecular assemblage of SS-proteins and the arrangements structure of threads and recombinant spider dragline silk (RSDS). The general wet spinning techniques for producing recombinant spidroins results in uncorrected explanation to the natural spinning technique. In this study, we use tailored-SS with relative low molecular weight of 47 kD to produce a water-soluble RSDS protein. We built a microfluidic ship and used it to spun SS using aqueous solutions-micro-technique (wet spinning). This was done in order to mimic the spider-spinning processes using a steady post-spin drawing process. We succeeded to produce assemblies of spidroins with fibril structure. Then, compact constituting of micro-threads followed these wet spinning processes. Wet spinning was followed by improving the orientation, crystalline structure, and fibril melting of the hierarchical structure. The initial mechanical characterization (tensile strength) of the RSDSs attained about 510 MPa with respective extension 44%.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"140 6 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2017-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79748775","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 : 2017-10-31DOI: 10.4172/2169-0022.1000384
J. G. Suárez, C. Colombo, S. MaríaElvira, I. Fernández
Shot peening is a cold work treatment that consists in impacting a metallic surface with a flux of spherical shots with the aim to introduce compressive residual stresses field and work hardening on the surface layer. Both aforementioned parameters are responsible for improved fatigue behaviour of treated components. Recent studies have shown that if applied using severe parameters (severe shot peening), this treatment can be categorized as a severe plastic deformation surface treatment. Severe shot peening is able to strongly modify the microstructure of the surface layer of material by increasing the dislocation density that define new grain boundaries and progressively form ultrafine structure. In this work, conventional shot peening and severe shot peening treatments were applied to 39NiCrMo3 steel samples with the aim to study the microstructural changes. The samples were also characterized in terms of surface roughness, micro hardness, residual stresses, and surface work-hardening. Particular attention was focused on the microstructural analysis as a function of the coverage level, with the aim to assess the evolution of grain size from the surface to the inner material and induced gradient microstructure. The results indicated that severe shot peening causes a more remarkable improvement of the general surface mechanical characteristics with respect to conventional shot peening, and revealed a notable microstructural alteration induced by the treatment.
{"title":"Severe Shot Peening to Get a Nano-Structured Surface Layer in Low-Alloy Steel","authors":"J. G. Suárez, C. Colombo, S. MaríaElvira, I. Fernández","doi":"10.4172/2169-0022.1000384","DOIUrl":"https://doi.org/10.4172/2169-0022.1000384","url":null,"abstract":"Shot peening is a cold work treatment that consists in impacting a metallic surface with a flux of spherical shots with the aim to introduce compressive residual stresses field and work hardening on the surface layer. Both aforementioned parameters are responsible for improved fatigue behaviour of treated components. Recent studies have shown that if applied using severe parameters (severe shot peening), this treatment can be categorized as a severe plastic deformation surface treatment. Severe shot peening is able to strongly modify the microstructure of the surface layer of material by increasing the dislocation density that define new grain boundaries and progressively form ultrafine structure. In this work, conventional shot peening and severe shot peening treatments were applied to 39NiCrMo3 steel samples with the aim to study the microstructural changes. The samples were also characterized in terms of surface roughness, micro hardness, residual stresses, and surface work-hardening. Particular attention was focused on the microstructural analysis as a function of the coverage level, with the aim to assess the evolution of grain size from the surface to the inner material and induced gradient microstructure. The results indicated that severe shot peening causes a more remarkable improvement of the general surface mechanical characteristics with respect to conventional shot peening, and revealed a notable microstructural alteration induced by the treatment.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"1 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2017-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76791648","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 : 2017-10-26DOI: 10.4172/2169-0022.1000388
N. Shah, Syed Aa, A. Murrawat
Zinc telluride (ZnTe) thin films were fabricated by thermal evaporation method on corning glass substrates. ZnTe thin films were doped with silver (Ag) by dipping in low concentrated solution (0.2 g/200 ml) of AgNO3 × H2O at room temperature. X-ray diffraction technique was used to investigate the structural behavior of ZnTe samples. Optical investigations were done by using spectrophotometer. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze the surface and composition of the thin film samples respectively. Electrical investigations were done by using Van Der Pauw and Hall measurement system. It was found that prepared samples showed polycrystalline structure with as preferred orientation. Optical study showed that with increasing thickness, grain size increased but optical transmission and energy band gap were decreased. It was observed that value of resistivity of these samples decreased with increasing thickness and Ag composition. The results were compared before and after Ag doping in ZnTe thin films samples for the solar cell applications.
{"title":"Silver Doping Effects on ZnTe Thin Films by Thermal Evaporation Technique","authors":"N. Shah, Syed Aa, A. Murrawat","doi":"10.4172/2169-0022.1000388","DOIUrl":"https://doi.org/10.4172/2169-0022.1000388","url":null,"abstract":"Zinc telluride (ZnTe) thin films were fabricated by thermal evaporation method on corning glass substrates. ZnTe thin films were doped with silver (Ag) by dipping in low concentrated solution (0.2 g/200 ml) of AgNO3 × H2O at room temperature. X-ray diffraction technique was used to investigate the structural behavior of ZnTe samples. Optical investigations were done by using spectrophotometer. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze the surface and composition of the thin film samples respectively. Electrical investigations were done by using Van Der Pauw and Hall measurement system. It was found that prepared samples showed polycrystalline structure with as preferred orientation. Optical study showed that with increasing thickness, grain size increased but optical transmission and energy band gap were decreased. It was observed that value of resistivity of these samples decreased with increasing thickness and Ag composition. The results were compared before and after Ag doping in ZnTe thin films samples for the solar cell applications.","PeriodicalId":16326,"journal":{"name":"Journal of Material Sciences & Engineering","volume":"39 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2017-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91244860","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}
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