Kazutaka Kamitani, T. Hyodo, Y. Shimizu, M. Egashira
Highly porous alumina-based ceramics were fabricated by a slip casting method by employing polymethylmethacrylate (PMMA) microspheres having different diameters as a template and MgO or SiC powder as a sintering aid and subsequent calcination at 1600∘C. Spherical pores reflecting the morphology of the PMMA microspheres could be fabricated. In addition, the formation of much smaller connected space among the pores was observed on the pore's inner walls of all ceramics. In this method, porous structure, for example, pore diameter, shape (open or closed), and mechanical properties, could be controlled by varying the particle size of PMMA microspheres and its concentration in alumina-based slurries. Highly porous and mechanically strong alumina-based ceramics having an open porosity of 62%, a connected space size of 1.3 𝜇m, and a compressive strength of 147.6 MPa could be fabricated by employing PMMA microspheres with a mean particle size of 22.6 𝜇m and an appropriate amount of SiC.
{"title":"Fabrication of Highly Porous Alumina-Based Ceramics with Connected Spaces by Employing PMMA Microspheres as a Template","authors":"Kazutaka Kamitani, T. Hyodo, Y. Shimizu, M. Egashira","doi":"10.1155/2009/601850","DOIUrl":"https://doi.org/10.1155/2009/601850","url":null,"abstract":"Highly porous alumina-based ceramics were fabricated by a slip casting method by employing polymethylmethacrylate (PMMA) microspheres having different diameters as a template and MgO or SiC powder as a sintering aid and subsequent calcination at 1600∘C. Spherical pores reflecting the morphology of the PMMA microspheres could be fabricated. In addition, the formation of much smaller connected space among the pores was observed on the pore's inner walls of all ceramics. In this method, porous structure, for example, pore diameter, shape (open or closed), and mechanical properties, could be controlled by varying the particle size of PMMA microspheres and its concentration in alumina-based slurries. Highly porous and mechanically strong alumina-based ceramics having an open porosity of 62%, a connected space size of 1.3 𝜇m, and a compressive strength of 147.6 MPa could be fabricated by employing PMMA microspheres with a mean particle size of 22.6 𝜇m and an appropriate amount of SiC.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2009 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2009/601850","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64201160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zr-Al-Ni-Cu thin films were deposited by the radio-frequency sputtering method at low substrate temperature using three kinds of targets: Zr55Al10Ni5Cu30 bulk metallic glass target (𝛼-BMG target), crystallized bulk metallic glass target (c-BMG target), and an elemental composite target composed of each Zr, Al, Ni chips, and Cu plate. XRD profiles of the films prepared when using these targets indicated that all of the films showed amorphous structures. While XRD profiles of the films using 𝛼- and c-BMG targets revealed a broad peak of 2𝜃=38 degree in the same way as the 𝛼-BMG target indicating amorphous structures, that of the film using elemental composite targets showed a broad peak of 2𝜃=42 degree, which is higher compared to the latter material. As a result of annealing the films at various temperatures for 900 seconds, the film using the 𝛼-BMG target showed a crystallization temperature of 748 K, higher than that of BMG with 723 K, while the other films had lower crystallization temperatures below 723 K. XRD profiles also indicated that the crystallized compounds of the films were different from those of BMG target.
{"title":"Structural Characteristics and Crystallization of Metallic Glass Sputtered Films by Using Zr System Target","authors":"K. Kondoh, K. Kawabata, T. Serikawa, H. Kimura","doi":"10.1155/2008/312057","DOIUrl":"https://doi.org/10.1155/2008/312057","url":null,"abstract":"Zr-Al-Ni-Cu thin films were deposited by the radio-frequency sputtering method at low substrate temperature using three kinds of targets: Zr55Al10Ni5Cu30 bulk metallic glass target (𝛼-BMG target), crystallized bulk metallic glass target (c-BMG target), and an elemental composite target composed of each Zr, Al, Ni chips, and Cu plate. XRD profiles of the films prepared when using these targets indicated that all of the films showed amorphous structures. While XRD profiles of the films using 𝛼- and c-BMG targets revealed a broad peak of 2𝜃=38 degree in the same way as the 𝛼-BMG target indicating amorphous structures, that of the film using elemental composite targets showed a broad peak of 2𝜃=42 degree, which is higher compared to the latter material. As a result of annealing the films at various temperatures for 900 seconds, the film using the 𝛼-BMG target showed a crystallization temperature of 748 K, higher than that of BMG with 723 K, while the other films had lower crystallization temperatures below 723 K. XRD profiles also indicated that the crystallized compounds of the films were different from those of BMG target.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/312057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64166945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The resonance frequency of vibrations of dislocation dipoles in fatigued f.c.c. metals is found rather high, in the range of 100 GHz. Because of high attenuation of ultrasound in the GHz range, the contributions of these self-vibrations to degradation of the dipole structures could be expected only in thin layers.
{"title":"Internal Vibrations of Edge Dislocation Dipoles","authors":"J. Kratochvíl, F. Kroupa","doi":"10.1155/2008/907895","DOIUrl":"https://doi.org/10.1155/2008/907895","url":null,"abstract":"The resonance frequency of vibrations of dislocation dipoles in fatigued f.c.c. metals is found rather high, in the range of 100 GHz. Because of high attenuation of ultrasound in the GHz range, the contributions of these self-vibrations to degradation of the dipole structures could be expected only in thin layers.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"3 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2008-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/907895","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64183620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hip resurfacing technique is a conservative arthroplasty used in the young patient in which the femoral head is reshaped to accept metal cap with small guide stem. In the present investigation, a hybrid composite-metal resurfacing implant is proposed. The cup is made of carbon fiber/polyamide 12 (CF/PA12) covered with a thin layer of cobalt chrome (Co-Cr). Finite element (FE) method was applied to analyze and compare the biomechanical performances of the hybrid hip resurfacing (HHR) and the conventional Birmingham (BHR). Results of the finite element analysis showed that the composite implant leads to an increase in stresses in the cancellous bone by more than 15% than BHR, indicating a lower potential for stress shielding and bone fracture and higher potential for bone apposition with the HHR.
{"title":"Biomimetic Composite-Metal Hip Resurfacing Implant","authors":"H. Bougherara, M. Bureau","doi":"10.1155/2008/368985","DOIUrl":"https://doi.org/10.1155/2008/368985","url":null,"abstract":"Hip resurfacing technique is a conservative arthroplasty used in the young patient in which the femoral head is reshaped to accept metal cap with small guide stem. In the present investigation, a hybrid composite-metal resurfacing implant is proposed. The cup is made of carbon fiber/polyamide 12 (CF/PA12) covered with a thin layer of cobalt chrome (Co-Cr). Finite element (FE) method was applied to analyze and compare the biomechanical performances of the hybrid hip resurfacing (HHR) and the conventional Birmingham (BHR). Results of the finite element analysis showed that the composite implant leads to an increase in stresses in the cancellous bone by more than 15% than BHR, indicating a lower potential for stress shielding and bone fracture and higher potential for bone apposition with the HHR.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/368985","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64168458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The application of X-ray photoelectron spectroscopy to the analysis of paint flakes from a painting by Henry Fuseli (1741–1825) is presented. Historically, the application of XPS to art conservation and restoration studies has been limited by the poor spatial resolution of the technique. Presented here is the successful analysis of paint flakes in the order of 100 𝜇 m using “imaging” XPS in conjunction with selected area analysis. Raman microscopy failed to satisfactorily identify the compounds present in this instance, and energy dispersive spectroscopy could not differentiate between lead and sulphur (two of the elements of interest) due to the limited energy resolution inherent in that technique. Using XPS analysis of the lead 4f peak revealed that the pigment was a lead-based pigment, in this case comprising exclusively lead-sulphur compounds.
{"title":"Selected Area XPS Analysis for Identification of Pigment Compounds in Microscopic Paint Flakes","authors":"B. James, R. Cameron, Camilla Baskcomb","doi":"10.1155/2008/247053","DOIUrl":"https://doi.org/10.1155/2008/247053","url":null,"abstract":"The application of X-ray photoelectron spectroscopy to the analysis of paint flakes from a painting by Henry Fuseli (1741–1825) is presented. Historically, the application of XPS to art conservation and restoration studies has been limited by the poor spatial resolution of the technique. Presented here is the successful analysis of paint flakes in the order of 100 𝜇 m using “imaging” XPS in conjunction with selected area analysis. Raman microscopy failed to satisfactorily identify the compounds present in this instance, and energy dispersive spectroscopy could not differentiate between lead and sulphur (two of the elements of interest) due to the limited energy resolution inherent in that technique. Using XPS analysis of the lead 4f peak revealed that the pigment was a lead-based pigment, in this case comprising exclusively lead-sulphur compounds.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/247053","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64164867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Saraf, Chong M. Wang, M. Engelhard, P. Nachimuthu
Ultrathin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface, and microstructural properties of ultrathin (∼10–12 unit cells thick) epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM) and substrate roughness of ∼1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, lattice mismatch, substrate roughness, and surface reduction creating secondary phase was likely the cause of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.
{"title":"Surface and Interface Properties of 10–12 Unit Cells Thick Sputter Deposited Epitaxial CeO2 Films","authors":"L. Saraf, Chong M. Wang, M. Engelhard, P. Nachimuthu","doi":"10.1155/2008/206019","DOIUrl":"https://doi.org/10.1155/2008/206019","url":null,"abstract":"Ultrathin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface, and microstructural properties of ultrathin (∼10–12 unit cells thick) epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM) and substrate roughness of ∼1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, lattice mismatch, substrate roughness, and surface reduction creating secondary phase was likely the cause of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2008-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/206019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64164125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The deterioration of the mechanical properties of yield strength and modulus of elasticity is considered as the primary element affecting the performance of steel structures under fire. In this study, hot-rolled S220 and S420 reinforcement steel rebars were subjected to high temperatures to investigate the fire performance of these materials. It is aimed to determine the remaining mechanical properties of steel rebars after elevated temperatures. Steels were subjected to 20, 100, 200, 300, 500, 800, and 950∘C temperatures for 3 hours and tensile tests were carried out. Effect of temperature on mechanical behavior of S220 and S420 were determined. All mechanical properties were reduced due to the temperature increase of the steel rebars. It is seen that mechanical properties of S420 steel was influenced more than S220 steel at elevated temperatures.
{"title":"Properties of Reinforced Concrete Steel Rebars Exposed to High Temperatures","authors":"I. Topcu, C. Karakurt","doi":"10.1155/2008/814137","DOIUrl":"https://doi.org/10.1155/2008/814137","url":null,"abstract":"The deterioration of the mechanical properties of yield strength and modulus of elasticity is considered as the primary element affecting the performance of steel structures under fire. In this study, hot-rolled S220 and S420 reinforcement steel rebars were subjected to high temperatures to investigate the fire performance of these materials. It is aimed to determine the remaining mechanical properties of steel rebars after elevated temperatures. Steels were subjected to 20, 100, 200, 300, 500, 800, and 950∘C temperatures for 3 hours and tensile tests were carried out. Effect of temperature on mechanical behavior of S220 and S420 were determined. All mechanical properties were reduced due to the temperature increase of the steel rebars. It is seen that mechanical properties of S420 steel was influenced more than S220 steel at elevated temperatures.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/814137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64181016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.
{"title":"Erosion-Oxidation Response of Boiler Grade Steels: A Mathematical Investigation","authors":"Suvarthi Das, S. Hegde, P. Dey, S. Mehrotra","doi":"10.1155/2008/542161","DOIUrl":"https://doi.org/10.1155/2008/542161","url":null,"abstract":"A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/542161","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64173982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enhanced photoluminescence (PL) is reported from Mn-doped ZnS nanocrystals (NCs) capped with ZnS (ZnS:Mn/ZnS core-shell NCs) and thioglycolic acid (TGA) (ZnS:Mn/ZnS core-shell NCs dispersed in an alkaline TGA solution). The NCs were prepared using a reverse micelle route. Comparing with initial ZnS:Mn core NCs, the ZnS:Mn/ZnS core-shell NCs exhibit much stronger orange PL (~580 nm). This is presumably the result of effective passivation of quenching ZnS:Mn NCs surface states by a pure ZnS shell. As for TGA-capped ZnS:Mn/ZnS core-shell NCs, the parallel decrease of a defect-related emission of ZnS is associated with the formation of a shell surface layer of TGA-Zn complexes. In summary, the combination of ZnS shells with TGA ligands was demonstrated to yield ZnS:Mn NCs with narrow size distribution and intense PL.
{"title":"Surface Passivation and Photoluminescence of Mn-Doped ZnS Nanocrystals","authors":"Ping Yang, M. Bredol","doi":"10.1155/2008/506065","DOIUrl":"https://doi.org/10.1155/2008/506065","url":null,"abstract":"Enhanced photoluminescence (PL) is reported from Mn-doped ZnS nanocrystals (NCs) capped with ZnS (ZnS:Mn/ZnS core-shell NCs) and thioglycolic acid (TGA) (ZnS:Mn/ZnS core-shell NCs dispersed in an alkaline TGA solution). The NCs were prepared using a reverse micelle route. Comparing with initial ZnS:Mn core NCs, the ZnS:Mn/ZnS core-shell NCs exhibit much stronger orange PL (~580 nm). This is presumably the result of effective passivation of quenching ZnS:Mn NCs surface states by a pure ZnS shell. As for TGA-capped ZnS:Mn/ZnS core-shell NCs, the parallel decrease of a defect-related emission of ZnS is associated with the formation of a shell surface layer of TGA-Zn complexes. In summary, the combination of ZnS shells with TGA ligands was demonstrated to yield ZnS:Mn NCs with narrow size distribution and intense PL.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"25 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2008-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/506065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64173099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ag and Pt nanoparticles have successfully been synthesized by hydrolysis of either Ag2Na or PtNa at room temperature. The oxidation of sodium in the Pt-Na pellets was much faster than that in the Ag-Na pellets since Pt is a catalyst for H2O formation reaction from hydrogen and oxygen at room temperature. The hydrolysis byproduct, NaOH, has a high solubility and easily is removed. This method offers a simple method of preparing transition metal nanoparticles. The Ag and Pt nanoparticles prepared by this method were crystalline in nature, and spherical in shape with a mean size of around 10 nm.
{"title":"Synthesis of Ag or Pt Nanoparticles by Hydrolysis of Either Ag2Na or PtNa","authors":"Huabin Wang, D. Northwood","doi":"10.1155/2008/619032","DOIUrl":"https://doi.org/10.1155/2008/619032","url":null,"abstract":"Ag and Pt nanoparticles have successfully been synthesized by hydrolysis of either Ag2Na or PtNa at room temperature. The oxidation of sodium in the Pt-Na pellets was much faster than that in the Ag-Na pellets since Pt is a catalyst for H2O formation reaction from hydrogen and oxygen at room temperature. The hydrolysis byproduct, NaOH, has a high solubility and easily is removed. This method offers a simple method of preparing transition metal nanoparticles. The Ag and Pt nanoparticles prepared by this method were crystalline in nature, and spherical in shape with a mean size of around 10 nm.","PeriodicalId":7345,"journal":{"name":"Advances in Materials Science and Engineering","volume":"2008 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2008-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2008/619032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64176211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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