Papers by Keyword: Metallization

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Authors: Alexandru Pascu, Iosif Hulka, Mircea Horia Tierean, Catalin Croitoru, Elena Manuela Stanciu, Ionut Claudiu Roată
Abstract: This paper addresses to the characterization of Ni based coatings realized by two different processes e.g. thermal spray coating and laser cladding. For the relevance of the experimental tests, the same base material, AISI 5140 and Metco 15E powder was used. The results highlight the advantages and disadvantages of the both techniques. The cladded layer obtained through laser cladding is pore and crack free, being characterized by a high hardness and a very good adherence to the substrate, while the flame coating presents oxides inclusions, high porosity, lower hardness and minimal dilution with the substrate as resulted from the EDS analyses. In depth characterization of the samples is made using optical and scanning electron microscopy, EDS analysis and microhardness testing.
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Authors: Zlatan Milutinovic, Marko Ristic, Ivana Vasovic, Milan Prokolab, Bojan Gligorijevic
Abstract: The aim of this paper is, improving the characteristic of Ventilation mill for grinding coal which is one of the main part of steam power plants in the system that makes a significant influence on the level of energy efficiency with its work. Working parts of the mil during exploitation are dominantly exposed to intensive abrasive and erosive wear and also to impact loading at elevated temperatures, which can lead to damage and fracture of homogeneous materials, thus shortening their working life. For solving the problem of increasing the wear resistance of the parts for transport and coal grinding in power plants, to investigate the optimum application of technology in hard coatings by different procedures, and filer materials. Hard coatings were carried out with cold (plasma and arc treatment) and hot metallization (with concurrent and subsequent drowning). It has been used the additional materials of different chemical composition and properties based on Ni (NiCrBSi; NiCrBSiFe; NiCrBSi / WC) and Fe (FeCrCSiMo; FeCrCBSiTi; FeCrCBNiSi). The main goal of this paper is to make the selection of optimum hardfacing procedures, group of filler materials and hardfacing technology definition based on the results of structural and mechanical properties of samples, experimental model hardfacing. These were investigation of its structure, measurement and distribution of hardness in the samples, tribology characteristic samples with hard coatings. Based on the results of these tests there were selected the additional materials and procedures for applying hard coatings, which would be apply in the revitalization of parts in transport at and coal grinding.
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Authors: Walter Daves, A. Krauss, Martin Le-Huu, S. Kronmüller, Volker Haeublein, Anton J. Bauer, Lothar Frey
Abstract: We investigated the performance of different metallization/passivation systems for high temperature applications. The metallizations comprised a 150 nm sputtered Pt or a 150 nm e-beam evaporated PtRh layer on Ti/TiN underlayers, respectively. The passivation coatings consisted of amorphous PECVD SiOx, of amorphous stress-reduced PECVD SiNy, and of a SiOx/ SiNy stack. For samples with SiOx and SiOx/ SiNy passivation layers the electrical properties changed after a short high temperature anneal at 600 °C but then remained stable during further annealing. This was attributed to the formation of PtTi alloys, which stabilized the metallization stack. In samples with SiNy passivation a significant Pt out-diffusion into the passivation layer was observed. This led to a degradation of the electrical and mechanical properties. The best performance was achieved with Pt-based metallizations and SiOx or SiOx/SiNy passivations.
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Authors: P. Siemroth, P. Wenzel, Th. Witke, Bernd Schultrich
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Authors: R. Getto, J. Freytag, M. Kopnarski, H. Oechsner
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Authors: Chiko Yorita, Tatsuya Kobayashi, Ikuo Shohji
Abstract: Semiconductor packages that use metallization and lead-free solders are increasingly being used in electronic products. In this study, interface reactions and joint-strength reliability were investigated for Sn-3W%Ag-0.5W%Cu solder ball joints joined to Cr/Cu and Cr/Ni-40W% metallization layers that were heat treated at 260°C. The strength of the joint with the Cr/Cu metallization layer decreased as the duration of the heat treatment increased. Sn and Cr interface reactive layers were generated after the loss of Cu in the Cr/Cu metallization layer, but the connection was maintained. By contrast, the connection of the joint to the Cr/Ni-40W metallization layer was relatively stable under the heat treatment conditions investigated.
849
Authors: Jin Dan Zhang, Mei Yu, Jian Hua Liu, Song Mei Li, Yan Bing Meng
Abstract: Under the photoirradiation, DNA works as both template and reducing agent to drive the formation of metallic nanomaterials. In this study the plasmid DNA with different base pairs was applied as biotemplate to synthesize Ag nanoparticles (NPs) by using photoirradiation approach. The evolution of DNA dimension changed during the synthesis process, and their effect on the morphology of the synthesized Ag NPs was studied by UV-Vis spectra, FT-IR spectra, Raman spectra, AFM, and TEM. It is found that the plasmid DNA shrinked twice during the synthesis, the first time happened when the Ag (I) cations neutralized the negative charge along the DNA chain, and the second time happened when plasmid DNA reduced Ag (I) induced by the ultraviolet C (254 nm) irradiation. The size of the synthesized Ag NPs showed approximately linear relationship with the dimension of plasmid DNA scaffolds under this photo-induce condition. The compaction degree of the plasmid DNA during the Ag formation was shown by the slope of the linear relationship.
194
Authors: Ick Soo Kim, Kai Wei, Tomohiro Ohta, Byoung Suhk Kim, Yoshimi Watanabe
Abstract: The conductive metallic nanofibers were prepared by using a combined technology of electrospinning and metallization. The electrospun polyurethane and poly(vinyl alcohol) (PVA) nanofibers are metallized with different thicknesses of metal (Cu, Ni) layer via a metallization. The thickness of the metallic layer, which is ranging from 50 nm to 200 nm, was controlled. The resultant metallized nanofibers are characterized using field emission scanning electron microscopy (FE-SEM), wide angle X-ray diffraction (WAXD), and thermogravimetric analysis (TGA). FE-SEM micrographs demonstrate that the nano-scaled metallic layers are well deposited onto the nanofibers. TGA result indicates that thermal stability of the metallized nanofibers was enhanced due to the barrier effects of the metallic thin layer. WAXD data also confirm that the metallic layers are well deposited onto the nanofibers. Remarkably, the fibrous morphologies were satisfactorily conserved after removal of the nanofiber template by heat treatment at ca. 400 oC for 24 hr., suggesting the successful deposition of metal layer onto the nanofiber template, and thereby resulted in the formation of metallic nanofibers and nanotubes depending on the diameter of electrospun nanofibers and the thickness of the deposited metallic layers in the conductive metallic nanofibers. In addition, it was observed that the metallized nanofibers exhibit higher conductive properties depending on the thickness of the deposited metallic layers.
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Authors: Li Li Wang, Yu Wang, De An Yang
Abstract: In this paper, the sol-gel process was used to synthesize a glass binder in thick-film paste for aluminum nitride (AlN) metallization. Some major factors that influenced the sol-gel process including PH value, quantity of water were discussed in detail. The xerogel was analyzed by means of TG-DSC in order to determine its optimum heat treatment process. Meanwhile, the sintering behavior of silver/glass composite thick film had been studied by varying the glass content. The results show that a glass powder of a low melting point and chemically compatible with AlN substrate can be obtained by sol-gel method when the composition (wt %) is CaO (40), B2O3 (15), SiO2 (35), BaO (10). During sintering, the glass becomes liquid and largely affects the microstructure development and square resistance of the thick film. When the glass content is optimum (10wt %), the film adhesion strength achieves maximum and the square resistance has a relatively low value.
366
Authors: M. D'Angelo, H. Enriquez, M. Silly, V. Derycke, V.Yu. Aristov, P. Soukiassian, C. Ottaviani, M. Pedio, P. Perfetti
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