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The study of infrared brazing Ti-6Al-4V and 17-4 PH using the BAg-8 filler
No full text本研究以紅外線加熱法，使用50μm厚之Ag基填料BAg-8來硬銲接合Ti-6Al-4V鈦合金及17-4 PH不鏽鋼(S.S.)。硬銲接合前分別對Ti-6Al-4V及17-4 PH進行表面處理，以鍍膜作為擴散阻隔層，期能阻擋填料與基材形成硬脆的介金屬相，以得到最佳剪力強度之條件。實驗結果顯示，在17-4 PH S.S.表面鍍鎳與鉻膜，可得到的最佳接合剪力強度約為117 MPa；而在Ti-6Al-4V表面鍍鉻膜，可得到的最佳接合剪強度約為120 MPa。由破斷途徑之分析可得知，在17-4 PH不鏽鋼進行表面處理，破斷面主要為Ti2Cu介金屬相。而在Ti-6Al-4V進行表面處理，破斷面主要為Ti2Cu介金屬相或少數為(Ti, Cu, Fe)三元合金相。在擴散阻隔層較厚時，因擴散阻隔層的阻擋效果較強，未能形成硬脆的Ti-Cu介金屬化合物，因此破斷都發生於鍍膜與被鍍基材界面之間；若是擴散阻隔層較薄時，因生成較厚的Ti-Cu硬脆介金屬相，此時破斷則發生於Ti-Cu介金屬化合物與基材界面之間。Two kinds of dissimilar metals, Ti-6Al-4V and 17-4 PH stainless steel (S.S.), are joined by infrared vacuum brazing using BAg-8 filler metals with 50μm thickness. Before brazing, diffusion barrier coatings on Ti-6Al-4V or 17-4 PH S.S. are introduced. The aim of diffusion barriers is to prevent interdiffusion between two dissimilar metals from forming intermetallic compounds, and thus to get better shear strength. Experimental results show that Ni and Cr films coated on 17-4 PH S.S. can obtain the shear strength of 117 MPa, and Cr film coated on Ti-6Al-4V can obtain the shear strength of 120 MPa. By the SEM analysis of crack propagation, for surface coatings on 17-4 PH S.S., the specimens are fractured at the Ti2Cu intermetallic compound; and for surface coatings on Ti-6Al-4V, the specimens are fractured mostly at the Ti2Cu but few at the (Ti, Cu Fe) ternary alloy phases. As diffusion barriers are thick, the hard and brittle Ti-Cu intermetallic is not formed because the effect of diffusion barriers is significant. In this case, the crack takes place in between coating film and substrate. As diffusion barriers are thin, the hard and brittle Ti-Cu intermetallic is formed. Thus the crack takes place in between this brittle Ti-Cu intermetallic and the substrate.中文摘要...................................................................................Ⅰ
英文摘要...................................................................................Ⅱ
目錄..........................................................................................Ⅲ
第一章 前言...............................................................................1
第二章 文獻回顧........................................................................5
2-1 合金機械性質...................................................................5
2-1-1 Ti-6Al-4V....................................................................5
2-1-2 17-4 PH 不鏽鋼...........................................................5
2-2 合金接合性質評估............................................................7
2-2-1 Ti-6Al-4V銲接特性.....................................................7
2-2-2 17-4 PH 不鏽鋼的銲接特性.......................................10
2-2-3 Ti-6Al-4V擴散接合不鏽鋼之研究..............................11
2-2-4 擴散阻隔層對接合之研究.........................................12
2-3 薄膜相關製程簡介..........................................................15
2-4 硬銲接合........................................................................17
2-4-1 硬銲接合之特性.......................................................17
2-4-2 硬銲填料所需具備之特性.........................................18
2-5 紅外線接合製程..............................................................19
2-5-1 紅外線加熱之原理....................................................19
2-5-2 紅外線接合製程.......................................................20
第三章 實驗方法......................................................................36
3-1 硬銲基材之試片準備.......................................................36
3-2 試片切割........................................................................36
3-3 試片表面處理.................................................................37
3-3-1 化學電鍍..................................................................37
3-3-2 磁控濺鍍..................................................................37
3-3-
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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