Silver Sintering for Silicon Carbide Die Attach: Process Optimization and Structural Modeling
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Carbothermal Synthesis of Silicon Nitride
Carbothermal Synthesis of Silicon Nitride Xiaohan Wan A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy School of Materials Science and Engineering Faculty of Science March 2013 THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Wan First name: Xiaohan Other name/s: Abbreviation for degree as given in the University calendar: PhD School: Materials Science and Engineering Faculty: Science Title: Carbothermal synthesis of silicon nitride Abstract 350 words maximum Carbothermal synthesis of silicon nitride Si3N4 followed by decomposition of Si3N4 is a novel approach to production of solar-grade silicon. The aim of the project was to study reduction/nitridation of silica under different conditions and to establish mechanism of silicon nitride formation. Carbothermal reduction of quartz and amorphous silica was investigated in a fixed bed reactor at 1300-1650 °C in nitrogen at 1-11 atm pressure and in hydrogen-nitrogen mixtures at atmospheric pressure. Samples were prepared from silica-graphite mixtures in the form of pellets. Carbon monoxide evolution in the reduction process was monitored using an infrared sensor; oxygen, nitrogen and carbon contents in reduced samples were determined by LECO analyses. Phases formed in the reduction process were analysed by XRD. Silica was reduced to silicon nitride and silicon carbide; their ratio was dependent on reduction time, temperature and nitrogen pressure. Reduction products also included SiO gas which was removed from the pellet with the flowing gas. In the experiments, reduction of silica started below 1300 °C; the reduction rate increased with increasing temperature. Silicon carbide was the major reduction product at the early stage of reduction; the fraction of silicon nitride increased with increasing reaction time. -
The Development of the Periodic Table and Its Consequences Citation: J
Firenze University Press www.fupress.com/substantia The Development of the Periodic Table and its Consequences Citation: J. Emsley (2019) The Devel- opment of the Periodic Table and its Consequences. Substantia 3(2) Suppl. 5: 15-27. doi: 10.13128/Substantia-297 John Emsley Copyright: © 2019 J. Emsley. This is Alameda Lodge, 23a Alameda Road, Ampthill, MK45 2LA, UK an open access, peer-reviewed article E-mail: [email protected] published by Firenze University Press (http://www.fupress.com/substantia) and distributed under the terms of the Abstract. Chemistry is fortunate among the sciences in having an icon that is instant- Creative Commons Attribution License, ly recognisable around the world: the periodic table. The United Nations has deemed which permits unrestricted use, distri- 2019 to be the International Year of the Periodic Table, in commemoration of the 150th bution, and reproduction in any medi- anniversary of the first paper in which it appeared. That had been written by a Russian um, provided the original author and chemist, Dmitri Mendeleev, and was published in May 1869. Since then, there have source are credited. been many versions of the table, but one format has come to be the most widely used Data Availability Statement: All rel- and is to be seen everywhere. The route to this preferred form of the table makes an evant data are within the paper and its interesting story. Supporting Information files. Keywords. Periodic table, Mendeleev, Newlands, Deming, Seaborg. Competing Interests: The Author(s) declare(s) no conflict of interest. INTRODUCTION There are hundreds of periodic tables but the one that is widely repro- duced has the approval of the International Union of Pure and Applied Chemistry (IUPAC) and is shown in Fig.1. -
The Preparation and Reactions of the Lower Chlorides and Oxychlorides of Silicon Joseph Bradley Quig Iowa State College
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1926 The preparation and reactions of the lower chlorides and oxychlorides of silicon Joseph Bradley Quig Iowa State College Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Inorganic Chemistry Commons Recommended Citation Quig, Joseph Bradley, "The preparation and reactions of the lower chlorides and oxychlorides of silicon " (1926). Retrospective Theses and Dissertations. 14278. https://lib.dr.iastate.edu/rtd/14278 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UlVli films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and impiroper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overiaps. -
Unit 2 Matter and Chemical Change
TOPIC 5 The Periodic Table By the 1850s, chemists had identified a total of 58 elements, and nobody knew how many more there might be. Chemists attempted to create a classification system that would organize their observations. The various “family” systems were useful for some elements, but most family relationships were not obvious. What else could a classification system be based on? By the 1860s several scientists were trying to sort the known elements according to atomic mass. Atomic mass is the average mass of an atom of an element. According to Dalton’s atomic theory, each element had its own kind of atom with a specific atomic mass, different from the Figure 2.31 Dmitri atomic mass of any other elements. One scientist created a system that Ivanovich Mendeleev was so accurate it is still used today. He was a Russian chemist named was born in Siberia, the Dmitri Mendeleev (1834–1907). youngest of 17 children. Mendeleev Builds a Table Mendeleev made a card for each known element. On each card, he put data similar to the data you see in Figure 2.32. Figure 2.32 The card above shows modern values for silicon, rather than the ones Mendeleev actually used. His values were surprisingly close to modern ones. The atomic mass measurement indicates that silicon is 28.1 times heavier than hydrogen. You can observe other properties of silicon in Figure 2.33. Mendeleev pinned all the cards to the wall, in order of increasing atomic mass. He “played cards” for several Figure 2.33 The element silicon is melted months, arranging the elements in vertical columns and and formed into a crystal. -
Effects of Sio2/Al2o3 Ratios on Sintering Characteristics of Synthetic Coal Ash
Article Effects of SiO2/Al2O3 Ratios on Sintering Characteristics of Synthetic Coal Ash Hongwei Hu 1, Kun Zhou 1, Kesheng Meng 1,2, Lanbo Song 1 and Qizhao Lin 1,* 1 Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China; [email protected] (H.H.); [email protected] (K.Z.); [email protected] (K.M.); [email protected] (L.S.) 2 Anhui Civil Aviation Airport Group, Hefei 230086, China * Correspondence: [email protected]; Tel.: +86-551-6360-0430; Fax: +86-551-6360-3487 Academic Editor: Mehrdad Massoudi Received: 01 December 2016; Accepted: 14 February 2017; Published: 16 February 2017 Abstract: This article explores the effects of SiO2/Al2O3 ratios (S/A) on sintering characteristics and provides guidance for alleviating ash depositions in a large-scale circulation fluidized bed. Five synthetic coal ash (SCA) samples with different S/As were treated in a muffle furnace for 12 h at different temperatures (from 773 K to 1373 K, in 100 K intervals). The morphological and chemical results of the volume shrinkage ratio (VSR), thermal deformation analysis by dilatometer (DIL), scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), and X-ray diffraction (XRD) were combined to describe the sintering characteristics of different samples. The results showed that the sintering procedure mainly occurred in the third sintering stage when the temperature was over 1273 K, accompanied with significant decreases in the VSR curve. Excess SiO2 (S/A = 4.5) resulted in a porous structure while excess Al2O3 (S/A = 0.5) brought out large aggregations. -
Nanoparticle Sintering
Application Note Nanoparticle Sintering Introduction the catalyst to be studied, and (iii) is observed (Fig. 2a). Analysis of Δλ preventing the catalyst from directly during the course of the experiment, Catalyst sintering is a major cause of interacting with the Au nanodisks by shows that the LSPR shifts fast in catalyst deactivation, which yearly e.g. alloy formation. the beginning and then more slowly causes billions of dollars of extra cost The Pt model catalyst is formed onto towards the end of the experiment associated with catalyst regeneration the sensor chip by evaporating a 0.5 (Fig. 2b, black curve). In contrast, and renewal. nm thick (nominal thickness) granu- when the same experiment is per- In order to develop more sintering- lar film. This results in individual Pt formed in pure Ar (or in 4% O2 on resistant catalysts, a detailed under- nanoparticles with an average diam- a “blank” sensor without Pt) no standing of the sintering kinetics and eter of <D> = 3.3 nm (+/- 1.1 nm), significant shift during the entire ex- mechanisms is required. It is therefore which mimics the size range of real periment is observed (Fig. 2b, blue of great importance to investigate sin- supported catalysts. curve). These results indicate that tering in situ, in real time and under The change of the localized surface INPS can be used to monitor the realistic catalyst operation conditions plasmon resonance (LSPR) centroid sintering of nanoparticle catalysts (i.e. at high temperatures and pres- wavelength, Δλ, is monitored during (since O2 is a known sintering pro- sures in reactive gas atmospheres). -
Directed Gas Phase Formation of Silicon Dioxide and Implications for the Formation of Interstellar Silicates
ARTICLE DOI: 10.1038/s41467-018-03172-5 OPEN Directed gas phase formation of silicon dioxide and implications for the formation of interstellar silicates Tao Yang 1,2, Aaron M. Thomas1, Beni B. Dangi1,3, Ralf I. Kaiser 1, Alexander M. Mebel 4 & Tom J. Millar 5 1234567890():,; Interstellar silicates play a key role in star formation and in the origin of solar systems, but their synthetic routes have remained largely elusive so far. Here we demonstrate in a combined crossed molecular beam and computational study that silicon dioxide (SiO2) along with silicon monoxide (SiO) can be synthesized via the reaction of the silylidyne radical (SiH) with molecular oxygen (O2) under single collision conditions. This mechanism may provide a low-temperature path—in addition to high-temperature routes to silicon oxides in circum- stellar envelopes—possibly enabling the formation and growth of silicates in the interstellar medium necessary to offset the fast silicate destruction. 1 Department of Chemistry, University of Hawai’iatMānoa, Honolulu, HI 96822, USA. 2 State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China. 3 Department of Chemistry, Florida Agricultural and Mechanical University, Tallahassee, FL 32307, USA. 4 Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. 5 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN, UK. Correspondence and requests for materials should be addressed to R.I.K. (email: [email protected]) or to A.M.M. (email: mebela@fiu.edu) or to T.J.M. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:774 | DOI: 10.1038/s41467-018-03172-5 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-03172-5 — 28 + 28 + he origin of interstellar silicate grains nanoparticles ( SiO2 ), and 44 ( SiO ). -
High Density Sintering of Ikon-Carbon Alloys Via
TWO-WEEK lOAN COPY This a Ubrar~ Circulating Cop~ which rna~ be borrowed for two weeks. For a personal retention cop~, call Tech. Info. Dioision, Ext. 6782 LBL tf8001 HIGH DENSITY SINTERING OF IRON-CARBON ALLOYS VIA TRANSIENT LIQUID PHASE Tin Tseuk Lam Materials and Molecular Research Division Lawrence Berkeley Laboratory and Department of Mechanical Engineering University of California Berkeley, California 94720 June 1978 HIGH DENSITY SINTERING OF IRON-CARBON ALLOYS VIA TRANSIENT LIQUID PHASE Abstract • , . v I. Introduction 1 II. Experimental Procedure 4 III. Experimental Results and Discussion . ' 8 IV. Conclusions 11 Acknowledgement , 12 References 13 Figure Captions 14 Figures 17 HIGH DENSITY SINTERING OF IRON~CARBON ALLOYS VIA TRANSIENT LIQUID PHASE Tin Tseuk Lam Materials and Molecular Research Division Lawrence Berkeley Laboratory and Department of Mechanical Engineering Uni vers1ty of California Berkeley, California 94720 ABSTRACT Because of the transient presence of a liquid phase during sintering of graphite coated iron powder, a high percentage (95% ~ 99.4%) of theoretical density can be achieved in a short time ( -10 min.) and at a moderate temperature (1175°C). As a result, the mechanical properties of the graphite coated sintered steel are close to those of commercial plain carbon steels and much better than those of commercial powder metallurgy sintered steels. In addition, the physical and mechanical properties of Fe 2%C 20%W were studied in the as~sintered condition. I Introduction The primary objective of this research project was to develop iron base materials with useful mechanical properties via a practical powder metallurgical process. Steels are very useful engineering materials. -
Alumina : Sintering and Optical Properties
Alumina : sintering and optical properties Citation for published version (APA): Peelen, J. G. J. (1977). Alumina : sintering and optical properties. Technische Hogeschool Eindhoven. https://doi.org/10.6100/IR4212 DOI: 10.6100/IR4212 Document status and date: Published: 01/01/1977 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. -
Periodic Trends Lab CHM120 1The Periodic Table Is One of the Useful
Periodic Trends Lab CHM120 1The Periodic Table is one of the useful tools in chemistry. The table was developed around 1869 by Dimitri Mendeleev in Russia and Lothar Meyer in Germany. Both used the chemical and physical properties of the elements and their tables were very similar. In vertical groups of elements known as families we find elements that have the same number of valence electrons such as the Alkali Metals, the Alkaline Earth Metals, the Noble Gases, and the Halogens. 2Metals conduct electricity extremely well. Many solids, however, conduct electricity somewhat, but nowhere near as well as metals, which is why such materials are called semiconductors. Two examples of semiconductors are silicon and germanium, which lie immediately below carbon in the periodic table. Like carbon, each of these elements has four valence electrons, just the right number to satisfy the octet rule by forming single covalent bonds with four neighbors. Hence, silicon and germanium, as well as the gray form of tin, crystallize with the same infinite network of covalent bonds as diamond. 3The band gap is an intrinsic property of all solids. The following image should serve as good springboard into the discussion of band gaps. This is an atomic view of the bonding inside a solid (in this image, a metal). As we can see, each of the atoms has its own given number of energy levels, or the rings around the nuclei of each of the atoms. These energy levels are positions that electrons can occupy in an atom. In any solid, there are a vast number of atoms, and hence, a vast number of energy levels. -
A Review of the Diamond Retention Capacity of Metal Bond Matrices
Review A Review of the Diamond Retention Capacity of Metal Bond Matrices Xiaojun Zhao and Longchen Duan * Faculty of Engineering, China University of Geosciences, Wuhan 430074, China; [email protected] * Correspondence: [email protected]; Tel.: +86-138-8608-1092 Received: 30 March 2018; Accepted: 27 April 2018; Published: 29 April 2018 Abstract: This article presents a review of the current research into the diamond retention capacity of metal matrices, which largely determines the service life and working performance of diamond tools. The constitution of diamond retention capacity, including physical adsorption force, mechanical inlaying force, and chemical bonding force, are described. Improved techniques are summarized as three major types: (1) surface treatment of the diamond: metallization and roughening of the diamond surface; (2) modification of metal matrix: the addition of strong carbide forming elements, rare earth elements and some non-metallic elements, and pre-alloying or refining of matrix powders; (3) change in preparation technology: the adjustment of the sintering process and the application of new technologies. Additionally, the methods used in the evaluation of diamond retention strength are introduced, including three categories: (1) instrument detection methods: scanning electron microscopy, X-ray diffractometry, energy dispersive spectrometry and Raman spectroscopy; (2) mechanical test methods: bending strength analytical method, tension ring test method, and other test methods for chemical bonding strength; (3) mechanical calculation methods: theoretical calculation and numerical computation. Finally, future research directions are discussed. Keywords: diamond retention capacity; holding strength; bonding strength; metal matrix; improved techniques; evaluation methods 1. Introduction Diamond tools are widely used for cutting, grinding, sawing, drilling, and polishing hard materials, such as stone, concrete, cemented carbides, optical glass, advanced ceramics, and other difficult-to-process materials [1–3]. -
Properties of Silicon Hafensteiner
Baran Lab Properties of Silicon Hafensteiner Si vs. C Siliconium Ion - Si is less electronegative than C - Not believed to exist in any reaction in solution - More facile nucleophilic addition at Si center J. Y. Corey, J. Am. Chem. Soc. 1975, 97, 3237 - Pentacoordinate Si compounds have been observed Average BDE (kcal/mol) MeSiF4 NEt4 Ph3SiF2 NR4 C–C C–Si Si–Si C–F Si–F 83 76 53 116 135 - Lack of cation justified by high rate of bimolecular reactivity at Si C–O Si–O C–H Si–H Mechanism of TMS Deprotection 86 108 83 76 OTMS O Average Bond Lengths (Å) C–C C–Si C–O Si–O 1.54 1.87 1.43 1.66 Workup Si Si Silicon forms weak p-Bonds O O F F NBu4 p - C–C = 65 kcal/mol p - C–Si = 36 kcal/mol Pentavalent Silicon Baran Lab Properties of Silicon Hafensteiner Nucleophilic addition to Si b-Silicon effect and Solvolysis F RO–SiMe3 RO F–SiMe3 SiMe3 Me H H vs. Me3C H Me3C H OSiMe O Li 3 H OCOCF H OCOCF MeLi 3 3 A B Me-SiMe3 12 kA / kB = 2.4 x 10 Duhamel et al. J. Org. Chem. 1996, 61, 2232 H H SiMe Me b-Silicon Effect 3 vs. Me3C H Me3C H - Silicon stabalizes b-carbocations H OCOCF3 H OCOCF3 - Stabalization is a result of hyperconjugation 4 kA / kB = 4 x 10 SiR3 CR3 Evidence for Stepwise mechanism vs. Me3Si SiMe2Ph SiMe2Ph A B Me3Si SiMe2Ph *A is more stable than B by 38 kcal/mol * Me3Si SiMe2Ph Me3Si Jorgensen, JACS, 1986,107, 1496 Product ratios are equal from either starting material suggesting common intermediate cation Baran Lab Properties of Silicon Hafensteiner Evidence for Rapid Nucleophilic Attack Extraordinary Metallation Me SiMe3 SiMe3 Li Si t-BuLi Me SnCl4 Cl Me3Si Cl Me2Si Cl SiMe MeO OMe 3 OMe OMe Me2Si Cl vs.