Advances in Ultrasonic Disk Cutting and Precision Dimpling

1991 ◽  
Vol 254 ◽  
Author(s):  
Paul E. Fischione ◽  
Thomas F. Kelly ◽  
Amber M. Dalley ◽  
Louis M. Holzman ◽  
David Dawson-Elli
Keyword(s):  
Electronic Devices ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Single Specimen ◽  
Ion Milling ◽  
Analytical Results ◽  
Metal Ceramic ◽  
Made In

AbstractMany of today's advanced materials are prepared using a combination of ultrasonic disk cutting, dimpling, and ion milling. In order to optimize the analytical results from a single specimen, several improvements have been made in instrumentation for ultrasonic disk cutting. Also, a system has been developed for detecting either at or near-electron transparency in TEM specimens. Both of these aspects are described. Examples are provided for silicon, metal/ceramic composites and blanket substrate layers for electronic devices.

Microwave melting and processing of metal–ceramic composite castings

2016 ◽  
Vol 232 (7) ◽  
pp. 1235-1243 ◽  
Author(s):  
Satnam Singh ◽  
Dheeraj Gupta ◽  
Vivek Jain
Keyword(s):  
Microwave Heating ◽  
Ceramic Composite ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
X Ray Diffraction ◽  
Uniform Dispersion ◽  
Metal Ceramic ◽  
The Cost ◽  
Equiaxed Grain ◽  
Structure Properties

Applications of metal–ceramic composites are increasing in advanced materials field; however, efficient utilization of these materials depends on the cost involved in processing and structure–properties correlations. Processing of materials through microwave energy has already been accepted as a well-established route for many materials. In this work, composites of nickel-based metallic powder (matrix) and SiC powder (reinforcement) were successfully casted by microwave heating. The mechanism for the development of composite castings using microwaves is discussed with proper illustrations. The results of microstructure analysis of the developed cast revealed that uniform equiaxed grain growth with uniform dispersion of reinforcement. The results of X-ray diffraction analysis revealed that during microwave heating some metallurgical changes took place, which led to higher microhardness of cast. Micowave processed casting revealed lower defects (~1.75% porosity) and average Vickers microhardness of 920 ± 208 HV. This work reports the successful applications of microwaves in manufacturing, in the form of melting and casting of metallic powders.

scholarly journals Development of Novel Lightweight Metastable Metal–(Metal + Ceramic) Composites Using a New Powder Metallurgy Approach

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3283 ◽  
Author(s):  
Khin Sandar Tun ◽  
Akshay Padnuru Sripathy ◽  
Sravya Tekumalla ◽  
Manoj Gupta
Keyword(s):  
Powder Metallurgy ◽  
Synthesis Method ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Synthesis Process ◽  
Powder Metallurgy Method ◽  
Scanning Calorimetry ◽  
Intermetallic Formation ◽  
Metal Metal ◽  
Metal Ceramic

In the current study, metal–(metal + ceramic) composites composed of biocompatible elements, magnesium (Mg), zinc (Zn), calcium (Ca) and manganese (Mn) were synthesized using a sinter-less powder metallurgy method. The composite has a composition of Mg49Zn49Ca1Mn1 (wt.%) in which the compositional ratio between Mg and Zn was chosen to be near eutectic Mg-Zn composition. The synthesis method was designed to avoid/minimize intermetallic formation by using processing temperatures lower than the Mg-Zn binary eutectic temperature (~ 340 °C). The synthesis process involved extrusion of green compacts at two different temperatures, 150 °C and 200 °C, without sintering. Extrusion was performed directly on the green compacts as well as on the compacts soaked at temperatures of 150 °C and 200 °C, respectively. Microstructure and mechanical properties of the materials synthesized under various processing conditions were investigated. Effect of extrusion temperature as well as soaking temperature on the materials’ properties were also evaluated in details and different properties showed an optimum under different conditions. All the synthesized materials showed no evidence of intermetallic formation which was confirmed by SEM/EDS, XRD, and Differential Scanning Calorimetry (DSC) techniques. The study establishes development of unconventional metal–(metal + ceramic) eco-friendly composites and provides important insight into realizing certain properties without using sintering step thus to minimize the energy consumption of the process. The study also highlights the use of magnesium turnings (recyclability) to develop advanced materials.

Study of dislocation loops in Arsenic-Rich as-grown GaAs

1987 ◽  
Vol 45 ◽  
pp. 350-351
Author(s):  
Byung-Teak Lee
Keyword(s):  
Point Defects ◽  
Electronic Devices ◽  
Arsenic Concentration ◽  
Stoichiometric Compound ◽  
Dislocation Loops ◽  
Gaas Crystal ◽  
Ion Milling ◽  
Transmission Electron ◽  
Arsenic Source ◽  
High Arsenic

Grown-in dislocations in GaAs have been a major obstacle in utilizing this material for the potential electronic devices. Although it has been proposed in many reports that supersaturation of point defects can generate dislocation loops in growing crystals and can be a main formation mechanism of grown-in dislocations, there are very few reports on either the observation or the structural analysis of the stoichiometry-generated loops. In this work, dislocation loops in an arsenic-rich GaAs crystal have been studied by transmission electron microscopy.The single crystal with high arsenic concentration was grown using the Horizontal Bridgman method. The arsenic source temperature during the crystal growth was about 630°C whereas 617±1°C is normally believed to be optimum one to grow a stoichiometric compound. Samples with various orientations were prepared either by chemical thinning or ion milling and examined in both a JEOL JEM 200CX and a Siemens Elmiskop 102.

Biomimetic materials: An introduction

1992 ◽  
Vol 50 (2) ◽  
pp. 1020-1021 ◽  
Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay
Keyword(s):  
Self Assembly ◽  
Structural Control ◽  
Hierarchical Structures ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Length Scale ◽  
Spider Webs ◽  
Biomimetic Materials ◽  
Synthetic Materials ◽  
All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

scholarly journals Tough metal-ceramic composites with multifunctional nacre-like architecture

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Erik Poloni ◽  
Florian Bouville ◽  
Christopher H. Dreimol ◽  
Tobias P. Niebel ◽  
Thomas Weber ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Sol Gel ◽  
Ceramic Composites ◽  
High Fracture Toughness ◽  
Processing Route ◽  
High Fracture ◽  
Metal Ceramic ◽  
Attractive Option ◽  
Brick And Mortar ◽  
Robotic Applications

AbstractThe brick-and-mortar architecture of biological nacre has inspired the development of synthetic composites with enhanced fracture toughness and multiple functionalities. While the use of metals as the “mortar” phase is an attractive option to maximize fracture toughness of bulk composites, non-mechanical functionalities potentially enabled by the presence of a metal in the structure remain relatively limited and unexplored. Using iron as the mortar phase, we develop and investigate nacre-like composites with high fracture toughness and stiffness combined with unique magnetic, electrical and thermal functionalities. Such metal-ceramic composites are prepared through the sol–gel deposition of iron-based coatings on alumina platelets and the magnetically-driven assembly of the pre-coated platelets into nacre-like architectures, followed by pressure-assisted densification at 1450 °C. With the help of state-of-the-art characterization techniques, we show that this processing route leads to lightweight inorganic structures that display outstanding fracture resistance, show noticeable magnetization and are amenable to fast induction heating. Materials with this set of properties might find use in transport, aerospace and robotic applications that require weight minimization combined with magnetic, electrical or thermal functionalities.

Processing and Elastic Property Characterization of Porous SiC Preform for Interpenetrating Metal/Ceramic Composites

2012 ◽  
Vol 95 (10) ◽  
pp. 3078-3083 ◽  
Author(s):  
Siddhartha Roy ◽  
Karl Günter Schell ◽  
Ethel Claudia Bucharsky ◽  
Pascal Hettich ◽  
Stefan Dietrich ◽  
...  
Keyword(s):  
Elastic Property ◽  
Ceramic Composites ◽  
Metal Ceramic ◽  
Porous Sic ◽  
Property Characterization

InSb Czochralski Growth Single Crystals for InGaSb Substrates

2014 ◽  
Vol 1616 ◽  
Author(s):  
J. E. Flores Mena ◽  
R. Castillo Ojeda ◽  
J. Díaz Reyes
Keyword(s):  
Low Cost ◽  
Electronic Devices ◽  
Czochralski Method ◽  
Liquid Nitrogen Temperature ◽  
Longitudinal Optical ◽  
Czochralski Growth ◽  
Etch Pit ◽  
Growth System ◽  
Radiation Sensors ◽  
Made In

ABSTRACTThe massive crystal growth of single crystal semiconductors materials has been of fundamental importance for the actual electronic devices industry. As a consequence of this one, we can obtain easily a large variety of low cost devices almost as made ones of silicon. Nowadays, the III-V semiconductors compounds and their alloys have been proved to be very important because of their optical properties and applications. It is the case of the elements In, Ga, As, Sb, which can be utilized for the fabrication of radiation sensors. In this work we present the results obtained from the ingots grown by the Czochralski method, using a growth system made in home. These results include anisotropic chemical attacks in order to reveal the crystallographic orientation and the possible polycrystallinity. Isotropic chemical attacks were made to evaluate the etch pit density. Metallographic pictures of the chemical attacks are presented in this work. Among the results of these measurements, the best samples presented in this work showed mobilities of 62.000 cm2/V*s at room temperature and 99.000 cm2/V*s at liquid nitrogen temperature. Typical pit density was 10,000/cm2. The Raman spectra present two dominant peaks associated at Transversal Optical (TO)- and Longitudinal Optical (LO)-InSb, the first vibrational mode is dominant due to the crystalline direction of the ingots and second one is associated to high defects density.

Sol-gel control of the micro/nanostructure of functional ceramic-ceramic and metal-ceramic composites

1998 ◽  
Vol 13 (4) ◽  
pp. 803-811 ◽  
Author(s):  
Philippe Colomban
Keyword(s):  
Sol Gel ◽  
Ceramic Composites ◽  
Matrix Interface ◽  
Specific Chemical ◽  
Fine Powders ◽  
Metal Ceramic ◽  
Long Life ◽  
Fiber Matrix Interface ◽  
3D Composite ◽  
Functional Ceramic

The problems encountered to tailor simultaneously various specific chemical or physical properties are discussed. Selected polymeric precursors used in association with fine powders allow the control of the nano/microstructure of composites and hence the preparation of functional (FGM) and hierarchical reinforced (HRC) composites, making it possible to combine several kinds of fibers, interphases, and matrices in the same composite (hot microwave absorbent), to control the fiber/matrix interface (long life times composites), to achieve net-shape sintering of 3D composite matrices, and to prepare thick films of metal-ceramic composites with tailored microwave absorption (radar stealthiness).

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