scholarly journals MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATION OF CONSOLIDATED NANO- AND MICRON- SIZE Cu POWDERS

2012 ◽  
Vol 05 ◽  
pp. 18-23
Author(s):  
A. SALEH ◽  
S. HESHMATI-MANESH ◽  
A. ATAIE ◽  
S. SHEIBANI
Keyword(s):  
Crystallite Size ◽  
Mechanical Characterization ◽  
Sintering Temperature ◽  
Sem Images ◽  
Crystalline Sample ◽  
Nano Crystalline ◽  
Micron Size ◽  
The Mean ◽  
Cold Pressed

In this paper, nano-crystalline Cu powder with a mean crystallite size of 45 nm and commercial micron-size Cu powder were either hot pressed or cold pressed and sintered conventionally to fabricate bulk samples. Hardness, density, crystallite size and microstructure of the samples after consolidation were examined. The results show that the hardness of the hot pressed nano-crystalline Cu is in the range of 0.75-1.2 GPa which is higher than that of commercial Cu . The density of the bulk nano-crystalline sample showed that the rising sintering temperature increases the density up to 97% of the theoretical value. The mean crystallite size of the hot pressed sample was 64 nm, which still was in the nano scale. The scanning electron microscopy (SEM) images revealed that the hot pressed samples contain less porosities compared to the conventionally consolidated samples.

scholarly journals HDPE/SILICA COMPOSITES- PART I: PREPARATION AND CHARACTERIZATION OF METHYLSILANE AND OCTYLSILANE-MODIFIED SILICAS

2019 ◽  
Vol 16 (32) ◽  
pp. 263-278
Author(s):  
Vanessa Machado Babinski RAMOS ◽  
Maurício Gammertt RÖHNELT ◽  
Rodrigo BRAMBILLA
Keyword(s):  
Silica Gel ◽  
Morphological Characteristics ◽  
Specific Area ◽  
Sem Images ◽  
Adsorption Sites ◽  
Pyrogenic Silica ◽  
The Mean ◽  
Complementary Techniques ◽  
Adsorption Desorption

This paper reports the main results concerning the synthesis and characterization of methylsilane and octylsilane-modified silicas. The modification of the silicas with these groups aims to make the silica surface hydrophobic and thus compatible with high-density polyethylene (HDPE) in HDPE/silica composites. In the present work, two types of silica were organofunctionalized: a pyrogenic silica and a silica gel. The silicas were characterized by a series of complementary techniques with the objective of investigating the nature of the surface species and their textural and morphological characteristics. The SEM images showed that the modification of the silicas with organosilanes has been not resulted in changes on the morphology and on the size of silica particles. In relation to the texture properties, determined by N2 adsorption-desorption porosimetry, the silica modification resulted in a decrease of the specific area (SBET) and the mean pore volume, a behavior attributed to the partial coverage of the adsorption sites by the organosilane molecules. The TGA analysis showed that both the methylsilane groups and the octylsilane groups on the surface of silica and silica gel are thermally stable up to 200 ° C, which enables the organofunctionalized silicas in terms of thermal stability, for the process of preparing the composites by extrusion. The results of applying these organofunctionalized silicas in the development of HDPE/silica composites will be presented in a subsequent article, part II of this research.

scholarly journals Investigation of Ferrimagnetic Sr-hexaferrite Nanocrystals for Clinical Hyperthermia

2021 ◽  
pp. X
Author(s):  
Burcu ERTUĞ
Keyword(s):  
Crystallite Size ◽  
Room Temperature ◽  
Vibrating Sample Magnetometry ◽  
Sem Images ◽  
Ceramic Method ◽  
X Ray ◽  
The Mean ◽  
Xrd Patterns ◽  
Potential Use ◽  
Scanning Electron

Sr-hexaferrite samples were produced via the conventional ceramic method. X-ray diffractometry (XRD) patterns confirmed the single nanocrystal phase as Sr-hexaferrite where any pattern peaks of unreacted Fe2O3 phase were  not detected. The mean crystallite size values were determined to be 44.12±3.4nm and 41.2±3.2nm for SHF-O1 and SHF-O2, respectively. The chemical bonding peaks of our sample indicated that the structure of Sr-hexaferrite formation was confirmed by FTIR spectra result. Scanning electron microscopy (SEM) images indicated clearly observed porosity regions with relative densities as high as 94% and 87% for SHF-O1 and SHF-O2 samples.The vibrating sample magnetometry (VSM) of each sample at 2K and under a magnetic field of 10 kOe yielded saturation magnetizations, Ms of 93.5 and 94.1 emu/g; remanence values, Mr of 76.4 and  67.8 emu/g for SHF-O1 and SHF-O2, respectively. The magnetization loops of both samples indicated a soft ferrimagnetic behaviour in which the saturation magnetizations were higher than those measured  at room temperature in the previous studies. The coercivities, Hc were measured to be 150Oe for both samples. The squareness values, SQR (Mr/Ms) were measured to be high, approximately 0.82 and 0.72 for SHF-O1 and SHF-O2, respectively. Depending on the adequate values of magnetization and coercivity along with small mean crystallite size and low porosity values of the obtained Sr-hexaferrite samples, we estimate that these samples are likely to be evaluated further for the potential use as thermoseeds in the field of clinical hyperthermia.

Preparation and Characterization of β-SiAlON Ceramics from High Aluminium Fly Ash via Carbothermal Reduction-Nitridation

2007 ◽  
Vol 561-565 ◽  
pp. 587-590 ◽  
Author(s):  
Jin Hong Li ◽  
Hong Wen Ma ◽  
Ying Cao
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Physicochemical Properties ◽  
Water Absorption ◽  
Bulk Density ◽  
Carbothermal Reduction ◽  
Sintering Temperature ◽  
Sem Images ◽  
High Aluminium

In this work, β-sialon ceramics were prepared from high-aluminium fly ash via carbothermal reduction-nitridation (CRN) and the physicochemical properties of the materials such as bulk density, apparent porosity, water absorption and flexural strength were also discussed. The results showed that the percentage of β-sialon phase in the product decreases as the temperature increases from 1400°C and the weight of the sintered specimen experienced an increase during 1350°C~1450°C due to the nitridation reactions, and followed by a gradual decrease till 1550°C for the decomposition of β-sialon. It is indicated that the optimum sintering temperature to obtain the highest yield of β-sialon ~93% lies in 1400°C~1450°C. The SEM images revealed that the prepared β-sialon sintered at 1400°C were mainly in shape of elongated prisms, typically ~5μm in length and 0.5~1μm in width. As the temperature increased to 1500°C and above, β-sialon decomposed and the new phases of SiC and AlN were formed at 1550°C as confirmed by XRD.

Elaboration and Mechanical Characterization of Al2O3-ZrO2-YAG Ultrafine Composites

2010 ◽  
Vol 62 ◽  
pp. 76-81 ◽  
Author(s):  
Paola Palmero ◽  
Valentina Naglieri ◽  
Giulia Spina ◽  
Laura Montanaro
Keyword(s):  
Mechanical Characterization ◽  
Alumina Powder ◽  
Nano Crystalline ◽  
Slip Cast ◽  
Second Phases ◽  
Crystalline Alumina ◽  
Inorganic Precursors ◽  
Full Densification

Al2O3-YAG-ZrO2 composites have been produced by surface modification of a commercial nano-crystalline alumina powder with inorganic precursors of the desired second phases. The doped powders were calcined at various temperatures and for different times: as a function of the thermal treatment, zirconia directly crystallized on the alumina surface, while YAG phase was yielded by solid state reaction among an amorphous yttrium-rich precursor and alumina powder. Several compositions, with increasing second phases volume fractions, were investigated, precisely, Alumina-5vol.%YAG-5vol.%ZrO2, Alumina-20vol.%YAG-20vol.%ZrO2 and Alumina- 33vol.%YAG-33vol.%ZrO. Slip cast bodies were produced by aqueous suspensions of calcined and well-dispersed powders; free-sintering performed at 1500°C for 3 h allowed to reach full densification. The role of the second phases amount on the microstructural features and on some mechanical data preliminary evaluated was established.

Effect of mechanical alloying on the synthesis of Fe-TiC nanocomposite

2017 ◽  
Vol 24 (5) ◽  
pp. 739-745 ◽  
Author(s):  
Ali Reza Jam ◽  
Mansour Razavi ◽  
Leila Nikzad
Keyword(s):  
Mechanical Alloying ◽  
Crystallite Size ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Sem Images ◽  
The Mean ◽  
Xrd Patterns ◽  
Tic Particulates ◽  
Mean Strain ◽  
Microstructural Studies

AbstractTiC particulates-reinforced Fe-based nanocomposites were fabricated using ferrotitanium and carbon black powders by mechanical alloying (MA). The raw materials were milled in a planetary ball mill and sampled in different times. The phase type, crystallite size, and mean strain of milled samples were estimated by X-ray diffraction (XRD) instrument. The scanning electron microscopy (SEM) images of milled powders showed that titanium carbide was synthesized gradually after 90 min of milling and its formation was completed after 5 h and the crystallite size of the produced carbide was in nanometer scale. Increasing milling times gave rise to the reduction of crystallite size as well as the augmentation of the mean strain. Microstructural studies confirmed the accuracy of crystallite size calculations by XRD patterns.

Morphological and Structural Characterization of YSZ Thin Film Fabricated by Electrophoretic Deposition on LSM/YSZ Substrate

2018 ◽  
Vol 775 ◽  
pp. 224-228
Author(s):  
Alexis Karla Garcia ◽  
Rinlee Butch M. Cervera
Keyword(s):  
Electrophoretic Deposition ◽  
Sintering Temperature ◽  
Deposition Process ◽  
The Other ◽  
Film Morphology ◽  
Average Thickness ◽  
Sem Images ◽  
Ysz Thin Film ◽  
Xrd Patterns

YSZ film was fabricated by a facile electrophoretic deposition process using commercial YSZ powders. YSZ films with average thickness of around 10 µm were deposited on LSM/YSZ substrate at 20 V for 20 minutes and subsequently sintered at 1200 °C, 1300 °C, and 1350°C. XRD patterns of the deposited and sintered films can be attributed to mostly cubic YSZ phase. On the other hand, SEM images revealed that a sintering temperature above 1300 °C was needed to obtain a denser YSZ film. The film morphology also showed that as the sintering temperature increases, the YSZ grain size also increases.

scholarly journals Preliminary Mechanical Characterization of the Small Bowel for In Vivo Robotic Mobility

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Benjamin S. Terry ◽  
Allison B. Lyle ◽  
Jonathan A. Schoen ◽  
Mark E. Rentschler
Keyword(s):  
Small Bowel ◽  
Coefficient Of Friction ◽  
Axial Length ◽  
Mechanical Characterization ◽  
Biaxial Stress ◽  
Biaxial Test ◽  
The Mean

In this work we present test methods, devices, and preliminary results for the mechanical characterization of the small bowel for intra luminal robotic mobility. Both active and passive forces that affect mobility are investigated. Four investigative devices and testing methods to characterize the active and passive forces are presented in this work: (1) a novel manometer and a force sensor array that measure force per cm of axial length generated by the migrating motor complex, (2) a biaxial test apparatus and method for characterizing the biomechanical properties of the duodenum, jejunum, and ileum, (3) a novel in vitro device and protocol designed to measure the energy required to overcome the self-adhesivity of the mucosa, and (4) a novel tribometer that measures the in vivo coefficient of friction between the mucus membrane and the robot surface. The four devices are tested on a single porcine model to validate the approach and protocols. Mean force readings per cm of axial length of intestine that occurred over a 15 min interval in vivo were 1.34 ± 0.14 and 1.18 ± 0.22 N cm−1 in the middle and distal regions, respectively. Based on the biaxial stress/stretch tests, the tissue behaves anisotropically with the circumferential direction being more compliant than the axial direction. The mean work per unit area for mucoseparation of the small bowel is 0.08 ± 0.03 mJ cm−2. The total energy to overcome mucoadhesion over the entire length of the porcine small bowel is approximately 0.55 J. The mean in vivo coefficient of friction (COF) of a curved 6.97 cm2 polycarbonate sled on live mucosa traveling at 1 mm s−1 is 0.016 ± 0.002. This is slightly lower than the COF on excised tissue, given the same input parameters. We have initiated a comprehensive program and suite of test devices and protocols for mechanically characterizing the small bowel for in vivo mobility. Results show that each of the four protocols and associated test devices has successfully gathered preliminary data to confirm the validity of our test approach.

Structural Characterization of Nano-Crystalline BaTiO3 Powder Prepared Using Hydrothermal Method

2011 ◽  
Vol 324 ◽  
pp. 205-208 ◽  
Author(s):  
Ziyad S. A. Al Sarraj ◽  
Mukhlis M. Ismail ◽  
Sabah M. Ali ◽  
Wan Q. Cao
Keyword(s):  
Ftir Spectroscopy ◽  
Crystallite Size ◽  
Structural Characterization ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Nano Crystalline ◽  
Vibrational Bands ◽  
Ft Raman

BaTiO3powders were prepared hydrothermally using TiCl4, Ba(OH)2.8H2O and NH4OH as starting materials at 150°C for 2h. The structure of the prepared nanocystalline BT powders were a metastable cubic perovskite according to XRD and HRTEM analysis, while FT Raman spectra showed that BT powders have a tetragonal structure. Hydroxyl and carbonate groups were observed in all prepared powders that showed in FTIR spectroscopy as vibrational bands. The tetragonal phase of BT powder was identified clearly by slow scan XRD at 2θ between 44.6 to 46°. The crystallite size of BT powders have increased with the increase of annealing temperature from 19 nm at room temperature to 70 nm at 1000°C.

Processing and characterization of YBa2Cu3O7−x/Ag composites

1990 ◽  
Vol 48 (4) ◽  
pp. 46-47
Author(s):  
Jafar Javadpour ◽  
Bradley L. Thiel ◽  
Sarikaya Mehmet ◽  
Ilhan A. Aksay
Keyword(s):  
Composite System ◽  
Precursor Solution ◽  
Microstructural Development ◽  
Superconducting Properties ◽  
Practical Applications ◽  
Nitrate Precursor ◽  
Cold Pressed ◽  
Tape Cast ◽  
Composite Samples

Practical applications of bulk YBa2Cu3O7−x materials have been limited because of their inadequate critical current density (jc) and poor mechanical properties. Several recent reports have indicated that the addition of Ag to the YBa2Cu3O7−x system is beneficial in improving both mechanical and superconducting properties. However, detailed studies concerning the effect of Ag on the microstructural development of the cermet system have been lacking. Here, we present some observations on the microstructural evolution in the YBa2Cu3O7−x/Ag composite system.The composite samples were prepared by mixing various amounts (2.5 - 50 wt%) AgNO3 in the YBa2Cu3O7−x nitrate precursor solution. These solutions were then spray dried and the resulting powders were either cold pressed or tape cast. The microstructures of the sintered samples were analyzed using SEM (Philips 515) and an analytical TEM (Philips 430T).The SEM micrographs of the compacts with 2.5 and 50 wt% Ag addition sintered at 915°C (below the melting point of Ag) for 1 h in air are displayed in Figs. 1 and 2, respectively.

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