scholarly journals Structure-Property Correlation in Ir Transparent Zinc Sulphide (Zns) Ceramics Under Chemical Vapour Deposited & Hot Iso-Statically Pressed Conditions

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Grain Size ◽  
Hot Isostatic Pressing ◽  
Chemical Vapour ◽  
Complex Impedance ◽  
Ac Impedance ◽  
Spectroscopic Studies ◽  
Structure Property ◽  
Frequency Range ◽  
Equivalent Circuit Analysis ◽  
Isostatic Pressing

IR Transparent ZnS ceramics processed through chemical vapour deposition were subjected to Hot Isostatic pressing and the samples in both the conditions were characterized by XRD, microstructure and high temperature impedance spectroscopic studies for the dielectric and electrical properties. Both the samples have shown cubic sphalerite phase with enhanced orientation along (111) plane as a result of hot isostatic pressing as revealed by XRD.HIP treatment to ZnS facilitated the enhancement of the homogeneity of microstructure and enhancement in the grain size from 10μm to 50μm. The electrical behavior of both the samples was investigated by AC impedance spectroscopy in the frequency range 1Hz to 1MHz from RT to 500°C in dry air. HIP has resulted in a significant increase in the dielectric constant, which can be attributed to the increase in homogeneity and the grain size. Further, the complex impedance plots exhibited two impedance semicircles identified in the frequency range is explained by the grain and grain boundary effects. An equivalent-circuit analysis of AC impedance spectra based on the brick-layer model was performed. Activation energies obtained from the conductivity plots indicates an Arrhenius type thermally activated process.

Effect of Sintering Temperature on Structure and Dielectric Properties of Lead Free K0.5Na0.5NbO3 Prepared via Hot Isostatic Pressing

2017 ◽  
Vol 888 ◽  
pp. 42-46 ◽  
Author(s):  
Fatin Khairah Bahanurdin ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Hot Isostatic Pressing ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Tangent Loss ◽  
Isostatic Pressing ◽  
Tan Δ

In this research, alkaline niobate known as K0.5Na0.5NbO3 (KNN) lead-free piezoelectric ceramic was synthesis by solid state reaction method which pressing at different sintering temperatures (1000 °C and 1080 °C) prepared via hot isostatic pressing (HIP)). The effect of sintering temperature on structure and dielectric properties was studied. The optimum sintering temperature (at 1080 °C for 30 minutes) using hot isostatic pressing (HIP) was successfully increase the density, enlarge the particle grain size in the range of 0.3 µm – 2.5 µm and improves the dielectric properties of K0.5Na0.5NbO3 ceramics. The larger grain size and higher density ceramics body will contribute the good dielectric properties. At room temperature, the excellent relative permittivity and tangent loss recorded at 1 MHz (ɛr = 5517.35 and tan δ = 0.954), respectively for KNN1080HIP sample. The KNN1080HIP sample is also exhibits highest relative density which is 4.485 g/cm3. The ɛr depends upon density and in this work, the density increase as the sintering temperature increase, which resulting the corresponding ɛr value also increases.

Mechanical properties and low-temperature aging of tetragonal zirconia polycrystals processed by hot isostatic pressing

2003 ◽  
Vol 18 (10) ◽  
pp. 2415-2426 ◽  
Author(s):  
J. Muñoz-Saldaña ◽  
H. Balmori-Ramírez ◽  
D. Jaramillo-Vigueras ◽  
T. Iga ◽  
G. A. Schneider
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Low Temperature ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Hot Water ◽  
Full Density ◽  
Isostatic Pressing ◽  
Low Temperature Aging ◽  
Temperature Aging

The influence of grain size and density of yttria-tetragonal zirconia polycrystals (Y-TZPs) ceramics on mechanical properties and on low-temperature aging degradation (LTD) in air and in hot water was investigated. A TZP powder containing 3 mol% Y2O3 was consolidated by slip casting and densified by the sintering/hot isostatic pressing (HIP) method. Only the presintered samples that contained less than 0.15% open porosity reached near full density after HIP. The best conditions to reach full density were found to be attained by presintering and HIP both at 1400 °C. At these conditions, some of the best mechanical properties such as modulus of rupture and Weibull modulus reached 1397 ± 153 MPa and, 10.6, respectively. These values were clearly higher than those obtained from sintered bodies and samples hot isostatically pressed at 1600 °C. Aging degradation of 3Y-TZP materials can be avoided through microstructural design. Fully dense materials with a critical grain size <0.36 μm did not show any evidence of degradation after extreme aging conditions at pressurized autoclaving in hot water at 100, 200, and 260 °C for 8 h. We propose a criterion to predict degradation in air as well as in hot water for the characterized materials based on the microstructure and density control of the samples.

Simultaneous Synthesis and Sintering of Al2O3/Mo2N Composites Using Capsule-Free Nitrogen Hot Isostatic Pressing and their Characterization

2010 ◽  
Vol 62 ◽  
pp. 197-202
Author(s):  
Hirota Ken ◽  
Takaoka Katsuya ◽  
Murase Yasushi ◽  
Kato Masaki
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Isostatic Pressing ◽  
Simultaneous Synthesis ◽  
Powder Compacts ◽  
Al2o3 Matrix

Synthesis of dense materials with the compositions of Al2O3/Mo2N=100/0 ~ 40/60 vol% has been attempted directly from Al2O3/Mo mixed raw powder compacts using capsule-free N2 hot isostatic pressing (HIP). During HIPing [1500°C/(16~20)MPa]/1h], solid/gas reaction between Mo and N2 was introduced to form Mo2N. Most sintered composites consisting of only Al2O3 and Mo2N phases reached a higher relative density than 98.0% with closed pores nevertheless capsule-free HIPing. Distribution of Mo2N particles just formed suppressed the grain growth of Al2O3 during sintering. Mechanical properties, such as bending strength (Σb), Vickers hardness (HV), fracture toughness (K1C), and other properties have been evaluated as a function of their compositions. The best mechanical values of Σb (c.a. 573 MPa), HV (c.a. 20.3 GPa) and K1C (c.a. 5.00 MPa･m1/2) were attained at the composition of Al2O3/Mo2N=90/10 vol%, due to a high density (98.6%) and small grain size of Al2O3 matrix (Gs c.a. 4.70 μm). Further addition of Mo2N reduced the sinterability of matrix grains, resulting in low densities of around 90% at the 40/60 vol% composition.

High-temperature stability of nanocrystalline structure in a TiAl alloy prepared by mechanical alloying and hot isostatic pressing

1998 ◽  
Vol 13 (12) ◽  
pp. 3399-3410 ◽  
Author(s):  
O. N. Senkov ◽  
N. Srisukhumbowornchai ◽  
M. L. Öveçoglu ◽  
F. H. Froes
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Grain Growth ◽  
Hot Isostatic Pressing ◽  
Nanocrystalline Structure ◽  
Temperature Stability ◽  
Growth Exponent ◽  
Pinning Force ◽  
High Temperature Stability ◽  
Isostatic Pressing

A fully dense nanocrystalline compact of the Ti–47Al–3Cr (at. %) alloy was produced by mechanical alloying and hot isostatic pressing at 725 °C. Microstructure characteristics and grain growth behavior of this compact were studied after annealing for up to 800 h in the temperature range of 725 to 1200 °C, using analytical transmission electron microscopy techniques. The temperature and time dependencies of the grain sizes and the grain size distributions were determined. The grain growth occurred, with a timeand temperature-invariant single-peak grain size distribution (when normalized by the mean grain size), which was consistent with normal grain growth. The experimentally measured grain growth exponent decreased from 10 to 4.6 when the temperature was increased. The grain growth kinetics was described by a single thermally activated rate process limited by a permanent pinning force on the grain boundaries. The microhardness decreased on annealing and followed the Hall–Petch relationship with the parameters Hυo = 5.8 GPa and KH = 1.6 MPa m0.5.

Fabrication of dense nanocrystalline ZrO2−3 wt. % Y2O3 by hot-isostatic pressing

1998 ◽  
Vol 13 (7) ◽  
pp. 1875-1880 ◽  
Author(s):  
R. Chaim ◽  
M. Hefetz
Keyword(s):  
Grain Size ◽  
Hot Isostatic Pressing ◽  
Chemical Precipitation ◽  
Argon Pressure ◽  
Nitrate Salt ◽  
Salt Solutions ◽  
Isostatic Pressing ◽  
Temperature Range ◽  
Cold Pressed

Amorphous to nanocrystalline ZrO2−3 wt. % Y2O3 powders were formed by chemical precipitation from mixed nitrate salt solutions. The powders were cold pressed and presintered in air for 2 to 6 h within the temperature range of 1100 °C and 1300 °C. Hot isostatic pressing was performed for 2 to 3 h within the temperature range of 1150 °C to 1350 °C in argon pressure of 150 MPa. Fully dense pellets with grain size of 22 nm to 45 nm were formed by application of low presintering temperatures.

Effect of Processing Conditions on Microstructure and Mechanical Behaviour of Metals Sintered from Nanopowders

2012 ◽  
Vol 729 ◽  
pp. 49-54 ◽  
Author(s):  
Jenő Gubicza ◽  
Guy Dirras ◽  
Salah Ramtani
Keyword(s):  
Grain Size ◽  
Hot Isostatic Pressing ◽  
Handling Time ◽  
Amorphous Layer ◽  
Inert Atmosphere ◽  
Considerable Change ◽  
Plastic Behavior ◽  
Oxide Content ◽  
Powder Particle Size ◽  
Isostatic Pressing

The influence of the consolidation conditions on the microstructure and plastic behavior of ultrafine-grained Ni and Al sintered from nanopowders was studied. It was found that the smaller initial Ni powder particle size yielded a smaller grain size and a larger oxide content in the as-consolidated sample resulting in a higher strength and lower ductility. When the Ni nanopowder was in contact with air (instead of an inert atmosphere) during the short handling time before sintering, the oxide content increased without a considerable change of the grain size that also decreased the ductility. The reduced time and temperature in Spark Plasma Sintering compared to Hot Isostatic Pressing led to a smaller grain size that resulted in a higher strength of Ni. In the case of an Al nanopowder processed by Hot Isostatic Pressing at 450 °C, the consolidation was hindered by the strongly limited diffusion due to the presence of a rigid amorphous layer on the surface of particles. However, at the sintering temperature of 550 °C, the crystallization and the fragmentation of the layer occurred that yielded a better densification.

scholarly journals Electrical properties of magnesium titanate ceramics post-sintered by hot isostatic pressing

2017 ◽  
Vol 49 (4) ◽  
pp. 373-380
Author(s):  
Antonije Djordjevic ◽  
Dragan Olcan ◽  
Nina Obradovic ◽  
Vesna Paunovic ◽  
Suzana Filipovic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Negative Temperature Coefficient ◽  
Sintered Material ◽  
Hot Isostatic Pressing ◽  
Negative Temperature ◽  
Frequency Range ◽  
Free Atmosphere ◽  
Magnesium Titanate ◽  
Isostatic Pressing ◽  
Titanate Ceramics

Post-sintering of magnesium titanate ceramics by hot isostatic pressing (HIP) in an oxygen-free atmosphere significantly alters various electrical properties of the product. In particular, the sintered material becomes a semiconductor. The aims of this paper are: to extend our investigations of the electrical properties of this material by expanding the frequency range of measurements, to design interpolation formulas for the frequency dependence of the complex relative permittivity, and to propose HIP-sintered magnesium titanate as a material for thermistors that have a negative-temperature-coefficient resistance (NTCR), as well as for varistors.

scholarly journals Effect of Hot Isostatic Pressing on Microstructures and Mechanical Properties of Ti6Al4V Fabricated by Electron Beam Melting

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 593
Author(s):  
Changyong Liu ◽  
Zhuokeng Mai ◽  
Deng Yan ◽  
Mingguang Jiang ◽  
Yuhong Dai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Grain Size ◽  
Electron Beam ◽  
Electron Beam Melting ◽  
Hot Isostatic Pressing ◽  
Phase Ratio ◽  
Lamellar Thickness ◽  
Isostatic Pressing ◽  
Β Phase

This study investigated the effects of hot isostatic pressing (HIP) on the microstructures and mechanical properties of Ti6Al4V fabricated by electron beam melting (EBM). The differences of surface morphologies, internal defects, relative density, microstructures, textures, mechanical properties and tensile fracture between the as-built and HIPed samples were observed using various characterization methods including optical metallography microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) and tensile tests. It was found that the main effects of HIP on microstructures include—the increase of average grain size from 7.96 ± 1.21 μm to 11.34 ± 1.89 μm, the increase of α lamellar thickness from 0.71 ± 0.15 μm to 2.49 ± 1.29 μm and the increase of β phase ratio from 4.7% to 10.5% in terms of area fraction on the transversal section. The combinatorial effects including densification, increase of grain size, α lamellar thickness, β phase ratio, reduction of dislocation density and transformation of dislocation patterns contributed to the improvement of elongation and ductility of EBM-fabricated Ti6Al4V. Meanwhile, these effects also resulted in a slight reduction of the yield strength and UTS mainly due to the coarsening effect of HIP.

IMPEDANCE SPECTROSCOPIC STUDIES ON GdBi5Fe2Ti3O18 CERAMIC

2001 ◽  
Vol 15 (14) ◽  
pp. 2053-2065 ◽  
Author(s):  
N. V. PRASAD ◽  
G. PRASAD ◽  
T. BHIMASANKARAM ◽  
S. V. SURYANARAYANA ◽  
G. S. KUMAR
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Solid State Reaction Method ◽  
Spectroscopic Studies ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Reaction Method ◽  
Complex Impedance Measurement

GdBi 5 Fe 2 Ti 3 O 18 (GBFT), a compound of Aurivillius family, was prepared by solid state reaction method. Complex impedance measurement was made on these samples from room temperature to 500°C in the frequency range of 1 kHz–1 MHz. Cole–Cole plots were found to become very broad near 400°C. Dielectric and dc conductivity measurements were made on these samples. The results are analysed to understand the conductivity mechanism.

Sign in / Sign up

Export Citation Format

Share Document