Tribology in Superplastic Forming Processing of 3Y-TZP/Al2O3 Ceramic at Elevated Temperatures

2007 ◽  
Vol 551-552 ◽  
pp. 507-512
Author(s):  
F. Wang ◽  
Kai Feng Zhang ◽  
Wen Bo Han
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Friction Factor ◽  
Elevated Temperatures ◽  
Hexagonal Boron Nitride ◽  
Superplastic Forming ◽  
Ceramic Materials ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Higher Temperature

Superplastic forming processing of ceramic materials at high temperatures and high pressure puts forward very high requests to moulds and lubricants, at which conditions seeking for appropriate lubricants is one of important preconditions in the superplastic forming of ceramic materials. Using ring compressive testing, lubricities of hexagonal boron nitride in superplastic compressive forming processing of 3Y-TZP/Al2O3 ceramic composite at elevated temperatures were investigated. Theoretical curves of friction factor were drawn according to upper bound method. Ring compressive tests were adopted at temperature of 1400 °C-1600 °C. The results indicate that when BN is used, friction factor is about 0.4, meanwhile friction factor don’t have great changes with higher temperature and increasing strain rate. X-ray diffraction shows that under high temperature and high pressure no boron nitride converts to cubic phase, which remains at room temperature.

scholarly journals High-Pressure Energy Dispersive X-Ray Diffraction Investigation of Lithium-Manganese Spinel

2007 ◽  
Vol 130 ◽  
pp. 69-72 ◽  
Author(s):  
Paweł Piszora
Keyword(s):  
High Pressure ◽  
Hexagonal Boron Nitride ◽  
Axial Ratio ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Teller Distortion ◽  
Cell Experiment ◽  
Jahn Teller ◽  
Diamond Anvil ◽  
Jahn Teller Distortion

The formation of the tetragonal high-pressure structure, attributed to the Jahn-Teller distortion, was proved. The c/a axial ratio shows an increasing trend towards a stronger tetragonal distortion at high pressure. Rietveld refinement after the pressure relaxation demonstrates the presence of tetragonal artefacts of the high-pressure structure only for the LiMn2O4 sample compressed in hexagonal boron nitride (h-BN), whereas the sample compressed in silicone reveals the pure cubic phase. Confrontation with the result of the first angle-dispersive diamond-anvil-cell experiment is presented.

Chemical vapor deposition of boron nitride using premixed borontrichloride and ammonia

1991 ◽  
Vol 6 (11) ◽  
pp. 2393-2396 ◽  
Author(s):  
Vladimir Pavlović ◽  
Horst-Rainer Kötter ◽  
Christoph Meixner
Keyword(s):  
Chemical Vapor Deposition ◽  
Boron Nitride ◽  
Vapor Deposition ◽  
Elevated Temperatures ◽  
Hexagonal Boron Nitride ◽  
Chemical Vapor ◽  
Deposit Formation ◽  
Deposition Zone ◽  
Single Tube ◽  
N Compounds

Chemical vapor deposition (CVD) of boron nitride (BN) is most readily performed using BCl3 and NH3, which are brought into the deposition zone through two separate tubes. This causes some problems: inadequate mixing leading to a nonuniform deposit, formation of solid intermediates, etc. To avoid these problems, the process was performed by mixing BCl3 and NH3 at elevated temperatures (120–220 °C) prior to entering the deposition zone. The reaction between them took place by the forming of volatile stoichiometric B–N compounds (trichloroborazine and iminochloroborane), which were then transported through a single tube into a deposition zone. The resulting deposit was found to be hexagonal boron nitride.

Boron Nitride Doped Polypyrrole Hybrid Composites for Photocatalytic Degradation of 2-Chlorophenol from Aqueous Solution

2020 ◽  
Vol 301 ◽  
pp. 145-152 ◽  
Author(s):  
Faizah Yunus ◽  
Muhammad Syazwan Kassim ◽  
Syed Shahabuddin ◽  
Nur Rahimah Said ◽  
Siti Nor Atika Baharin
Keyword(s):  
Aqueous Solution ◽  
Boron Nitride ◽  
Photocatalytic Degradation ◽  
Hybrid Composites ◽  
Hexagonal Boron Nitride ◽  
Solar Irradiation ◽  
X Ray Diffraction ◽  
Initial Concentration ◽  
Polymerization Method

This investigation focused on the photocatalytic degradation of o2-chlorophenol in aqueous solution by using hexagonal boron nitride (h-BN) doped polypyrrole (PPy) composite under solar irradiation. The composite was prepared via in-situ oxidation polymerization method using FeCl3 as oxidation agent. The synthesized h-BN/PPy composite were comprehensively characterized using x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The photodegradation of 2-chlorophenol was performed under direct sunlight for 180 minutes with initial concentration (50-250 mg/L) and pH (3-9). h-BN/PPy composite efficiently degraded 2-chlorophenol (91.1%) with optimum conditions at pH 6 and 50 mg/L initial concentration compared to PPy and h-BN.

The Features of a High-Temperature Synthesis of ZrO2 in a Core-Shell ZrO2@C Structure

2019 ◽  
Vol 950 ◽  
pp. 133-137
Author(s):  
Alexander M. Volodin ◽  
Vladimir O. Stoyanovskii ◽  
Vladimir I. Zaykovskii ◽  
Roman M. Kenzhin ◽  
Aleksey A. Vedyagin
Keyword(s):  
Elevated Temperatures ◽  
Cubic Phase ◽  
Core Shell ◽  
X Ray Diffraction ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Carbon Coated ◽  
Physicochemical Methods ◽  
Argon Adsorption

Zirconium oxide was obtained via traditional precipitation from a ZrOCl2 solution with ammonia followed by drying at 110 °C. The carbon-coated samples were synthesized by calcination of the pristine zirconia mixed with polyvinylalcohol. The obtained ZrO2@C samples of core-shell structure as well as the reference samples of pristine zirconia were calcined at different temperatures from 500 to 1400 °C. All the materials were examined by a set of physicochemical methods (a low-temperature argon adsorption, transmission electron microscopy, X-ray diffraction analysis, photoluminescence spectroscopy). It was found that the carbon coating prevents the sintering of the oxide nanoparticles, which allows one to maintain the specific surface area, the size of the oxide core and, finally, stabilize its phase composition. Transformation of the cubic phase into monoclinic phase becomes significantly complicated. Thus, 40% of the cubic phase was detected even after calcination of the ZrO2@C sample at 1400 °C. Moreover, the carbon-coated samples treated at elevated temperatures with subsequent removal of the carbon shell were found to possess the highest concentration of the defects related to a presence of the anion vacancies in zirconia.

Effects of CaB2O4 Content on the Sintering Behavior of Hexagonal Boron Nitride

2011 ◽  
Vol 675-677 ◽  
pp. 131-134
Author(s):  
Yu Xia Cao ◽  
Ling Zhong Du ◽  
Wei Gang Zhang
Keyword(s):  
Boron Nitride ◽  
Diffraction Analysis ◽  
Apparent Density ◽  
Cross Sections ◽  
Hexagonal Boron Nitride ◽  
Sintering Behavior ◽  
Rockwell Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes

CaB2O4 was added into hexagonal boron nitride (hBN) to improve the sintering behaviors of hBN. CaB2O4 and hBN were mixed and then pressed into plates. The plates were sintered at 2000°C for 5h under a N2 ambience. The phase compositions with different CaB2O4 contents were examined with X-ray diffraction analysis. The fracture cross-sections of the hBN plates were investigated by SEM. The apparent density and Rockwell hardness were also measured. The results show that the hBN particles had a plate-like shape and the grain sizes of hBN increased with increasing CaB2O4 contents. The apparent density and Rockwell hardness decreased with increasing CaB2O4 contents. When the CaB2O4 content was 15(wt) %, the hBN has the average grain sizes of 3μm in diameter and 200nm in thickness, the apparent density of 1.06 g/cm3 and the Rockwell hardness of 3, respectively.

Lattice thermal expansion of Pu1−yAmyO2−xplutonium–americium mixed oxides

2017 ◽  
Vol 50 (6) ◽  
pp. 1782-1790 ◽  
Author(s):  
Romain Vauchy ◽  
Alexis Joly ◽  
Christophe Valot
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Mixed Oxides ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Lattice Thermal Expansion ◽  
Linear Lattice ◽  
The Face

Plutonium–americium mixed oxides, Pu1−yAmyO2−x, with various Am contents (y= 0.018, 0.077, 0.21, 0.49, 0.80 and 1.00) were studiedin situby high-temperature X-ray diffraction. In this study, the lattice thermal expansion of the six compounds subjected to heat treatments up to 1773 K under reconstituted air (N2+ 21% O2+ ∼5 vpm H2O) was investigated. The materials remained monophasic throughout the experiments and, depending upon the americium content, the lattice parameter of the face-centred cubic phase deviated from linear lattice expansion at elevated temperatures as a result of the progressive reduction of Am4+to Am3+.

Evaluation Of Amorphous Diamond-Like Carbon And Boron Nitride Films As Low Permittivity Dielectrics

1995 ◽  
Vol 381 ◽  
Author(s):  
J. P. Sullivan ◽  
T. A. Friedmann ◽  
C. A. Apblett ◽  
M. P. Siegal ◽  
N. Missert ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Cyclotron Resonance ◽  
Hexagonal Boron Nitride ◽  
Dielectric Constants ◽  
Environmental Stability ◽  
Cubic Phase ◽  
Diamond Like Carbon ◽  
Metal Insulator ◽  
Dielectric Characteristics ◽  
Metal Insulator Metal

AbstractAlthough films of diamond-like carbon (DLC) and hexagonal boron nitride (h-BN) have shown low dielectric constants in the range of 3 to 4, these materials have been unsuitable for use as interconnect dielectrics due to poor thermal stability and environmental degradation. These deficiencies can be addressed by depositing DLC films free of hydrogen (a-tC) and depositing the cubic phase of BN (c-BN). The dielectric characteristics of hydrogen-free DLC and c-BN that have been deposited by pulsed-laser deposition (PLD) have been evaluated using metal-insulator-metal and metal-insulator-semiconductor structures. For comparison, the dielectric characteristics of h-BN deposited by electron cyclotron resonance (ECR) were also evaluated. Despite the superior thermal and environmental stability of the a-tC and c-BN films and the attractively low deposition thermal budget (room temperature deposition for a-tC films, 400°C for c-BN films), the films exhibit dielectric constants comparable to those of bulk diamond and bulk BN, ∼ 6. Furthermore, the a-tC and c-BN films exhibit high compressive stress in the GPa range which limits their usefulness only to those applications requiring a thin dielectric layer, e.g. diffusion barriers or encapsulants.

Polycrystalline boron nitride constructed from hexagonal boron nitride

RSC Advances ◽  
2014 ◽  
Vol 4 (73) ◽  
pp. 38589-38593 ◽  
Author(s):  
N. Xu ◽  
J. F. Li ◽  
B. L. Huang ◽  
B. L. Wang
Keyword(s):  
High Pressure ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Polycrystalline Structure ◽  
Shed Light

Two classes of structural families of boron nitride allotropes (named as X-BNs and L-BNs) are proposed to shed light on the polycrystalline structure of high pressure h-BN.

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