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Journal of Ceramic Science and Technology 3/2018
Vol. 9, No. 3 · September 2018
Structure Features and Properties of Graphene/Al2O3 Composite
E. A. Klyatskina, A. Borrell, E. G. Grigoriev, A. G. Zholnin, M. D. Salvador, V. V. Stolyarov, V. V. Stolyarov
Pages 215-224 · DOI: 10.4416/JCST2018-00006
Since its discovery, graphene has attracted worldwide attention in the scientific community owing to its unique combination of properties. Thus, graphene is an ideal second phase to improve the structure and properties of metal, ceramic and polymer composite materials. This work presents a comparative study of two types of alumina-graphene composites fabricated with two sizes of δ-Al2O3 powders, nanometer and submicrometer, reinforced by graphene nanoplatelets (GNPs) and consolidated with the spark plasma sintering technique. The microstructure, mechanical and tribological properties of Al2O3- …
Surface Modification of Alumina Powder to Prevent Exfoliation of Samples Fabricated by Gelcasting
A. Wieclaw-Midor, P. Wiecinska, M. Szafran
Pages 225-234 · DOI: 10.4416/JCST2018-00008
The aim of this work was to study the influence of the Al2O3 surface modification 2-hydroxyethyl acrylate (HEA) on the properties of green and sintered ceramic bodies. As a reference, non-modified Al2O3 was used in the research. The modified Al2O3 powder was characterized with TEM and thermal analysis coupled with mass spectrometry. The rheological behaviour of slurries containing modified and non-modified alumina powder was measured, as well as the properties of green bodies. The proposed surface modification enables the production of green ceramic samples with homogeneous microstructure, hig …
Monitoring Damage Accumulation in Continuous Fiber-Reinforced Ceramic-Matrix Composites with Different Fiber Preforms under Cyclic Loading Using Hysteresis-Based Damage Parameters
Li Longbiao
Pages 235-262 · DOI: 10.4416/JCST2018-00010
In this paper, the damage accumulation of continuous fiber-reinforced ceramic-matrix composites (CMCs) with different fiber preforms, i.e. 2D and 2.5D woven, 3D braided and needled C/SiC, 2D and 3D woven SiC/SiC composites, subject to cyclic tensile loading/unloading at room temperature has been investigated using the hysteresis-based damage parameters. Based on the damage mechanisms of matrix multiple cracking modes and relative frictional sliding between fibers and the matrix, the relationships between the hysteresis-based damage parameters and damage mechanisms of matrix cracking modes, fib …
Microstructure, Growth Kinetics and Formation Mechanism of Oxide Layers on AlN Ceramic Substrates
Ye Cao, Haixian Xu, Jun Zhan, Hao Zhang, Song Cui, Wenming Tang
Pages 263-270 · DOI: 10.4416/JCST2018-00011
AlN ceramic substrates doped with 2 wt% Y2O3 were oxidized at temperatures ranging from 1000 °C to 1300 °C for various times in air. Microstructure, growth kinetics and formation mechanism of the oxide layers were studied. The results show that oxidation originates from the AlN grain boundaries and then extends into the AlN grains to form a core-shell structure composed of the unoxidized AlN core wrapped in the continuous nanocrystalline Al2O3 layer. A continuous pore network is distributed over the oxide layer and connected with the AlN reaction interface, which actually acts as the O2/N2 rap …
M. Stumpf, J. Biggemann, T. Fey, T. Fey, K. Kakimoto, P. Greil
Pages 271-278 · DOI: 10.4416/JCST2018-00013
Nb2AlC-particle-loaded ZrO2-matrix composites were manufactured by means of pressureless sintering (PS) and spark plasma sintering (SPS) at 1300 °C. The MAX phase Nb2AlC was synthesized based on the reaction of Nb, NbC and Al powder mixtures at 1600 °C in Ar-atmosphere. Nb2AlC formation was confirmed with XRD and ICP-OES. Nano-particulate tetragonal 3Y-TZP powder was mixed with Nb2AlC powder with a mean particle size of 7.93 µm up to a volume fraction of 19.5 %. While the microstructure of the PS composites revealed a residual porosity of 20 – 22 %, almost dense materials with a residual poros …
Influence of Heat Treatment of Amorphous Ti- and B-Containing SiC-Based Fiber in Air on Microstructure and Strength
Jiangxi Chen, Baojie Zhang, Danni Xu, Zhaoju Yu, Guomei He
Pages 279-288 · DOI: 10.4416/JCST2018-00014
The oxidative behavior of amorphous Ti- and B-containing SiC-based fiber exposed to air flowing at 1100 – 1300 °C for 2 – 300 min was investigated. The results showed that the strength of the SiC-based fiber slightly decreased when the fibers were exposed to air for 2 min at 1000 – 1300 °C. When the exposure time was lengthened to 300 min or the exposure temperature was increased from 1000 °C to 1300 °C, the strength of the SiC-based fiber did not change significantly. The morphology studies with SEM revealed that defects on the fiber surface were generated at the beginning of oxidation, while …
Influence of Reaction-Sintering and Calcination Conditions on Thermoelectric Properties of Sm-doped Calcium Manganate CaMnO3
S. Bresch, B. Mieller, F. Delorme, C. Chen, M. Bektas, R. Moos, T. Rabe
Pages 289-300 · DOI: 10.4416/JCST2018-00017
A wide range of solid-state synthesis routes for calcium manganate is reported in the literature, but there is no systematic study about the influence of the solid-state synthesis conditions on thermoelectric properties. Therefore, this study examined the influence of calcination temperature and calcination cycles on the Seebeck coefficient, electrical conductivity, and thermal conductivity. Higher calcination temperatures and repeated calcination cycles minimized the driving force for sintering of the synthesized powder, leading to smaller shrinkage and lower densities of the sintered specime …
The Corrosion of Mg-Partially Stabilized Zirconia During Service in Continuous Casting Tundish
K. Wiśniewska, D. Madej, J. Szczerba
Pages 301-308 · DOI: 10.4416/JCST2018-00019
One possible application for zirconium oxide is as a metering nozzle in a tundish for continuous steel casting. Such nozzles are mounted at the bottom of the tundish, and they are exposed to the corrosive effect of liquid steel at a temperature up to 1600 °C. In this study, the corrosion behavior of the zirconia metering nozzle after service in a tundish for continuous steel casting was investigated. The phase composition and chemical composition were investigated by means of x-ray diffraction and x-ray fluorescence, respectively. The microstructure of the nozzles was observed using a scanning …
Hot Corrosion Behavior of ZrB2-SiC-Graphite Composite in NaCl and Na2SO4 Molten Salts
X. Liu, G. Wang, L. Liu, Z. Wang, Z. Wu, M. Liu
Pages 309-318 · DOI: 10.4416/JCST2018-00020
In the present work, the hot corrosion behavior of ZrB2-SiC-graphite (G) composite in different media at 900 and 1000 °C was investigated in detail. The results indicated that the ZrB2-SiC-G composite became slightly corroded in NaCl molten salts owing to the ZrB2 phase of the ZrB2-SiC-G composite being oxidized by oxygen molecules dissolved in the NaCl molten salts. However, the ZrB2-SiC-G composite underwent more severe corrosion in Na2SO4 molten salts, owing to the complex oxidation and sulfidation reaction of the ZrB2-SiC-G composite exposed to oxygen molecules and decomposition products o …
Interlaminar Shear Response of Carbon/Carbon in Torsion Tests
T. Krause, R.S.M. Almeida, E. Volkmann, K. Tushtev, D. Koch, K. Rezwan, K. Rezwan, G. Grathwohl
Pages 319-326 · DOI: 10.4416/JCST2018-00021
Ceramic matrix composites offer remarkable strength and toughness and are usually designed based on the stacking of fiber plies. These composites are susceptible to debonding of these plies, as their interlaminar strength is significantly lower than in direction of the fibers. In this study, the application of torsion tests for the measurement of the interlaminar shear strength was evaluated using carbon/carbon composites with different porosities. Results obtained with the proposed technique are in accordance with standard methods such as short-beam flexure or double-notched compression. In c …
Slurry Development for Spray Granulation of Ceramic Multicomponent Batches
P. Höhne, B, Mieller, T. Rabe
Pages 327-336 · DOI: 10.4416/JCST2018-00022
The granules commonly yielded by spray drying procedures exhibit a hard shell and an irregular, dimpled shape, which is often described as donut-like morphology. Sintered parts produced from such granules suffer from microstructural defects and reduced mechanical properties resulting from these disadvantageous granule properties.Using the example of alumina, zirconia and zirconia-toughened alumina (ZTA) batches, this paper shows that the morphology of the granules can be tuned by adjusting slurry stability. High zeta potential is essential to optimally disperse the particles. But to achieve sp …
Impact of Ba2+on Structure and Electrical Properties of 0.65PMN-0.35PT Ceramics
C. Lu, C. Lu, Y. Liu, Y. Liu, C. Lyu, C. Lyu, F. Chen, F. Chen, H. Xi, H. Xi, Y. Lyu, Y. Lyu, Y. Lyu
Pages 337-344 · DOI: 10.4416/JCST2018-00023
Ba-doped PMN-0.35PT (PMN-0.35PT-xBa) (x = 0 – 0.05) relaxor ferroelectric ceramics were prepared with a two-step columbite precursor method. The effect of using Ba2+ to modify the structure and electrical properties of PMN-0.35PT-xBa ceramics near the morphotropic phase boundary was investigated. The introduction of Ba dopant significantly improved the densification of the ceramics and the growth of the grain, but also profoundly modified the phase structure. The study demonstrated that the substitution of Ba main doping for A-site in the PMN-0.35PT lattice could affect electrical properties o …
Co-Precipitation Synthesis of La2O2SO4:Tb3+ Phosphor and its Conversion to La2O2S:Tb3+ Ceramic Scintillator via Pressureless Sintering in Hydrogen
G.X. Xu, J.B. Lian, N.C. Wu, X. Zhang, J. He
Pages 345-352 · DOI: 10.4416/JCST2018-00018
This research reports on the synthesis of a series of lanthanum compounds. As an intermediate product, La2O2SO4:Tb3+phosphors were prepared with a co-precipitation method. La2O2S:Tb3+ ceramic scintillator was then synthesized by means of pressureless reaction sintering in a hydrogen atmosphere. XRD patterns show that the crystal structure of the precursor is unidentified, and it can be transformed into pure La2O2SO4 phase after calcination at 800 °C in air. Compared with the Tb3+-ions-doped precursor, the La2O2SO4:Tb3+ phosphor has a stronger green emission peak at around 542 nm, which is attr …
