scholarly journals Dielectric and Ferroelectric Studies on High Dense Pb(Zr0.52Ti0.48)O3 Nanocrystalline Ceramics by High Energy Ball Milling and Spark Plasma Sintering

Ceramics ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Venkata Ramana Mudinepalli ◽  
Feng Leng

In our previous work, we synthesized Pb(Zr0.52Ti0.48)O3 (PZT) ceramics by conventional and microwave sintering methods and studied their structural and electrical properties. We observed that the microwave sintered PZT ceramics show higher densification, fine and uniform grain size, higher dielectric constant, remnant polarization (Pr), and spontaneous polarization (Ps) in comparison to conventional sintered ones. In the present work, we studied the microstructure, phase formation, dielectric, ferroelectric and piezoelectric properties of the PZT ceramics synthesized by using Spark plasma Sintering (SPS) method. The SPS sintering temperature is lower (300 to 400 °C) than both conventional and microwave sintering methods. The dielectric constant at room temperature and at transition temperature shows higher values compared to the microwave and conventional sintering methods. This SPS sintering technique is currently attracting growing attention among productions engineers and materials researchers.

2017 ◽  
Vol 52 (19) ◽  
pp. 2609-2619 ◽  
Author(s):  
Ehsan Ghasali ◽  
Masoud Alizadeh ◽  
Touradj Ebadzadeh

Aluminum-10 wt% TiO2 metal matrix composites were fabricated with conventional, microwave, and spark plasma sintering processes. Aluminum and nano-sized TiO2 powders were mixed using a high-energy mixer, and the sintering process was done at 450℃ by spark plasma sintering and 600℃ under both microwave and conventional heating. The results showed microwave sintering led to form Al3Ti intermetallic compounds with flaky shape, while in the conventional heating at the same sintering temperature, Al3Ti was formed and confirmed by X-ray diffraction and scanning electron microscope investigations. Moreover, the nano-sized TiO2 particles as reinforcement with no additional phase were obtained by spark plasma sintering at the lowest sintering temperature. The maximum bending strength of 254 ± 12 MPa and Vickers hardness of 235 ± 13 were measured for samples sintered in microwave as a consequence of Al3Ti formation. The SEM and energy-dispersive X-ray spectroscopy analyses showed uniform distribution of Al3Ti particles in the microstructure of microwave sintered samples and nonuniform distribution of agglomerated Al3Ti particles and porosities in samples sintered by spark plasma sintering and conventional heating.


2010 ◽  
Vol 42 (3) ◽  
pp. 259-267 ◽  
Author(s):  
K. Rajeswari ◽  
U.S. Hareesh ◽  
R. Subasri ◽  
Dibyendu Chakravarty ◽  
R. Johnson

Yttria stabilized zirconia (8YSZ) powders were subjected to densification studies employing various sintering techniques like spark plasma sintering (SPS), microwave sintering (MWS) and two-stage sintering (TSS). The densification and microstructural evolution of the samples are studied and compared with that of conventionally sintered samples (ramp and hold). Depending on the technique employed the samples were sintered at different temperatures to arrive at a minimum density of 99%TD. Detailed microstructural evaluation indicated that a low temperature densification leading to finer sintered grain sizes (~1 ?m) could be achieved by spark plasma sintering followed by the two stage sintering technique with an average sintered grain size of 2.6 microns.


Author(s):  
B Stalin ◽  
M Ravichandran ◽  
M Balasubramanian ◽  
C Anand Chairman ◽  
D Pritima ◽  
...  

2013 ◽  
Vol 1513 ◽  
Author(s):  
R.C. Picu ◽  
J.J. Gracio ◽  
G.T. Vincze ◽  
N. Mathew ◽  
T. Schubert ◽  
...  

ABSTRACTIn this work Al-SiC nanocomposites were prepared by high energy ball milling followed by spark plasma sintering of the powder. For this purpose Al micro-powder was mixed with 50 nm diameter SiC nanoparticles. The final composites had grains of approximately 100 nm dimensions, with SiC particles located mostly at grain boundaries. To characterize their mechanical behavior, uniaxial compression, micro- and nano-indentation were performed. Materials with 1vol% SiC as well as nanocrystalline Al produced by the same means with the composite were processed, tested and compared. AA1050 was also considered for reference. It was concluded that the yield stress of the nanocomposite with 1 vol% SiC is 10 times larger than that of regular pure Al (AA1050). Nanocrystalline Al without SiC and processed by the same method has a yield stress 7 times larger than AA1050. Therefore, the largest increase is due to the formation of nanograins, with the SiC particles’ role being primarily that of stabilizing the grains. This was demonstrated by performing annealing experiments at 150°C and 250°C for 2h, in separate experiments.


2022 ◽  
pp. 131671
Author(s):  
Dina V. Dudina ◽  
Tatyana F. Grigoreva ◽  
Vyacheslav I. Kvashnin ◽  
Evgeniya T. Devyatkina ◽  
Sergey V. Vosmerikov ◽  
...  

Author(s):  
Enrique Martínez-Franco ◽  
Ming Li ◽  
Ricardo Cuenca Álvarez ◽  
Jesús González Hernández ◽  
Chao Ma ◽  
...  

Metal matrix nanocomposites (MMNCs) are anticipated to offer significantly better performance than existing superalloys. Nickel/alumina nanocomposite samples were fabricated with a powder metallurgy method, combining high-energy ball milling (HEBM) and spark plasma sintering (SPS). The objective of this research is to determine the effect of alumina nanoparticle fraction and HEBM parameters on the powder preparation and sintering processes, and resultant microstructure and properties. Nickel-based powders containing various fractions (1, 5 and 15 vol.%) alumina nanoparticles were prepared by HEBM. The initial particle sizes were 44 μm and 50 nm for nickel and alumina, respectively. The milling process was conducted by starting with mixing at 250 rpm for 5 min, followed by cycling operation at high and low speeds (1200 rpm for 4 min and 150 rpm for 1 min). Samples at different milling times (30, 60, 90 and 120 min) of each composition were obtained. Scanning electron microscopy (SEM) was used to evaluate the dispersion of nanoparticles in the powders at different milling times. SPS technique was used for consolidation of the prepared powders. SEM images showed that alumina nanoparticles are homogeneously dispersed in the metal matrix in the sample containing 15 vol.% alumina. Hardness measurements in cross sections of SPSed samples showed higher values for Ni/Al2O3 MMNC compared to pure Ni.


Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1276 ◽  
Author(s):  
Dariusz Garbiec ◽  
Volf Leshchynsky ◽  
Alberto Colella ◽  
Paolo Matteazzi ◽  
Piotr Siwak

Combining high energy ball milling and spark plasma sintering is one of the most promising technologies in materials science. The mechanical alloying process enables the production of nanostructured composite powders that can be successfully spark plasma sintered in a very short time, while preserving the nanostructure and enhancing the mechanical properties of the composite. Composites with MAX phases are among the most promising materials. In this study, Ti/SiC composite powder was produced by high energy ball milling and then consolidated by spark plasma sintering. During both processes, Ti3SiC2, TiC and Ti5Si3 phases were formed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction study showed that the phase composition of the spark plasma sintered composites consists mainly of Ti3SiC2 and a mixture of TiC and Ti5Si3 phases which have a different indentation size effect. The influence of the sintering temperature on the Ti-SiC composite structure and properties is defined. The effect of the Ti3SiC2 MAX phase grain growth was found at a sintering temperature of 1400–1450 °C. The indentation size effect at the nanoscale for Ti3SiC2, TiC+Ti5Si3 and SiC-Ti phases is analyzed on the basis of the strain gradient plasticity theory and the equation constants were defined.


2008 ◽  
Vol 368-372 ◽  
pp. 601-603
Author(s):  
Xi Wei Qi ◽  
Ji Zhou ◽  
Zhen Xing Yue ◽  
Ming Ya Li ◽  
Xiu Mei Han

Dense NiCuZn ferrites consisting of fine grains were prepared by spark plasma sintering (SPS) at 750°C for 3 min under a uniaxial pressure of 15 MPa. The powders were densified to >95% of theoretical density by the SPS process, and the average grain size of the prepared NiCuZn ferrite was < 1 /m. The saturation magnetization of prepared specimens (without further annealing treatment) was approximate 50.54 emu/g, which was slightly smaller than that of 52.21 emu/g for specimens prepared by conventional sintering at 980°C for 4 h. Phase identifications indicated that prepared NiCuZn ferrite existed impurity phase (Cu2O), and Cu2O would gradually transform to CuO when annealing temperature increased.


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