Effect of Nano-Al2O3 Addition on the Densification of YSZ Electrolytes

2009 ◽  
Vol 6 ◽  
pp. 115-122 ◽  
Author(s):  
Dachamir Hotza ◽  
Adrian Leo ◽  
Jaka Sunarso ◽  
João C. Diniz da Costa
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Sintered Density ◽  
Sintering Temperature ◽  
Phase Segregation ◽  
Phase Evolution ◽  
Second Phase ◽  
Suspension Particle ◽  
Powder Suspension ◽  
Ysz Electrolyte

This work investigates the effect of nanosized Al2O3 addition on the sinterability of YSZ electrolyte. (1−x)YSZ + Al2O3 ceramics with compositions x = 0 to 0.01 were prepared by the conventional mixed oxide route from a commercial powder suspension (particle size <50 nm), and sintered at 1200 to 1500°C for 2 hours in air. Densification, phase evolution, and microstructure were characterized by SEM/EDS and XRD. An improvement in sintered density was observed for the samples with 0.2 to 0.5 mol% Al2O3, though depending on the sintering temperature. Only cubic zirconia was detected as crystalline phase, although XRD features suggested chemical interactions depending upon the amount of Al2O3. The grain size of YSZ was homogeneous and no second phase segregation was detected in the tested range of incorporated nano-Al2O3 and sintering temperatures.

The Effects of Sintering Temperature on the Properties of Mg-Mn-Zn Ferrites

2013 ◽  
Vol 680 ◽  
pp. 31-34 ◽  
Author(s):  
Ji Wei Fan ◽  
Wen Qing Li ◽  
Hui Jun Zhao ◽  
Xiao Li Zhang ◽  
Zhen Guo Zhang
Keyword(s):  
Grain Size ◽  
Sintered Density ◽  
Environmental Temperature ◽  
Sintering Temperature ◽  
Temperature Sensitive ◽  
Similar Function ◽  
Ntc Thermistor ◽  
Testing Range

The present work shows the results of investigation on the effects of sintering temperatures of (Mg0.25Mn0.1Zn0.65)Fe2O4 ferrite on its sintered density, initial permeabilty, resistivity and microstructure. To achieve better sintered density and initial permeabilty, the sintering temperature should be ≥1200oC. However, the higher sintering temperature results in larger the grain size, which causes the reduction of the resistivities of Mg-Mn-Zn ferrites. Furthermore, the resistivities of samples are environmental temperature sensitive, and possibly possess the similar function of NTC thermistor over the testing range 25-225oC.

Effect of Sintering Temperature on the Mechanical Properties of Nanostructured Zirconia Fabricated via Colloidal Processing

2013 ◽  
Vol 686 ◽  
pp. 44-48 ◽  
Author(s):  
Noor Faeizah Amat ◽  
Andanastuti Muchtar ◽  
Norziha Yahaya ◽  
Mariyam Jameelah Ghazali
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Sintered Density ◽  
Sintering Temperature ◽  
Tetragonal Zirconia ◽  
Sintered Specimen ◽  
Full Density ◽  
Colloidal Processing ◽  
Zirconia Powder ◽  
Dental Ceramic

This study aims to evaluate the effects of sintering temperature on the density and hardness of tetragonal zirconia polycrystals stabilized with 3 mol% 3Y-TZP dental ceramic type. Five cylindrical specimens were fabricated from zirconia powder of particle size 50 nm via colloidal processing. The specimens were sintered densely at the final sintering temperatures of 1000, 1100, 1200, and 1300 °C, respectively. The sintered density and hardness of the sintered specimen were then examined. The results showed that the sintered densities and hardness of the specimen increased as the temperature increased from 1000 °C to 1300 °C. Zirconia 3Y-TZP could gain near full density and reach hardness of as high as 11.30 GPa at the final sintering temperature of 1300 °C. The density and hardness of zirconia structured from 3Y-TZP can be improved by controlling the final sintering temperature.

scholarly journals The effect of milling time on the alumina phase transformation in the AMCs powder metallurgy reinforced by silica-sand-tailings

2022 ◽  
pp. 103-117
Author(s):  
Sukanto ◽  
Wahyono Suprapto ◽  
Rudy Soenoko ◽  
Yudy Surya Irawan
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Powder Metallurgy ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Sintering Temperature ◽  
Silica Sand ◽  
Second Phase ◽  
The Matrix ◽  
The Impact

This study aims to determine the effect of milling time and sintering temperature parameters on the alumina transformation phase in the manufacture of Aluminium Matrix Composites (AMCs) reinforced by 20 % silica sand tailings using powder metallurgy technology. The matrix and fillers use waste to make the composites more efficient, clean the environment, and increase waste utilization. The milling time applied to the Mechanical Alloying (MA) process was 0.5, 6, 24, 48, and 96 hours, with a ball parameter ratio of 15:1 and a rotation of 93 rpm. Furthermore, hot compaction was carried out using a 100 MPa two-way hydraulic compression machine at a temperature of 300 °C for 20 minutes. The temperature variables of the sintering parameter process were 550, 600 to 650 °C, with a holding time of 10 minutes. Characterization of materials carried out included testing particle size, porosity, X-Ray Diffraction (XRD), SEM-Image, and SEM-EDX. The particle measurement of mechanical alloying processed, using Particle Size Analyzer (PSA) instrument and based on XRD data using the Scherrer equation, showed a relatively similar trend, decreasing particle size occurs when milling time was increased 0.5 to 24 hours. However, when the milling time increases to 48 and 96 hours, the particle size tends to increase slightly, due to cold-weld and agglomeration when the Mechanical Alloying is processed. The impact is the occurrence of the matrix and filler particle pairs in the cold-weld state. So, the results of XRD and SEM-EDX characterization showed a second phase transformation to form alumina compounds at a relatively low sintering temperature of 600 °C after the mechanical alloying process was carried out with a milling time on least 24 hours

Phase Field Simulation of Grain Growth with Particle Pinning

2016 ◽  
Vol 724 ◽  
pp. 8-11
Author(s):  
Chun Yu Teng ◽  
Yun Fu ◽  
Zhan Yong Ren ◽  
Yong Hong Li ◽  
Yun Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Phase Field ◽  
Particle Number ◽  
Boundary Energy ◽  
Service Condition ◽  
Second Phase ◽  
Pinning Effect

The properties of alloys depend on its microstructure, such as the size of grains. In general, the balanced mechanical properties of alloys can be obtained with small grain size. While the grain size of alloys may increases under heat treatment, thermal mechanical processing and service condition of high temperature, i.e., the grain growth is inevitable. The effort of most research is to control the rate of grain growth and avoid abnormal grain growth. For example, pinning the grain boundary and reduce its mobility with the second phase particles in order to prevent grain growth. Therefore, the properties of the alloys will not decreases dramatically and the structure retains a high degree of integrity. The details of grain growth with particle pinning were investigated by phase field simulations in the present paper. It is found that, with the same size of pinning particles, the pinning effect increases with the increases of the pinning particle number. With the same pinning particle number, the pinning effect increases with the increases of pinning particle size. Under the same total volume of pinning particles while different particle size and number, the pinning effect is complicated and it will be discussed in details. The pinning effect decreases with the increases of grain boundary energy. These findings could shed light on the understanding of the grain growth kinetics with particle pinning.

On the theory of the effect of precipitate particles on grain growth in metals

1966 ◽  
Vol 294 (1438) ◽  
pp. 298-309 ◽  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Second Phase ◽  
Pinning Force ◽  
Essential Difference ◽  
The Matrix ◽  
Critical Particle Size

A theoretical model of the energy changes accompanying grain boundary movement has been developed. It has been shown that small boundary movements will reduce the energy of a polycrystalline metal only when there is a heterogeneous grain size. The pinning force exerted by precipitate particles of a second phase on the grain boundary has also been considered. The release of grain boundary energy which accompanies grain growth has been considered as a source of energy for the unpinning process. The theory predicts a critical particle size which is dependent on the volume fraction of second phase, the matrix grain size, and the degree of heterogeneity of the matrix. Coalescence of the precipitate to a size in excess of the critical radius will permit grain growth to occur. Theoretical predictions of the critical particle size are in good agreement with values determined experimentally. The essential difference between grain growth and secondary recrystallization is indicated by the theory.

Effect of Milling Medium on Alumina Additivated with Niobia

2014 ◽  
Vol 798-799 ◽  
pp. 677-681
Author(s):  
Willian Trindade ◽  
Marcelo Henrique Prado da Silva ◽  
Alaelson Vieira Gomes ◽  
Carlos Frederico Matos Chagas ◽  
Luis Henrique Leme Louro
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Milling ◽  
Sintering Temperature ◽  
Ceramic Particle ◽  
Microstructure And Properties ◽  
Sintering Additive ◽  
Final Density ◽  
Significant Contamination ◽  
Milling Medium

Niobia has been successfully used as sintering additive to alumina in order to lower its sintering temperature. This effect can also be obtained by reducing the ceramic particle size. This work investigated the effect of the particle size on the ceramic final density of alumina with 4 wt% niobia. For that two milling media were used. The as-received powders were submitted to ball and planetary milling and then sintered at 1450°C. The planetary milling medium was more efficient in reducing particle size when compared to ball milling. However, planetary milling caused significant contamination in the niobia powder, from the alumina balls used as milling agents. It forced composition balance in order to keep the original proposed formulation. The planetary milled sintered samples showed better densification and lower grain size in comparison with ball milled ones. It could be concluded that the milling medium choice directly affected both microstructure and properties of the sintered alumina with 4wt% of niobia. .

Phase Evolution and Surface Morphology of Niobate Hydrate Template Nanoparticles Synthesized by Hydrothermal Method

2016 ◽  
Vol 697 ◽  
pp. 105-108
Author(s):  
Yuan Yu Wang ◽  
Nuo Xin Xu ◽  
Jin Zhuang Liu ◽  
Qi Long Zhang ◽  
Hui Yang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Surface Morphology ◽  
Hydrothermal Method ◽  
Alkaline Solution ◽  
Phase Structure ◽  
Reaction Rate ◽  
Phase Evolution ◽  
Starting Solution ◽  
Alternative Approach

In this work, an alternative approach to synthesize (K,Na)NbO3 (KNN) particles is investigated. KNN hydrate particles were prepared by hydrothermal method in a mixed alkaline solution with different KOH/(KOH+NaOH) ratios , and phase structure as well as surface morphology of these niobate hydrate particles were systematically studied. For the reaction rate of Na+ is faster than K+, a mixed alkaline solution with K+/Na+ changing from 4/1 to 5/1was required as a starting solution so a to obtain KNN hydrate particles with K/Na=1. Besides, the results show that particle size of KNN hydrate particles synthesized in different starting solution is dependent on K+/Na+ of the starting solution, and grain size of as-sintered KNN ceramics through hydrothermal method decreases sharply.

Effects of Sintering Temperature on Structure and Electronic Properties of Mg0.2Zn0.8O:Al Ceramics

2011 ◽  
Vol 320 ◽  
pp. 236-239
Author(s):  
Hong Yan ◽  
Hua Wang ◽  
Shang Ju Zhou
Keyword(s):  
Grain Size ◽  
Electronic Properties ◽  
Sintering Temperature ◽  
Raw Materials ◽  
High Density ◽  
Homogeneous Structure ◽  
Second Phase ◽  
Pressureless Sintering ◽  
Nano Scale ◽  
Phase Nucleation

Mg0.2Zn0.8O:Al ceramics with high density using nano scale ZnO, MgO and Al2O3 powders as raw materials were obtained by pressureless sintering. The influence of presintering powder and sintering temperature on microstructure of Mg0.2Zn0.8O:Al ceramics were studied. The experiment indicated that presintering powder might decrease produce of the second phase nucleation. The grain size became gradually larger and density of ceramic became obviously higher from 1100°C to 1300°C, but the rising-trend became slower after 1300°C. The Mg0.2Zn0.8O:Al ceramics with high density and homogeneous structure can be made at 1300°C for

Particle and grain size effects on the dielectric behavior of the relaxor ferroelectric Pb(Mg1/3Nb2/3)O3

1990 ◽  
Vol 5 (12) ◽  
pp. 2902-2909 ◽  
Author(s):  
Philippe Papet ◽  
Joseph P. Dougherty ◽  
Thomas R. Shrout
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Growth ◽  
Morphological Changes ◽  
Dielectric Behavior ◽  
Relaxor Ferroelectric ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
Scaling Effects

The role of particle and grain size on the dielectric behavior of the perovskite relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 [PMN] was investigated. Ultrafine powders of PMN were prepared using a reactive calcination process. Reactive calcination, the process by which morphological changes take place upon reaction of the component powders, produced particle agglomerates less than 0.5 μm. Through milling, these structures were readily broken down to ∼70 nanometer-sized particulates. The highly reactive powders allowed densification as low as 900 °C, but with corresponding grain growth in the micron range. Such grain growth was associated with liquid phase sintering as a result of PbO–Nb2O5 second phase(s) pyrochlore. Sintering, assisted by hot uniaxial pressing, below the temperature of liquid formation of 835 °C, allowed the fabrication of highly dense materials with a grain size less than 0.3 μm. The dielectric and related properties were determined for samples having grain sizes in the range of 0.3 μm to 6 μm. Characteristic of relaxors, frequency dependence (K and loss) and point of Tmax were found to be related to grain and/or particle size and secondarily to the processing conditions. Modeling of particle size/dielectric behavior was performed using various dielectric properties of 0–3 composites comprised of varying size powder in a polymer matrix. An intrinsic-microdomain perturbation concept was proposed to interpret observed scaling effects of the relaxor dielectric behavior in contrast to normally accepted extrinsic grain boundary models.

scholarly journals A Comparative Study of Spark Plasma and Conventional Sintering of Undoped SnO2 Sputtering Targets

2021 ◽  
Author(s):  
Levent Koroglu ◽  
Cem Aciksari ◽  
Erhan Ayas ◽  
Emel Ozel ◽  
Ender Suvaci
Keyword(s):  
Grain Size ◽  
Relative Density ◽  
Dwell Time ◽  
Sintering Temperature ◽  
Phase Evolution ◽  
Microstructural Development ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Spark Plasma

Abstract SnO2 ceramics were fabricated by spark plasma sintering (SPS) and conventional (pressureless) sintering techniques by using undoped submicron SnO2 powders. The effect of sintering temperature and dwell time on the densification behavior, phase evolution and microstructural development of sintered ceramics were investigated. The relative density of SPSed ceramics increased when dwell time was raised from 1 to 10 min at 950ºC. However, full densification was prevented by the decomposition of SnO2 to Sn and O2(g). The decomposition starts after ~ 10 min at 950ºC. In parallel to this observations, as sintering temperature increases, amount of the elemental Sn in agglomerated form increases. On the other hand, the relative densities of conventionally sintered ceramics (at 1200ºC-1400ºC) were relatively low (i.e., 63 % relative density), and abnormal grain growth was observed due to the shift in sintering mechanisms to evaporation-condensation as a dominant mechanism. Since the undoped SnO2 ceramics, SPSed at 950°C for 5 min under 30 MPa exhibit 93 % relative density, high chemical purity, homogeneous grain size distribution and smaller average grain size, they demonstrate great potential as sputtering targets for production of high-quality thin film gas sensors.

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