Previews from the Intl. Journal of Applied Ceramic Technology—February 2012
Published on March 6th, 2012 | By: Eileen De Guire
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New papers that have been accepted for publication in the International Journal of Applied Ceramic Technology are posted to “Early View” on the Wiley website and can be read even before the issue is printed. Below are summaries of selected papers currently available via Early View.
All members of The American Ceramic Society receive free online access to IJAGS. To access any of the ACerS journals, or to become a member, visit www.ceramics.org.
Microstructure of air plasma sprayed coatings sprayed with large spray distance. Credit: Stuke et al., ACT; Wiley.
The objective of this research team from Germany was to optimize the diffuse reflectance of yttria-partially-stabilized zirconia plasma-sprayed thermal barrier coatings by improving the coating microstructure such that the reflectance of radiation was increased to better thermally screen the underlying metallic substrate. The team air-plasma-sprayed and suspension-plasma-sprayed coatings of seven-percent YSZ using powders of various grain-size distributions and various spray parameters. The team reports it was able to decrease thermal conductivity and increase radiation scattering, which resulted in lower heat flow to and lower temperature at the metallic substrate.
TEM images of conformal (left) and sporadic (right) alumina coatings on graphite particles. Credit: Lichty et al., ACT; Wiley.
This team composed of researchers from the United States and Switzerland used atomic layer deposition to coat graphite particles with alumina. The team reports that, although alumina adherence was limited and nonconformal, the coatings produced changes in particle interaction and dispersability with low materials loadings. It also reports that the coated particles can result in sintered composites with enhanced thermal properties.
SEM micrograph of Li2ZnTi3O8 ceramic sintered at 1,050°C/4 h. Credit: Chen et al., ACT; Wiley.
These researchers from China’s Guilin University of Electronic Technology investigated the effects of LZB additions on sintering, phase purity, microstructure and dielectric properties of Li2ZnTi3O8 ceramics using a conventional solid-state method. They report that LZB addition lowers the sintering temperature and causes little degradation of dielectric properties and that TiO2 addition markedly improves microwave properties. Moreover, they report that compatibility with silver electrodes indicates that this material can be applied to low-temperature cofired ceramic devices.
The FE-SEM micrographs of nearly full dense specimens sintered by microwave at 1,400°C/10 min. Credit: Borrell et al., ACT; Wiley.
This research team in Spain used conventional and microwave-heating sintering techniques to fabricate three-mole-percent-yttria-stabilized tetragonal-zirconia compacts. They report that the microwave-sintered compacts achieved a higher density in a shorter time at the same temperature and exhibited a superior Vickers hardness than the conventionally sintered compacts.
TEM images of NiFe2O4 particles prepared by 20 wt% NaCl, 800°C, 1 h. Credit: Zhang et al., ACT; Wiley.
These researchers from China’s Northeastern University used a solid-state reaction to investigate the effects of dispersant content, calcination temperature and annealing time on the particle size and morphology synthesis NiFe2O4 nanoparticles. They report the NiFe2O4 particles formed were nanometer sized with various morphologies dependent on reaction conditions and that the solid-state reaction is a simple, convenient, inexpensive and effective preparation method of high-yield NiFe2O4.
SEM image of the cross section of Si3N4 composite coating (The ca. 200 μm thick brighter area from the right is attributed to the upper surface of the specimen). Credit: Károly et al., ACT; Wiley.
This team of researchers in Hungary reports that it has circumvented the problem of SiC and Si3N4 decomposition during elevated-temperature atmospheric plasma spraying. The team says it circumvents the problems of oxidation and decomposition by depositing the non-oxide ceramics as a composite powder mixed with non-oxide ceramic particles that results in a ceramic/ceramic composite structure.
FESEM of 50% w/w bauxite treated FA3 sintered at 1,600 °C. Credit: ACT; Wiley.
These researchers based in India have developed a novel ceramic material by sintering fly ash with bauxite that acquires increased hardness because of enhanced mullite content and has an additional property of decreasing pathogenic bacterial growth by more than 90 percent. They believe that this process provides a sustainable approach of using fly ash in developing antimicrobial ceramics in an ecology friendly way for use in bacteria-prone areas, such as hospitals.
A cross-sectional view of one turn of the antenna showing the silver paste and top low temperature co-fired ceramic layer. Credit: Taff et al., ACT; Wiley.
This team from Boise State University and Schweitzer Engineering Laboratories in Utah reports that it is developing a miniature electrostatic thruster composed of an antenna to create a plasma, a cylinder to contain the plasma and grids to extract the plasma beam at high velocity. The team reports here fabrication and performance of the inductively coupled plasma antenna using low-temperature cofired ceramics.