Rapid microwave sintering of zinc oxide-based varistor ceramics

Grain growth is inevitable in the sintering of pure nanopowder zinc oxide. Sintering depend on diffusion kinetics, thus this growth could be controlled by ultra-fast sintering techniques, as microwave sintering. The purpose of this work was to investigate the nanostructural evolution of zinc oxide nanopowder compacts (average grain size of 80 nm) subjected to ultra-rapid microwave sintering at a constant holding temperature of 900°C, applying different heating rates and temperature holding times. Fine dense microstructures were obtained, with controlled grain growth (grain size from 200 to 450nm at high heating rate) when compared to those obtained by conventional sintering (grain size around 1.13µm), which leads to excessively large average final grain sizes.

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Effect of heating rate on microwave sintering of nanocrystalline zinc oxide

Ceramics International ◽

10.1016/j.ceramint.2014.03.051 ◽

2014 ◽

Vol 40 (7) ◽

pp. 10667-10675 ◽

Cited By ~ 16

Author(s):

Rodolfo F.K. Gunnewiek ◽

Ruth H.G.A. Kiminami

Keyword(s):

Zinc Oxide ◽

Heating Rate ◽

Microwave Sintering ◽

Nanocrystalline Zinc Oxide

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Synthesis and characterization of zinc oxide reinforced aluminum metal matrix composite produced by microwave sintering

Journal of Composite Materials ◽

10.1177/0021998320918646 ◽

2020 ◽

Vol 54 (24) ◽

pp. 3625-3636

Author(s):

Neeraj Kumar Bhoi ◽

Harpreet Singh ◽

Saurabh Pratap

Keyword(s):

Zinc Oxide ◽

Diffraction Pattern ◽

Microwave Sintering ◽

Matrix Material ◽

Effective Diffusion ◽

Milled Powder ◽

Cost Effective ◽

Zinc Oxide Nanorods ◽

Bright Spot ◽

Oxide Nanorods

The study focuses on the microstructural, phase transformation, and physical and mechanical aspects of aluminum/zinc oxide composite produced by a hybrid microwave sintering technique. In the present case, zinc oxide nanorods were synthesized through a cost-effective thermal decomposition method. The obtained zinc oxide nanorods’ length was in the range of 76–168 nm observed through high-resolution transmission electron microscopy images and crystallinity nature was confirmed by the bright spot in the selected area electron diffraction pattern. Two different wt% (i.e. 0.5 and 2) of zinc oxide nanorods were utilized for the fabrication of the composite material. The diffraction pattern of the milled powder and energy dispersive spectroscopy results shows effective diffusion of zinc oxide nanorods in the aluminum. The elemental mapping of milled powder illustrates the uniform distribution of the reinforcement over matrix material. The micro-hardness results exhibit a higher hardness of 27.78% with a small fraction of 2 wt%. The nano-indentation results confirm the improvement in the nano-hardness by 32.21% with 2 wt% of zinc oxide with a marginal decrease in elastic modulus by 4.92%.

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Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163332 ◽

1996 ◽

Vol 54 ◽

pp. 174-175

Author(s):

P. Sadhukhan ◽

J. B. Zimmerman

Keyword(s):

Zinc Oxide ◽

Electron Microscope ◽

Carbon Black ◽

Natural Rubber ◽

Transmission Electron Microscope ◽

Rolling Resistance ◽

Synthetic Polymers ◽

Nitrogen Atmosphere ◽

Transmission Electron ◽

Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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Analysis of Sputtered Zinc Oxide Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001781 ◽

1980 ◽

Vol 38 ◽

pp. 416-417

Author(s):

T. A. Emma ◽

M. P. Singh

Keyword(s):

Electron Microscopy ◽

Zinc Oxide ◽

Piezoelectric Materials ◽

Oxide Films ◽

Optical Quality ◽

Zno Films ◽

Rf Power ◽

X Ray Diffraction ◽

Sputtered Films ◽

Zinc Oxide Films

Optical quality zinc oxide films have been characterized using reflection electron diffraction (RED), replication electron microscopy (REM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Significant microstructural differences were observed between rf sputtered films and planar magnetron rf sputtered films. Piezoelectric materials have been attractive for applications to integrated optics since they provide an active medium for signal processing. Among the desirable physical characteristics of sputtered ZnO films used for this and related applications are a highly preferred crystallographic texture and relatively smooth surfaces. It has been found that these characteristics are very sensitive to the type and condition of the substrate and to the several sputtering parameters: target, rf power, gas composition and substrate temperature.

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