Dielectric properties of plasma sprayed silicates subjected to additional annealing


Journal: Vol.10, No.2, Spring 2017 - Article 5   Pages :  105 Until 114



Article Code:
PCCC-2017-01-06-350

Authors:
P. Ctibor: Institute of Plasma Physics Academy of Sciences of the Czech Republic - Materials Engineering Department
J. Sedlacek: Faculty of Electrical Engineering Czech, Czech Technical university - Department of Elecrotechnology
B. Nevrla: Faculty of Mechanical Engineering, Czech Technical University - Department of Materials Engineering
K. Neufuss: Institute of Plasma Physics Academy of Sciences of the Czech Republic - Materials Engineering Department


Article's abstract:

Several silicate materials were plasma sprayed and characterized by the authors in recent years from the point of view of their chemical and phase compositions, microstructure and mechanical as well as thermal properties. Present work is concerned with selected dielectric properties of these deposits. Synthetic mullite and steatite as well as natural olivine-forsterite were plasma sprayed using the water-stabilized plasma system WSP®. The deposits were striped-out, ground and polished to produce samples in form of plates with a smooth surface. Part of samples was later annealed in air. These samples – after coverage by metal electrodes functioning as monoblock capacitors – were tested in the alternative low voltage electric field to measure capacity and loss factor in the frequency range from 200 Hz to 1 MHz. Relative permittivity was calculated from the measured capacity. Volume resistivity was measured in the direct electric field. It is shown that the relative permittivity of plasma as-sprayed silicates is less stable compared to bulk in the whole studied frequency range. However, thermal annealing modifies the structure much closer to the sintered bulk. This is reflected also in dielectric properties. Insulating ability of plasma-sprayed silicates with and without annealing is discussed in consequence with chemical changes and phase changes induced by annealing.


Keywords:
Annealing, Dielectric properties, Plasma spraying, Silicates

References:
[1] P. Chraska, K. Neufuss, H. Herman, Plasma Spraying of Zircon, J. Thermal Spray Technol., 6 (1997), 445-448. [2] K. Neufuss, B. Kolman, P. Chraska, J. Dubsky, Plasma Spraying of Silicates, in Proceedings of the Int. Thermal Spray Conference, Nice, France (1998), 636-640. [3] B. Kolman, K. Neufuss, J. Ilavsky, J. Dubsky, P. Chraska, Chemical Inhomogeneity of Silicates Treated by Plasma Spraying. J. Analytical Atomic Spectrometry, 14(1999), 471-473. [4] K. Neufuss, J. Dubsky, B. Kolman, P. Chraska, V. Brozek, P. Bohac, APS Spraying of MgO and CeO2 with WSP, in Proceedings of the 14th Int. Symposium on Plasma Chemistry, Prague, Czech Republic (1999), 2075-2079. [5] P. Chraska, J. Dubsky, K. Neufuss, J. Pisacka, Alumina-Base Plasma-Sprayed materials - Part I - Phase Stability of Alumina and Alumina-Chromia, J. Thermal Spray Technol., 6 (1997), 320-26. [6] P. Ctibor, J. Sedlacek, K. Neufuss, J. Dubsky, P. Chraska, Dielectric Properties of Plasma Sprayed Silicates. Ceram. Intl., 31(2005), 315-321. [7] Z. Strnad, Glass-Ceramic Materials, Elsevier, Amsterdam, The Netherlands, 1986, p.72 . [8] J. Hlavac, Basics of the Silicate Technology (in Czech), SNTL publishing, Prague, Czechoslovak Republic, 1988, p.26-29. [9] P. Rohan, K. Neufuss, J. Matejicek, J. Dubsky, L. Prchlik, C. Holzgartner. Thermal and Mechanical Properties of Cordierite, Mullite and Steatite Produced by Plasma Spraying. Ceram. Intl., 30 (2004), 597-606. [10] F. Singer, S. Singer, Industrial Ceramics, 3th Band - The Ceramic Products (in German), Springer, Berlin, 1966, p. 115. [11] Z. Pospisil, A. Koller, Fine-grained Ceramics - 1st Band (in Czech). SNTL publishing, Prague, Czechoslovak Republic, 1981, p. 127. [12] CSN EN 60243-1, IEC 60243-1:1998, Czech Standard, (in Czech), Czech Institute for Standardization, 1999. [13] Czech Standard CSN IEC 250, (in Czech), Czech Institute for Standardization, 1997. [14] H. Scholze, The Physical and Chemical Basics of Ceramics (in German), Springer, Berlin, 1968, p. 137-140. [15] H. Landolt, R. Boernstein, Values and Functions in Physics, Chemistry, Astronomy, Geophysics and Technology - Part 3 (in German), Springer, Berlin, 1957, p. 391. [16] L. Pawlowski, The Relationship between Structure and Dielectric Properties in Plasma-sprayed Alumina Coatings, Surf. Coat. Technol., 35 (1988), 285-298. [17] A. Koller, Structure and Properties of Ceramics, Elsevier, New York, USA, 1994, p. 53-55. [18] H. Insley, V.D. Frechette, Microscopy of Ceramics and Cements, Academic Press, New York, USA, 1955, p. 82-90. [19] N.E. Hill, Dielectric properties and molecular behaviour, Van Nostrand – Reinhold, UK, London, 1969, p. 215-216.


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