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This experimental paper comprises the results of acoustic emission (AE), microscopic and ultrasonic measurements of samples subjected to slowly increasing compressive stress. On the basis of conducted measurements the successive stages of the material structural degradation have been recognized. The objects of study were samples made of C 120 aluminous porcelain. The investigated material has found at present the application in the fabrication of technical elements like overhead power line insulators. In the case of such objects, not only high mechanical strength, but especially elevated durability as well as operational reliability are required. The expected "life time" of net insulators during exploitation is about 40 years. The analysis of obtained mechanoacoustic dependences pointed out a complex mechanism of degradation of the material. Microscopic investigation of samples, which were stressed to different levels of load, enabled to specify the development of gradual growth of microcracks and successive crushing out of elements of the structure. These processes appear to be similar to the ageing processes occurring in the material during long period of exploitation under a working load. Three stages of the structure degradation were distinguished. The preliminary and subcritical ones show low or moderate intensity of AE signals and considerable variety for the particular samples. The critical stage directly precedes the destructtion of samples. Its range is relatively narrow and reveals the AE activity of high energy. The effectiveness of dispersive and fibrous reinforcement of modern aluminous porcelain C 120 type has been described. Structural strengthening by corundum grains and mullite needle shaped crystals improves mechanical parameters and distinguishes this material from typical aluminosilicate ceramics. The presented results enable drawing up the conclusions concerning the resistance of investigated material to the ageing degradation process development during long term operation.
Czasopismo
Rocznik
Tom
Strony
109--128
Opis fizyczny
Bibliogr. 17 poz., rys., tab.
Twórcy
autor
autor
autor
autor
autor
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, 02-106 Warszawa
Bibliografia
- [1] Dziadkowiec J., Kupiec E., Ageing Processes in Ceramic Insulators. Energetyka 5: 166-170 (1992), (in Polish).
- [2] Carty W., Senapati U., Porcelain – Raw Materials. Processing, Phase Evolution and Mechanical Behavior, J. Am. Ceram. Soc. 81(1): 3-20 (1998).
- [3] Schüpp P., Gion L., Influence des conditions atmospherique sur les variations de temperature des isolateurs. Revue Générale de l’Electricité 60(6) (1951).
- [4] Frese H.J., Pohlmann H. , Operating Experience with, and Investigations of Long Rod Insulators, Elektrizitätswirtschaft. H. 22: 38-43 (1999), (authorized translation of the report).
- [5] Liebermann J. , Avoiding Quartz in Alumina Porcelain for High-Voltage Insulators. American Ceramic Society Bulletin 80(6-7): 37-48 (2001).
- [6] Ranachowski P., Rejmund F., Jaroszewski M., Wieczorek K., Study of Structural Degradation of Ceramic Material of Insulators in Long Term Operation. Archives of Metallurgy and Materials 54(1): 205-216 (2009).
- [7] Kordek M., Pohl Z., Ranachowski J. et al. Analysis of usefulness of application porcelain C 130 kind for production of electrotechnical insulators of the highest quality and reliability. Study edited by Institute of Power Engineering, Warsaw 1998 (in Polish).
- [8] Richerson D.W., Modern Ceramic Engineering. Properties, Processing and Use in Design, CRC Taylor & Francis, Boca Raton London, chapter 14, 19, New York 2006.
- [9] Malecki I., Physical Foundations of Technical Acoustics. Pergamon Press, Oxford – Braunschweig, chapter 3 (1969).
- [10] Śliwiński A., Ultrasounds and their application. (Second ed.),Wydawnictwo Naukowo-Techniczne, chapter 4, Warsaw 2001 (in Polish).
- [11] Pohl Z., Outdoor high voltage insulation in electrical engineering, Wrocław Technical University, chapter 3 (2003), (in Polish).
- [12] Ranachowski J., Rejmund F., Acoustic Emission in Technical Ceramics, in: Acoustic Emission – Sources Methods Applications. Malecki I., Ranachowski J. (Ed.), Biuro PASCAL, pp. 55-107, Warsaw 1994, (in Polish).
- [13] Evans A.S., Langdon T.G., Structural Ceramics. (In:) Progress in Materials Science. Chalmers S., Christian J.W., Massalski T.S. (Ed.), 21: 171-441, Pergamon Press (1976).
- [14] Evans A.G., Linzer R.M., Russel J.R., Acoustic Emission and Cracks Propagation. (In:) Polycrystalline Alumina. Mat. Science Eng. 2/3: 253-261 (1974).
- [15] Futakawa M., Kikuchi K., Tanabe Y., Muto Y. Dynamic Effect on Fatigue Strength on Brittle Materials. Journal of European Ceramic Society 17: 1573-1578 (1997).
- [16] Ranachowski P., Rejmund F., Ranachowski Z. et al. Comparison of Acoustic Emission and Structure Degradation in Compressed Porcelain and Corundum Materials. Archives of Acoustics 34(4): 655-676 (2009).
- [17] Ranachowski P., Rejmund F., Ranachowski Z. et al. Acoustic Investigations of Long-rod Insulators and Their Material Properties. IEEE Transactions on Dielectrics and Electrical Insulation 17(1): 81-88 (2010).
Typ dokumentu
Bibliografia
Identyfikator YADDA
bwmeta1.element.baztech-article-BPS2-0060-0017