Method of determining the thermal stability of a dense (compact) ceramic by ultrasonic monitoring

Zborovskii, I. D.; Kushnirskii, G. M.; Landa, Ya. A.; Litovskii, E. Ya.; Milovidova, T. V.; Polonskii, Yu. A.; Rapoport, Yu. M.

doi:10.1007/bf01528105

Cited by 4 publications

(5 citation statements)

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“…In order to determine the thermal shock resistance of the specimens, we employed the thermal cycling method with subsequent measurement of the transmission time of the ultra-sonic waves (USW) through the specimen [4]. Cylindrical specimens measuring 36 mm in diameter and ~5 mm in height or cubic specimens with an edge length of 25 mmwere tested in an electric furnace having a tubular graphite heating element under argon atmosphere.…”

Section: Composi~ Tion Numbermentioning

confidence: 99%

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A study of the thermomechanical properties of the graphite-bearing refractores

et al. 1985

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Determining the properties of the graphite-bearing refractories is of considerable importance in view of the wide application of these refractories and the stringent specifications on their properties [I].This paper presents the test results on the strength and the thermal shock resistance of the corundum-graphite refractories used in continuous preform casting machines. The tests were carried out on the laboratory specimens made from the industrial (No. i) and the experimental (Nos. 2-6) hatches that are used for producing submerged nozzles and monoblock stoppers. Table i gives the composition of the specimens under study.The laboratory specimens were made on a hydraulic press at a pressure of i00 MPa, and were fired at 1620-1670~ in a coke-powder charge.The high-temperature strength and the compressive creep were determined in argon atmosphere. The heating elements, the loading pads, and the protective screens of the heating chamber of the test set-up were made from graphite [2]. For determining the ultimate compressive strength, cylindrical specimens measuring 50 mm in height and 36 mm in diameter were heated at a rate of 180~ up to 1470~ at a rate of 720-900~ in the 1470-1770~ range, and at a rate of 120-180~ up to 18200K; at a given test temperature, the isothermal holding period amounted to 0.5 h. Table 2 shows the test results along with the data on the ultimate tensile strength obtained using the radial (diametric) compression method [3]. For all the specimens the temperature of strain initiation under load (determined according to GOST 4070-83) was above 2020~For the purpose of comparison, we measured the high-temperature strength of the specimens cut out from an imported monoblock stopper. It was equal to 8.4 MPa at 1820~ Almost all the experimental specimens, except specimen No. 6 having combined (alloyed) graphite, were found to be inferior to the specimens of the monoblock stopper with respect to strength. The temperature dependence of the ultimate compressive strength was determined in the 1720-1870~ range for the specimens of the batch No. i used for producing submersible nozzles. Composi~ tion number

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Section: Composi~ Tion Numbermentioning

confidence: 99%

“…It was equal to 8. 4 MPa at 1820~ Almost all the experimental specimens, except specimen No. 6 having combined (alloyed) graphite, were found to be inferior to the specimens of the monoblock stopper with respect to strength.…”

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A study of the thermomechanical properties of the graphite-bearing refractores

et al. 1985

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“…In connection with this, as has been noted by a number of authors [i, 5,6], determination of crack resistance from the reduction in strength properties (modulus of elasticity, compressive strength, etc.) during cyclic thermal tests is promising.…”

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Ultrasonic evaluation of the heat resistance of refractories

Rapoport¹

1989

Refractories

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“…The mean-integral value of the criterion of heat resistance in the T2-T I temperature range The intensity of thermal failures was determined from the length of cracks and the distance between them after service of the refractory plates and also from the reduction in the speed of passage of an ultrasonic signal after a 1300~ thermal cycle [15]. The results of the investigations shown in Table 2 confirm the increase in failure resistance in the order of the materials of KP-95, MKTsP-82, and KTsMKhP-90 (MKSPK-90).…”

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Means of increasing the service reliability of high-alumina slide gate plates

et al. 1988

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A major requirement imposed on steel melting production under conditions of intensification of the processes in the iron and steel industry is the production of high quality metal, which to a large degree is determined by the teeming conditions. The appearance of leaks of metal in teeming of steel from ladles with slide gates unavoidably leads to poorer ingot quality in top teeming into molds. In this case it is difficult to overrate the value of reliable operation of the slide gate, the final link in the process of teeming steel from ladles. With observation of the temperature conditions of the metal being teemed and of the method of preparation of the ladles and assembly of the slide gates one of the reasons for breakdowns in the teeming conditions is failure of slide plates.An increase in the operating reliability of slide plates is an important problem for refractory personnel.Its solution is impossible without a clear concept of the mechanism of a failure of plates in service. However, in the literature there is insufficient information on the mechanism of wear of slide plates.In many steel plants in the USSR and abroad plates of high-alumina composition are used. Therefore the purpose of this work is a study and analysis of the wear of high-alumina plates in service, construction of a model of the wear and failure of the refractories, and determination of the resulting requirements for plate quality. A solution of this problem makes it possible to determine means of improving the technology for high-alumina composition plates.Refractory plates of types KP-95 and MKTsP-82 to Technical Specification 14-8-385-81 and also plates of CZ* composition were investigated. The investigations were made in the AllUnion Refractory Institute and under the conditions of Western Siberia Metallurgical Combine. The characteristics of the refractory materials of these plates and the method of their production were given earlier [1][2][3][4].It is desirable to note only the main differences in their structure -the quantity and character of distribution of the glassy phase. For example, the KP-95 plates are made up of crystals of corundum between which the glassy phase is uniformly distributed. The quantity of glassy phase (7-8 wt.%) and the character of its distribution are similar in the grain and binder portions of the charge [2, 4].In the MKTsP-82 plates the same quantity of glassy phase is concentrated in the grains of the filler while in the binder portion of the charge the glassy phase is present only in the form of separate drop inclusions [2].The structure of the KTsMKhP-90 plates and of the inserts of the MKSPK-90 plates is characterized by the minimum (about 1.3%) content of glassy phase in the form of separate drop inclusions in the grains of the filler and in the binder [4].Such a distribution of the glassy phase in the plates is the result of technical features of their production. The KP-95 plates are produced according to a briquette method *At present, plates of CZ composition are designated type and composite ...

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Method of determining the thermal stability of a dense (compact) ceramic by ultrasonic monitoring

Cited by 4 publications

References 1 publication

A study of the thermomechanical properties of the graphite-bearing refractores

A study of the thermomechanical properties of the graphite-bearing refractores

Ultrasonic evaluation of the heat resistance of refractories

Means of increasing the service reliability of high-alumina slide gate plates

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