Creep and reaction of mullite ? Corundum refractories

Vishnevskii, I. I.; Aksel'rod, E. I.; Tal'yanskaya, N. D.

doi:10.1007/bf01284423

Cited by 4 publications

(14 citation statements)

References 6 publications

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“…It is close to the results obtained by the hot wire method for this method earlier [7], the values of I measured by the cylinder method [5] agree with those obtained by the hot wire method above 500~ within the limits of the total measuring errors, while at lower temperatures the spread increases to about 35% in the direction of too high data [5].…”

supporting

confidence: 89%

“…Therefore for interpolation of the experimental data there was selected a function of the form ~=~o+at+bt ~. (5) In accordance with this the solid lines in Fig. 6 were drawn according to the equations:…”

Section: ~O(t) +~(T) ~P (3)mentioning

confidence: 99%

“…2). The thermal conductivity of this material was measured in the Ukrainian Scientific-Research Institute for Refractories using the cylinder method on the instrument described in [4] in 1972 and on the instrument described in [5] in 1974. These results are also shown in Fig.…”

mentioning

confidence: 99%

“…To determine the thermal conductivity of the MKRR fiber material pieces from the roll were loaded into corundum containers with inside dimensions of 230 x 115 x 65 mm and compressed (density 130 kg/m3)= As is known [5,8,9], the thermal conductivity of fiber materials increases rapidly with an increase in temperature as the result of the constituent Ira d ~ T s caused by the high porosity (not less than 90%) and the share of radiation in heat transfer reaches about 50% at !O00~ [i0]. This feature of the temperature relationship of thermal conductivity in determination of it by the hot wire method leads to an increase in the measured values of 1 with an increase in the specific power Wsp supplied to the wire.…”

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confidence: 99%

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Use of the hot wire method for measuring the thermal conductivity of lightweight, fiber, and powder refractory materials

Aksel'rod

Vishnevskii

1984

Refractories

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In a number of countries of the European Ceramic Union and the Council for Mutual Economic Aid the method of a linear probe of constant power, known as the hot wire method, has been adopted as the standard for determination of the thermal conductivity of refractories with % < 2 W/(m-K).At present a plan has been developed for a standard of the Council for Mutual Economic Aid including the steady method of a plate (All-Union State Standard (GOST) 12170-76) and the hot wire method (German Democratic Republic standard TC/32153-76). The higher the thermal conductivity of the sample the lower the measuring error of the first of them while the second method is the optimum for low thermal conductivity parts and materials.In the USSR the hot wire method was first used for determining the thermal conductivity of refractories by the All-Union Institute for Refractories [i]. In the Ukrainian ScientificResearch Institute for Refractories an instrument based on the hot wire method has been built for measurements of % up to 1400~ with an error of • [2]. Standardization of the instrument using certified samples of organic and quartz glasses has shown a difference from metrological data of <2%. This article considers the possibilities of the hot wire method for thermal insulation materials with different structures including lightweight, fiber, and powder refractories.* Lightweight refractories to GOST 5040-78 with low (ShL-0.4 chamotte), medium (MKRL-0.8 mullite--silica), and high (KL-I.3 corundum) thermal conductivities were used for the tests. The sample was two bricks of normal dimensions.Between the largest surfaces of the samples was placed a measuring cross of platinum--rhodium wire with a PP thermoelectric transducer welded to it. The determinations were made in a wide range of values of power (3-60 W/m) supplied to the wire.The features of the method and the equipment used are described in The absolute values and character of the temperature relationship of thermal conductivity of the investigated lightweight parts reflect features of the influence of phase composition and structure on the processes of heat transfer in dispersed systems [3]. For the most porous material, ShL-0.4, a significant increase in thermal conductivity % with an increase in temperature t, indicating a significant contribution of radiation to heat transfer at high temperatures, is characteristic.The approximation of the experimental data by a cubic parabola ,Z=0,175+0,90 9 10-m(t,+.is shown in Fig. 1 by a broken line.The thermal conductivity of ShL-0.4 samples was also measured by methods of a cylinder [4] and a plate (GOST 12170-76).In both cases two samples each were tested, one of them cut from the brick which had served as half of the sample for measurement by the hot wire method and the other from a random brick of the same lot. The reproducibility of each method for the two samples is no poorer than 5%. Both of the methods provided results agreeing with the hot wire method within the limits of instrument errors, which are • and • respectivel...

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supporting

confidence: 89%

Section: ~O(t) +~(T) ~P (3)mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Use of the hot wire method for measuring the thermal conductivity of lightweight, fiber, and powder refractory materials

Aksel'rod

Vishnevskii

1984

Refractories

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“…The thermal conductivity of the specimens was determined in a device specially developed at the Ukrainian Institute of Refractories and described in [6]. The amount of mullite in the specimens after firing was estimated using the method developed at the Institute by determining the insoluble residue and glass phase in the fibrous material, t followed by an inspection of the phase under a microscope.…”

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confidence: 99%

Effect of the type of binding material on the properties of refractory glass-fiber heat-insulation products

et al. 1982

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One of the most important components of refractory glass-fiber heat insulation products which determine the main working properties is the binder, which links the separate glass fibers and gives the strength of the finished articles.Moreover, the binder has a significant effect on the density and thermal conductivity of the heat-insulation products and also on their shrinkage during service.In addition, the effect of the type of binder on the properties of thermal-insulation glass-fiber refractory articles has received inadequate coverage in the literature.Thus, in [i] it was shown that the nature of the binder has a significant effect on the adsorption capacity of the fiber, on its structural features at high service temperatures, and also on the temperature interval in which a change occurs in the mass and volume of the materials. According to the data in [2], inorganic binders do not affect the crystallization of the refractory glass fiber, which is barely possible, particularly at high temperatures when an interaction is observed in most cases between the glass fiber and the binder.The present paper gives some results from a study of the effect of the binder on the main properties of glass-fiber refractory products.We used water glass, silica sol, chromium--aluminophosphate binder (CAPB), and an alumina binder of the bentonite type as the inorganic binders for the production of articles based on aluminosilicate fibers; for the organic binders we used a polyvinyl acetate dispersion (PVAD)We used the refractory glass-fiber ~ and 46-48% Si02 developed for the first of an aluminosilicate composition with 51-53% AI=Os time in the USSR at the All-Union Scientific-Research Institute of Glass Laminates and Fibers and produced at the Bogdanovich Refractory Plant [3][4][5].Because of the different natures of the binders and, consequently, of their adhesive quality, experimental amounts of binder were different and varied from 4-16 to 50-65% (dry material).The main criterion was the use of a minimum amount of binder that would ensure the ultimate bend strength of ~ 0.5 MPa after drying at least.All the specimens with the various binders were made up as a slurry and subsequently evacuated and pressed in equipment which included a mill and vacuum press. The specimens were dried in a hot chamber at 120-150~ for 16-18 h and then fired at various temperatures between 400 and 1300~ with a dwell of 2 h at each temperature.We then studied the temperature dependence of the main properties of the articles and the interaction process between the binder and the glass fiber.The linear shrinkage (or growth) of the heat-insulation products was calculated by measuring the linear dimensions of the specimens to an accuracy of 0.I mm; the ultimate bend strength was determined on an MR-0.5-1 device using a three-point bend method; the specimen was loaded at the center and the distance between the supports was 40 mm. The thermal conductivity of the specimens was determined in a device specially developed at the Ukrainian Institute of Refra...

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Structure and creep of single-phase and two-phase ceramics in the ZrO2-CaO system

et al. 1989

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Creep and reaction of mullite ? Corundum refractories

Cited by 4 publications

References 6 publications

Use of the hot wire method for measuring the thermal conductivity of lightweight, fiber, and powder refractory materials

Use of the hot wire method for measuring the thermal conductivity of lightweight, fiber, and powder refractory materials

Effect of the type of binding material on the properties of refractory glass-fiber heat-insulation products

Structure and creep of single-phase and two-phase ceramics in the ZrO2-CaO system

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