Axial densification of porous refractory materials in creep regime

Vishnevskii, I. I.; Smirnova, L. D.; Kushchenko, A. V.

doi:10.1007/bf01539592

Cited by 2 publications

(5 citation statements)

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“…The values of p are determined from (1)-(4) with a rather large error: 0M0_o I = (3.31 • 0.12), ppp = (3.52 • 0.07), 0PShG = (3.53 • 0.12), PPKhP = (3.35 • 0.ii) g/cm s. This leads to high errors (about i4%) in computing 0ci from expression (5). Nevertheless, the assessment shows that the closed porosity values of refractories PP and PShG are close to zero.…”

Section: Aot~=ao Op +Ao D =--A~/0-(6)mentioning

confidence: 98%

“…It is precisely this fact, providing there is adequately uniform distribution of the glass phase, that causes a high plasticity in such refractories and their substantial densification during axial compression. Specimens of mullite-corundum refractory may be, for example, [5] deformed by about 20% without marked damage, and in this case their open porosity is reduced by 30% (rel. ), and a deformation of about 50% facilitates a reduction in the porosity of 80% (rel.…”

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Structure and creep in magnesia refractories

et al. 1986

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The mechanical properties of heterogeneous-composition refractories and polycrystalline ceramics at high temperatures vary considerably, both qualitatively and quantitatively. The deformation of polycrystalline aggregates is controlled by elementary diffusion-dislocation acts of cooperative or individual displacement of atoms in the volume and at the surface of crystallites [i]. The high-temperature plasticity of refractories made by the chamotte technology has a macroscopic character, and ensures mutual displacement of the structural elements due to the reduction in the viscosity of the bond mass [2, 3] (a similar deformation mechanism develops also in polycrystalline ceramics in the case of the formation of fusible interphase layers [4]). It is obvious that the strength properties of such materials, and in particular creep, are determined by the quantity, composition, and distribution of the bond, its structure, and the strength of binding with the chamotte grains.One of the main constituents of the bond in aluminosilicate refractories is the glass phase whose amount reaches 10-30% (parts by volume) depending on the type of refractory. It is precisely this fact, providing there is adequately uniform distribution of the glass phase, that causes a high plasticity in such refractories and their substantial densification during axial compression. Specimens of mullite-corundum refractory may be, for example, [5] deformed by about 20% without marked damage, and in this case their open porosity is reduced by 30% (rel.), and a deformation of about 50% facilitates a reduction in the porosity of 80% (rel.).Magnesia refractories, in contrast to aluminosilicate, do not contain glass phase. This contributes to the development of a large amount of direct bonds between the grains of periclase and chromite in periclase-spinel refractories [6,7] and hence extended sections of continuous crystalline framework. The bond part contains crystalline silicates, montichellite, merwinite, and forsterite with higher fusing temperatures than the softening temperatures of silicate glasses. These facts cause relatively weak deformation in magnesia refractories, and close to brittle destruction even at 1600~We carried out studies of the structural changes developing in high-temperature creep processes with monoaxial compression in magnesia refractories of several types.The objects of the study consisted of industrial articles produced by the Magnezit combine: periclase MO-91 (GOST 4689-76), periclase--chromite PKhP from fused powders , and periclase with a spinel bond PShG with the addition of alumina , and also experimental refractories made from fused periclase PP containing more than 95% MgO (mass parts) prepared at the Experimental factory of the Ukrainian Institute. For the creep measurements we cut out cylinders from the articles with diameter 36 and height 50 mm, and with axial apertures of 6 mm diameter. The axes of the specimens coincided with the direction of the pressing force of the articles. The properties of the specimens are s...

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Section: Aot~=ao Op +Ao D =--A~/0-(6)mentioning

confidence: 98%

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confidence: 98%

Structure and creep in magnesia refractories

et al. 1986

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“…The first is typical of aluminosilicate refractories containing significant amounts of glass phase [7], and the second -for magnesia refractories in which the absence of the glass phase contributes to the develop- ment of direct bonds between the grains of periclase and chromite [8]. It is of interest to establish how the difference in the structural changes, taking place during creep of refractories, affects the functional relationship between the deformation and time~ Actual approximation of curves c(~) with the aid of (4) requires a knowledge of the degree factor p. Then the remaining coefficients can be used to determine the construction of the relatioships…”

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confidence: 99%

“…1 shows the results of treating data for the creep of mullite corundum refractories, undergoing significant densification during deformation [7,9]. As an illustration Fig.…”

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confidence: 99%