Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B33/00—Clay-wares
  • C04B33/32—Burning methods
  • C04B33/323—Burning methods involving melting, fusion or softening
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B33/00—Clay-wares
  • C04B33/32—Burning methods
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/20—Patched hole or depression

Definitions

• a typical example of these materials is the product sold commercially under the name of Corhart 104 and described in United States patent specification No. 2,599,566, for which a typical composition is: 55-56% of MgO, 20% of Cr O 12-13% of FeO, 7-8% of A1 0 2.5% of Si0 and 1.3% of CaO.
• This product is manufactured in the form of slabs, from which the commercial units are cut.
• the dispersion of the shrinkage cavity is achieved by means of various well-known procedures, such as the introduction into the casting of the slabs of a certain amount of a small-grain substance made up of the materal crushed up (a method described on page 247 of the English translation of the book by A. A. Litwakovskii: Fused Cast Refractories, 1961, or in French patent specification No. 738,117), or such as the introduction into the casting of the slabs of a product able to liberate gases (a method described in French patent specification No. 922,954), or in a combination of these methods.
• the present invention has for its object electrically fused, cast refractory products of improved appearance and quality, and the manufacturing cost of which is slightly less than that of products at present available.
• the said refractory products are characterized in that the holes from the dispersed shrinkage cavity are filled in and made good by means of a suitable grout.
• the filling-in and making good of the holes from the dispersed shrinkage cavity can be put into effect by various methods.
• One of these methods consists in subjecting the block to be filled in (the sawn faces of which have been arranged horizontally) to horizontal vibrations or to vertical shocks, and to apply the grout with a trowel successively to the two sawn faces.
• Another of the said methods consists in arranging the block requiring to be filled in in a chamber which can be de-pressurized, creating a vacuum in the said chamber, placing the chamber in communication with a source of grouting material while preventing the entry of air into the chamber so as to introduce the grout into the chamber and to fill the holes with grout, then interrupting the vacuum, removing the block, scraping it over and in recovering the remaining grout for the following operation.
• the block is then allowed to dry in the air or under any other appropriate conditions.
• a further possible method consists in arranging the block to be filled in in a chamber which can be linked to a pressure source, introducing the grout into the chamber, and placing the chamber under pressure, after which the pressure is relieved, the block is removed and is scraped over, as in the previous instance.
• This method can moreover be usefully combined with the preceding one, it being possible to effect the pressurization of the chamber after the introduction in vacuo of the grout. It is this latter method which constitutes the best way or filling in the refractory products which are the aim of the invention.
• vacuum and pressure are not critical. It is possible, for instance, to apply a vacuum of the order of 10 to 50 mm. of Hg by means of an impeller pump, and/or a pressure of the order of several atmospheres by making a connection to a source of compressed air.
• the grout employed should naturally satisfy a number of conditions. In particular, it should not pour out excessively under the effect of the vibrations or shocks in question or of the suction of the liquid by the vacuum: it should be sufliciently fine to pentrate into the narrow orifices of the refractory product requiring treatment, but should not be too fine, so as to prevent too great a contraction upon drying; it should be thixotropic, so as not to run out of the external shrinkage holes after the treatment; it should not harden too rapidly in the presence of cold; it should harden in the presence of heat, so as not to collapse into powder at the commencement of the heating process when actually in use; it should be adequately resistant to corrosion.
• Various examples of grout will be given hereinafter.
• the filling-in and making good of the dispersed shrinkage holes is, in the case of a method for filling in and making good and for a given grout, all the better, the more extensive the communication between the holes is.
• slabs of Corhart 104 prepared by the normal procedure may be treated in accordance with the invention so as to obtain slabs of improved quality
• the present applicant has found that better results are achieved when the slabs are manufactured by a special method which leads to the formation of an open porosity in the final slabs.
• Such a method for example, consists in dispersing the shrinkage cavity by the addition of smallgrain material and by employing a fusion technique which brings about degasification of the bath of melted material of the kind described in French patent specification No. 1,208,577 and its addition, No. 75,893, 82,057, 82,310 and 84,153.
• the refractory products according to the invention possess, in relation to the products whose dispersed shrinkage holes have not been filled in, an improved appearance, a density increased by approximately 5%, and a resistance to corrosion which is higher by about 15%.
• the treatment covered by the invention makes it possible to decrease the efiects of tur-
• the material concerned is the commercial product Corhart 104, pulverized and passing through a sieve o! 0.5 mm. mesh.
• the material concerned is the commercial product Corhart 104, (pulverized irli1 an Alslng-Brand ball-mill and passing through a sieve of mm. mes
• EXAMPLE 2 The grout A and B of Example 1 were employed in the carrying out of tests on the filling-in eifect in respect of blocks of Corhart 104 specially manufactured to obtain a degassed product.
• the block to be treated was placed on a frame set vibrating by a pneumatic hammer 1
• the block to be treated was subjected to shocks of an amplitude equal to 3 cm. and at a frequency of 160 shocks per minute.
• EXAMPLE 1 The following table indicates the composition of the grouts employed for filling in the cavities or holes in refractory products with a base of chromium oxide and of magnesium oxide.
• the method in vacuo yields the best results, with an average gain in density of 0.15 g./ cm.
• the gain does not appear to depend especially on the initial density, but rather on the volume of the accessible holes or cavities, one large hole filling up better than several small ones.
• Grout B which contains 1% of commercial clay, is slightly superior to grout A.
• the blocks, duly filled in, are good enough to use.
• the block to be treated was subjected to shocks with an amplitude equal to 3 cm. and with a frequency of 160 shocks per minute.
• Example 3 shows that the best method of filling in is carried out in vacuo, followed by pressurization.
• Grout C with a finer grainsize is superior to grout B from the point of view of penetration, as the results of tests 31 to 35 show.
• Grout C however, has the drawback of being more awkward and of suffering from greater contraction upon being dried.
• Grout D leads to results which are slightly inferior to those with grout C (the average gain is the same, but the results given by grout C refer to normal blocks, whereas whose of grout D relate to special blocks). Nevertheless, grout D constitutes the best comprise from the point of view of quality/ cost of manufacture.
• hardenable, thixotropic grout comprising, as main solid components, powdered refractory materials having a composition similar to that of the said refractory product.
• Cast refractory products comprising, by weight, about 55-56% MgO, about 20% Cr O about 12-13% FeO, about 78% A1 about 2.5% Si0 and about 1.3% Q10, and having dispersed shrinkage cavities therein, characterized in that said cavities are filled with a heat hardenable, thixotropic grout comprising, as main solid components, powdered refractory materials having a composition similar to that of the cast refractory products.
• Process for upgrading cast refractory products of any known oxide-based composition having dispersed shrinkage cavities therein characterized by filling said cavities with a heat-hardena-ble, thixotropic grout comprising, as main solid components, powdered refractory materials having a composition similar to that of the cast refractory product.
• Process for upgrading cast refractory products comprising, by Weight, about -56% MgO, about 20% Cr O about 12-13% FeO, about 7-8% A1 0 about References Cited UNITED STATES PATENTS 707,670 8/1902 Zuckatdt 117-123 A 2,968,083 1/1962 Lentz et a1 117-2 R 3,141,790 7/1964 Davies et al 117123 A 2,534,328 12/1950 Whitman 117--169 R 2,187,324 1/1940 Many 1172 R ALFRED L. LEAVITI, Primary Examiner M. F. ESPOSITO, Assistant Examiner US. Cl. X.R.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Dispersion Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)
• Treatment Of Sludge (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8659300

Family Applications (1)

Country Status (3)

Cited By (1)

• 1968
  • 1968-12-27 FR FR181380A patent/FR1597288A/fr not_active Expired
• 1969
  • 1969-12-23 DE DE19691964493 patent/DE1964493B2/de not_active Withdrawn
  • 1969-12-23 US US887774A patent/US3667981A/en not_active Expired - Lifetime

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