US 2915893 A
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Description (OCR text may contain errors)
Dec. 8, 1959 r a. o. WILKINS METAL GLAD REFRACTORY BRICK Filed March 27. 1953 Fl 5. E:
IN VEN TOR. [ar/ D. Wl/k/ ns.
United States Patent 2,915,893 METAL CLAD REFRACTORY BRICK Earl D. Wilkins, Los Altos, Calif., assignor t0 Kaiser Aluminum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Application March 27, 1953, Serial No. 345,219 6 Claims. (Cl. 72-35) This invention relates to the production of metal-clad or metal-plated refractory bricks or shaped pieces especially suitable for use in furnace linings; and also to the refractory pieces produced.
It has been known in the past to provide refractory brick or other pieces for use in furnace linings, wherein the refractory material bears a metallic coating on two or more sides of the piece. Many various means for holding the metal onto the refractory have been devised. For instance, it has been known to place the metal casing or lining in the brick mold and then to fill the mold, fitted with the casing, with the brick mix, and press. The metal lining is made with tabs or ears which are bent inwardly and engage the brick mix, or, alternatively or in addition, can contain apertures through or into which the brick mix extrudes, thereby fixedly engaging the casing when the mix hardens. This mode of procedure involves the operations of providing the metal casing with the ears, or apertures, and the disadvantages attendant upon placing the lining in the brick press or mold, then filling with brick mix and pressing. Furthermore, in this procedure, the metal ears or tabs tend to swell from oxidation upon heating or firing and thereby disrupt the refractory structure. It has also been proposed to make the green or unfired brick in the usual way, and then to press metal casings on to the green brick, the metal casings being fitted with ears or tabs to engage the brick. However, this method is not suited to the applications of casings to some kinds of brick, especially, for instance, to bricks composed substantially of nonplastic materials, such as highly refractory magnesia or or periclase-chrorne bricks, because cracks tend to develop in the bricks upon later firing. Still another means of applying the casings to brick, especially when a three-sided or U-shaped casing is employed, is to merely spring the casing onto the brick and depend upon frictional engagement to retain the casing on the brick. This also has not been satisfactory beacuse it has been found that the casings tend to slip off the brick in handling or during placing in the furnaces where it is desired to employ them, and constitute a hazard to the workmen. It has also been proposed to cement the casings to the .brick with a refractory cement such as arefractory or inorganic bonding material but this has proved quite unsatisfactory in practice.
It is an objectv of the present invention, therefore, to provide a simple,'inexpensive and effective means for attaching metal casings to bricks of all types. It is a further object to provide such means for applying metal 'casingsof various types to many varieties of bricks. It .is a still further object to provide metal-cased bricks,
whereof the casings are fixedly attached and will more .certainly remain so during handling, shipping, placing and heating.
According to the present invention, the bricks are molded or formed as desired, and there is applied between .the brick and the metal casing an amount of a sticky, rubbery organicadhesive which adheres to both the brick Patented Dec. 8, 19 59 ice and the metal, and the metal casing is then applied to the brick over the applied adhesive. The adhesives useful herein do not dry to a hard, brittle state under the conditions of use but remain sticky or tacky, and adherent. They are water-insoluble and are employed in the form of emulsions in water. When the adhesive comes into contact with the brick, the emulsion appears to break and the rubbery constituents are believed to coagulate or condense. The adhesives useful herein are rubbery materials, or polymeric organic materials, such as natural rubber latex, synthetic rubber latex or synthetic polymeriZab-le elastomers such as isoprene, butadienestyrene copolymer, butadiene-acrylonitrile copolymer or other substances polymerizable to form synthetic rubber, polyethylene, and vinyl resin latex, for example, of polyvinyl acetate and polyvinyl chloride. Mixtures of these adhesives can be employed. If desired, an admixture of rubbery material or a rubber latex or polymeric organic material, as described, and a resin or resins can be employed. The adhesives useful herein adhere well to the brick and metal surfaces in the cold, i.e. at ordinary atmospheric temperatures, and also remain adhesive at the temperatures encountered in furnace rooms. These latter temperatures are, in general, higher than ordinary air temperatures but the adhesives disclosed above do not lose their strength of bond or stickiness when the cased bricks are held for some time under such conditions. In this manner, the adhesives herein employed behave'well, in contrast to sodium silicate which tends to become hard and brittle, and to asphalt which softens, under these conditions.
Figures 1 to 8 are illustrative of some embodiments of the present invention wherein there are shown metal casings applied to one or more sides of a refractory brick or block adapted for use in a furnace. In Figure l, a single metal plate is shown, applied to one side of a brick, and in this embodiment the adhesive is shown as distributed fairly evenly over the metal and brick surfaces, whereas in each of the other figures there is shown a partial distribution of the adhesive, i.e., over only a part of the surface to which applied. Such partial distribution of adhesive ca n be employed in any desired embodiment of the invention, and, in general, adhesive is required between only one surface of the brick and a continuous metal piece. Figure 2 shows a brick encased by an L- shaped plate; Figure 3, plated on three sides by a U- shaped plate; Figure 4, plated on four sides by two L- shaped plates; Figure 5, single plates applied on opposite faces of a brick; Figure 6, a brick adapted to be suspended, as by means of recessed portion 13, and encased or plated over a major portion of four sides by means of a U-shaped plate and a single plate, as shown, adhesive being applied between brick and bottom of the U and between brick and the top 'plate; Figure 7, a refractory block adapted to be suspended from one end, the lower portion being plated or encased on four sides, by means of two L-shaped plates, and the upper portion being plated or encased on three sides by a U-shaped plate and having recessed portion 14 on the unplated side adapted to engage a supporting element; and Figure 8, anirregular block having offset portions on opposite faces, in efiect, substantially a T-shaped block, at least one face of the leg'and offset or shoulder of the T being covered bya continuous metal plate of conforming configuration. In each Figure, 10 represents a refractory brick; 11, adhesive as herein defined; and 12, metal plate or casing.
The brick to be encased in metal, or to which a spacer plate is to be applied, can be any type of refractory brick. The term metal case in the specification and claims is intended to include a metal plate 'applied to one side of the brick, or a case applied to more than one side,.and to the'whole or a portion of the side. Preferi usually iron 1 or steel known infthis art) is shaped into brick in the known manner, for instance by pressing. The brick can be cased directly, or it can be first dried or fired. An amount of adhesive is dropped or placed on the brick surface or surfaces and the metal casing laid on. Alternatively, the adhesive can be applied to the metal and the, sotreated metal then applied to the brick. The bricks are allowed to stand'until the adhesive has set, which usually requires only about one-half hour, and are then ready for shipment, handling, or use. V
In one embodiment of this. invention, a brick batch is prepared which contains high purity periclase grain in graded sizes according to good commercial practice in this art, and a bonding material which comprises finely divided magnesia of high purity, volatilized silica and a water solution of magnesium chloride. Bricks are pressed from this batch and are dried. Upon one surface is dropped an amount, or gob, of a water emulsion of a synthetic rubbery material. The emulsion has a solids content of 42%, 'a pH of 8 to 9, viscosity 850 .to 1000 cps. at 25 C. and a unit weight of 8.45 lbs. per gallon.; It is a synthetic rubber-resin emulsion. Films formed from this emulsion are clear, substantially colorless, odorless, and unaffected by the temperatures .encountered in practice, before firing. The adhesive film is extremely water-resistant. ,An L-shaped steel casing is laid on the brick to which the adhesive emulsion has been applied, and the Whole is allowed to set, to form a strongly bonded masonry unit as shown in Figure 2. ,Apparently the adhesive-water emulsion breaks when it comes into contact with the brick surface, and the moisture or Water is absorbed into the brick or evaporates, and the adhesive component deposits. It is be,
lieved that, when such emulsion is applied to thetsurface of a nonacid or a basic brick containing a salt or electrolyte in its composition, for example, in the bond, 7 the salt or electrolyte aids in or effects the breaking of the emulsion.
'Another adhesive material useful in this invention is a water emulsion of polyvinyl acetate (50% solids), containing about 20% .ofbrtho-nitrobiphenyl. For in stance, there can be employed a mixture of 100 parts by weight of polyvinyl acetate-water emulsion, containing 50% solids, by weight of the emulsion, and from 20 .to 25 parts by weight of ortho-nitrohiphenyl, the admixture being applied' in the manner described above.
There can also be employed in this invention natural rubher latex, that is, Hevea latex.
' 1 Bricks which have been metal cased in this manner .have been installedin steelfurnaces andhave proved exceptionally satisfactory. Bricks or blocks, each having a; metal plate on one or morefaces or sides, prepared according to the invention, are particularly useful in lining rotary kilns, e.g. for cement-burning operations. Organic fibrous spac ers,"e.g. of paper or wood, can also be applied in the samemanner. The bond formed is so strong handling and installation. useful in this invention have good initial tackiness and set to a strong, resilient bond which retains its desired qualities during long storage and under varying temperature conditions. It is advantageous also that these Water emulsions avoid the circumstance of using toxic or noxious solvents or vehicle sythat the emulsions are easy to apply and produce cased bricks of neat appearance. It is sometimes desirable to employ in the emulsion one or more plasticizers or tackiness-promoters, such as ortho-nitrobiphenyl, dibutyl phthalate, tricresyl phosphate or others as known to this art. As indicated in the above example, a resin or resins can also be admixed in the emulsion.
It is an advantage of the present invention that metal cases or plates can be securely aflixed in a simple and eflicient manner to any desired type of brick. With respect to metal cases which previously have been fixed to brick by springing, it has been necessary that the size of the case be controlled with extreme care in order to ensure proper contact. The present invention enables strong bonding of the case to the brick even though there I may be such variation in size. as would have precluded 7 good springing contact.
that pieces of the refractory are pulled away when the case is pried 0 1 :after the bricks metal-cased in this manner can be handled, shipped, held for a time in the furnace .room,'*if desired, and then-installed in a steelfmaking furnace, and exhibit great-strength and stability of adhesive bond during these operations. It is desirable that the bonding adhesive be elastic and it is preferred that it exhibit suflicient resilf an e Q ith I d1he shocks and strains incidentalto adhesive bond has set. The
. faces being in opposed diverging relation,
, disposed between said plate It is also an advantage that .plates'can be separately affixed to sides, e.g. opposite or other, sides of the brick; and also, that to ,brick of ginusual or irregular configuration there can be afiixed a metal plate or plates of conforming configuration. It is a further advantage that the organic adhesives of this invention are destroyed when the brick is fired, yielding volatile products, predominantly carbon dioxide and water, which go olf with the furnace gases and which do.
not combine with or deleteriously afiect the refractory bricks. It is also advantageous that handling and costs can be substantially reduced by applying the adhesive .and metal case to the brick directly after the pressing or forming step.. Alternatively, it is very advantageous in some instances to apply the metal case to an already burned brick, whereas thisoperation would not be possible if eared cases were to be pressed onto the brick.
In this specification, percentages are by weight unless otherwise specified, ifdesired, themetal plate can .cover less ,than'the whole ,ofa bricksurface, e.g., side, to which it is applied. It is to 'be understood that variations and modifications can be made .inthe invention without departing from the scope of the appended claims, the above specific description and the drawings having been given for purposes of illustration only. This application is a continuation-in-part of my copending application, Ser. No. 345,181, filed March 27, 19-53, and now abandoned, pertaining to metal-cased bricks. Having now described the invention, what is claimed 1s:
1. A composite refractory furnace lining article corriprising anonacid refractory block having side faces and end faces, ,a metalplate covering at least the major portion of at least one of said side faces, and aco mbus tible organic adhesive interposed between said plate and'said block and vafiixing said plate to said side face, said adhesive being sticky at ordinary atmospheric temperatures.
2. A composite refractory fnmace lining article comprising a substantially wedge-shaped, nonacid refractory block having side faces and end faces, two of said side one of said end faces being smaller than the' other end face, a metal plate covering at .least a major-portion of one of said divergent .sidefaces, and a combustible, organic rubbery adhesive and said side face and aflixing said plate to said side face of said refractory block, said adhesive being sticky at ordinary atmospheric temperatures.
3. An article as in claim a steel plate. v
4. A composite refractory furnace lining article comrising a :nonacid refractory block having side faces and 2 wherein said metalplate is The rubbery base adhesives end faces, a metal plate covering at least the major portion of one of said side faces, and a combustible adhesive interposed between said plate and said block and affixing said plate to said side face, said adhesive being sticky at ordinary atmospheric temperatures.
5. A composite refractory furnace lining article comprising a substantially wedge-shaped, nonacid refractory block having side faces and end faces, at least the major portion of two of said side faces being in opposed diverging relation, one of said end faces being smaller than the other end face, a metal plate covering at least a maior portion of one of said divergent side faces, and a combustible adhesive disposed between said plate and said side face and affixing said plate to said side face of said refractory block, said adhesive being sticky at ordinary atmospheric temperatures.
6. A composite refractory furnace lining article composed of a nonacid refractory brick having four side faces and two end faces, a U-shaped steel plate covering three side faces of said brick, and a combustible, organic adhesive interposed between said brick and said steel plate and resiliently aflixing said plate to said brick, said adhesive being sticky at ordinary atmospheric temperatures.
References Cited in the file of this patent UNITED STATES PATENTS Harvey July 2, 1929 Kittredge et al. Oct. 12, 1937 Goldsehmidt Oct. 8, 1940 Rothbart Apr. 15, 1941 Batcheller Sept. 16, 1941 Hemming Apr. 18, 1944 Prentice Feb. 5, 1946 Morrison et al. Jan. 25, 1949 Chester July 17, 1951 FOREIGN PATENTS Great Britain Jan. 11,1940 Great Britain Apr. 4, 1951