US1769708A - Composite refractory brick - Google Patents

Description

July 1, 1930. J MQRGAN 1,769,708 I COMPOS ITE REFRACTORY BRICK Filed Oct. 10, 1927 gvwewtoz JOHN D. MoRsA/v 851;; /1 i s a t tow;

Patented July 1, 1930 S '\UN ITEDS STATES .PATELNT OFFICE JOHN D. MORGAN, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR TO DOHERTY RESEARCH 7 COMPANY, OENEW YORiK, N. Y.,

A CORPORATION OF DELAWARE' COMPOSITE REFRACTORY BRICK Application filed October 10, 1927.. Serial No. 225,187.

The present invention relatesto the production of a composite furnace wall, to a brick suitable for making a furnace .wall of composite character and to a method of making a composite brick.

It has been proposed to make furnace walls of a composite character to reduce the large N t1on to provide acomposite wall having high radiation losses common when the furnace Walls are of ordinary firebrick and red brick. m It has been found that decreasing the radiation from the furnace walls has increas'ed'the average temperature inthe furnace and has increased the rate of deterioration of-the firebrick. T It has been proposed also to use furnace linings of'high refractory character in composite walls to permit the use ofhigh temperatures. experienced in obtaining a-durable wall havin 'a'highly refractory lining.- go %)ne of the refractory materials which it has been'proposed to use'as a coating for furnace bricks and as a layer liningior furnaces is carborundum. Carborundum, however, although very refractory, is highly con- 5- ductive at high temperatures. Consequent- 131, if it is attempted to push the average furnace temperature much above that commonly employed, the heat insulating materialin contact with the carborundum layer is apt" to swell or soften, leading unless thecarborundum' layer is very thick, to the early destruction of the'connection or bond between the carborundumlayer. audits backing. As carborundum is'relatively expensive, it is impractical to employ it in thick layers and its use in heat insulated furnaces has been very I limited.

Another: material which it has been pro posed to useas a refractory lining for fur- 40 naces, is zirconia Th s'material does not transmit heat as-read1ly as carborundum,

but it changes in volume when heated under ordinary furnace conditions much more than a most refractories and much more than the -materials desirable for use as backmgs for the zirconia. Consequently, the bond between the zirconia and its backing is soon weakened and the zirconia displaced from the furnace wall. No serious attempt has been made to use zirconia linings in commercial furnaces.

It is one of the objects of the present invenheat insulating capacity and adapted for use in commercial furnaces.

Other objects and advantages of the present invention will hereinafter ap ear.

In the drawing forming part of the present disclosure, the figur'e is a perspective view of a portion of a furnace wall according to the present invention. However, difliculty has been It is advantageous to be able to build a fur-, nace or other wall of bricks. It is preferred therefore to apply the present invention to bricks or furnace walls built'of bricks, but it is. not limited thereto.

In said figure, 10 indicates a portion of a vertical furnace wall according to the present invention. Said wall is laid up of bricks 12-12 of any convenient or desired size and preferably of the ordinary rectangular shape.

Walls 10 may have an outer metal casing 13 thereon if desired. The main body portion of bricks 12 is of a heatinsulating material, preferably diatomaceous earth. However, puffed clay, cellular zircon, zirconia, or clay may be used as the material for the main body portion of the bricks. Ordinary plastic clay, although making bricks of much higher heat insulating capacity than fireclay, can be used as the material for the body of the bricks only when a refractory layer of high heat insulating capacity is used on the face of the bricks to be exposed to fire. Each of the bricks 12 has a surface layer 14 attached 'to the main body portion of the brick along a plane 16. The loricks 12 are so placed in the furnace wall that the layers 14 all face in one direction or, in other words, lie along the vertical face of the wall on the side toward the furnace chamber. The layers 14 are of a highly refractory composition and preferably also of non-conductive characteristic. Zircon (native zirconium silicate) is the preferred material from which to form layers 14. This material has been further desirable characteristic of being free from either permanent, growth or permanent shrinkage u on being heated to high temperatures. here is therefore no material change in the volume of the -material forming the facing over long periods of use. But few other refractory materials possess this characteristic, these being such substances as electrically fused magnesia, electrically fuzed quartz, electrically fused chromium oxide, and similar products of the electric furnace. It will be understood that by substantially constant volume material as used in the following specification and claims such refractories are intended. Zirconia may be used only if mixed with sufficient zircon to prevent the zirconia from shrinking so much when the bricks are heated in use as to weaken the layers 14 or the bond between the layers and the main portion of the bricks.

The bricks 12 may be fired in two parts and the arts cemented together or they may be fired all in one piece.

If the bricks are to be fired in two parts, the body portions of the bricks 12 are formed,

forexample,of diatomaceous earth or of a clay which is capable of pufiing when burned and then fired to at least 2500 F. Bonded plates 14 of highly refractory non-conductive, nonswelling material such as zircon or zirconzirconia are then formed, preferably of about one inch in thickness, and including a sui-table bonding agent such asless than one per cent of a precipitated hydroxide, a few percent of ortho hosphoric acid or less than one percent 0 precipitated carbonate. -The plates are'then fired. The preferred temcounter in use. The hydroxide and carbo-' nate bodies, of course, decompose when heated and the bonding action is due directly to their decomposition products. Precipitated barium carbonate gives good results. After the plates have been fired, the plates 14 are then cemented to the body portions of bricks 12 by placing powdered boro-silicate enamel,

or the like, betweenadja'cent faces of the body portions and the plates and heating the body portions and plates to fuse the enamel and to bond or cement the plates to the body kiln will permit. It is good i portions. A brick having a sil-o-cel porous silica body and a zircon cap cemented on one of its faces by a fused silicate as just described has been tested by applying an oxyacetylene flame to the center of the cap until the cap had reached a high temperature. No alteration of the surface of the cap was observed as a result of this test and the cap remained firmly united to the porous body. If the bricks are to be fired in one piece, the bonds between the high refractory layers 14 and the high insulating body portions of bricks 12 may be made at the same time as the two refractories themselves are bonded.

For example, the body ortions of the bricks 12 may be formed of iatomaceous earth or crushed puffed clay togetherwith a binder and the high refractory layers 14 formed .of zircon grain or a mixture of zircon and zirconia together with a binder or bond supplying agent. Preferably the body portions are formed with the same hinder or bond-supplying agent as the high refractorylayers 14, and the two assembled to form bricks while still moist. Either of the bonding agents mentioned above is suitable for the entire brick. Upon drying and subsequent firing theinsulating body portions and high refractory layers 14 are bonded together with out any definite plane of cleavage between them, the layers 14 being integrally united to the body of the bricks by a common bonding substance which extends throughout the entire mass of the brick. The resulting bricks 12 are highly resistant to thermal and mechanical shocks tending to separate the layers from the bodies under furnace conditions. In this case also it is desirable that the firing temperature reach 2500 F.

i It has been found that a wall made up according to the present invention having a layer of zircon one inch thick backed bya stances, it has been found that the zirconium compounds, such as zircon and zirconia which contain oxygen as well as zirconium, resist spalling and cracking under furnace conditions to a notable degree and that they sustain a higher load at high temperatures than other materials which have a heat-insulating effect at high temperatures of a higherorder than the ordinary fire-brick. Also, while it is preferred to use these zirconium refractories on bodies of material having higher heat-insulating effect at at high temperatures than fire-brick, the invention is not limited to this.

Having thus described my invention, I

claim zirnonium compound firmly attached to a body of refractory non-conducting material, saidlayer and body being bonded throughout by the same bonding material.

5. As an article of manufacture, a composite brick having a layer of refractory, substantially constant volume, non-conducting material firmly attached to a non-conducting body of diatomaceous earth, said layer and body being bonded throughout by the same bonding material.

6. As an article of manufacture, a composite brick having a layer of high refractory, substantially constant volume, non-conducting material firmly attached to a non-conducting body of non-conducting material, said layer and body being bonded throughout by the products of decomposition of precipitated barium carbonate.

7. As an article of manufacture, a compos- Jite brick having a layer of substantially constant volume zircon material firmly attached to a non-conducting body of diatomaceous earth, said layer and body being bonded throughout by the products of decomposition of barium carbonate.

8. As an article of manufacture, a composite brick having a layer ofzircon firmly atconstant volume, I

to withstand high temperatures Without sep a ration.

14. A furnace Wall having a layer of highly refractory substantially constant volume non-conducting material of high heat-insulating capacity as a facing for a body portion of refractory material of higher heat-insulating capacity and less refractivity than said layer.

In testimony whereof I affix my signature.

JOHN D. MORGAN.

tached to a refractory non-conducting body.

9. As an article of manufacture, a compos ite brick having a layer of zircon firmly attached to a body of diatomaceous earth, said layer and body being bonded throughout with the same bonding material. a

10. As an article of manufacture, a composite brick having a zircon layer and a body of diatomaceous earth, said layer being cemented to said body by a silicate bond.

11. The article as set forth in claim' 10 in which the cementing bond is a boro-silicate.

12. A comoosite brick having a facelayer of substantially constant volume zircon composition firmly attached to a body portion of

Images