US1594402A - Refractory and method of its production - Google Patents

Description

Aug. 3 H926. 11,594 40? M. c. BOOZE REFRACTORY AND METHOD OF ITS PRODUCTION Filed Jan. 6, 1926 FIELI.

FIGJI.

//VVE/V70/? WITNESSES Patented Aug. v3, 1926.

UNITED STATES 1,594,402 PATENT OFFICE.

MACDONALD C. BOOZE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 AMERICAN REFRACTOBIES INSTITUTE, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

REFRACTORY AND METHOD OF ITS PRODUCTION.

Application filed January 6, 1926. Serial No. 79,522.

My invention relates to bricks and other ceramics, and consists both in the article itself and in the method of its production. While the invention is of wide applicability, I have developed it in the production of refractory bricks for furnace linings and in that particular application I shall first describe it. In the sequel I shall return again to the matter of its wider applicability.

In the accompanying drawings Fig. I is a view in perspective of a broken brick in which and in the production of which my invention is achieved; Fig. II is a view of certain small bodies in which the invention centers.

A. fire-brick is typically and essentially composed of fire-clay. Native fire-clay is comminuted, mixed with water and so brought to a condition of coherence. From the plastic mass bricks are shaped, and then the shaped bricks are burned in a kiln. Fire-bricks are chiefly used for building the linings of furnace chambers and when so used they have to withstand in service high and widely ranging temperatures. And they are liable in service to spa-ll, that is to say to crack and crumble, with consequent impairment of the wall or furnace lining of which they are part. It is part of the common knowledge of the industrythat if the bricks be molded from a mass which contains not fire-clay only, but fire-clay diluted or adulterated with other finely divided refractory material, itself incapable of being worked with water to plastic condition, a brick may be produced which in service will be found less liable to spalling than a brick made from fire-clay alone. A diluent material so commonly employed is known as grog, and grog is clay which has already been calcined. Another commonly used particular material, not ordinarily termed grog, is old bricks ground again to finely granulated condition. Such a'modification of the brick composition, though advantageous, is not completely remedial; the bricks still are liable to spall.

My invention may be characterized as another spall-preventing measure; or, more accurately speaking, a measure preventive of the otherwise badv effects of spalling. It is of general applicability, available either alone or along with, or in association with and in effect cumulative upon other measures to the same end. It consists in the pro- VlSlOll of certain preformed bodies which, mixed with the mass of material of which the brick is formed, will in the finished brick serve as bonding bodies, tying the substance of the brick together, part to part.

The effect is that when the brick of my invention, being in service, cracks, it will not fall apart; its pieces'will be held to place, and the furnace lining built of bricks of my invention will be durable through longer periods of time, and therefore more economical, than linings otherwise the same but lacking the invention.

In Fig. I of the drawings the body material of the brick is indicated by the numeral l and the preformed bodies of which I have spoken are indicated at 2. These preformed bodies are shown separately in Fig. II. I have sufiiciently characterized the body material; it remains to speak of these preformed bodies.

In this particular instance these preformed bodies 2 are elongate bodies of cir- 1 cula-r cross-section, somewhat less than an eighth of an inch in diameter, varying in length from a half to three quarters of an inch, and vermiculan in shape. They are themselves formed of refractory material, including fire-clay, prepared in usual manner by comminution and working with water to plastic condition. The mass when prepared is extruded under pressure through a circular orifice, and in such extrusion assumes vermicular shape and breaks itself into such lengths as I have mentioned. I characterize the shape as vermicular, in that these bodies formed in the manner described are curved or arc-shaped longitudinally, instead of being straight.

The so-formed bodies may or may not be burned in a kiln before being mixed into and distributed in the mass of brick-making coating was removed by the treatment of the brick. After burning the bodies remained in the finished brick somewhat loose in the body substance of the brick which as a matrix sustains and encloses them. Such ultimate looseness of the bodies in their matrix, allowing the body substance of the brick to respond without restraint to thermal expansion and contraction, is advantageous and affords a more durable and serviceable brick. The particular coating substance which in this Instance was employed was pitch. This pitch coating, during the operation of burnlng the brick in the kiln, was of course rendered fluid and in fluid condition it dispersed through the substance of the brick and then being volatilized passed off, leaving no appreciable trace of its presence.

The material of which these preformed bodies are composed may be any suitable ceramic materialthat is to say, earthen material molded to sha e. The bodies may be burned or unburne before being combined with the mass of material within which ultimately they are to serve as a bond. If they are of sufficient strength while still unburned to allow them to be combined with the mass of material in which they are to serve for the ends described, they may be combined while still unburned. They may or may not be coated preliminarily, to serve the particular ends described. I have named pitch as a suitable coating material. Any material which is destructible or removable under the conditions and at the temperature of brick-burning may be employed. Other suitable coating materials are rosin, tar, glue, and, generally any material will serve which will in the process of burning the whole product, be burned off or melted and dissipated, or volatilized.

These preformed .bodies may be mixed with the mass of brick forming material, in widely ranging ratio, say from 15% to 90%. Mixing may. be effected in a pug mill, or in any other mixer usual to brick-making processes. The processes of brick-making are not otherwise altered, and the bricks may be formed by hand or machine, in usual manner. And after formation the bricks will be dried and burned in usual manner, or they may be set unburned in the furnace wall and be subjected there to the high temperature of furnace operation.

The vermicular shape attained by extrusion through an orifice is good. The short arc-shaped bodies are most satisfactory in their bonding effect. It will however be understood that other particular shapes will achieve the end in view and will lie within my contemplation. For instance, straight, uncurved elongated bodies will measurably serve the same end, and if these straight bodies be provided with terminal enlargements, they will be comparable in efilciency with the hook-like verm lar bodies which I prefer;-

The particular size of the preformed bodies is not a matter of first importance. In the making of fire-brick they should not be more than a quarter of an inch in diameter, nor more than one inch long.

Furnace bricks are made of other substances than fire-clay. Chrome bricks, for example, and magnesite bricks are made by dead-burning particular minerals, crushing the burned material, mixing it with a binder, shaping, and burning again Such bricks too are subject to spalling, and to them also my invention is ap llcable. That is to say the elongate bodies which I have described may be mixed in the brick-making mass, and in the finished brick they wil have the same bonding effect as in the case "first described.

Refractory material is not always sha ed to bricks. For instance, it may be applied in plastic condition to furnace walls, and so spread in constitute a furnace lining shaped in situ. My invention may be practiced by mixing in the elongate bodies which I have described, into the plastic mass before it is spread. These bodies then in the finished furnace lining will serve their purpose, holding in place pieces of the lining which cracking away would otherwise fall.

The value of the invention lies in this, that the preformed bodies not relied upon primarily for refractory effect, may be made of relatively great mechanical strength. And this characteristic, combined preferably with a certain looseness of the embedding of the preformed bodies within the matrix body, affords a product bonded together to resist crumbling, and a product of superior durability for the purpose stated.

I claim as my invention:

1. The method herein described of producing a body of refractory material which consists in shaping elongate ceramic bodies, mixing such preformed bodies in a plastic mass of refractory material, and shaping the mass.

2. The method herein described of producing a body of refractory material which consists in shaping and burning elongate ceramic bodies, mixing such preformed bodies in a plastic mass of refractory material, and shaping the mass.

3. The method herein described of producing a body of refractory material which consists in shaping elongate ceramic bodies, coating such bodies with a coating removable by heat, mixing such preformed and coated bodies in a plastic mass of refractory material, and shaping the mass.

4. The method herein described of producing a body of refractory material which consists in shaping elon ate ceramic bodies, coating such bodies wit a coating fusible at a temperature less than that of brick- -mixing such sha burning, mixing such preformed and coated bodies in a plastic mass of refractory material,k shaping to brick form, and burning the 5 The method herein described of making fire-brick which consists in shaping and firing vermiform bodies of ceramic material, d and fired bodies in a lastic mass of e-clay, and molding and ring the mixed mass.

6.. A refractory body in which a matrix of refractory material contains embedded in its substance preformed vermiform bodies of refractory material.

7. A refractory body in which a matrix burnt fire-clay and containing embedded in its substance preformed elongate bodies consisting essentially of burnt fire-clay, such matrix body being relatively weak and such 25 embedded bodies being relatively strong to resist spalling strains.

In testimonywhereof I have hereunto set In hand.

y MACDONALD C. BOOZE.

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