US1956895A - Refractory - Google Patents

Description

May 934- I w. M. CHARMAN Er AL I 1,956,895

REFRACTORY Original File d Feb. 27, 1932 //V V f/V 70R 5 h AL 72-13 N. CHARM/4 N.

7 /01. IP l9. WARD.

m'xa an /52% Patented May 1, 1934 messes mscronr wlltel' u. Charman and Philip 1:. Ward, Cleveland Heights, Ohio; said Ward assignor to The Engineering Ferro a corporation of Ohio Company, Geveland, Ohio,

application February 27, 1932, Serial No.

Divided and this application Decemher 23, 1932, Serial No. 648,611 x 1. Claims. (Cl. 1

This invention relates to improvements in refractories, particularly refractories for hot to and has reference w chemi and physical constitution of such refractories. The

I refractories which are the subject of the invention may be employed for the production directly of hot tops either as unitary or built up assemblies, or they may be employed as lining elements for metal casings or frames. The

- in present invention is a division of my copending application Serial No. 595,579, filed February 27, 1932.

One of the objects of the invention is the provision of a refractory of this character which F shall be economical to produce, and one which can be formed with a relatively high degree of accuracy in comparatively large units, the large units facilitating the assembly of the hot top or its reconditioning after use.

Another object is the provision of a hard rigid "refractory which shall be resistant to deterioration during storage and capable of withstand- -ing rough handling in shipment.

4 In the drawing: 2 Figure 1 is a perspective view looking down- -wardly upon a one-piece lower lining ring for a hot top, formed in accordance with the present invention. Fig. 2 is a transverse sectional view of the 30 same taken substantially on the line 2-2 of Fig. 1, thereby showing the ring in an inverted position. -Theringillustratedinthedrawingismerely one example of a hot top refractory which may be formed of the composition of the present invention. Complete hot tops consisting of refractory material alone may be built up of a plurality of molded elements, or in some cases may be molded as a unitary structure employing the present composition, and where I. met- :1 casing or frame is employed it may be protected by means of a refractory lining inone or a plurality of pieces formed of the composition of this invention. The ring herein illustrated constitutes one element of a lining for ahottopcasing,beingintendedtobeused as a substitute for a lowerlining course formerly constructed of a plurality of refractory blocks. such for instance as those illustrated in Patent 1,804,206 to Charman et al, dated May 5, 1931.

top isto be used. Along its inner edge the ring is formed with an upstanding rim 11 which is 1 pted to protect the inner edge of the casing ledge, by means of which the other lining elements of the hot top are supported. Any suitable means may be employed for attaching 00 the ring 10 to the casing, holes 12 being provided in the present instance for the reception of wire ties.

The ingredients which we employ in making up these refractories include a suitable aggreo5 gate that is free from any impurity that will react chemically in a harmful manner with the binder, and one in which the particles are of suitable size. The size of particles should be such that the resul 10 e is ense enough to have considerable strength, and yet not too dense to prevent any vapors or gases, set free at the time the metal is poured, from venting off. The sggregatesghich we prefer to employ is silica sandof a relatively fine grade, washed to remove p ies. x While it is possible to employ various binders with different degrees of success, we have discovered after extensive experiments that by far the best results are obtained, particularly with silica sand as the aggregate, from the use of sor dium silicate. This is employed preferably in solu 1011 although the moisture content may be varied more or less, we prefer to employ a silicate containing 36.47 0 0 water. To produce the maximum adhesive strength of sodium silicate the ratio of sodium oxide to silicon ggdashould be approximate y one y material deviation from this re. 0 w cause a marked decrease in adhesiveness. For reasons of manufacture, and to obtain the proper physical condition, we prefer to use a sodium silicate solution having a ratio of one part sodium oxide to three and twenty-five hundredths parts silicon oxide. As the alkalinity of sodium silicate increases the water resistance decreases quite rapidly. The quantity of silicate solution which should be used may be varied within workable limits, the maximum of which would be twenty percent by weight.

ne of the requisites of a good commercial re- I06. COMPOSITIONS,

COATING OR PLASTIC quantity of the oxide of some metal, preferably 321 or lead. Aluminum oxide is suitable for the purpose, but on account of its greater cost, we prefer to employ instead either zinc or lead oxide. The oxides of thesemetals have the effect. of combining with silica and silicates to form a water resistant bond somewhat akin to a glaze except that the bond is not limited to the surface but is uniform throughout the mass of the molded article. Although the amount of this water-proofing agent may be increased to some little extent, the proportion which we have found sufficient is one percent by weight of the whole mass. Less Ha n ve-ten he would be too little to be eifective, and more than five percent would increase the cost of the article without corresponding benefits.

A metal reenforcement of any suitable form is desirable but not essential. A steel rod for this purpose is indicated at 13 in Fig. 2 of the drawing.

The following proportions by weight of the ingredients named have been found in practice to produce a highly satisfactory mixture:

Approximate 2; percentage Silica sand 86.5 Sodium silicate solution 12 Zinc oxide or lead oxide 1 Water 5 -89 Referring now to the method of making the refractories, the mixture is placed in the mold and compacted by ramming or otherwise. When the refractory is thus molded, it is placed in an oven and dried b baking it at a fairly high temperature. The mosphere substantially free fro rBon monoxide and carbon dioxide, as for instance in an electric oven or in a mufile type oven. If a substantial amount of carbon monoxide or carbon '40 dioxide is present the silicate is converted to a carbonate and loses the attributes of a binder, with the result that the article crumbles and has no strength. q The drying is carried far enough to expel 5 nearly all of the moisture occurring in the mixture, both as free water and as part of the sodium silicate solution. The temperature of the drying oven should be high enough to drive off this moisture, but it should not be too high, because if a very high temperature is maintained for any considerable length of time, an excessive loss of moisture will result and the binding qualities of the silicate will be impaired to a greater or lesser extent. A temperature of 400 F. has been found to be satisfactory.

Immediately after the drying operation is completed the moisture content of the refractory may vary up to about one percent by weight, but preferably approximates four-tenths of one percent.

69 After the refractory has been stored for a considerable time some additional moisture may be taken up from the atmosphere.

If the water content of the mixture be considered to include the water in the silicate solution as well as the free water, the weight of the silicate being taken as that of the solids therein only,

(hereinafter referred to as dry silicate equivalent) the ingredients of the mixture in the proportions by weight which we prefer to employ will be as 70 follows:

' Per cent Sand 86.5 Dry silicate equivalent 4.3

Metal oxide 1 Water 8.1

s ould be done in an at- After completing the drying of a refractory me rom no rx ur e p oportion of the ingredients in their propo ions by weight will be found to be substantially follows:

In the foregoing description we have necessarily gone somewhat into detail in order to fully explain the invention, but we desire it to be understood that such detail disclosures are not to be construed as amounting to limitations, except as they may be included in the appended claims.

Having thus described our invention, we claim:

1. A refractory comprising the following ingredients uniformly distributed throughout its mass approximately the proportions by weight stated: one percent to nine percent dry sodium silicate equivalent, five-tenths percent to five percent zinc oxide and approximately eighty-five percent to ninety-eight percent an aggregate chemically inert to sodium silicate.

2. A refractory comprising the following ingredients in approximately the following proportions by weight: sand ninety-four percent, dry sodium silicate equivalent four and seven-tenths percent, and zinc oxide having waterproofing characteris- I05 tics one percent.

3. A refractory comprising the following ingredients in approximately the following proportions by weight: sand ninety-four percent, dry sodium silicate equivalent four and seven-tenths percent, 1 10 zinc oxide having waterproofing characteristics one percent, and moisture not over one percent.

4. A rigid refractory comprising the following ingredients in approximately the following proportions by weight: sand eighty-five :percent to r15 ninety-eight percent, dry'sodium silicate equivalent one percent to nine percent, zinc oxide fivetenths percent to five percent, and sodium carbonate between zero and minute quantities less than one percent.

5. A refractory comprising the following ingredients uniformly distributed throughout its mass in approximately the following proportions by weight: sand ninety-four percent, dry sodium silicate equivalent four and seven-tenths percent, and zinc oxide one percent.

6. A refractory comprising the following ingredients uniformly distributed throughout its mass in approximately 'the following proportions 'by 7 weight: sand ninety-four percent, dry sodium silii cate equivalent four and seven-tenths percent,

zinc oxide one percent,-and moisture notover one percent. V

'7. A refractory comprising the following ingredients uniformly distributed throughout its mass 7-}35 in approximately the following proportions *by weight: sand ninety-four percent,-dry sodium silicate equivalent four and seven-tenths percent,

zinc oxide onepercent, and moisture four-tenths of one percent. .3140

Examiner.

dients uniformly distributed throughout its mass in approximately the proportions by weight stated: one percent to nine percent dry sodium silicate equivalent, five-tenths percent to five percent zinc oxide, and approximately eighty-five percent to ninety-eight percent a silicious aggregate.

10. A refractory comprising the following ingredients uniformly distributed throughout its

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