US 1445083 A
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Description (OCR text may contain errors)
I Feb. 13, 1923. 1,445,083.
G. N. JEPPSON ET AL.
SAFETY TREAD CERAMIC TILE.
ORIGINAL .FILED Juni 5.1918.
:J www Geofge .N '../Zppson www@ wegzm M/fon Beecher Patented Feb., 13, `1923.
GEORGE N. JEPPSON AND MILTON E. BEECHEE, or WORCESTER, MASSACHUSETTS, ASSIGNORS To NORTON COMPANY, OEWORCESTER, MASSACHUSETTS, A COR- PORATION OF MASSACHUSETTS.
SAFETY-TREAD CERAMIC TILE.
Continuation of application vSerial No. 238,404, filed June 5, 19l8. This v1922. 'Serial No. 556,505.
To all whom imag Concern.' y
Be it known that we, GEORGE N. JErrsoN andv MILTON F. BEEOHER, citizens of the United States of America, residing at Worcestenin the county of Worcester and State of Maachusetts, have. invented certain new and useful Imp-rovements in Safety-Tread Ceramic Tiles, of which the following is a full, clear, and exact specification.
Our invention relates to a safety tread and more particularly to aceramic tile having an' anti-Slipping surface comprising hard, durable and Wear-resisting granular ma.- terial. This case is a continuation of the application filed on June 5, 1918, Serial Num'- ber 238,404, by George N. Jepps'on which became forfeited and was renewed .as Serial No. 506,918, October l0, 1921.l One\.object of our invention is the provision of a safety 'tread tile havin' an l inexpensive ceramic body and a surface portion comp-rising a hard, anti-slipping granular' material, which is Simple in its construction and economical lto manufacture, which l is hard,
durable and of high tensile strength capable of withstanding the crushing effect of heavy objects moving overthe tile,'and which will be highly efficient for liooring and tread surfaces. f
vWith this and other objects in view, as will appear .from the following disclosure,
our'invention resides in the subject matterset forth in the specification and covered by the claims-appended hereto.
p It has been' proposed to incorporate har wear-resisting granular material, such as s previously fused alumina or Silicon carbide, 1n a ceramic tlle foruse as a floor tread.
Such tiles containing the bonded granular material uniformly distributed throughout their entire volume have been very-,expensive to manufacture, owing to the fact that alumina and silicon carbide are electric furi nace products requiring a large current consumption. It is not possible, however, to avoid using such costly materials, since hardness and durability are prime requisites, and since no other form of safety tread has been found'- satisfactory; hence we propose to reduce the initial cost of these articles by utili zing a construction and a composition of tile whlch permlt a material reduction of `the amount of the expensive ingredient necessary for making 'a Safety tread. Furthermore, as a lmoreimportant consideratiorus- -Of ceramic material, but by utilizing a ceram ic substance alone as the main lbody pori tion and rendering the tileanti-slipping 'by combining therewith a. surface tread portion having lwear-resisting, anti-slipping material embedded therein and preferably suitably held in place by a ceramic bond. IVe furthermore provide a ceramic tile in which the backing preferably has the same shrinkage and warpage as the topvportion, so that during drying 4and burningthe t1le will not be seriously injured by fractures for splitting, and we. make the two portions' of such relative thicknesses that when lthe top anti-slipping portion has worn away the tile is then too thin for`.further wear and must be replaced, this ultimate thickness applicati-on filed April 25,
of the ltile body depending upon the nature of trafHc to which itis to be exposed.
In accordance with our invention', we make'the tile. backing of a vitrified ceramic material, which may comprise a pure ball clay, such" as that variety. known as `Mississippi ball clay, o-r modifications there of eontainingvario-us ingredients. In order to modify the propertiesof this clay material, we miay combine with clay various substances Ysuch as feldsp-ar, Whiting, flint talc, stea-tite, etc., these vvarious ingredients being utilized to changethe burning temperature or ,vitrifying point of the mass or tol modify the physiealrcharacteristies of the tile to conform with the uses to which it may be put. A specific example of a satisfactory compositionmay comprise ball clay mixed with feldspar and flint in the following proportions: f
Parts by weight. Ball clay Feldspar 25 .Flint 4:0
lf such materials as above described are heated toa vitrifying temperature for a proper length of' time the mass is rendered exceedingly tough and durable. A l
ln order to provide a satisfactory safety tread surface, we combine with the backing a ceramic bonded mass'of extremely hard granular material which is wear-resisting and durable under the abrasions of footwearand, for treads intended to be exposed to severe traflic conditions, we preferably utilize a material having a hardness of 9 or more on Mobs7 scale. Of the best 'available materials for the-fanti-slipping si ib"A a stance/which are found to be' crystalline or previously fused alumina and 1silicon carbide, we prefer crystalline alumina because of its durability and wear-resisting qualities under the strains and stresses of foot abrading action. `The granular crystalline alumina,which may be ofthe nature of coy i rundum and contain other ingredients besides pure alumina, may be prepared by any suitable process, such as, for example, 'by
fusing alumina on. bauxite in an electric furnace, allowing it to. cool slowly in the pig, and then crushing and grading it to obtain the desired size. This granular alumina is combined lwith a suitable ceramic bond and burned to a hard composition adapted. to resist foot' wear and prevent slipping thereon;
Since the ceramic material containing the alumina granules which'are substantially non-fusible at the burning temperatures has a diderent shrinkage from the ceramic material used alone for the tile body, therev is a tendency for the combined body to warp orto split apart between the two portions. Vile may adopt various'expedients to overcome this difficulty. For example, the shrinkage of the backing might be reduced by adding to the' clay material a granular non-plastic substance such as flint, burned clay, etc., in suitable proportions to make the shrinkage of the backing correspond with that ofthe facing containing the alumina granules. .We, however, prefer to control the shrinkage of the two portions by altering the composition of the bond utiliz'ed in the face layer, so as to cause a high shrinkage of the mixture of'alumina gran- 'ules and the bond, this bond being so constituted that the shrinkage of the face is approximately that of the vitriied backing,
Laaaoes whereby warping of the bod and cracking, parting or other detrimenta eects are obviated. 'l
To accomplish`l this purpose, we may incorporate a shrinkage-increasing material such as manganese carbonate with the clay and other ingredients, although it is obviously within the scope of our invention to utilize various combinations which prevent sucli warpage or breaking of the tile. A. specific example of the composition of a satisfactory tile may be given as follows:y
As avspecific method of combining the tread portion with thel backing and making a safety tile embodying one phase of our invention, we may mix the desired proportionsy of alumina and facing bond with water #soiv that the mass may preferably be molded by pressing va plastic` mass.I This is placed in the bottom of a mold of suitable dimensions and the mold is filled with the vitriiiable clay backing material which has been moistene'd with water to the desired amount to irender the material capable of being moldy ed in a dry press. .After subjectingthe mass to pressure to form the body, it is dried and then burned in a suitable ceramic kiln to a maximum temperature of about 13000 C. for a suitable length of' time, e. g?, one hundred hours,l after which it is cooled slwly for a similarly long time. By this tiring operation the alumina granules are bonded together by the ceramic material, the backing is formed into a hard vitrified lbodyand the two portions of the tile are intimately and permanently united into a unitary wear-resisting tile. j
rlhe grain, size of the particles may be as desired, but it is to be noted that the coarse, large .particles have ltoo severe an abrading action upon leather or other footcovering materials and that a tile made of 'or.`a fine grain or to combine coarse particles which have large anti-slipping characteristics with fine grains which fill in the interstic'es between the largerparticles and render the tile dense and Aof. low porosity.
Referring to the drawing, which represents a perspective view, partly in section, of a ceramic tile, we have there shown one embodiment'of our invention comprising a ceramic body 1 having a tread port'ion 2 of bonded alumina granules, which has a wearresisting surface 3 and forms the sameas the tile wears away. If desired, grooves 4 may be provided in the'under side of theA tile, these grooves being adapted to be filled with concrete in which the whole tile is embedded and vthereby constituting means to keep the tile from shifting'I from its original position.A If desired, holes may be provided through the tile for bolt'ing or screwing the same to a wooden or any .typeosurface While :the tile may be 'made of any desired shape, it isfound preferable to `have the upper surface ofI a rectangular or other form which may\ be laid ih patterns over an eX- tended area. i A
Having thusdescribed our invention, what we claimas new and desire to secureA by Letters Patent is: e
'1. A safety tread tile comprising a body l of vitriiiedceramic material having abrasive granules embedded mainly inthe tread portion thereof, vsa-id granules Ibeing integrally bounded by said material and forming therewith an anti-slipping, wear-.resisting surface. y 1
2. A safety tread tile comprising a vitri- "ed ceramic backing integrally united with a tread layer ofabrasive granules bounded by vitrified ceramlc material, 'said abrasive face.
A safety tread tile comprising a vitried ceramic backing, a tread layer of antislipping granules of a hardness of 9 or 'more united 'by a -vitrified ceramic bond,l said backing and bond forming an integral vitriiedmass. v .g
4. A safety tread tile cbm'prising a porcelain backing and a tread layer of abrasive granules bonded by a vitriied ceramic material, said backing and layer being integrally united by vitrification.
5. A safety tread tile comprising a `vitrified ceramic backingintegrally united'with v -a\tread layer of crystalline lalumina granules bonded by a vitried-ceramic material. f'
6. A safety tread tile comprising a porcelain body united by vitriflcation with a surface layer of anti-slipping granular mater'ial of` a hardness' of 9b or more bonded by a vitreous material. a 7.l A safetytread tile comprising a por-v celain backing united by vitriication with a tread layer offcrystalline alumina granules bonded by a vitreous ceramic mass, saidgranules forming the major portion of the wear-receiving surfaces. y
8. A safety tread 4tile comprising a tread -portionof anti-slipping granules bonded by a vitrifiedceramic/material and a backing integrally unlted with the. tread .portion conslsting of 'a Vitriied ceramic `material of substantially lthe 9. A safety tread tile comprising'a surface tread. portion of crystalline alumina granules bondedtogether by a vitriied clay material having 'a high shrinkage value, and
a rbacking of vitried clay material having shocksv of 'foot wear. l
Signed at Worcester, Massachusetts, this f v 18th day of April 1922.." i j forming themajor portion of the tread surrcarolien nunrrsoN. gmLToNr. BnEoHER-.p
same" vitrification shrinkage as the tread portion.