USRE16845E - A gobposakost - Google Patents

Description

- A. J. JAcKMAN a Jan. 3, 1928. 16,845 REFRACTORY ARTICLE AND PROCESS OF MAKING THE SAME Original Filed May 26, 1925 2 Sheets-Sheet l N l I I a Lw/L ,l 1 g "TY T'; g g 77% 1;, \YI',

. INVENTOR 2 Sheets-Sheet A. J. JACKMAN Original Filed May 26, 1923 REFRACTORY ARTICLE AND PROCESS OF MAKING THE SAME lNV ENTOR LrL /LrLr.

. mw l Rn R1 Jan 3, 192&

' clay,

if they are not carefu fore, liableto dama breakage. Such cruci les, particularly when,

cible rior to use to a tern vitrifi I aw 1m. 3.1m-

UNITED STATES PATENT OFFICE.

an'rmm J'. JAN, 0] FOREST BOROUGH, IENNSY LV ANIA, ASSIGNOIB, TO VISUVIUB OBUCIBLI GOIPANY, OI SWISSVALE, PENNSYLVANIA, A CORPORATION 01 PINNBYLVAN Original application fled lay 26, 1988, Serial No. 841,754.- Continued and application tiled August 2,

name-roar an'rrcnn sun raocass or name rm: same.

in; sum No. 728,817. Original no. 1,517,124, dated larch s, 1926. Application 1 reiuue ma Iovenber 82, 1987. Serial No. 885,104.

This application is a continuation of my application Serial No. 641,754, filed May26, 1923.

The present invention relates to refractory 0 articles and more particularly to refractory vessels, such as crucibles, saggers and the like, containing graphite and a ceramic bonding material, and to the process of makingthem.

.In makin graphite crucibles, ball clay is usually used as a bond. According to the usual practice now in vogue, after the ware is formed, it is fired in kilns to a temperature lower than the vitrifying. point of the siderably less than 2000 F. The clay bond being unvitrified will rehydrate in a moist atmos here* and the cruci les are therefore sensitive and liable to spallin particularly ly re eated or annealed by the user prior to using. Even then such crucibles are liable to spell when used. Moreover, such crucibles are relatively soft when put into use and are, therefrom abrasion and silica sand is used in the mixture, may have formed on them a glaze-like crust m use. Such glaze-like crust, however, is not adherao ant and spalls OR at each heating when the crucible is used.

In making my improved (graphite crucibles, I emploz a ceramic bon referably in the nature 0 a porcelain, an urn the, crurature above the cation point of the nding material. This burning is preferably carried out until there is a substantiall complete maturin and vitrification of t e bonding materia 1 throughout the body of the material. The

so burned will not rehydrate and do not need'to be reheated or annealed by crucibles the user rior to use. The crucible is also y stronger and is less liable to be dama by brea ing in transit before delivery to the user. A glaze is formed on the surface of the crucible which is integral with the vitrified bond and which will not spall. Even if the glaze is knocked ofi by rough such temperature being as a I'HIQCOII'.

for iving the crucibles the first burn ;f

Figures 2, 3 and 4 are a horizontal section, a vertical section and an end elevation, respecti'vely, of a continuous kiln for carrymgd out the final burning" of the crucibles; an 4' Figure 5 isa tion of such continuous kiln.

I will now describe in detail the preferred rocess of making my improved crucibles, 1t bein understood that the invention is not limlted to such preferred procedure.

detail section through apor- I take graphite and a ceramic bonding material and mix them together with water in the usual manner and mold the mix into crucibles in the-usual manner. Graphite may be used alone as the non-fusing nert constituent or some other non-fusing inert I material maybe mixedwith it, such as silicon carbide, tridymite, zirconium silicate or alumina. The ceramic bonding material is preferably of a rcelain nature in which the several terial mature or chemically combine into a vitrified bond during the burning of the crucibles.

, As a typical example of suitable mix, I take graphite, either crystalline or flake, 45 parts, settling tank silicon carbide fines 15 arts and a porcelain bonding mixture 40 arts. Settling tank silicon carbide fines constituents of the bonding mais the fine material which settles in the tanks after grinding and washing silicon carbide grains in the manufacture of silicon carbide abrasives. Such fines, exce t for an occasional larger grain, consist o silicon carbide in powdered form. In order to give the resent, e

wellstbnelO ch :5 4 n "I a course,be vsriedtomeetthepsrhculsruses towhichthecrucibleserepu and various otherfluxing' "entsmsy such as raw doomite, lime ston 'olite, ,fel be or en er of the so i. ii-'21..

lnln and urned in s non-oxidising, preferably. reducing, shnosphereto up mnnistely 1200 F. In 1 of the w ngs is illustrated a suiteblekilnfor purpose. This'kilnisof the ususl'sort, hs smuf- ,flechsmberl inwhich the-cm: 2-sre stacked, heated by inthe pusphere in this '7 For this urpose n ps $5.9m mn I Q pipe g-om e kiln and blowing it t l f'ough .the pipe 7 through the bed of coke 4 which is heatedto incsndescenee snd which maintainseredu atmosphere in sllpsrtsof thekilmamndthehlnbenotsbsolutely air be After the wsreis into t e "'I'prefer-to fill the kiln with carbon dioxide which may be conven- 80 V p I preferabli maintain s reducing iently introduced from a tank 8 of uefied carbon dioxide; After-the carbon oxide hasexpelledtheaiinthetenkSisshntofi and the 1 is maincondition by the circulation the ged'of o This urmng open on, w my ex,- te'nd over a. 0d of several days, thoro y dehy tes the bonding material on in case the bonding mterisl'contsins csrbonst'es, it converts the csrbomtes to the oxide form throughout the mess. The dehydration and reduction of cslrbonetes, if tive to chernicel combinations which et the higher tunperatures ofthe fi'nsl operation. e reducing'etmosphem vents the oxidation of the so,

the crucibles come from operation with the v I were I inth'ekilnpre-isnowno' lonersusee 'bleto ydration put into use withburmng ou danger o or mneshng with graphite crucibles as ususlthegrsphite in an unreduced um matured fend vitrified P? should .only skin f thirty second u an in abouts hundredthpf an Thessh here,'so

' is preferebl carried oh: in s 'the crucibles, but ould exceed abouttwo hours. A

12 in. dimension usually half hour for the oxidiz- The on on Y 33' p 'prefersbl not end upon the. mix 13 w the crucible is to of over Emferably at from refer-ably reducing ate surface oxidation is to which the n e ILIOI' or the ty of heretofore The" . by heat such a degree of compactness of structurebysolution between the constituents of the bond that the mass as a whole. has the characteristics above pointed out, and is hard, strong and substantially impervious to moisture under normal condi- 'sists wear and abrasion.. In case the adherent.

tions ofuse. Tests have shown that the hardness of my crucible material -is such that a 10 millimeter hard steel ball under a load of 175 kilograms makes an indentation not over 4 millimeters in diameter, and its strength, as determined b breaking a bar approximately one inc 1 s uare in cross-section and a four inch span, s ows a modulus of rupture of over 1500 ounds r uare inch. Ex erienee has emonstrate that such ha ess and stren th in materials of this class can be developed only by vitrifying the bond under proper conditions as herein described. The adherent aze formed on the surface of the crucible y the fluxin of the surface bonding ma-- terial from w ich the graphite was burned during the oxidizing heat is formed from the bod of the bonding material and is integra (y united therewith, there being no line of emareation between the glaze'and the bonding material in the body of the crucible. This glaze is entirely different from the surface cunt-like glaze formed onthe crucibles in service by the exudationof silica, which crust-like glaze readily spalls off of the crucibles. The laze which is formed on my crucibles is a herent and will not spall off like the crust-like lazes formed on cruciblesi'n. the metal me tin furnaces or like the glazes applied b ipping or painting. 'Tie glaze gives t e crucible a lfll'd attractive looking surface substantially free from crazing or cracks and 'which1re-,

aze becomes chip ed ofi inuse, the expose vitneath it immediately forms a glaze when exposed to the heat of the furnace in which the crucibles are used. Such replacement glaze being formed from the vitrified bonding material is likewise Continued use. of the crucibles made in accordance with m process .has shown a greatly increased life over crucibles made y the usual processes now in V e.

In Figures 2 to 5 of the drawings, I have shown a continuous furnace for carrying out the final burning of the crucibles. This furnace is of the tunnel kiln ty e, consisting of an elongated tunnel of rick work having tracks 11 along which travel cars 12 bearin he crucibles 2. The crucibles travel through the furnace from right to left, as indicated b the arrows on the drawings. The crucib es first pass into an oxidizing material.

7 in a continuous ortunnel type kiln in which case the first chamber of such kiln would position used in'making my crucibles to.-

chamber 13 in which the are given the oxidizing heat to oxidize eir surface. They then pass from oxidizing chamber into a chamber 14 in which is maintained a nonoxidizing atmosphere and in which the crucibles are brought up to a temperature above the vitrification point of the bonding The non-oxidizing atmosphere checks the oxidation of the graphite and serves to protect the: graphite in the body of the crucible from further oxidationduring the final or high temperature firing of the crucible. The chamber '14 is separated.

from the chamber 13 by baflies 15 which serve to confine the gases of combustion and 7'- prevent entry of the oxidizing atmosphere into the chamber 14. also separatedby bafiies 16 from another chamber 17 into which are, discharged the gases of combustion from the burners 18 and in which the cruciblesare given their final and highest heat. The air for the burners 18 is restricted so that a reducing atmosphere is maintained in the chamber. 17. As the gases of combustion pass by the bafiles 16 in the chamber 14 some secondary combustion takes place, although the atmosphere in the chamber 14 is maintained in a reducing or neutral condition. Asthegases of combustion pass the baflles 15, further secondary combustion takes place, suflicient air being admitted to the chamber 13 to produce an oxidizing atmosphere therein. The crucibles pass from the chamber '17 intoan annealing'chamber 19 fron 1 which they are finally discharged through the outletdoor opening 20. buitable closures, not shown, maybe provided for the outlet opening 20 as Well as the inlet opening 21.

As shown in the drawings, the crucibles around from the outlet-tothe inlet and reloaded, and travels again through the "kiln,

as is the usual practice in operating a tunnel kiln.

On account of the relatively longer time of the dehydration firing of the crucibles, I prefer to carry out thefirst burning 0 eratlon in a separate kiln 1, "as indicate in the drawings. However, if desired, the entire burning process may be carried out correspond in its action to the dehydration burning carried out in the kiln indicated in Figure 1 of the drawings.

While I have described the. preferred com- The chamber 14 is ether with the preferred process and kilns for carrying out such process, it is to be understood that the invention is not limited to the specific details of its preferred embodiment but may be otherwise .embodied within the scope of the following claims:

I claim:

1. As a new article of manufacture, a refractory article consisting principally of ture. a

' fractory article consisting principal] graphite and, a porcelain and burned prior to use to a temperature graphite and-a vitritiable ceramic bond, and burned prior to, use to a tem erature above thel vitrification point of the onding matcria 2. As a new article of manufacture, a reofgraphite and a vitrifiuble ceramic bon and burned prior -to use to a temperature above 2000 F. 4 i

3. As a new article of manufacture, a refractory article consisting principally of graphite and a vitrifiable ceramic bond, and burned prior to use to a temperature between 2000 and 2800 F. v I

4. As a new article ofmanufacture, a refractory article consisting principally of aphite and a vitrifiable ceramic bond, and urned prior to use to a temperature suflicient to substantially completely vitrify the bonding material throughout the body of the article toproduce a structure which is hard, strong and substantially impervious to mois- 5. As a new article of manufacture, a refractory article consisting principally of onding material,

above the vitrification point of the porcelain I bonding material.

6. As a new article of manufacture, a refractory article consistin principally of graphite and a porcelain onding material, and burned prior to use to a temperature above 2000 F. v

' 7. As a new article of manufacture, a refractory article consisting principally of graphite and a vitrifiable ceramic bond, and

urned prior to use to a temperature above the vitrification point of the bonding material and having an adherent glaze formed integral with the bond.

8. As a new article of manufacture, a refractory article consistin principally, of graphite and a porcelain nding material and burned prior to use to .a temperature sufiicient to substantiall completely vitrify the bonding material tirough'outthe body of the article, and to form on the surface thereof an adherent vitrified bond.

- 9. As a new article of manufacture, a re-- fractory article consisting principally of graphite and clay, and containing a fluxing ingredient, and burned prior to use'to a temperature above fusion mg ingredient into a y which is hard,

of the total mass, an burned a mix conta'ini vbonding glaze integral with the int of the flux-- strong and substantially impervious to moisture.

2P0. As a new article of manufacture a refractory article consisting principally of graphite and a vitrifiable ceramic bond containing clay and a fluxing ingredien the 11. As anew article of manufacture a re- 'fractory article consisting principally of graphite and a vitrifiable ceramic bond containing clay and a fluxing ingredient, the bonding material bein over 25% by weight prior to use to a temperature above the fusion point of the fluxing ingredient into a body which is hard, strong and substantially impervious to moisture.

12. As a new article of manufacture, a re the fluxing ingredient into a body which is' hard, strong and substantially impervious to moisture. I

14. The process of making refractory article's', which comprises molding them from a mix containing graphite and a ceramic bonding material, burnin the-articles ,to substantially completely de ydrate the bond-' ing materia then oxidizing the graphite at the surface of the article, and, thereafter burning the articles to atem the vitrification point of the rial.

15. The process of makin refractory articles, which comprises mol in them from graphite an a ceramic materi burning the articles .in a non-oxidizing atmosphere, then burning the articles in an oxlding atmosphere, and

nding matethereafter burning the articles at a temfperathe Inn

rature above Y a mix containin thereafter burning the articles in a non-oxidizing atmosphere to a temperature above thel vitrification point of the bonding materia 17. The rocess of makin refractory articles, whic comprises moldin them from raphite an a porcelain bonding materia, u'rning the articles in a non-oxidizing atmosphere to dehydrate the bonding material, burning the articles in an oxidizing atmosphere to oxidize the graphite at their surfaces, and thereafter burning the articles in a non-oxidizin atmosphere to a temperature suflicient to vitrify and mature the orcelain bondin -material throughout the ody of the artic es. and form on their surfaces a laze integral with the vitrified bond .in the ody.

rocess of makin refractory ar- 18. The

ticles, whic comprises molding them'from a m x containing graphite and a ceramic bonding materlal, burning the articles in a non -oxidizin atmosphere for a sufficient time to dehy rate the bonding material, and then burning the articles so as to oxidize the graphite in the surface skin of-the article and fuse the thus oxidized surface skin into a glaze.

19. The ticles, whic comprises molding the articles from a mix containin raphite and a porcelain bonding materia urni ng the articles in a non-oxidizing atmos cient time to thoroughly de ydrate the bond ing material, burning the articles for a relatively short time in an oxidizing atmosphere tooxidize the graphite in the-surface skin only of the, articles, and thereafter liurning the articles ,in a non-oxidizing atmosphere to a temperature above 2000 F. so as to vitrify and mature the porcelain bonding material throughout the body of the articles and fuse the oxidized surface skin into a glaze.

20. The rocess of making refractory articles, whic comprises molding them from a mix containin graphite and a ceramic bonding materia burning the articles in a non-oxidizing atmosphere, then burning the articles in an oxidizing atmosphere so as to oxidize the graphite at their surface, and

thereafter burningFthe articles to a temperature above 2000 v v p 21. The recess of maln'ng refractory articles, whi comprises, molding them from mp4s ticles,,

a mix consisting principally of graphite andprocess of mak in refractory :1r--

here for a sufli my hand.

a mix consistingprincipally of graphite and a vitrifiable ceramic bonding material, and burning the molded articles rior to use to a temperature above the vitri cation point of the bonding material. I

22. The process of making refractory arwhich comprises molding them from a vitrifiable ceramic bonding material, and burning the molded .articles prior to use to a temperature above 2000 F.

23. The process of makin refractory artil) ticles, which comprlses molding them from v a mix consisting principally of graphite and a vitrifiable ceramic bonding material,

and burning the moldedarticles prior to use to a temperature sufficient to substantially vitrify the bonded material throughout the bod of the article, the proportions of the ingre ients and the burning temperaturebeing such as to form a body having a structure which is hard, strong andsubstantially inpervious to moisture.

24. The process of making refractory articles, which comprises .molding them from a mix consisting principally of graphite and a porcelain bonding material, and burning the articles prior to use to a "tem erature sufficient to vitrify the porcelain onding material "and form it into a glaze at the surface of the article. i

25. The process of making'refractory articles, which comprises molding them from a mix containing graphite and a vitrifiable ceramic bonding material, burning the articles to substantially-completely dehydrate but not fuse the bonding material, and'thereafter burning the articles to a tem erature above thevitrification point of the onding material.

26. The process of making refractory arfrom ticles, which comprises molding them a mix consisting principall of graphite and a vitrifiable ceramic bon containing clay and a fluxing ingredient, burning the articles 7 at a temperature below the fusion point of the fluxing ingredient but sufficiently high to substantially completely dehydrate the bondin arlficles to a temperature above" the fusion point of the fluxing ingredient.

In testimony whereof I have hereunto set ARTHUR J. .momu.

material, and thereafter burning the-

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