CA1202464A - Composite refractory articles - Google Patents
Composite refractory articlesInfo
- Publication number
- CA1202464A CA1202464A CA000414840A CA414840A CA1202464A CA 1202464 A CA1202464 A CA 1202464A CA 000414840 A CA000414840 A CA 000414840A CA 414840 A CA414840 A CA 414840A CA 1202464 A CA1202464 A CA 1202464A
- Authority
- CA
- Canada
- Prior art keywords
- refractory
- flow passage
- passageway
- article
- fusion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/14—Closures
- B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
- B22D41/28—Plates therefor
Abstract
ABSTRACT
The invention is concerned with a method of manufacturing a composite refractory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of refrac-tory material which defines a surface of that passage, the first body being bonded to a second body of re-fractory material. The method of the invention is characterized in that the second body defines a passage-way of greater cross-sectional dimensions than the flow passage and that the first body of refractory material is provided within such passageway for defining the flow passage surface, the first body being formed in the larger passageway by causing its refractory material to cohere and bond to the second body by fusion or partial fusion in situ. The composite refractory article thus obtained has the first body located within a passageway formed in the second body, such passageway being of greater cross-sectional dimensions than the flow passage so that the first body coheres and bonds to the second body by fusion or partial fusion of those bodies at least at their joint. The first re-fractory body may be composed of fused or partially fused refractory material and it may be a relatively high grade refractory body while the second body is a lower grade refractory body.
The invention is concerned with a method of manufacturing a composite refractory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of refrac-tory material which defines a surface of that passage, the first body being bonded to a second body of re-fractory material. The method of the invention is characterized in that the second body defines a passage-way of greater cross-sectional dimensions than the flow passage and that the first body of refractory material is provided within such passageway for defining the flow passage surface, the first body being formed in the larger passageway by causing its refractory material to cohere and bond to the second body by fusion or partial fusion in situ. The composite refractory article thus obtained has the first body located within a passageway formed in the second body, such passageway being of greater cross-sectional dimensions than the flow passage so that the first body coheres and bonds to the second body by fusion or partial fusion of those bodies at least at their joint. The first re-fractory body may be composed of fused or partially fused refractory material and it may be a relatively high grade refractory body while the second body is a lower grade refractory body.
Description
6~
COMPOSITE RE~RACTO~Y ARTICLES AND_METHOD OF MANUFACTURING
THEM
This in~ention relates to a method of manufacturing a composite refractery article having a flow passage through which a molten metal stream may be conducted a~d comprislng a first body of re~ractory material whlch de~ines a surface of that passage~ such first body being bonded to a second body of refractory material, and the invention includes composite refractory articles of the type referred to.
The composite refractory articles ~ith which this invention is particularly concerned are useful as parts of and fittings ~or apparatus used in metallurgy and more p~r-; ticularly in foundry practice. Such ar-ticles include pieces used to guide or control the flow of molten metal streams such as slide plates and collector nozzles. of sliding gate val~es.
15A problem encountered in foundry practice is the erosion of refractory material b~ a molten metal stream whlch flows past it. For example it ~s k~otrn to use a magnesia-based ~liding gate valve plate for controlling the flow of molten steel from a pot furnace~ but generally speaking the.val~e plat.e requires replacement each time the pot furnace is filled because the flow o~ steel through tb.e flow passage in the ~lide plate .tends to enlarge that passage and make it ~rregular. After u~e such valve plates are discarded. It is also known to make such ~ulnerable refractory parts of a higher grade of refractory ~aterial such as alumina~ but this is e~pen.si~e It is also knot~n to cement inserts of high grade ret-rac~or~ ma~erlal 7 Por ... . . ... . . . . . ... . . .. .. .. .. . ....
~2~ 6~
example zirconia, into bodies of refractory material at their most vulnerable regions. This is inconvenient in practice since the insext and the remainder of the re-fractory body must be carefully matched in shape and size.
Furthermore, it is known from Flogates I,imited's British Patent Application N GB 2 065 27~ A published June 24, 1981 to form a refractory article having a surface portion which, in service, is contacted by a molten metal stream, comprising an integral composite bod.y having a first refractory member providing the said surface portion, a trough or cup shaped metal foil en-compassing the first refractory member, and a second, back-up refractory member supporting the foil-encompassed first refractory member, the first refractory member being made from a higher duty refractory material than the second refractory member. This Flogates application also teaches a method of making such a refractory article including the steps of (i) forming a first mould space from a trough or cup shaped metal foil and a companion, permanent mould member the shape of which is a negative of said surface portion, (ii) filling said first mould space with a mouldable refractory concrete and at least partially curing the co~icrete, (iii) assembling the foil and moulding therein a second mould space formed from companion mould members, (iv) filling the second mould space with a second refractory concrete which is of lower duty than the first concrete, and (v) curing the second concrete and, to the extent that it may not already be completely cured, the first concrete also.
It is an object of the present invention to provide new and useful alternative methods of manufacturing com-posite articles which present certain advantages over what has hitherto been known as will be adverted to in the course of this specification.
According to the present invention, there is provided a method of manufacturing a composite refractory article havi.ng a flow passage through which a molten metal stream ~)2 may be conducted and comprising a first body of refractory material which defines a surface of that passage, said first bod~ being bonded to a second body of refractory material, charac-terised by ths steps of providing a said second body def`ining a passageway of greater cross-sectional dimensions than said flow passage and providing within said passageway a said first body of refractory material for defining said flow passage surface, said first body being formed in the larger pa3sageway by causing its refractory material to cohere ancl bond to said second body by fusion or partial ~usion in situ.
A method according to the present invention presents the advantages of being applica~le both to the manufacture of new refractory articles and to the reconditioning or repair of used refractory articlel. A method according to the invention is also especially simple and con~enient to put into practice since a surface of the first refrac-tory~body formed in the performance of such method will conform to the second refractory body without the need for any special shaping operations.
The expression "fusion or partial fusion of refractory material't as used herein denotes an operation in the course of which that material is wholly in the liquid phase or in which particles of refractory material are substantially all melted at at least their surfaces so that on cooling they form a fused coherent mass, Such fusion bonding is to be distinguished from mere sintering in which a com-pacted powder is heated to a temperature lower than is necessary to produce a liquid phase but high enough for solid-state reaction or intercrystallisation to take place, and from other bonding techniques in ~hich refractory particles are bonded unfused in a binder matrix, such matrix itself being either fused or not. In the most important embodiments of the in~ention said first refrac-tory body is composed of fused or partially fused refrac~to~y material. The internal structure of a sald first ~202~
refractory body which is fused or partially fused together in accordance with this prcferred feature of the present invention is different from that of a sintered body or of a body formedby unfused refractory particles in a binder matrix and presents particularly lmpor-tant advantages for the purposes in view since that structure is highly cohesive and resistant to erosion by molten metal.
It is especially preferred that said~irst refractory - body is formed as a relatively high grade refractory body -and said second refractory body is formed as a lower grade refractory body~ The terms higher and lower grade refrac-tory are used herein to denote relative degrees of resis-tance to erosion at high temperature. In general, the cost of a re~ractory body increases with increase in its resis tance to erosion at high temperature. Thus the adoption of this feature presents the important advantage of in-creased cost effectiveness, since the relatively costly high grade first refractory body may form regions o~ the composi-te refractory article which are most exposed to erosion while being supported by a lower grade and less costly second refractory body.
Preferably, said first refractory body is formed by a spraying technique~ Such spraying may be plasma-spraying, but such body is advantageously formed by flame-spraying a mixture of exothermically oxidisable material and other material so a3 to form a coherent refractory mass. This is a very simple and con~enient way of forming a refractory body in situ on another refractGry body, and may ~or example be performed using a process anl apparatus as de3cribed in Glaverbel~s British Patents Nos~ 1,3309894 and 1,330~895.
Said oxidisable material is advantageously sprayed in the form of particles having an average si~e of less than 50/~m and preferably less than 10/~ m Alternatively, or in addition, said oxidisable material may with advantage 3~ be spray0d in the form of particles having a specific s~r~
face of at least 500 cm2/gram and preferably at least 3000 .. . . . . . .... .. .. . .
~o~
cm /gram. These features promote rapid and reliable combustion of the oxidlsable materlal~
Said other material is advantageously ~prayed in the forrn of particles having an a~erage grain size below 500/~ m.
Said oxidisable material advantageously cons~ts at least in part of a metal or metalloid preferably selectod from the group: aluminium, magnesium9 sllicon~ zirconium and mixtures of two or more of ~uch materials. Other oxidisable materials which may be used include calcium, manganese and iron.
Advantageously, said combustible material constitutes less than 35/c by weight of the mixture sprayed~ The proportion of combustible material required dopends of cour~e, inter alia, on the amount of heat which must be e~olved by the combustion, and the proportion used must be sufficient for that purpose. ~owever another factor to be kept in mind is the amount of unburnt combustible substance (if any) left in the re.fractory body formed.
Especial3y when using a metal as combustible, it is desirable for all the metal to be burnt sinco the oxid0 generally has better refractory properties than tha metal.
The use of excoss metal add~ needlessly to costs and can result in an inferior productc Said other material preferably comprises one or more of: zirconia, zircon, silica9 alumi~a, chrome-magnesia~ ~agne~ia9 these being highly refractory materials~
It will be appreciated that the choice of materials for forming the first refractory body will affect the quality of the bond between -that body and the second re~ractory body in dependence upon the rnaterial of wh~ch that second body is made. It is also desirable to salect the first and second refractory materialq so that their coefficients of thermal expansion are similar A method according to the in~ontion is particularly valuable in the manufacture of composite refractory .. ...... .... . . . .
~Z~2 articles wherein the first refractory body is forrned in a sllding ga~e valve plate. Such plate may be a slide plate or a plate against which the slide plate slido3.
In some preferred embodiments of th~ invention, such valve plate has an integral collector nozzle at least partially lined by said first refractory body.
It ~s found especially convenient in practice to form ~he first refractory body and then drill it to define the flo~ passage.
As has been referred to before7 this invention is not only applicable in the manufacture of new refractory articles9 but is also of value in restoring or repairing used refrac-tory articles, and some embodiments of the invention have the preferrQd optional feature that said first refractory body is formed in a hole made by removing material from around a flow passage of a used refractory article.
The inventi~n.includes a composite refractory article manufactured by a method as herein defined.
The invention also includes a composite refractory article having a flow passage through which a molten metal s-tream may be conducted and comprising a first body of refractory material which defines a surface of that passage7 ~aid first body being bonded to a second body of refractory material~ characterised in that said first body is formed within a passageway formed in said second body, such passageway being of greater cross sectional dimensions than said flow passage and in that said first body coheres and bonds to the second body by fusion or partial fusion in situ.
Said first refra~tory body is preferably composed of fused or partially fused refractory material.
In preferred embodiments of the invention, said first refractory article is a relatively high grade refractory body and said second body is a lower grade refractory body~
.. . . .. . .. . . . . ... ...
~2a~6 Said first refractory body preferably co~prises one or more of zirconia, zircon, silica, alumina, chrome-magnesia, magnesia.
Preferably9 the materials of said first and second re~ractory bodies i:nterpene-trate at a boundary layer. Ad~antageously, sai~ first refractory body surrounds a flow passage in a sliding gate va].ve plate, and in some preferred embodiments of the invention, said valve plate has an integral collector nozzle at least partially linad by.said first refractory bodyO
Preferred embodimerlts of the invention will now be described in greater detail with reference to the accom-panying diagrammatic drawings in which:
Figure l is a ~ectional view of a sliding gate valve at the bottom of a po-t furnace;
~igure 2 shows two stages in the repair of a usad gate valve slide plate; and ~igure 3 shows a further stage in the manufacture of a gate valve slide plate according to the invention.
In Flgure l, the sole l of a pot furnace has an orifice 2 for teeming molten metal contained in the fur-nace~ The orifice 2 is closable by a sliding gate valve comprising a slide plate 3 and a second plate (the nozzle plate) 4 which has.an integral collector nozzle 50 The slide plate 3 is a compcsite refractory article consisting of a first refractory body in the form of a hollow plug 6 defining a flow passage 7 and supported by a second refractory body 8 which mal~es up the bulk of the slide plate The nozzle plate 4~ is also a composite refrac-tory article and consists of a first refractory body 9 in the form of a liner for a flow passage lO through a second refractory body ll making up the nozzle plate 4 - with its integral collector nozzle 5.
The hollow plug 6 or the liner 9 is formed of a relatively high grade refractory material and i.s formed in situ in a passageway in the second refractory body 8 or 11 of its respectlve valve plate 3 or 4 in s~ch a way that it coheres and bonds to the second re~ractory body 8 .. . . , . . . . . ~ .
by ~usion or partial fusion. Such second refractory body is formed of a lower grade refractory ma-terial. Such in situ formation tends to cause inter-penetratiorl of the refractory materials at the boundary between the respective refractory bodies 6 and 8 or 9 and 11~
In addition1 the hollow plug 6 or liner 9 may be com-~osed of refractor~ materiaL which is fused or partial]y fused and bonded to its respectîve second refractory hody 8 or Il.
~igure 2 îllustrates a stage in the repair of a used slide plate 12 of a sliding gate valve. The slide plate 12 was originally of a single refractory body having a flow passage 13 indicated in dotted lines. During use the flow passage 13 became enlarged by erosion of material as indicated at the right hand side of Figure 2, this erosion being particularly severe at the ends of the flow passage 13. In order to repair this slide plate 12, additional refractory material is removed from around the flow passage 1J to leave an enlarged passageway 14 whose profile is indicated in solid lines on the left hand side of the ~igure and in dotted lines on the right. It will be noted that the profile of the enlarged passageway 14 is stepped to provide a shoulder 15 to provide additional, mechanical support for a refractory plug which is to be contained within that enlarged passageway. As an alterna-tive way of providing such support, the profile of the passageway 14 may be conical. Of course a part conical, optionally stepped, profile may be provided if desired.
After the pas~ageway 14 has been formed, it is filled with a plug 16 (~igure 3) of re-fractory material so that the slide plate consists of first and second re-fractory bodies 16, 170 In fact in no-rmal practice, the plug 16 when first formed rnay stand proud from the upper surface of the second refracto~y body 17~ In such a case machining will be necessary to provide the slidc plato 12 with a flat upper surfaceO After -the plug 16 is formed it is drilled to provide a flow passage such as the flow passage 7 in the slide plate 3 of ~igure 1. In order that the lo~er surface of the plug 16 may be formed fla-t, a mould plate 18 of refractory material such as silica or a suitable metal is placed against the under surfac0 of the slide 12 prior to forming the plug.
It i3 especially suitable to forrn the plug 16 using apparatus as described in Glaverbel's British Patent specification 1,330,895~ that i~ to say, apparatu~ for flame spraying a mixture of fin0 particles comprising combustible (e.g. metal or metalloid) particles and particles of other material such a refractory oxide particles to form a coherent refractory mass.
It will of course be appreciated that the plug 16 f Figure 3 may equally well be formed in an unused body of refractory material, and that a nozzle plate such as the plage 4 of Figure l may equally be manufactured or repaired in a similar way.
In order to form a plug in a body of ba~lc refractory material consisting mainly of magnesia, a mixture of partlcles was prepared and pro~ected into a hole formed in the basic type refractory materlal using the apparatus described in British Patent specification No. 1,330,895 The refractory body was preheated to 500 C.
The mixture of particles was projected at a rate of 20 kg/hour in a stream of oxygen delivered at 13000 L/h~ur and had the following composition by weight: ZrO2 45%, Si2 280/C~ A12o3 15%9 Si 12~/o~ The silicon particles had a maximum average grain 5ize of lO~ m and a specific surface of 5000 Cm /gram, z~d the other par-ticles had a ma~imum average grain size of 500~ m~ The heat of`
combustion of the silicon was sufficient to melt at least the surface of the other particles so a~ to form a cohere~t plug of refractory material which was fused together and directly bonded to the magnesia type refractory body~
... . .. ..
6~
In a variant of Example 1, the oxide particles o~
the projected mixture were replaced by ZrO2 (50% by weight of -ths mixture) and Alz03 (38%) .
5 Exam~
In order to form a plug in a basic re~ractory block con~isting mainly of magnesia, a starting mixture of finely divided particle~ con isting of 40% MgO, 40% ZrO2 and 20% Of silicon was projected at a rate of 0.7 kg/minute in an oxygen stream delivered at 240 L/minute~
The block was preheated to a temperature of about 5O C.
Again a coherent mass of f~lsed-together refractory matsrial was obtained.
In a ~ariant of this Example9 small quantities of SiO2 were present in the starting mixture.
Exampl~ 4 -In order to form a plug in a basic refractory block consisting mainly o~ magnesia? a starting mixture of ~inely divided particles consisting of, by weight, 600/o chrome-magnesia, 20~o ZrO2 and 20% comb~stible material was pro-jected at a rate o~ 0.7 kg/minute in an oxygen ~tream delivered at 240 L/minute. The combustible material used was silicon, and the block was preheated to a tempera-t~re of 500C before spraying.
~a~ ~
A basic re~ractory block wa3 plugged by projecting, at a rate of 007 kg/minute in an oxygen stream delivered at 220 L/minute a mixture o~ finely dl~ided particles consisting of, by weight, 15% A1203~ 12% SiO2~ 600/o ZrS10 and 13/c combustible materialO
The block was preheated -to 500 C.
COMPOSITE RE~RACTO~Y ARTICLES AND_METHOD OF MANUFACTURING
THEM
This in~ention relates to a method of manufacturing a composite refractery article having a flow passage through which a molten metal stream may be conducted a~d comprislng a first body of re~ractory material whlch de~ines a surface of that passage~ such first body being bonded to a second body of refractory material, and the invention includes composite refractory articles of the type referred to.
The composite refractory articles ~ith which this invention is particularly concerned are useful as parts of and fittings ~or apparatus used in metallurgy and more p~r-; ticularly in foundry practice. Such ar-ticles include pieces used to guide or control the flow of molten metal streams such as slide plates and collector nozzles. of sliding gate val~es.
15A problem encountered in foundry practice is the erosion of refractory material b~ a molten metal stream whlch flows past it. For example it ~s k~otrn to use a magnesia-based ~liding gate valve plate for controlling the flow of molten steel from a pot furnace~ but generally speaking the.val~e plat.e requires replacement each time the pot furnace is filled because the flow o~ steel through tb.e flow passage in the ~lide plate .tends to enlarge that passage and make it ~rregular. After u~e such valve plates are discarded. It is also known to make such ~ulnerable refractory parts of a higher grade of refractory ~aterial such as alumina~ but this is e~pen.si~e It is also knot~n to cement inserts of high grade ret-rac~or~ ma~erlal 7 Por ... . . ... . . . . . ... . . .. .. .. .. . ....
~2~ 6~
example zirconia, into bodies of refractory material at their most vulnerable regions. This is inconvenient in practice since the insext and the remainder of the re-fractory body must be carefully matched in shape and size.
Furthermore, it is known from Flogates I,imited's British Patent Application N GB 2 065 27~ A published June 24, 1981 to form a refractory article having a surface portion which, in service, is contacted by a molten metal stream, comprising an integral composite bod.y having a first refractory member providing the said surface portion, a trough or cup shaped metal foil en-compassing the first refractory member, and a second, back-up refractory member supporting the foil-encompassed first refractory member, the first refractory member being made from a higher duty refractory material than the second refractory member. This Flogates application also teaches a method of making such a refractory article including the steps of (i) forming a first mould space from a trough or cup shaped metal foil and a companion, permanent mould member the shape of which is a negative of said surface portion, (ii) filling said first mould space with a mouldable refractory concrete and at least partially curing the co~icrete, (iii) assembling the foil and moulding therein a second mould space formed from companion mould members, (iv) filling the second mould space with a second refractory concrete which is of lower duty than the first concrete, and (v) curing the second concrete and, to the extent that it may not already be completely cured, the first concrete also.
It is an object of the present invention to provide new and useful alternative methods of manufacturing com-posite articles which present certain advantages over what has hitherto been known as will be adverted to in the course of this specification.
According to the present invention, there is provided a method of manufacturing a composite refractory article havi.ng a flow passage through which a molten metal stream ~)2 may be conducted and comprising a first body of refractory material which defines a surface of that passage, said first bod~ being bonded to a second body of refractory material, charac-terised by ths steps of providing a said second body def`ining a passageway of greater cross-sectional dimensions than said flow passage and providing within said passageway a said first body of refractory material for defining said flow passage surface, said first body being formed in the larger pa3sageway by causing its refractory material to cohere ancl bond to said second body by fusion or partial ~usion in situ.
A method according to the present invention presents the advantages of being applica~le both to the manufacture of new refractory articles and to the reconditioning or repair of used refractory articlel. A method according to the invention is also especially simple and con~enient to put into practice since a surface of the first refrac-tory~body formed in the performance of such method will conform to the second refractory body without the need for any special shaping operations.
The expression "fusion or partial fusion of refractory material't as used herein denotes an operation in the course of which that material is wholly in the liquid phase or in which particles of refractory material are substantially all melted at at least their surfaces so that on cooling they form a fused coherent mass, Such fusion bonding is to be distinguished from mere sintering in which a com-pacted powder is heated to a temperature lower than is necessary to produce a liquid phase but high enough for solid-state reaction or intercrystallisation to take place, and from other bonding techniques in ~hich refractory particles are bonded unfused in a binder matrix, such matrix itself being either fused or not. In the most important embodiments of the in~ention said first refrac-tory body is composed of fused or partially fused refrac~to~y material. The internal structure of a sald first ~202~
refractory body which is fused or partially fused together in accordance with this prcferred feature of the present invention is different from that of a sintered body or of a body formedby unfused refractory particles in a binder matrix and presents particularly lmpor-tant advantages for the purposes in view since that structure is highly cohesive and resistant to erosion by molten metal.
It is especially preferred that said~irst refractory - body is formed as a relatively high grade refractory body -and said second refractory body is formed as a lower grade refractory body~ The terms higher and lower grade refrac-tory are used herein to denote relative degrees of resis-tance to erosion at high temperature. In general, the cost of a re~ractory body increases with increase in its resis tance to erosion at high temperature. Thus the adoption of this feature presents the important advantage of in-creased cost effectiveness, since the relatively costly high grade first refractory body may form regions o~ the composi-te refractory article which are most exposed to erosion while being supported by a lower grade and less costly second refractory body.
Preferably, said first refractory body is formed by a spraying technique~ Such spraying may be plasma-spraying, but such body is advantageously formed by flame-spraying a mixture of exothermically oxidisable material and other material so a3 to form a coherent refractory mass. This is a very simple and con~enient way of forming a refractory body in situ on another refractGry body, and may ~or example be performed using a process anl apparatus as de3cribed in Glaverbel~s British Patents Nos~ 1,3309894 and 1,330~895.
Said oxidisable material is advantageously sprayed in the form of particles having an average si~e of less than 50/~m and preferably less than 10/~ m Alternatively, or in addition, said oxidisable material may with advantage 3~ be spray0d in the form of particles having a specific s~r~
face of at least 500 cm2/gram and preferably at least 3000 .. . . . . . .... .. .. . .
~o~
cm /gram. These features promote rapid and reliable combustion of the oxidlsable materlal~
Said other material is advantageously ~prayed in the forrn of particles having an a~erage grain size below 500/~ m.
Said oxidisable material advantageously cons~ts at least in part of a metal or metalloid preferably selectod from the group: aluminium, magnesium9 sllicon~ zirconium and mixtures of two or more of ~uch materials. Other oxidisable materials which may be used include calcium, manganese and iron.
Advantageously, said combustible material constitutes less than 35/c by weight of the mixture sprayed~ The proportion of combustible material required dopends of cour~e, inter alia, on the amount of heat which must be e~olved by the combustion, and the proportion used must be sufficient for that purpose. ~owever another factor to be kept in mind is the amount of unburnt combustible substance (if any) left in the re.fractory body formed.
Especial3y when using a metal as combustible, it is desirable for all the metal to be burnt sinco the oxid0 generally has better refractory properties than tha metal.
The use of excoss metal add~ needlessly to costs and can result in an inferior productc Said other material preferably comprises one or more of: zirconia, zircon, silica9 alumi~a, chrome-magnesia~ ~agne~ia9 these being highly refractory materials~
It will be appreciated that the choice of materials for forming the first refractory body will affect the quality of the bond between -that body and the second re~ractory body in dependence upon the rnaterial of wh~ch that second body is made. It is also desirable to salect the first and second refractory materialq so that their coefficients of thermal expansion are similar A method according to the in~ontion is particularly valuable in the manufacture of composite refractory .. ...... .... . . . .
~Z~2 articles wherein the first refractory body is forrned in a sllding ga~e valve plate. Such plate may be a slide plate or a plate against which the slide plate slido3.
In some preferred embodiments of th~ invention, such valve plate has an integral collector nozzle at least partially lined by said first refractory body.
It ~s found especially convenient in practice to form ~he first refractory body and then drill it to define the flo~ passage.
As has been referred to before7 this invention is not only applicable in the manufacture of new refractory articles9 but is also of value in restoring or repairing used refrac-tory articles, and some embodiments of the invention have the preferrQd optional feature that said first refractory body is formed in a hole made by removing material from around a flow passage of a used refractory article.
The inventi~n.includes a composite refractory article manufactured by a method as herein defined.
The invention also includes a composite refractory article having a flow passage through which a molten metal s-tream may be conducted and comprising a first body of refractory material which defines a surface of that passage7 ~aid first body being bonded to a second body of refractory material~ characterised in that said first body is formed within a passageway formed in said second body, such passageway being of greater cross sectional dimensions than said flow passage and in that said first body coheres and bonds to the second body by fusion or partial fusion in situ.
Said first refra~tory body is preferably composed of fused or partially fused refractory material.
In preferred embodiments of the invention, said first refractory article is a relatively high grade refractory body and said second body is a lower grade refractory body~
.. . . .. . .. . . . . ... ...
~2a~6 Said first refractory body preferably co~prises one or more of zirconia, zircon, silica, alumina, chrome-magnesia, magnesia.
Preferably9 the materials of said first and second re~ractory bodies i:nterpene-trate at a boundary layer. Ad~antageously, sai~ first refractory body surrounds a flow passage in a sliding gate va].ve plate, and in some preferred embodiments of the invention, said valve plate has an integral collector nozzle at least partially linad by.said first refractory bodyO
Preferred embodimerlts of the invention will now be described in greater detail with reference to the accom-panying diagrammatic drawings in which:
Figure l is a ~ectional view of a sliding gate valve at the bottom of a po-t furnace;
~igure 2 shows two stages in the repair of a usad gate valve slide plate; and ~igure 3 shows a further stage in the manufacture of a gate valve slide plate according to the invention.
In Flgure l, the sole l of a pot furnace has an orifice 2 for teeming molten metal contained in the fur-nace~ The orifice 2 is closable by a sliding gate valve comprising a slide plate 3 and a second plate (the nozzle plate) 4 which has.an integral collector nozzle 50 The slide plate 3 is a compcsite refractory article consisting of a first refractory body in the form of a hollow plug 6 defining a flow passage 7 and supported by a second refractory body 8 which mal~es up the bulk of the slide plate The nozzle plate 4~ is also a composite refrac-tory article and consists of a first refractory body 9 in the form of a liner for a flow passage lO through a second refractory body ll making up the nozzle plate 4 - with its integral collector nozzle 5.
The hollow plug 6 or the liner 9 is formed of a relatively high grade refractory material and i.s formed in situ in a passageway in the second refractory body 8 or 11 of its respectlve valve plate 3 or 4 in s~ch a way that it coheres and bonds to the second re~ractory body 8 .. . . , . . . . . ~ .
by ~usion or partial fusion. Such second refractory body is formed of a lower grade refractory ma-terial. Such in situ formation tends to cause inter-penetratiorl of the refractory materials at the boundary between the respective refractory bodies 6 and 8 or 9 and 11~
In addition1 the hollow plug 6 or liner 9 may be com-~osed of refractor~ materiaL which is fused or partial]y fused and bonded to its respectîve second refractory hody 8 or Il.
~igure 2 îllustrates a stage in the repair of a used slide plate 12 of a sliding gate valve. The slide plate 12 was originally of a single refractory body having a flow passage 13 indicated in dotted lines. During use the flow passage 13 became enlarged by erosion of material as indicated at the right hand side of Figure 2, this erosion being particularly severe at the ends of the flow passage 13. In order to repair this slide plate 12, additional refractory material is removed from around the flow passage 1J to leave an enlarged passageway 14 whose profile is indicated in solid lines on the left hand side of the ~igure and in dotted lines on the right. It will be noted that the profile of the enlarged passageway 14 is stepped to provide a shoulder 15 to provide additional, mechanical support for a refractory plug which is to be contained within that enlarged passageway. As an alterna-tive way of providing such support, the profile of the passageway 14 may be conical. Of course a part conical, optionally stepped, profile may be provided if desired.
After the pas~ageway 14 has been formed, it is filled with a plug 16 (~igure 3) of re-fractory material so that the slide plate consists of first and second re-fractory bodies 16, 170 In fact in no-rmal practice, the plug 16 when first formed rnay stand proud from the upper surface of the second refracto~y body 17~ In such a case machining will be necessary to provide the slidc plato 12 with a flat upper surfaceO After -the plug 16 is formed it is drilled to provide a flow passage such as the flow passage 7 in the slide plate 3 of ~igure 1. In order that the lo~er surface of the plug 16 may be formed fla-t, a mould plate 18 of refractory material such as silica or a suitable metal is placed against the under surfac0 of the slide 12 prior to forming the plug.
It i3 especially suitable to forrn the plug 16 using apparatus as described in Glaverbel's British Patent specification 1,330,895~ that i~ to say, apparatu~ for flame spraying a mixture of fin0 particles comprising combustible (e.g. metal or metalloid) particles and particles of other material such a refractory oxide particles to form a coherent refractory mass.
It will of course be appreciated that the plug 16 f Figure 3 may equally well be formed in an unused body of refractory material, and that a nozzle plate such as the plage 4 of Figure l may equally be manufactured or repaired in a similar way.
In order to form a plug in a body of ba~lc refractory material consisting mainly of magnesia, a mixture of partlcles was prepared and pro~ected into a hole formed in the basic type refractory materlal using the apparatus described in British Patent specification No. 1,330,895 The refractory body was preheated to 500 C.
The mixture of particles was projected at a rate of 20 kg/hour in a stream of oxygen delivered at 13000 L/h~ur and had the following composition by weight: ZrO2 45%, Si2 280/C~ A12o3 15%9 Si 12~/o~ The silicon particles had a maximum average grain 5ize of lO~ m and a specific surface of 5000 Cm /gram, z~d the other par-ticles had a ma~imum average grain size of 500~ m~ The heat of`
combustion of the silicon was sufficient to melt at least the surface of the other particles so a~ to form a cohere~t plug of refractory material which was fused together and directly bonded to the magnesia type refractory body~
... . .. ..
6~
In a variant of Example 1, the oxide particles o~
the projected mixture were replaced by ZrO2 (50% by weight of -ths mixture) and Alz03 (38%) .
5 Exam~
In order to form a plug in a basic re~ractory block con~isting mainly of magnesia, a starting mixture of finely divided particle~ con isting of 40% MgO, 40% ZrO2 and 20% Of silicon was projected at a rate of 0.7 kg/minute in an oxygen stream delivered at 240 L/minute~
The block was preheated to a temperature of about 5O C.
Again a coherent mass of f~lsed-together refractory matsrial was obtained.
In a ~ariant of this Example9 small quantities of SiO2 were present in the starting mixture.
Exampl~ 4 -In order to form a plug in a basic refractory block consisting mainly o~ magnesia? a starting mixture of ~inely divided particles consisting of, by weight, 600/o chrome-magnesia, 20~o ZrO2 and 20% comb~stible material was pro-jected at a rate o~ 0.7 kg/minute in an oxygen ~tream delivered at 240 L/minute. The combustible material used was silicon, and the block was preheated to a tempera-t~re of 500C before spraying.
~a~ ~
A basic re~ractory block wa3 plugged by projecting, at a rate of 007 kg/minute in an oxygen stream delivered at 220 L/minute a mixture o~ finely dl~ided particles consisting of, by weight, 15% A1203~ 12% SiO2~ 600/o ZrS10 and 13/c combustible materialO
The block was preheated -to 500 C.
Claims (28)
1. A method of manufacturing a composite refrac-tory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of refractory material which defines a sur-face of that passage, said first body being bonded to a second body of refractory material, characterized by the steps of providing a said second body defining a passageway of greater cross-sectional dimensions than said flow passage and providing within said passageway a said first body of refractory material for defining said flow passage surface, said first body being formed in the larger passageway by causing its refractory material to cohere and bond to said second body by fusion or partial fusion in situ.
2. A method according to claim 1, wherein said first refractory body is composed of fused or partially fused refractory material.
3. A method according to claims 1 or 2, wherein said first refractory body is formed as a relatively high grade refractory body and said second body is formed as a lower grade refractory body.
4. A method according to claim 1, wherein said first refractory body is formed by a spraying technique.
5. A method according to claim 4, wherein said first refractory body is formed by flame spraying a mixture of exothermically oxidizable material and other materials so as to form a coherent refractory mass.
6. A method according to claim 5, wherein said oxidizable material is sprayed in the form of particles having an average size of less than 50 µm.
7. A method according to claim 6, wherein said oxidizable material is sprayed in the form of particles having an average size less than 10 µm.
8. A method according to claims 5, 6 or 7, wherein said oxidizable material is sprayed in the form of particles having a specific surface of at least 500 cm2/gram.
9. A method according to claims 5, 6 or 7, wherein said oxidizable material is sprayed in the form of particles having a specific surface of at least 3000 cm2/gram.
10. A method according to claim 5, wherein said other material is sprayed in the form of particles having an average size below 500 µm.
11. A method according to claim 5, wherein said oxidizable material consists at least in part of a metal or metalloid.
12. A method according to claim 11, wherein said metal or metalloid is selected from the group consisting of aluminium, magnesium, silicon, zirconium and mix-tures thereof.
13. A method according to claim 5, wherein said oxidizable material constitutes less than 35% by weight of the mixture sprayed.
14. A method according to claim 5, wherein said other material comprises one or more of zirconia, zircon silica, alumina, chrome-magnesia, magnesia.
15. A method according to claim 1, wherein said first refractory body is formed in a sliding gate valve plate.
16. A method according to claim 15, wherein said valve plate has an integral collector nozzle at least partially lined by said first refractory body.
17. A method according to claim 1, wherein said first refractory body is formed and is then drilled to define said flow passage.
18. A method according to claim 1, wherein said first refractory body is formed in a hole made by removing material from around a flow passage of a used refractory article.
19. A composite refractory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of refractory material which defines a surface of that passage, said first body being bonded to a second body of refractory material, characterized in that said first body is formed within a passageway formed in said second body, such passageway being of greater cross-sectional dimen-sions than said flow passage and in that said first body coheres and bonds to the second body by fusion or partial fusion in situ.
20. An article according to claim 19, wherein said first refractory body is composed of fused or partially fused refractory material.
21. An article according to claims 19 or 20, wherein said first refractory body is a relatively high grade refractory body and said second body is a lower grade refractory body.
22. An article according to claim 19, wherein said first refractory body comprises one or more of zirconia, zircon, silica, alumina, chrome-magnesia, magnesia.
23. An article according to claim 19, wherein said first refractory body surrounds a flow passage in a sliding gate valve plate.
24. An article according to claim 23, wherein said valve plate has an integral collector nozzle at least partially lined by said first refractory body.
25. An article according to claim 19, wherein the materials of said refractory bodies inter-penetrate at a boundary layer.
26. A method for manufacturing a composite refractory article having a flow passage through which a molten metal stream may be conducted, said article comprising a first body of a relatively high grade refractory material which defines an axially extending surface of that passage, said first body being fused to a second body of relatively lower grade refractory material; comprising the steps of producing said second body defining a passageway of greater cross-sectional dimensions than said flow passage and providing within said passageway said first body of refractory material for defining said flow passage surface, said first body being formed in a sliding gate valve plate and being formed in the larger passageway by causing its refractory material to cohere and bond to said second body by fusion or partial fusion in situ.
27. A method of manufacturing a composite refrac-tory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of refractory material which defines a surface of that passage, said first body being bonded to a second body of refractory material, comprising the steps of providing said second body defining a passage-way of greater cross-sectional dimensions than said flow passage surface, said first body being formed in the larger passageway by causing its refractory material to cohere and bond to said second body, by fusion or partial fusion, in situ, said first body being formed and then drilled to define said flow passage.
28. A composite refractory article having a flow passage through which a molten metal stream may be conducted and comprising a first body of a relatively high grade refractory material which defines a surface of that passage, said refractory article surrounding a flow passage in a sliding gate valve plate, said first body being bonded to a second body of a relatively lower grade refractory material, wherein said first body is formed within a passageway formed in said second body, such passageway being of greater cross-sectional dimensions than said flow passage and in that said first body coheres and bonds to the second body by fusion or partial fusion in situ.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8133409 | 1981-11-05 | ||
| GB08133409A GB2109099B (en) | 1981-11-05 | 1981-11-05 | Composite refractory articles and method of manufacturing them |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1202464A true CA1202464A (en) | 1986-04-01 |
Family
ID=10525660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000414840A Expired CA1202464A (en) | 1981-11-05 | 1982-11-04 | Composite refractory articles |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4497473A (en) |
| JP (1) | JPS58104074A (en) |
| BE (1) | BE894868A (en) |
| CA (1) | CA1202464A (en) |
| DE (1) | DE3240732A1 (en) |
| FR (1) | FR2515546B1 (en) |
| GB (1) | GB2109099B (en) |
| IT (1) | IT1156539B (en) |
| SE (1) | SE453467B (en) |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4650619A (en) * | 1983-12-29 | 1987-03-17 | Toshiba Ceramics Co., Ltd. | Method of machining a ceramic member |
| US4568007A (en) * | 1984-01-23 | 1986-02-04 | Vesuvius Crucible Company | Refractory shroud for continuous casting |
| AT388549B (en) * | 1985-01-26 | 1989-07-25 | Glaverbel | Process for forming a refractory composition on a surface and formulations for forming such a refractory composition on a surface |
| DE3634447C1 (en) * | 1986-10-09 | 1988-02-11 | Didier Werke Ag | Refractory shaped body, in particular a plate for outlet closures |
| GB8729418D0 (en) * | 1987-12-17 | 1988-02-03 | Glaverbel | Surface treatment of refractories |
| GB2220875A (en) * | 1988-01-27 | 1990-01-24 | Vesuvius France Sa | Integral slide-valve member and casting tube member |
| US4981628A (en) * | 1988-10-11 | 1991-01-01 | Sudamet, Ltd. | Repairing refractory linings of vessels used to smelt or refine copper or nickel |
| US5013499A (en) * | 1988-10-11 | 1991-05-07 | Sudamet, Ltd. | Method of flame spraying refractory material |
| US5007615A (en) * | 1988-12-12 | 1991-04-16 | Dresser Industries, Inc. | Refractory slide gate assembly and method |
| US5011049A (en) * | 1989-04-17 | 1991-04-30 | General Electric Company | Molten metal transfer tube |
| US4946082A (en) * | 1989-07-10 | 1990-08-07 | General Electric Company | Transfer tube with in situ heater |
| US5242639A (en) * | 1989-07-25 | 1993-09-07 | Glaverbel | Ceramic welding process |
| GB8916951D0 (en) * | 1989-07-25 | 1989-09-13 | Glaverbel | Ceramic welding process and powder mixture for use in the same |
| US5686028A (en) * | 1991-07-03 | 1997-11-11 | Glaverbel | Process for forming a coherent refractory mass on a surface |
| JP2778869B2 (en) * | 1992-01-24 | 1998-07-23 | 東芝セラミックス 株式会社 | How to regenerate a sliding gate plate |
| FR2695335B1 (en) * | 1992-09-09 | 1994-11-18 | Lorraine Laminage | Linear steel pocket drawer. |
| US5363995A (en) * | 1993-12-14 | 1994-11-15 | Indresco Inc. | Slide gate plate and method |
| JP2731725B2 (en) * | 1994-08-25 | 1998-03-25 | 東芝セラミックス株式会社 | Regeneration slide gate plate |
| US5637802A (en) * | 1995-02-28 | 1997-06-10 | Rosemount Inc. | Capacitive pressure sensor for a pressure transmitted where electric field emanates substantially from back sides of plates |
| US6484585B1 (en) | 1995-02-28 | 2002-11-26 | Rosemount Inc. | Pressure sensor for a pressure transmitter |
| GB2307876A (en) * | 1995-12-09 | 1997-06-11 | Flogates Ltd | Metering nozzle for a tundish |
| US5954989A (en) * | 1997-03-20 | 1999-09-21 | Vesuvius Crucible Company | Erosion and abrasion resistant refractory composition and article made therefrom |
| US6505516B1 (en) | 2000-01-06 | 2003-01-14 | Rosemount Inc. | Capacitive pressure sensing with moving dielectric |
| US6508129B1 (en) | 2000-01-06 | 2003-01-21 | Rosemount Inc. | Pressure sensor capsule with improved isolation |
| US6520020B1 (en) | 2000-01-06 | 2003-02-18 | Rosemount Inc. | Method and apparatus for a direct bonded isolated pressure sensor |
| US6516671B2 (en) | 2000-01-06 | 2003-02-11 | Rosemount Inc. | Grain growth of electrical interconnection for microelectromechanical systems (MEMS) |
| US6561038B2 (en) | 2000-01-06 | 2003-05-13 | Rosemount Inc. | Sensor with fluid isolation barrier |
| BE1013540A3 (en) * | 2000-05-29 | 2002-03-05 | Rotary Nozzle Internat S A | Refractory plate. |
| US6848316B2 (en) * | 2002-05-08 | 2005-02-01 | Rosemount Inc. | Pressure sensor assembly |
| US20050003097A1 (en) * | 2003-06-18 | 2005-01-06 | Siemens Westinghouse Power Corporation | Thermal spray of doped thermal barrier coating material |
| DE102021004626A1 (en) * | 2021-09-14 | 2023-03-16 | PiRé Feuerfeste Produkte GmbH & Co. KG | Process for repairing a slider closure |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1663660A (en) * | 1924-12-08 | 1928-03-27 | Chicago Crucible Company | Refractory article and method of making same |
| GB694057A (en) * | 1957-09-23 | 1953-07-15 | Jack Sydney Gerber | Improvements in the production of repair of refractory articles |
| BE757466A (en) * | 1969-11-04 | 1971-04-14 | Glaverbel | |
| US3685707A (en) * | 1970-05-01 | 1972-08-22 | United States Steel Corp | Sliding-gate closure for bottom-pour vessel |
| US3737489A (en) * | 1970-10-01 | 1973-06-05 | Air Repair Inc | Method of applying refractory lining on hot metallurgical ladles,soaking pits and furnaces |
| JPS522813A (en) * | 1975-06-24 | 1977-01-10 | Kurosaki Refract Co Ltd | Method of repairing reaction furnaces |
| CS199377B1 (en) * | 1977-05-13 | 1980-07-31 | Valter Boehm | Connecting method of at least two ceramic materials |
| JPS5646853Y2 (en) * | 1977-11-15 | 1981-11-02 | ||
| US4218256A (en) * | 1979-03-06 | 1980-08-19 | Kaiser Aluminum & Chemical Corporation | Method of forming slide gate valve parts |
| IT1124030B (en) * | 1979-03-27 | 1986-05-07 | Sanac Spa Refrattari Argille & | PROCEDURE PERFECTED FOR OBTAINING AN ENCAPSULATED REFRACTORY BRICK PARTICULARLY SUITABLE FOR DRAWER UNLOADING BASKET AND SIMILAR LADIES AND REFRACTORY BRICK IN THIS WAY OBTAINED |
| GB2060842A (en) * | 1979-08-01 | 1981-05-07 | Fichera E | Methods of repairing refractories for sliding valves and means for performing it |
| GB2065278B (en) * | 1979-12-14 | 1983-10-12 | Flogates Ltd | Composite moulded refractory articles amd their manufacture |
-
1981
- 1981-11-05 GB GB08133409A patent/GB2109099B/en not_active Expired
-
1982
- 1982-09-17 US US06/420,505 patent/US4497473A/en not_active Expired - Lifetime
- 1982-10-27 IT IT68250/82A patent/IT1156539B/en active
- 1982-10-29 BE BE1/10628A patent/BE894868A/en not_active IP Right Cessation
- 1982-10-29 FR FR8218461A patent/FR2515546B1/en not_active Expired
- 1982-11-01 JP JP57192352A patent/JPS58104074A/en active Pending
- 1982-11-04 SE SE8206277A patent/SE453467B/en not_active IP Right Cessation
- 1982-11-04 CA CA000414840A patent/CA1202464A/en not_active Expired
- 1982-11-04 DE DE19823240732 patent/DE3240732A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2515546B1 (en) | 1986-12-12 |
| GB2109099B (en) | 1985-07-24 |
| SE453467B (en) | 1988-02-08 |
| FR2515546A1 (en) | 1983-05-06 |
| SE8206277D0 (en) | 1982-11-04 |
| BE894868A (en) | 1983-04-29 |
| US4497473A (en) | 1985-02-05 |
| IT1156539B (en) | 1987-02-04 |
| DE3240732A1 (en) | 1983-05-11 |
| GB2109099A (en) | 1983-05-25 |
| SE8206277L (en) | 1983-05-06 |
| JPS58104074A (en) | 1983-06-21 |
| IT8268250A0 (en) | 1982-10-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1202464A (en) | Composite refractory articles | |
| CA1202334A (en) | Forming coherent refractory masses | |
| CA1141159A (en) | Moulded composite refractory parts | |
| KR940002021B1 (en) | Nozzle for continuous casting and method of producing the same | |
| CN1029224C (en) | Ceramic composite and methods of making the same | |
| GB2066802A (en) | Refractory for casting | |
| US4871698A (en) | Carbon bonded refractory bodies | |
| CN105108110B (en) | The high chromium composite strengthening cast steel wear rib/plate casting technique of ceramics | |
| US5151201A (en) | Prevention of erosion and alumina build-up in casting elements | |
| WO1995028363A1 (en) | Alumina-zirconia refractory material and articles made therefrom | |
| JPS62297264A (en) | Carbon-bonded refractories | |
| US4880541A (en) | Hot filter media | |
| US4946806A (en) | Flame spraying method and composition | |
| US20100084441A1 (en) | Refractory material for nozzle for use in continuous casting, and continuous casting nozzle | |
| US4792070A (en) | Tubes for casting molten metal | |
| HRP950552A2 (en) | Production of a siliceous refractory mass | |
| KR20220058608A (en) | Casting ladle for aluminum alloy casting | |
| EP0583466B1 (en) | Vibratable refractory composition | |
| US6103651A (en) | High density ceramic metal composite exhibiting improved mechanical properties | |
| US4386765A (en) | Composite moulded refractory articles | |
| JP3265239B2 (en) | Immersion nozzle for continuous casting | |
| KR870008648A (en) | Casting nozzle and manufacturing method of the nozzle | |
| CA1119768A (en) | Continuous casting shroud apparatus and method | |
| CN112239353A (en) | Lining brick for one-pot hot metal ladle and preparation process thereof | |
| JPS6158867A (en) | Flame spray material for furnace wall maintenance |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |