PCT
`
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`
`
`
`IN'I‘ERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(51) International Patent Classification 7 :
`
`(11) International Publication Number:
`
`WO 00/30996
`
`C04B 35/00
`
`A2
`
`(43) International Publication Date:
`
`2 June 2000 (02.06.00)
`
`(81) Designated States: AE, AL, AM, AT, AU, AZ, BA, BB, BG,
`BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE,
`ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP,
`KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA,
`MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU,
`SD, SE, SG, SI, SK, SL, TJ, TM, TR, TI‘, TZ, UA, UG,
`US, UZ, VN, YU, ZA, ZW, ARIPO patent (GH, GM, KE,
`LS, MW, SD, SL, SZ, TZ, UG, ZW), Eurasian patent (AM,
`AZ, BY, KG, KZ, MD, RU, TJ, TM), European patent (AT,
`BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU,
`MC, NL, PT, SE), OAPI patent (BF, BJ, CF, CG, CI, CM,
`GA, GN, GW, ML, MR, NE, SN, TD, TG).
`
`Published
`Without international search report and to be republished
`upon receipt of that report.
`
`(21) International Application Number:
`
`PCT/BE99/00145
`
`(22) International Filing Date:
`
`16 November 1999 (16.1 1.99)
`
`(30) Priority Data:
`98 l21935.5
`98 l23391.9
`
`19 November 1998 (19.l1.98)
`9 December 1998 (09.l2.98)
`
`EP
`EP
`
`(71) Applicant (for all designated States except US): VESUVIUS
`CRUCIBLE COMPANY [US/US]; Suite 200, 103 Foulk
`Road, Wilmington, DE 19803 (US).
`
`(71) Applicant (for 72 only): VESUVIUS GROUP S.A. [BE/BE];
`Avenue du Commerce 40, B—1420 Braine—L’Alleud (BE).
`
`(72) Inventors; and
`GUILLO, Philippe
`(75) Inventors/Applicants (for US only):
`[FR/FR]; 2, rue de Provence, F-75009 Paris (FR). HOG-
`GARD, Dale, B. [US/US]; 53 Iroquois Drive, Pittsburgh,
`PA 15205 (US).
`
`(74) Agent: DEBLED, Thierry; Vesuvius Group S.A., Rue de
`Douvrain, 17, B—7011 Ghlin (BE).
`
`(54) Title: COMPOSITE MATERIAL
`
`(57) Abstract
`
`The present invention provides a composite pressure—sintered material comprising a continuous phase of hexagonal boron nitride
`and, dispersed therein, a second material comprising (a) at least one metal nitride selected from the group consisting of silicon, aluminium
`and titanium nitrides and (b) at least one stable metal oxide; wherein the amount of metal oxide is such that the second material does not
`contain more than 35% by weight of oxygen.
`It has been observed that this material possesses a low thermal expansion coefficient and
`therefore reveals good thermal shock resistance. Another characteristic of this material is its low wettability by molten steel which is thus
`responsible for excellent chemical resistance to liquid metal. Finally, this material is exceptionally mechanical wear resistant.
`
`000001
`
`Exhibit 1028
`
`IPR2016-0063
`
`Exhibit 1028
`IPR2016-00636
`AVX Corporation
`AVX Corpora
`
`000001
`
`

`

`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`SI
`SK
`SN
`SZ
`TD
`TG
`TJ
`TM
`TR
`TT
`UA
`UG
`US
`UZ
`VN
`YU
`ZW
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
`Albania
`Armenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Cote d'Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Germany
`Denmark
`Estonia
`
`ES
`FI
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungafi’
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`R0
`RU
`SD
`SE
`SG
`
`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The former Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`
`000002
`
`
`
`000002
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`

`

`WO 00/30996
`
`PCT/BE99/00145
`
`Composite material.
`
`Description.
`
`The present invention relates to a new composite material and more particularly to
`
`a pressure—sintered material comprising hexagonal boron nitride and a second material
`
`comprising at least one metal nitride. In a further aspect, this invention relates to a
`
`composite material, which is particularly useful for the manufacture of refractory pieces
`
`which are submitted to severe corrosion and temperature conditions such as refractory
`
`pieces for the metallurgic industry, in particular for the steel industry.
`
`In particular, this
`
`material is especially suitable for the manufacture of side dam plates for strip casting
`
`process.
`
`In this type of continuous casting, called “strip casting” or “twin—roll casting” for
`
`the casting of steel strip of approximately from 2 to 10 mm in thickness, the lateral
`
`containment of the liquid metal in the casting space defined by the rolls is provided by
`
`plates which are applied against the plane extremities of the rolls, called "ends", by a
`
`suitable device. These plates are usually termed “sidewall” or “side darn” plates. Their
`
`central part intended to be in contact with the liquid metal is made of refractory material,
`
`as is, in general, their periphery which rubs frictionally against the rolls, progressively
`
`wearing out the side dam plates.
`
`It is absolutely essential that these side darn plates be
`
`in contact with the rolls in as sealed a manner as possible, since infiltrations of liquid
`
`metal into their contact area would have disastrous effects on the dimensional quality of
`
`the cast strip. Parts of the strip would then run the risk of separating from the rest of the
`
`strip and remain stuck to the rolls.
`
`If this sticking were to persist during one complete
`
`revolution of the rolls and if the fragments of edges were thus to penetrate into the casting
`
`space, this could give rise to serious damage to the surfaces of the rolls and, by way of
`
`consequences, to the strip itself. At worst, these infiltrations of metal could reach as far
`
`as the outside of the machine, which would dictate stopping the casting immediately.
`
`Such problems may have many causes, among them being the following:
`
`- distortions of the rolls and of the side dam plates, due to mechanical and thermal
`
`stresses which they are exposed to, in particular at the very start of casting when a
`
`thermal regime is imposed on them;
`
`- progressive (mechanical and chemical) wear of the side dam plates or of the rolls, which
`
`is not always uniform over all their contact areas; and
`
`- instantaneous wear of the side dam plates caused by the passage of an infiltration of
`
`solidified metal.
`
`Thus a need exists for a material which would combine resistance to mechanical
`
`and thermal stresses and have an excellent resistance against chemical or mechanical
`wear.
`
`A pressure—sintered polycrystalline mixed material is already known from
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`WO 00/30996
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`PCT/BE99/00145
`
`2
`
`USP 4,885,264. This document discloses materials with a base of boron nitride, oxides
`and carbides in which the hexagonal boron nitride fraction is from about 30 to about 85%:
`
`by Weight. The oxide fraction is selected from the group comprising zirconium oxide and
`
`magnesium oxide and is from about 10 to about 50% by Weight. The carbide fraction is
`
`selected from the group comprising silicon carbide, titanium carbide and zirconium
`
`carbide and is from about 5 to about 20% by weight. This material has a density higher
`
`than 94% of the theoretically possible density (based on the boron nitride/ oxide / carbide
`
`mixture). According to USP 4,885,264, this material is resistant to liquid metals, wear
`
`resistant and thermal shock resistant and therefore, suitable for use as detachment or
`
`break rings in the horizontal continuous casting of steel and non-ferrous metals.
`
`However, it has been observed that, mainly due to a high thermal expansion
`
`coefficient, this material does not exhibit sufiicient thermal shock resistance. The
`
`chemical resistance to liquid metal also needs to be improved.
`
`Another material is known from USP 5,389,587 which discloses an ordinary
`
`pressure sintered ceramic material comprising at least 50% by Weight of hexagonal boron
`
`nitride and from 1 to 50°/o by Weight of two or more components selected from aluminium
`
`and silicon nitride and oxide. The mechanical resistance of this material is still far from
`
`the requirements of the steel industry, for example for the manufacture of side dam
`
`plates.
`
`Thus, a need still exists for a material which Would combine resistance to
`
`mechanical and thermal stresses and have an excellent resistance against chemical or
`
`mechanical Wear and especially, which would have an excellent chemical resistance to
`
`liquid metal.
`
`According to the invention, one or more of these needs are achieved with a
`
`composite pressure—sintered material comprising a continuous phase of hexagonal boron
`
`nitride and, dispersed therein, a second material comprising:
`
`— (a) at least one metal nitride selected from the group consisting of silicon, aluminium or
`
`titanium nitride, and
`
`— (b) at least one stable metal oxide; the amount of metal oxide being such that the second
`
`material does not contain more than 35 % by Weight of oxygen.
`
`It has been observed that this material possesses a relatively low thermal
`
`expansion coefficient and therefore exhibits good thermal shock resistance. Another
`
`characteristic of this material is its low Wettability by molten steel which is thus
`
`responsible for improved resistance to liquid metal and reduces the occurrence of steel
`
`solidification thereon. Finally, it has been observed that this material exhibits exceptional
`
`mechanical Wear resistance.
`
`The crystalline structure of hexagonal boron nitride is essentially constituted of
`
`planes which are supposed to play a role in the prevention of cracks propagation.
`
`Therefore, the composite material must contain a continuous phase of hexagonal boron
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`WO 00/30996
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`PCT/BE99/00145
`
`3
`
`nitride.
`It has been determined that an amount of at least 45 % by weight of hexagonal
`boron nitride, and more preferably of at least 55 % by weight of hexagonal boron nitride, J
`
`allows to obtain a continuous phase of boron nitride.
`
`On the other hand, material from hexagonal boron nitride alone is too soft and has
`
`unduly low mechanical strength with the result that the material has a high tendency to
`
`chipping and wearing. Therefore, the composite material should contain less than 80 %
`
`by weight of hexagonal boron nitride and more preferably less than 70 % by weight.
`
`Therefore, the invention also relates to composite pressure—sintered material
`
`comprising from 45 to 80 % by weight of hexagonal boron nitride and from 55 to 20 % by
`
`weight of a second material comprising:
`
`— (a) at least one metal nitride selected from the group consisting of silicon, aluminium
`
`and titanium nitride, and
`
`— (b) at least one stable metal oxide in an amount such that the second material does not
`
`contain more than to 35 % by weight of oxygen.
`
`The best results have been obtained with materials comprising 57.5 % by weight of
`
`hexagonal boron nitride.
`
`According to the invention, the composite material comprises at least one metal
`
`nitride selected from the group consisting of silicon, aluminium and titanium nitrides.
`
`Advantageously, silicon nitride is used.
`
`According to a preferred embodiment of the invention, the second material may
`
`contain at least one stable metal oxide in an amount such that the second material does
`
`not contain more than 35 % by weight of oxygen.
`
`Preferably, the second material contains at least 2.5 % by weight of oxygen.
`
`It is necessary that the selected stable metal oxides, if any, are able to form a solid
`
`solution into said metal nitride. This is generally the case when the atomic number of the
`
`heavier metal atom of said stable metal oxides is not higher than the atomic number of
`
`the heavier metal atom of said metal nitride.
`
`Suitable stable metal oxides comprise, but are not limited to, oxides of aluminium,
`
`titanium, silicon and magnesium or mixtures thereof. Among these, aluminium oxide is
`
`10
`
`15
`
`20
`
`25
`
`30
`
`preferred.
`
`In a particular embodiment of the invention, use is made of Sialon as second
`
`material containing oxygen. Sialon is a well—known material and, as the name implies is a
`
`material composed of Si—Al—O—N and may be described as a solid solution of alumina in
`
`silicon nitride. The normal chemical formula of Sialon is given by Si6_zAlzOzN8_Z,
`
`35
`
`wherein z is comprised between 0 and about 4.5. According to the invention, z is
`
`preferably comprised between 1 and 4.5 and more preferably between 2 and 3.
`
`It is to be understood that the composite material may also comprise conventional
`
`additives such as yttrium, magnesium, calcium and / or cerium oxides which present
`
`melting phases at high temperature and which are preferred over boron oxide.
`
`
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`000005
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`WO 00/30996
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`PCT/BE99/00145
`
`4
`
`These additives are added in minor amounts not exceeding 5 % by weight of the
`
`mixture hexagonal boron nitride/ second material.
`
`As starting materials for the production of the composite material of the invention,
`
`use is advantageously made of hexagonal boron nitride powder having an oxygen content
`
`of from about 2 to about 8% by weight and a specific surface of from about 5 to about
`
`30 m2 / g (measured by the BET method) and of the metal nitride and oxide powder,
`
`respectively, with a purity of at least about 95% in each case.
`
`These powders may be homogeneously mixed in a manner known, per se, in a
`
`standard mixing apparatus optionally with a temporary binder being used at the same
`
`time and then pressure—sintered until the density of at least about 94% of the theoretical
`
`density is achieved. In this process, the mixtures may be hot—pressed in graphite moulds,
`
`with axial pressure application at temperatures of from about 1500°C to about 1800°C,
`
`and preferably from about 1650°C to about l750°C, with a die pressure of from about 10
`
`to about 40 MPa, and preferably from about 15 to about 35 MPa. Alternatively, the
`
`mixtures may also be isostatically hot—pressed in a vacuum tight closed case at a
`
`temperature of from about 1400°C to about 1700°C, and preferably from about 1500°C to
`
`about 1600°C under a pressure of from about 100 to about 300 MPa, and preferably from
`
`about 100 to about 200 MPa in a high-pressure autoclave using an inert gas as a
`
`pressure transfer medium. Suitable shaped parts with the required dimensions are
`
`machined out of the ingots thus obtained.
`
`The new composite material according to the invention finds its main application
`
`as side dam plates for strip casting process, but also in other applications where its
`
`exceptional resistance to mechanical and thermal stresses and its excellent resistance
`
`against chemical or mechanical wear are of importance; for example as sliding plate, in a
`
`sliding gate for a metallurgical vessel such as a tundish or a ladle.
`
`The new composite material according to the invention is so performing, especially
`
`as to its erosion and thermal shock resistance, that it is now possible to use more than
`
`one time a side dam plate comprising a composite material according to the invention.
`
`This represents a major breakthrough in the strip casting process since this has never
`
`been achieved in the past and, even, was regarded as unimaginable.
`
`The subsequent use(s) of the side dam plate according to the invention may be
`
`carried out either with the same face contacting the metal or, alternatively, with the
`
`reverse side contacting the metal.
`
`The side dam plate according to the invention may be reused directly. However, if
`
`the face which has already been put into contact with the liquid metal is to be put again
`
`into contact with the liquid metal, it may be necessary to equalise said face of the plate.
`
`Therefore, the invention also relates to an improvement of the strip casting process
`
`wherein the lateral containment of the liquid metal in the casting space defined by the
`
`rolls is provided by side dam plates which are applied against the plane extremities of the
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`WO 00/30996
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`PCT/BE99/00145
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`5
`
`rolls. This improvement consists in using a side dam plate which is reusable and / or
`
`which has already been used.
`
`The subject of the invention is explained in more details in the following examples:
`
`Examples.
`
`The following powder mixtures have been prepared:
`
`In the examples 1 to 5 according to the invention, the second material is silicon
`
`nitride containing oxygen which has been introduced under the form of alumina and of
`
`10 magnesia. In these examples use has been made of a Sialon with z=2 obtained by known
`
`methods such as solid reaction of silicon nitride with alumina or by carboreduction under
`
`ammoniac atmosphere of a mixture of silicon and aluminium oxides. Three percent (by
`
`weight of Sialon) of MgO is added to the Sialon. This leads to oxygen content of 1 1.45 %
`for the second material.
`
`15
`
`In the examples 3 and 4, 1 % (by weight of Sialon) of yttrium oxide (Y203) was also
`
`added.
`
`TABLE 1
`
`Boron nitride
`
`Second material
`
`MgO
`
`YQO3
`
`(% by weight)
`
`(% by weight)
`
`(% by weight of
`
`(% by weight
`
`35
`
`Sialon)
`3
`
`of Sialon)
`
`50
`
`35
`
`50
`
`By way of comparison, a powder mixture comprising 50 % by weight of hexagonal
`
`boron nitride, 40 % by weight of zirconia (ZIO2) and 10 % by weight of silicon carbide was
`
`20
`
`also prepared (example C 1).
`
`The powder mixtures prepared at examples 1 to 5 and C1 were hot pressed at a
`
`temperature of 1650°C with a die pressure of 20 MPa.
`
`Table 2 shows the results achieved using the materials of example 1 to 5 and C1.
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`WO 00/30996
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`PCT/BE99/00145
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`6
`
`TABLE 2
`
`Thermal expansion R factor (AT necessary
`coefiicient
`
`to initiate a crack)
`
`<1o'6K'1)
`
`<°c)
`
`100 to 110°
`
`Wettability
`
`(vs.
`stainless steel at
`
`1550°C)
`
`130 to 150°
`
`130 to 150°
`
`It appears clearly from the comparison between examples 1 to 5 and example C1
`
`that the material according to the invention exhibits a very low coefficient of thermal
`
`expansion and has then an excellent resistance to thermal stresses. This appears also
`
`from the values measured for the R factor (thermal shock resistance calculated by the
`
`formula:
`
`10
`
`R :
`
`U0 — V)
`SZZ
`
`Wherein cr represents the flexural modulus (MOR), v represents the Poisson's ratio, 3
`
`represents the Young's modulus and on represents the thermal expansion coefficient)
`
`showing that the material according to the invention may resist to 2 to 3 times the AT
`
`which is sufficient to cause crack in the material of the art. The values observed for the
`
`15
`
`Wettability show that the material according to the invention is poorly Wettable by molten
`
`steel, this may also be observed ir1 placing a drop of liquid stainless steel at 1550°C under
`
`an atmosphere of argon on a sample of the material. After removal of the steel, an
`
`interaction zone of 250 um depth is observed with the material of example C1, While in
`
`the case of the material according to the invention (example 5), an interaction zone of only
`
`20
`
`50 um may be observed.
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`
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`WO 00/30996
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`Claims.
`
`7
`
`PCT/BE99/00145
`
`1. Composite pressure—sintered material comprising a continuous phase of hexagonal
`
`boron nitride and, dispersed therein, a second material comprising (a) at least one
`
`metal nitride selected from the group consisting of silicon, aluminium and titanium
`
`nitrides and (b) at least one stable metal oxide, characterised in that the amount of
`
`metal oxide is such that the second material does not contain more than 35 % by
`
`weight of oxygen.
`
`Composite material according to claim 1, characterised in that it comprises from 45
`
`to 80 % by Weight of hexagonal boron nitride and from 55 to 20 % by weight of said
`
`10
`
`second material.
`
`Composite pressure—sintered material comprising from 45 to 80 % by weight of
`
`hexagonal boron nitride and from 55 to 20 % by Weight of a second material
`
`comprising (a) at least one metal nitride selected from the group consisting of silicon,
`
`aluminium and titanium nitrides and (b) at least one stable metal oxide,
`
`15
`
`characterised in that the amount of metal oxide is such that the second material
`
`does not contain more than 35 % by Weight of oxygen.
`
`20
`
`25
`
`Composite material according to any one of claims 1 to 3, characterised in that said
`
`at least one metal oxide are able to form a solid solution into said metal nitride.
`
`Composite material according to claim 4, characterised in that the atomic number of
`
`the heavier metal atom of said at least one stable metal oxide is not higher than the
`
`atomic number of the heavier metal atom of said at least one metal nitride.
`
`Composite material according to any one of claims 2 to 5, characterised in that its
`
`hexagonal boron nitride contents is from 55 to 70% by weight.
`
`Composite material according to any one of claims 1 to 6, characterised in that, said
`
`at least one metal nitride comprises silicon nitride.
`
`Composite material according to claim 7, characterised in that said second material
`
`comprises at least 2.5 % of oxygen.
`
`Composite material according to any one of claims 1 to 8, characterised in that said
`
`at least one metal oxide is selected from aluminium, titanium, silicon and magnesium
`
`30
`
`oxides or mixtures thereof.
`
`10.
`
`11.
`
`Composite material according to claim 9, characterised in that said at least one
`
`metal oxide comprises aluminium oxide.
`
`Composite material according to any one of claims 1 to 10, characterised in that the
`
`second material comprises silicon nitride and aluminium oxide.
`
`35
`
`12.
`
`Composite material according to claim 1 1, characterised in that the second material
`
`
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`wo 00/30996
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`PCT/BE99/00145
`
`is essentially constituted of Sialon (Si6_ZAlzOzN8_z) with z being comprised between 1
`and 4.5.
`
`8
`
`13. Composite material according to claim 12, characterised in that z is comprised
`between 2 and 3.
`
`5
`
`14. Side dam plates comprising a refractory material according to any one of claims 1 to
`13.
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