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WO1999023050A1 - Article refractaire coule par fusion pour fours de fusion de verre garni d'un revetement de metal noble - Google Patents

Article refractaire coule par fusion pour fours de fusion de verre garni d'un revetement de metal noble Download PDF

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Publication number
WO1999023050A1
WO1999023050A1 PCT/GB1998/003103 GB9803103W WO9923050A1 WO 1999023050 A1 WO1999023050 A1 WO 1999023050A1 GB 9803103 W GB9803103 W GB 9803103W WO 9923050 A1 WO9923050 A1 WO 9923050A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating
fusion
cast
refractory
platinum
Prior art date
Application number
PCT/GB1998/003103
Other languages
English (en)
Inventor
Duncan Roy Coupland
Mark Laurence Doyle
Paul Matthew Williams
Original Assignee
Johnson Matthey Public Limited Company
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Johnson Matthey Public Limited Company filed Critical Johnson Matthey Public Limited Company
Priority to AU94522/98A priority Critical patent/AU9452298A/en
Publication of WO1999023050A1 publication Critical patent/WO1999023050A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/42—Details of construction of furnace walls, e.g. to prevent corrosion; Use of materials for furnace walls
    • C03B5/43—Use of materials for furnace walls, e.g. fire-bricks
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/51—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
    • C04B41/5122—Pd or Pt
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/85—Coating or impregnation with inorganic materials
    • C04B41/88—Metals
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas

Definitions

  • the present invention concerns improvements in coatings, and more especially concerns the protective coating of fusion-cast ceramics. 5
  • Slip-cast and sintered ceramic refractories are used extensively as parts for the handling of aggressive materials such as molten glass.
  • Such sintered ceramic refractories are generally manufactured by forming a dense slurry of the refractory oxide, optionally in the presence of inorganic binding agents, casting the slurry in a mould and sintering the 0 resulting cast item.
  • Such refractories are considered to be of low density, and generally exhibit 15-20% porosity.
  • Chemically, such refractories are mixtures of two or more of silica, alumina and zirconia, although other oxide components such as magnesia may be present.
  • fusion-cast refractories exhibit high performance in use, under many conditions they are still prone to attack and ultimate destruction. For example, in glass- melting furnaces, even fusion-cast refractories are subject to attack at or above the line of 0 molten glass. The lifetime of such components is determined by temperature, glass-type and the amount of glass processed. Damage to these refractories can lead to the need for shut- down of the furnace and loss of production. Because of the smooth, low porosity surface of fusion-cast refractories, it has generally been found to be impossible to satisfactorily coat such materials with protective materials such as the noble metals.
  • the present invention provides a fusion-cast refractory part, possessing at least one surface area having an etched surface either from which a portion of a siliceous phase has been removed, or, in the case of fusion-cast ⁇ / ⁇ alumina, the surface has been partially reduced on which is bonded a coating of at least 50 microns of a noble metal or alloy thereof.
  • the invention also provides a method of coating a fusion-cast refractory part, comprising etching at least one surface area of said part to remove a portion of a siliceous phase, or, in the case of ⁇ / ⁇ alumina, partially reducing said surface, to form an effective bonding surface, and subsequently depositing a coating of at least 50 microns of a noble metal or alloy thereof by flame spraying.
  • the noble metals useful in the present invention are one or more of the platinum group metals, namely platinum, rhodium, palladium, ruthenium, iridium and osmium, and alloys with each other or with base metals.
  • the metal is platinum, an alloy of platinum, eg Pt5%Au, Ptl0%lr, Ptl0%Rh, Pt5%Ru, or Pt with up to l%Zr, or grain stabilised Pt or Pd.
  • the fusion-cast refractory part may be of any of the conventional fusion-cast refractory compositions, incorporating one or more of Si0 2 , A1 2 0 3 , Zr0 2 and Mg0 2 , optionally including amounts of other refractory oxides such Cr 2 0 3 .
  • Other similar refractory parts, such as fusion-cast chromias may be platinum-coated using the present invention.
  • zirconia In the casting process, zirconia has the highest melting point of the regular components of an AZS refractory, and tends to crystallise preferentially at the surface of the mould. This can result in the surface of the fusion-cast part not being representative of the bulk material, and can be less amenable to etching. It may be desirable in such cases that the surface of the part is machined to expose bulk AZS material; in manufacturing certain parts this was done as part of the manufacturing process.
  • One suitable method is to coat or line the mould to provide a platinum coatable, etchable surface, on the as-cast face of the final ceramic.
  • the surface of the mould may be coated, eg by flame spraying, with alumina silicate and/or silica.
  • the mould surface may be coated with titania or a titania-enriched refractory material.
  • Another variation is to coat the mould with tetragonal zirconia prior to casting. As the molten AZS refractory is poured into the mould, the tetragonal zirconia converts into a higher volume cubic zirconia, causing expansion and micro-cracking.
  • Other mould coatings may prove to be adequate to change the surface composition of the cast refractory part, and either provide a more readily etchable surface or a surface capable of accepting a flame sprayed platinum coating.
  • a low-zirconia AZS material or a silica melt may be spin-cast in the mould, immediately followed by casting a regular bulk AZS material.
  • the mould may be pre-heated and solidification controlled to either eliminate or reduce the thickness of the Zr0 2 zone at the surface of the cast part.
  • the narrow Zr0 2 -rich zone may readily be machined off.
  • Another possibility is to increase the solidification rate by chilling the mould, thereby creating a surface Zr0 2 zone having a very fine microstructure and reducing the time available for the A1 2 0 3 and Si0 2 phases to migrate from the surface.
  • Increasing or decreasing the solidification rate may also be achieved by changing the mould material, as well as by heating or cooling, and it is possible to modify the surface roughness of the mould, providing micro-roughness in the as-cast surface, and thereby improve the adhesion of the noble metal coating.
  • the etching step may also be carried out in a number of different ways.
  • a first method which is highly effective, but may create production difficulties from health and safety viewpoints is to etch using hydrofluoric acid.
  • Initial optimisation tests resulted in a process involving immersing the ceramic in 48% HF diluted 1:1 with water for 10 minutes, which dissolves sufficient siliceous phase without unduly weakening the ceramic.
  • the adhesion of the subsequently deposited platinum coating was in excess of 10 MPa, in fact adhesion exceeded the capability of the test cell.
  • a caustic solution for example boiling KOH, is also effective to remove sufficient siliceous material to provide good adhesion; adhesion results are of the order of 5 to 6 MPa.
  • Alternative chemical etching can be achieved with NaOH and similar materials, including molten salts.
  • HF etching is etching using a fluoride gel, which can be made up from, for example, sodium bifluoride and sulphuric acid as essential components. Suitable compositions are commercially available as glass etching compositions. Treatment times are longer than for
  • HF treatment and may usefully be in the region of 24 to 72 hours. Suitable treatment times can be ascertained by routine experimental procedures, and will depend upon the grade of ceramic. Adhesion values for the Pt coating deposited onto a thus-etched surface are in excess of 10 MPa. This technique has the important advantage of enabling on-site treatment of refractories prior to on-site coating.
  • Certain fusion-cast ceramics do not possess a siliceous phase which may be removed by such etching procedures, but can be prepared for coating by alternative procedures.
  • a very thin layer of platinum may be deposited on the surface and then the part heat treated in a reducing atmosphere. Deposition may be achieved by sputtering, CVD, electroless and even by rubbing with a piece of platinum.
  • the heat treatment may be at temperatures in the range 600 to 1500°C for 1-5 hours in hydrogen or a mixture of hydrogen and an inert gas.
  • Alkali etching as described above for AZS ceramics may also be used, and other surface modification utilising mould coatings are to be considered.
  • the noble metal may be deposited on the etched surface in a number of different ways.
  • a preferred method is by combustion flame spraying in a method analogous to that described in EP 0 559 330.
  • Other methods include plasma flame spraying, and high velocity oxy-fuel combustion spraying. Further methods may be developed without departing from the scope of the present invention.
  • the coating desirably has a thickness of 50 microns up to 2mm (the thickness is probably limited only by the economics). More desirably, the thickness is 50 to 500 microns, suitably about 200 microns.
  • a post-treatment of the coating to remove or significantly reduce any porosity is desirably included.
  • Such post-treatment is preferably the peening described in detail in
  • EP 0559330 but other methods including burnishing may be used providing either there is mechanical energy or pressure applied, or the surface is glazed or re-melted by a high energy beam. It should be realised that although excellent results may be achieved according to the invention by etching and coating essentially all exposed surfaces of the fusion-cast ceramic, in many uses it may be sufficient and economical to etch and coat only a proportion of the surface. For example, in glass-melting furnaces, or other furnaces exposed to similarly aggressive conditions, erosion takes place in a relatively small area at the normal line of molten glass. For such furnaces or vessels, the invention permits coating those regions most at risk.
  • ER1711 supplied by SEPR were treated with the etching solution for 10 minutes at 25 °C before drying. A coating of 200 microns of pure platinum was applied to the etched surface by combustion flame spraying. The surface was thereafter shot-peened.
  • the adhesion of the platinum coating was tested by standard tensile testing methods. The samples exhibited failure stresses in excess of 10 MPa. Failure occurred in the ceramic itself immediately adjacent the coating.
  • Tensile samples of ER1711 and ER1681 refractories were prepared in the manner described in Example 1 except a sulphuric acid/sodium bifluoride etching gel was used instead of the HF. The etching times were between 24 and 72 hours. In all cases the adhesion of the coatings exceeded the capacity of the testing equipment having withstood tensile stresses in excess of 1 OMPa.
  • An AZS ER168 refractory block was prepared for coating in the manner described in Example 2. Platinum was deposited by a proprietary flame spray, followed by shot peening; it was then subjected to a high temperature (1500°C in air) soak for a total of almost 6 months, which included four excursions back to room temperature for examination.
  • Refel 1532 refractory was prepared as described in Example 2 and successfully coated with platinum over a 5x5cm area, with four free edges, using air plasma spraying. The adhesion was again excellent and enabled the coating to resist considerable mechanical efforts to force lifting at the free edges.
  • a part of commercial Jargel M ⁇ / ⁇ alumina supplied by SEPR was etched by rubbing the surface with a platinum wire to deposit a very thin layer of smeared platinum on the surface. The part was then heat treated at 1000°C for 3 hours in a H 2 /N 2 atmosphere.
  • the part was flame spray coated with 200 m platinum, shot peened and subjected to adhesion testing.
  • the adhesion values averaged 4.7 MPa.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Coating By Spraying Or Casting (AREA)

Abstract

La présente invention concerne une pièce réfractaire coulée par fusion, pouvant être revêtue d'un métal noble avec d'excellents résultats, notamment du platine. On prépare la surface de la pièce par attaque à l'aide de HF par exemple, de préférence un gel réactif de manière à retirer une partie d'une phase siliceuse, et par préparation par réduction partielle, dans le cas de α/β alumine, suivie par de projection à la flamme, de manière à déposer au moins 50 microns d'épaisseur. On obtient ainsi une excellente adhérence du revêtement.
PCT/GB1998/003103 1997-10-30 1998-10-16 Article refractaire coule par fusion pour fours de fusion de verre garni d'un revetement de metal noble WO1999023050A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU94522/98A AU9452298A (en) 1997-10-30 1998-10-16 Fusion-cast refractory article for glass melting furnaces provided with a noble metal coating

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9722901.7 1997-10-30
GBGB9722901.7A GB9722901D0 (en) 1997-10-30 1997-10-30 Improvements in coatings

Publications (1)

Publication Number Publication Date
WO1999023050A1 true WO1999023050A1 (fr) 1999-05-14

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PCT/GB1998/003103 WO1999023050A1 (fr) 1997-10-30 1998-10-16 Article refractaire coule par fusion pour fours de fusion de verre garni d'un revetement de metal noble

Country Status (3)

Country Link
AU (1) AU9452298A (fr)
GB (1) GB9722901D0 (fr)
WO (1) WO1999023050A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007049634A1 (de) 2007-10-17 2009-04-23 Technische Universität Bergakademie Freiberg Verfahren zur Erhöhung der Korrosionsbeständigkeit von Feuerfestmaterialien
WO2015108795A1 (fr) * 2014-01-15 2015-07-23 Corning Incorporated Procédé de préparation de feuilles de verre avec prétraitement gazeux de matériaux réfractaires
US20160340223A1 (en) * 2014-01-15 2016-11-24 Corning Incorporated Method of making glass sheets with vehicle pretreatment of refractory
WO2022209393A1 (fr) * 2021-03-31 2022-10-06 Ａｇｃ株式会社 Élément appliqué à une partie en contact avec du verre fondu et procédé de fabrication de l'élément

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0559330A1 (fr) * 1992-02-18 1993-09-08 Johnson Matthey Public Limited Company Article couché

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0559330A1 (fr) * 1992-02-18 1993-09-08 Johnson Matthey Public Limited Company Article couché

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
COUPLAND D R ET AL: "Exploiting the potential of platinum", GLASS;GLASS SEP 1997 DMG BUS MEDIA LTD, REDHILL, ENGL, vol. 74, no. 9, September 1997 (1997-09-01), pages 348 - 349, XP002088524 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007049634A1 (de) 2007-10-17 2009-04-23 Technische Universität Bergakademie Freiberg Verfahren zur Erhöhung der Korrosionsbeständigkeit von Feuerfestmaterialien
US9193633B2 (en) 2007-10-17 2015-11-24 Tu Bergakademie Freiberg Porous fireproof material suitable for glass production, method for the production thereof, and uses
WO2015108795A1 (fr) * 2014-01-15 2015-07-23 Corning Incorporated Procédé de préparation de feuilles de verre avec prétraitement gazeux de matériaux réfractaires
CN106103366A (zh) * 2014-01-15 2016-11-09 康宁股份有限公司 利用耐火材料的气体预处理的玻璃板制造方法
US20160340223A1 (en) * 2014-01-15 2016-11-24 Corning Incorporated Method of making glass sheets with vehicle pretreatment of refractory
JP2017503746A (ja) * 2014-01-15 2017-02-02 コーニング インコーポレイテッド 耐火物のガス前処理を含むガラスシート作製方法
US10047000B2 (en) 2014-01-15 2018-08-14 Corning Incorporated Method of making glass sheets with vehicle pretreatment of refractory
TWI655162B (zh) * 2014-01-15 2019-04-01 美商康寧公司 伴隨耐火材之氣體預處理的玻璃片製造方法
CN106103366B (zh) * 2014-01-15 2019-06-07 康宁股份有限公司 利用耐火材料的气体预处理的玻璃板制造方法
US10435323B2 (en) 2014-01-15 2019-10-08 Corning Incorporated Method of making glass sheets with gas pretreatment of refractory
WO2022209393A1 (fr) * 2021-03-31 2022-10-06 Ａｇｃ株式会社 Élément appliqué à une partie en contact avec du verre fondu et procédé de fabrication de l'élément

Also Published As

Publication number Publication date
GB9722901D0 (en) 1998-01-07
AU9452298A (en) 1999-05-24

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