GB2229652A - Manufacturing heat-insulating linings - Google Patents

Manufacturing heat-insulating linings Download PDF

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Publication number
GB2229652A
GB2229652A GB9003919A GB9003919A GB2229652A GB 2229652 A GB2229652 A GB 2229652A GB 9003919 A GB9003919 A GB 9003919A GB 9003919 A GB9003919 A GB 9003919A GB 2229652 A GB2229652 A GB 2229652A
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Prior art keywords
bonding agent
agent solution
fibres
spraying
silicon dioxide
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GB9003919A
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GB2229652B (en
GB9003919D0 (en
Inventor
Ingo Elstner
Harald Boess
Klays Kreuels
Alwin Vogel
Ullrich Nebe
Alfred Worms
Daniel Grimm
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Didier Werke AG
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Didier Werke AG
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    • 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
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0096—Provisions for indicating condition of the compositions or the final products, e.g. degree of homogeneous mixing, degree of wear
    • 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
    • C04B30/00—Compositions for artificial stone, not containing binders
    • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C04B35/111—Fine ceramics
    • C04B35/117—Composites
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/62605—Treating the starting powders individually or as mixtures
    • C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
    • C04B35/62655—Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/6303—Inorganic additives
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/6303—Inorganic additives
    • C04B35/6316—Binders based on silicon compounds
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/71—Ceramic products containing macroscopic reinforcing agents
    • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
    • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/16—Making or repairing linings increasing the durability of linings or breaking away linings
    • F27D1/1636—Repairing linings by projecting or spraying refractory materials on the lining
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00034—Physico-chemical characteristics of the mixtures
    • C04B2111/00146—Sprayable or pumpable mixtures
    • C04B2111/00155—Sprayable, i.e. concrete-like, materials able to be shaped by spraying instead of by casting, e.g. gunite
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3418—Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5208—Fibers
    • C04B2235/5216—Inorganic
    • C04B2235/522—Oxidic
    • C04B2235/5228—Silica and alumina, including aluminosilicates, e.g. mullite
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5208—Fibers
    • C04B2235/526—Fibers characterised by the length of the fibers
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9646—Optical properties
    • C04B2235/9661—Colour
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
    • F27D1/0009—Comprising ceramic fibre elements

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Composite Materials (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Products (AREA)
  • Inorganic Fibers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Laminated Bodies (AREA)
  • Thermal Insulation (AREA)

Description

1 MANUFACTURING HEAT-INSULATING LININGS The invention relates to a method
of manufacturing a heat-insulating lining on a carrier of the type in which a spraying composition comprising ceramic, refractory or heat-resistant fibres and at least one bonding agent in the form of the colloidal solution of silicon dioxide and/or aluminium oxide and water is sprayed through a nozzle onto the carrier, eg. a furnace wall, the bonding agent solution being added during the spraying process to dry fibres which are conveyed pneumatically in the spraying nozzle.
EP-A2-0213707 discloses the manufacture of a thermally insulating lining by spraying a fibrous spraying composition. The fibre spraying composition contains, in addition to ceramic fibres, an organic bonding agent, eg. a sol of colloidal silicon dioxide (Si02). A similar method of manufacturing an insulating lining using a fibrous spraying composition is also described in US-A-4664969 and US-A-4547403, in which colloidal solutions of aluminium oxide or aluminium hydroxide, silicon dioxide or zirconium dioxide are also disclosed as the bonding agent.
When spraying the composition the bonding agent solution is mixed during the spraying process in the spray nozzle with the fibres which are conveyed pneumatically, and the spraying composition which is formed in the spray nozzle is sprayed onto the carrier, eg. the walls of a furnace which are warm or even hot, to form a thermally insulating lining.
2 T It has been f ound that a disadvantage of the known methods is that it is not easy to maintain a constant amount of bonding agent in the sprayed fibrous composition since the rates of supply of bonding agent solution and of pneumatically conveyed fibres to the spray nozzle tend to vary so that the thermally insulating lining which is produced often contains varying concentrations of bonding agent. This is disadvantageousi since the concentration of the bonding agent in the sprayed and dried insulating lining can impair its refractory properties and also the mechanical strength of the dried lining varies with the concentration of the bonding agent in it.
It has also been found to be disadvantageous in the known methods that when the spraying composition is dried, migration of the bonding agent occurs together with the water which moves towards the surface of the lining during drying. It has been attempted to avoid such migration or wandering of the bonding agent during drying by the use of retention agents or more particularly, flocculating agents.
It is thus the object of the present invention to maintain the concentration of the bonding agent constant in a thermally insulating lining manufactured by means of a fibrous spraying composition in order to achieve uniform refractory properties and mechanical properties over the sprayed surface and to use a bonding agent system that does not exhibit:the disadvantages of known bonding agents or bonding agent systems, ie. in which no special retention agent, generally in the form of organic flocculating agents, 1 3 must be used and which nevertheless results in a sprayed and dried f ibrous lining which contains the bonding agent homogeneously distributed and thus has homogeneous physical and chemical characteristics.
According to the present invention, a method of manufacturing a heatinsulating lining of the type referred to above makes use of a coloured bonding agent and the method includes monitoring the colour intensity of the sprayed fibrous composition and adjusting the supply rate of the bonding agent solution to maintain the colour intensity of the bonding agent solution, and thus the concentration of the bonding agent in the sprayed composition,, substantially constant. The colour of the sprayed composition may be monitored automatically by a known optical device which is coupled to a valve or supply pump in the bonding agent's supply line and arrange to adjust the valve or pump automatically, so as to maintain the colour intensity of the spray composition substantially constant. Alternatively. the colour intensity of the sprayed composition may be observed visually and the supply rate of the bonding agent adjusted manually so as to maintain the colour intensity of the spray composition constant.
In a preferred embodiment Congo Red is used as the dye to colour the bonding agent solution. The use of Congo Red has proved to be particularly advantageous since this dye is stable in the colloidal solutions. of silicon dioxide and/or aluminium oxide.
In the method in accordance with the invention the 4 f ibres which are known 2er se are commonly characterised by their classification temperatures, eg. 12600C or 16000C. The ceramic fibres are commonly aluminosilicate fibres or fibres of aluminium oxide in the case of relatively high use temperatures. These -fibres can optionally be chopped in a manner known per set ie. their length can be limited to less than 50 or less than 10Omm.
The bonding agents used in the method in accordance with the invention in the form of colloidal solutions of silicon dioxide and/or aluminium oxide are commercially available materials known per se. The colloidal solutions of silicon dioxide, which are also designated silica sols, are aqueous solutions of colloidal silicon dioxide, and commonly have a concentration of between 20 and 40 wtA S'02 in the sol as delivered. The colloidal solutions of aluminium oxide are sols of aluminium oxide or aluminium hydroxide (Boehmite).
It is preferred that 6 to 20kg dry weight silicon dioxide and/or aluminium oxide are mixed, in each case in the form of colloidal solutions or sols, with 100kg dry weight fibres. The bonding agent sols, which are generally delivered in the concentrations referred to above, are diluted with water so that the amount of water added to 100kg of the fibres in the spray nozzle is 150 to 300 litres. The amount of water added to a predetermined weight of fibres depends on the particular circumstances, particularly on the thickness of the layer to be sprayed and on the absorbency of the carrier to be insulated.
1 1 It is of course possible to spray on a number of layers of the composition successively in a manner known per se, whereby prior to the spraying of each layer, the previously sprayed layer is advantageously first dried and optionally subjected to a temperature of 1800C so that an initial setting of the fibres with the bonding agent can occur.
In a further embodiment a bonding agent solution is used which contains a further component which effects a change of the pH value of the bonding agent solution at elevated temperatures.
This is achieved if the bonding agent contains a substance, preferably urea, which liberates NH3 at elevated temperatures.
In a further preferred embodiment the bonding agent contains 1 to 6 part by weight, preferably 1.5 to 4 parts by weight urea to 100 parts by weight of the Si02 and/or A1203 contained in the colloidal solution, calculated by dry weight. In a further embodiment both silicon dioxide and aluminium oxide in the form of the colloidal solutions or sols are used as the bonding agent, the weight ratio of Si02:A1203 being 80:20 to 20:80.
In a further preferred embodiment the bonding agent solution, which contains a substance which effects a change of the pH value at elevated temperatures, is adjusted by means of an acid, preferably hydrochloric acid, to a pH value of 2.0 to 4.0, preferably 2.5 to 6 3.0.
The f ibrous spraying compositions may contain not only ceramic fibres but also other fine-grained and/or finely divided heat-resistant and/or refractory materials, eg. pulverulant Si02, A' 2031 f ire clay, kaolin, zirconium dioxide, zirconium silicate, titanium dioxide and/or chromium oxide.
The fine-grained and/or finely divided materials include also pyrogenically produced materials whose grain size is in the nanometre range, such as pyrogenic S'02,A1203 and Zr02.
When using the fibrous spraying composition, dry, optionally comminuted or chopped ceramic fibres, optionally with further finely divided heatresistant or refractory materials are generally sprayed in a type of gun, water being added at the front portion of the gun or spray nozzle. In the present invention, instead of water, a coloured bonding agent which optionally contains a substance which effects a change in the pH value of the bonding agent at elevated temperatures, is used. When the temperature of the composition is increased a change in the pH value occurs, generally towards higher values due to liberation of NH3, so that the bonding agent is fixed in the form of silicon dioxide or aluminium oxide onto the individual fibres or the finely divided materials.
The coloured bonding agent used in accordance with the invention is stable at normal storage temperatures and has a storage life which is comparable to that of 1 7 commercially available silicon dioxide sols or aluminium oxide sols. The silicon dioxide sols or aluminium dioxide sols used in the bonding agent are also termed silica sols or aluminium hydroxide sols and in the case of the latter it is assumed that they contain colloidal aluminium hydroxide (Boehmite).
The invention will be described in more detail with reference to the following examples.
EXAMPLE 1
Chopped aluminosilicate fibres with a classification temperature of 12600C with 47% A1 203/53% Si02 were used. About 50 wt. % of the fibres had a length of 20 to 50mm and 50 wt. % a length of below 20mm. In a separate process 40kg commercially available Si02 so' with solids content of 40 wt. % Si02t 180kg water and 4g Congo Red were mixed together.
Using a conventional rotor spraying machine, of the type which is used for the spraying of plastic compositions, the fibres were pneumatically conveyed and mixed in the spray nozzle with the coloured bonding agent solution, in an amount which was monitored and controlled. For this purpose it is possible to use a conventional annular water nozzle and special spray nozzles are not necessary. The control was effected by visually observing the colour intensity of the composition, which was sprayed eg. onto a hot furnace wall, and adjusting the bonding agent supply rate, if necessary, to maintain the colour intensity and thus also the bonding agent concentration in the insulating 8 lining as constant as possible.
EXAMPLE 2
288kg aluminium oxide sol with a content of 57.6kg A1203 was mixed into 900 litres water to produce a storable supply volume of bonding agent solution. The pH value was subsequently adjusted with hydrochloric acid to 2. 5 to 3. 0. 36kg silicon dioxide sol with a content of 14.4kg SiO2 was then mixed in, and additionally 3.25kg urea dissolved in 5 litres hot water was added. The pH value was subsequently again adjusted by addition of hydrochloric acid to 2.5 to 3.0. Congo Red was used as the dye, as in Example 1.
In this bonding agent solution the ratio Si02:A1203 was 20:80.
The bonding agent system thus produced was used together with ceramic fibres in the application of a fibrous spraying composition in a manner similar to that described in EP-A2-0213707, and the amount of the bonding agent supplied to the spray nozzle was controlled, as described above.
On drying, the fibrous spraying composition applied to a hot furnace wall exhibited absolutely no migration of bonding agent to its surface.

Claims (10)

9 CLAIMS
1. A method of manufacturing a heat-insulating lining on a carrier by spraying a spraying composition comprising ceramic, refractory or heatresistant fibres and at least one bonding agent in the form of a coloured colloidal solution of silicon dioxide and/or aluminium oxide and water through a nozzle onto the carrier, the bonding agent solution being supplied during the spraying process to dry fibres which are pneumatically conveyed the method including monitoring the colour intensity of the sprayed fibrous composition and adjusting the supply rate of the bonding agent solution to maintain the colour intensity substantially constant.
2. A method as claimed in claim 1 in which Congo Red is used to colour the bonding agent solution.
3. Method as claimed in claim 1 or claim 2, in which 6 to 20kg dry weight silicon dioxide and/or aluminium oxide is added per 100kg dry weight of the fibres.
4. A method as claimed in any one of the preceding claims in which the coloured bonding agent solution additionally contains a component which effects a change in the pH value of the bonding agent solution at elevated temperatures.
5. A method as claimed in claim 4 in which the additional component liberates NH3 at elevated temperatures.
6. A method as claimed in claim 5 in which the 6. A method as claimed in claim 5 in which the additional component is urea.
7. A method as claimed in claim 6 in which urea is used in an amount of 1 to 6 parts by weight, preferably 1. 5 to 4 parts by weight to 100 parts by weight of the si02 and/or A1203.
8. A method as claimed in any one of claims 4 to 7 in which the bonding agent comprises colloidal solutions of silicon dioxide and aluminium oxider the si02 and A1203 being present in the ratio of 80:20 to 20:80.
9. A method as claimed in any one of claims 4 to 8, in which the pH value of the bonding agent solution is adjusted with acid to 2.0 to 4.0.
10. A method of manufacturing a heat-insulating lining substantially as specifically herein described in Example 1 or Example 2.
Pubhshed 2 990 at The Patent Wice. State House.66?J Mgb Holborn. London WC1R4TP. F=ther Coples Maybe obtatnedfrom The PatentOffice Sales Brancb, St Mary Cray. Orpingtan. Kent BR5 3RD. Printoed by Mi2upiex tacbriques ltd. St Mary Cray, Kent. Con. 1187 1 1 1 1
GB9003919A 1989-03-02 1990-02-21 Manufacturing heat-insulating linings Expired - Fee Related GB2229652B (en)

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DE3906620A DE3906620C1 (en) 1989-03-02 1989-03-02

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GB2229652A true GB2229652A (en) 1990-10-03
GB2229652B GB2229652B (en) 1992-01-02

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FR (1) FR2643972B1 (en)
GB (1) GB2229652B (en)
IT (1) IT1240770B (en)

Cited By (2)

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Publication number Priority date Publication date Assignee Title
US8006407B2 (en) * 2007-12-12 2011-08-30 Richard Anderson Drying system and method of using same
CN114574009A (en) * 2022-03-07 2022-06-03 中铸新材工业（江苏）有限公司 All-inorganic non-stick aluminum environment-friendly zirconium silicate coating and preparation method thereof

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Publication number Priority date Publication date Assignee Title
CN113292346B (en) * 2021-06-24 2022-11-29 中钢洛耐科技股份有限公司 Sintering promoting agent for preparing silica brick, composite silica brick and preparation method of composite silica brick

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Also Published As

Publication number Publication date
FR2643972A1 (en) 1990-09-07
IT9047661A1 (en) 1991-08-22
IT9047661A0 (en) 1990-02-22
GB2229652B (en) 1992-01-02
IT1240770B (en) 1993-12-17
FR2643972B1 (en) 1994-10-14
DE3906620C1 (en) 1990-10-25
GB9003919D0 (en) 1990-04-18

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