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
  • 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
  • C04B41/5022—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 with vitreous 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
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/60—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only artificial stone
  • C04B41/61—Coating or impregnation
  • C04B41/65—Coating or impregnation with inorganic materials

Definitions

• the invention relates to a method for glazing molded parts from at least latent hydraulic binder systems, in particular concrete.
• molded body includes molded parts each
• At least latent hydraulic binder stands for known binders and binder systems, for example made of or based on Portland cement, alumina cement or the like, with or without additives (for example blastfurnace slag, Traß, fly ash) and / or aggregates as well as related autoclave-hardened building materials such as sand-lime brick.
• Concrete containers such as those used in water treatment, are questionable. These containers will become damaged over time due to the action of the stored water on the concrete and will require repair. Glazing could help here, especially since the use of steel containers, for example, is often ruled out for both manufacturing and financial reasons
• the invention is based on the object of demonstrating a possibility of how molded parts made from at least latent hydraulic binder systems can be glazed while largely maintaining their strength.
• the invention is based on the knowledge that this can only be achieved by appropriate selection of a glaze material. It was found that hitherto for glazing concrete parts finally pul-shaped glaze materials were used. Such powders generally have an average grain size of approximately 50 ⁇ m. Although it is already a finely divided material, its reaction time is still so long that considerable firing times are necessary to melt the glaze. However, reaction times of several minutes or even hours cannot be accepted for glazing concrete bodies or the like, since strength losses of 80% or more can be observed from about 300 ° C and higher and the glazing body inevitably heats up to the above-mentioned temperatures during longer glazing times is used, even if low-melting glazes are used, for example at temperatures of
• the coarsest grain (for example 100 ⁇ m) also determines the thickness of a coating formed from it. The thicker the be
• Layering is all the more susceptible to cracking.
• the invention proposes, in a departure from the standard technique, the surface of the hardened molded part with a present in dissolved or colloidal form,
• the heat source is directed towards the coating until it melts to form a viscous glass phase and finally the body glazed in this way is cooled again to the ambient temperature.
• the glaze slip is therefore either liquid or contains solid particles at most in colloidal form (less than 0.5 ⁇ m average diameter).
• Application forms a reliable protection against corrosion and abrasion, for example against aggressive media.
• the invention proposes two types of such glaze slip.
• a glaze slip can be used as the SiO 2 support a formed by precipitation from solutions or thermal dissociation contains SiO 2 sol.
• a sol is produced, for example, by flame oxidation of SiCl 4 .
• Scientific studies have shown that such a sol still contains particulate SiOp particles, but with an average particle diameter below 0.01 ⁇ m, that is to say with a particle diameter which is about 10 smaller than that of conventional fine particles
• SiO 2 carriers in glaze materials SiO 2 carriers in glaze materials.
• the SiO 2 carrier is preferably a component of the type (RO) Si (OR ') 4-n where R, R' are alkyl or aryl radicals. Tetraethyl orthosilicate and tetramethyl orthosilicate can be mentioned as preferred typical representatives. On
• the advantage is that the organic Si compounds dissolve well in numerous organic solvents and are stable in this form in the long term.
• the organic radicals can have a wide range of variation in that they still contain functional groups hold, for example - OH, COOH or NH 2 .
• the slip is preferably prepared from components A (organic Si compound dissolved in a solvent, for example alcohol) and B (inorganic salts, for example dissolved in water) to form a sol.
• a decomposition of the Si compound upon contact with water gradually leads to a sol-gel conversion, from which the requirement for a timely glaze application before the decomposition of the silicates is derived.
• colloidal SiO 2 is chosen as the SiO 2 component, the slip can be produced as an aqueous, partially colloidal solution. If, on the other hand, an organic Si compound is used, a solution with an organic solvent should first be produced from this. The other components are dissolved in water. The slip can then be prepared by mixing the two solutions.
• the metal oxides present in a glaze are in
• Nitrate form introduced. Nitrates such as aluminum nitrate, calcium nitrate, sodium nitrate, lead nitrate and / or zinc nitrate are readily water-soluble. When using a glaze slip containing boron, boron is preferably in the form of
• the invention has recognized that the highest possible viscosity of the glaze slip is advantageous for this purpose, especially since less material can then penetrate into the pores of the shaped body.
• Methyicellulose proposed.
• the composition of the glaze slip depends on the specific application. However, the SiO 2 component will generally be between 15 and 55% by weight, based on the total mass of the glaze slip.
• a glaze slip Using the raw materials aluminum nitrate, boric acid, lead nitrate, zinc nitrate and one of the above-mentioned SiO 2 carriers, a glaze slip can then be used as follows
• composition to be made is made:
• SiO 2 15.0 to 39.8% by weight
• the sum of the components should always be 100.
• a solvent and, if necessary, a viscosity-increasing additive are then usually added to this basic solution.
• the glaze slip produced in this way can be applied to the shaped body to be coated in various ways, for example by pouring over or brushing, dipping the entire body in ⁇ er glaze, spraying or spinning.
• the subsequent drying takes place at temperatures of a maximum of 200 ° C., for example in a conventional dryer.
• the glaze is preferably melted by direct flame irradiation, for example by means of a
• Acetylene flame Infrared heating is also possible.
• the melting temperature of the glaze chosen should of course be as low as possible.
• the glazes mentioned above have melting temperatures of about
• the advantage of the method according to the invention is that even a brief temperature effect is sufficient to melt the glaze, the heat treatment time being so short that the concrete body to be coated is subjected to practically no significant heat load and in any case retains its strength without restriction. This is a consequence of the significantly increased reaction time of the glaze components to form a glass, starting from a sol-shaped slip, as already described above.
• the glaze is more homogeneous and less prone to cracking. It is visually appealing and can be applied in very thin layers ( ⁇ 10 ⁇ m). This also allows the temperature during the glazing to be reduced, which is of great advantage for the parts to be glazed.
• the glaze can be applied in one or more layers. Surprisingly, it has been found that a plurality of thin glaze layers applied in succession give a higher level of tightness than a glaze layer of greater thickness applied in one operation.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Aftertreatments Of Artificial And Natural Stones (AREA)

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Citations (4)

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• 1990
  • 1990-02-07 DE DE19904003627 patent/DE4003627C1/de not_active Expired - Fee Related
• 1991
  • 1991-02-06 WO PCT/DE1991/000097 patent/WO1991012219A1/de unknown

Patent Citations (4)

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