Method and composition for corrosion inhibiting water carrying metal systems

• Main Authors: WONS, WERNER, SCHMIDT, PETER
• Format: Patent
• Language: English; French; German
• Published: 26.08.1998
• Edition: 6
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLICMATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASSC23 AND AT LEAST ONEPROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25; NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE

Es ist bekannt, in wasserführenden Durchflußsystemen aus Metallen wie Eisen, Kupfer, Blei, dem Wasserstrom zum Korrosionsschutz Kombinationen aus Silikaten und Phosphaten zuzusetzen. Mit diesen bekannten Kombinationen kann jedoch das von Wasserqualität und Betriebsbedingungen abhängige optimale Verhältnis von Silikat und Phosphat nicht eingehalten werden. Die Erfindung schlägt vor, Silikat und Phosphat getrennt voneinander zuzusetzen und zu dosieren. Die Erfindung ist auf dem Gebiet der Wasserversorgung anwendbar. Process for corrosion protective treatment of water-conveying metal systems involves separate dosing of phosphates and silicates into the water flow. Preferably, the silicates are dosed in amount 1.0-40 mg SiO2/l as an aqueous silicate solution with a modulus of 1.8-3.5 and a SiO2 concentration of ≥ 20 wt.%, while the phosphates are dosed in amount 0.1-6.7 mg PO4/l as an aqueous phosphate solution with a PO4 concentration of ≥ 20 wt.%. Also claimed is a medium which is used in the above corrosion protective treatment process and which contains, in aqueous solution, (a) alkali metal silicates, carbonates and hydrogen carbonates, with SiO2 and CO3 concentrations of 20 wt.% and 0.1 wt.%, respectively; or (b) alkali metal orthophosphates and polyphosphates in amount (based on total phosphate content, expressed as PO4) 25-75 wt.% each, the total PO4 concentration being ≥ 20 wt.%.