PL158060B1 - Agent for steel surface passivation - Google Patents

Abstract

The steel surface passivator distinctive in that it is constituted by the Cr III compound with dicarboxylic or tricarboxylic organic acid, the molecular ratio of chromium to acid being 1:1.

Description

POLAND

PATENT DESCRIPTION® PL® 158060 @ BI

Application number: 272551

CZKTEIBA

OGĆLii A £ 9 IntCl ⁵ :

Patent Office of the Republic of Poland

Date of notification: May 17, 1988

C23F 11/04

C23C 22/06

Steel surface passivation agent

The holder of the patent: Institute of Inorganic Chemistry, Gliwice, PL ( ⁴³ ) ^The announcement was announced: November 27, 1989, BUP 24/89 Inventors: Joanna Gallus-Olender, Gliwice, PL Barbara Franc, Gliwice, PL Alicja Łanowy, Gliwice, PL Marek Szlęzak, Katowice, PL Janina Francuz, Tychy, PL The grant of the patent was announced on: 07/31/1992 WUP 07/92 Gerard Ratka, Przyszowice, PL Barbara Kapko, Gliwice, PL

(57) An agent for passivating steel surfaces, characterized in that it is a compound of Cr III with a dicarboxylic organic acid with a molar ratio of chromium to acid 1: 1.

PL 158060 BI

STEEL SURFACE PASSIVATION AGENT

Claims (2)

Patent designation of the agent of ^p asywaaji (steel surface, characterized by the fact that it is a compound of Cr III with a di or tricarboxy organic acid with a molar ratio of chromium to acid 1: 1, The object of l-azku ¹ is an agent for passivating the steel surface. A known passive of steel is sodium chromate. The surface of the steel treated with it is covered with a protective layer of teen iron with some Cr ^ Og. The passivation of mtal is explained by the gradual deprotonation of the adsorbed water molecules to form a teen hydroxide film. Due to its high introduction to water, chromium facilitates deprotonation in the boundary layer, increasing the concentration of hydroxide ions on the metal surface. Chromium in the form of Na ^ CrO ^ is a very good corrosion inhibitor, used in particular to protect an already existing tank protective layer. Compositions of sodium chromate or dichromate with other inorganic compounds such as NagCOg and NaNOg are known. One such chromate-based formulation is the agent of US Pat. No. 2 582 129, containing 500 - 3000 p.p.m. NagCrgOy 2HgO and 250 - 1000 p.p.m. NaNOg with a pH of 6.5 to 9.5, maintained by the addition of borax and Na2CO-g. However, the use of chromates is not safe. For example, in the presence of chlorides, when the chromate concentration is insufficient to completely protect the surface, perforation is easy. Another negative property of chromate is its toxicity, which makes the use of this passivator more and more limited. Solutions of organic chromium compounds are much safer than chromate or dichromate solutions. Application to the passivation of chromium glucosinates, which are similar to natural glucosides / DW Haering, is known. Ind.Eng.Chem., 30, No. 12, 1356-61, Dec. DW 1983 and Haering, Organic Metfiods of ^f Scale and Corrosion Control, ^C hlclgo ¹⁹⁴³ /. this measure ^will not, however, venous ławwo available and cheap. A similar formulation was the agent developed by Mrtin and Eberum according to US Pat. No. 2,658,817, othizmann with 2 - 5 parts. starch and 1 part. CrOg, effective at a concentration of 3-15 ppm Cr. means invented own preferences ^{g j} est chiromu compound III dwukarbo ^ y ^ trójkarboksytowym acid or with an organic acid chromium complex wytworzeneem durable colored IAMO c-ide o f wwym. The molar ratio of chromium to acid is 1: 1. An aqueous solution of this complex with a concentration of 5 - 6% Cr is non-toxic and stable. It acts as a belt / water to maintain the tightness of the protective metal coating, when diluted with water to a Cr concentration of 50-100 ppm and neutralized to a pH of 4-5. Example. 100 g of CrOg was added to 211 g of cytinic acid in 750 ml of water and heated slightly. The resulting thick dark fluid solution contained 5% Cr (III) bound in a 1: 1 molar ratio with citric acid. Department of Publishing of the UP RP. Circulation of 90 copies