Corrosion inhibitors and synergistic inhibitor combinations for the protection of light metals in heat-transfer fluids and engine coolants
AssigneesTexaco Inc., Texaco Development Corporation
InventorsJean-Pierre Leopold Maes, Serge Stefan Lievens
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Abstract
Corrosion protection of magnesium and aluminum alloys in engine coolants and heat-exchange fluids is achieved by the use of a select group of aliphatic and aromatic carboxylate acids or the alkaline metal, ammonium or amine salts thereof in combination with a fluoride and/or a fluorocarboxylic acid or salt thereof. These compositions have been found to significantly improve the high temperature magnesium corrosion protection properties of coolants, and are of use in automobile engine coolant systems.
Claims17
A corrosion-inhibitor formulation comprising
- 1) from 0.1 to 15 weight percent of one or more inhibitors selected from the group comprising an alkylbenzoic acid, a C5-C15 monobasic acid and a C5-C15 dibasic acid, or salts thereof;
- and
- 2) from 0.005 to 5 weight percent of a fluoride and/or a fluorocarboxylic acid, or salts thereof.
A heat transfer fluid formulation comprising:
- (a) from 65-99 weight percent of a water soluble liquid alcohol freezing point depressant;
- (b) from 0.1-15 weight percent of alkylbenzoic acid of general formula
- R—Ar—COOH
- where Ar is benzyl and R is a C1-C8 alkyl radical or an element of Group 7, or a salt thereof;
- (c) from 0.1-15 weight percent of C5-C15 aliphatic monobasic or dibasic acid or salt thereof;
- (d) from 0.01-5 weight percent of hydrogen fluoride and/or a fluorocarboxylic acid or salt thereof.
Dependencies are inferred from the claim text.