Lubricant Additive System for Copper and Lead Corrosion Control
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Solution Overview
Problem
Existing engine oils with high levels of organo-molybdenum compounds face corrosion issues with copper (Cu) and lead (Pb), limiting their use in heavy duty diesel engine oils due to failure in the High Temperature Corrosion Bench Test ASTM D 6594, which restricts the concentration of molybdenum compounds required for oxidation protection and wear control.
Innovation Solution
A lubrication composition comprising a sulfur-free organo-molybdenum compound, a sulfur-containing organo-molybdenum compound, and a triazole derivative, specifically an alkylated diphenylamine or alkylamine derivative of triazole, is added to engine oils to reduce Cu and Pb corrosion, allowing higher molybdenum levels up to 320 ppm without exceeding corrosion limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of organo-molybdenum compounds are used in engine oils, then oxidation protection and wear control are improved, but Cu and Pb corrosion increases causing failure in ASTM D 6594 test
Solution Approach 1:
A derivatized triazole compound is introduced as an intermediary substance that mediates between the organo-molybdenum compounds and the Cu/Pb metals. The triazole forms protective films on metal surfaces, preventing direct contact and corrosion reactions, while allowing the molybdenum compounds to maintain their oxidation and wear protection functions at higher concentrations
Solution Approach 2:
The invention creates a composite additive system combining organo-molybdenum compounds (sulfur-containing and/or sulfur-free) with derivatized triazole compounds. This composite formulation synergistically provides both high-level oxidation/wear protection from molybdenum and corrosion inhibition from triazole, enabling the system to pass ASTM D 6594 while maintaining elevated molybdenum levels for enhanced lubrication performance
2Productivity
If the concentration of molybdenum compounds is increased to enhance lubrication performance, then fuel economy and wear protection are improved, but the oil fails corrosion tests limiting practical application
Solution Approach 1:
The invention changes the chemical parameters of the corrosion inhibition system by introducing derivatized triazoles with specific molecular structures and concentrations. This parameter modification enables the system to tolerate higher molybdenum concentrations (improving fuel economy and wear protection) while maintaining corrosion resistance through the triazole's film-forming properties on Cu and Pb surfaces
Data Source
AI summary
A lubricating composition for use in heavy duty diesel engines which is formulated to allow the use of organomolybdnem compounds but which overcomes the issue of Cu and/or Pb corrosion. The lubricant is characterized by having a synergistic additive composition comprising (A) a sulfur-free organo-molybdenum compound, (B) a sulfur-containing organo-molybdenum compound and (C) a triazole derivative prepared by reacting 1,2,4-triazole, a formaldehyde source and an amine; (A), (B) and (C) being present in an amount sufficient to allow the lubricating composition to pass the High Temperature Corrosion Bench Test ASTM D 6594 with respect to Cu and/or Pb corrosion.