Lanthanide Pretreatment Composition for Metal Substrate Corrosion Resistance

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Solution Overview

Problem

Conventional techniques for coating metal substrates with chromate-containing compositions pose environmental and health concerns due to their toxicity.

Innovation Solution

A pretreatment composition comprising a lanthanide series metal, an oxidizing agent, and a fluorometallic acid, an organophosphate compound, an organophosphonate compound, or combinations thereof, which provides improved corrosion resistance and paint adhesion without using chromium.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chromate-containing compositions are used for pretreatment, then corrosion resistance and paint adhesion are improved, but environmental and health hazards increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidenvironmental and health hazards

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes chromium-based chemicals with lanthanide-based chemicals (such as cerium, neodyium, or lanthanum salts), fundamentally changing the chemical composition parameters. This substitution maintains the protective film-forming capability while eliminating the toxic chromate component, directly resolving the contradiction between effectiveness and environmental safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces lanthanide salts as intermediary substances that perform the same functional role as chromates in forming protective conversion coatings. These lanthanide compounds act as mediators between the metal substrate and the final paint coating, providing both corrosion protection and adhesion promotion without the harmful effects of chromium

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional chromate pretreatment is used, then paint adhesion is improved, but environmental compliance becomes difficult

Engineering Contradiction:

Improvepaint adhesionVSAvoidenvironmental compliance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition by replacing chromates with lanthanide salts, changing the fundamental chemical parameters of the pretreatment process. This substitution maintains paint adhesion performance through the formation of stable lanthanide-based conversion coatings that provide equivalent bonding properties without violating environmental regulations

Inventive Principle:

Principle #35Parameter changes

3Reliability

If chromium-based pretreatment compositions are used, then corrosion protection is achieved, but health and safety risks increase

Engineering Contradiction:

Improvecorrosion protectionVSAvoidhealth and safety risks

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Lanthanide salts serve as safe intermediary substances that replace toxic chromium compounds in the pretreatment process. These lanthanide-based intermediaries form protective conversion coatings on metal substrates, providing the same corrosion protection function while eliminating health and safety risks associated with chromium exposure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful chromium-based process into a beneficial lanthanide-based process. By substituting the toxic chromate chemistry with lanthanide chemistry, the same protective function is achieved but with beneficial environmental and health properties, turning a harmful process into a safe one

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed composition effectively enhances corrosion resistance and paint adhesion on metal substrates, as demonstrated by reduced scribe creep in various testing conditions, while eliminating the environmental and health hazards associated with chromate-containing compositions.

Implementation Method 1

an oxidizing agent

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

a lanthanide series metal

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Data Source

PatentUS20250154663A1Compositions, systems, and methods for treating a substrate

Publication Date: 2025.05.15 PPG INDUSTRIES OHIO INC

AI summary

Disclosed herein is a pretreatment composition comprising a lanthanide series metal; an oxidizing agent; and a fluorometallic acid, an organophosphate compound, an organophosphonate compound, or combinations thereof. Also disclosed is a pretreatment composition comprising a lanthanide series metal; a carboxylic acid; and an oxidizing agent in an amount of no more than 70 ppm based on total weight of the pretreatment composition. Also disclosed is a system for treating a substrate comprising a cleaning composition and one of the pretreatment compositions disclosed herein. Also disclosed are methods of treating a substrate comprising contacting at least a portion of the substrate with one of the pretreatment compositions disclosed herein. Also disclosed are substrates comprising a surface having a film on at least a portion thereof, wherein the film is formed from one of the pretreatment compositions disclosed herein. Also disclosed are substrates treated with any of the systems or methods described herein.