Titanium Separator Oxide Film for Conductive Corrosion Resistance

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Solution Overview

Problem

Existing technologies for polymer electrolyte fuel cells face challenges in achieving both corrosion resistance and electrical conductivity without using precious metals, leading to high costs and poor mass productivity.

Innovation Solution

A titanium material with a titanium oxide film formed on a pure titanium or titanium alloy base metal, where the titanium oxide film contains Ti2O3 and TiO phases, optimized through specific X-ray diffraction peak intensity ratios and production methods, provides both corrosion resistance and electrical conductivity without precious metals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an oxide film (TiO2) is formed on titanium material to improve corrosion resistance, then corrosion resistance is improved, but electrical conductivity deteriorates

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention changes the chemical composition parameters of the oxide film by controlling the ratio of TiO2 to conductive titanium oxide (TiOx where x<2). By adjusting oxidation conditions and heat treatment parameters, the film achieves optimal balance between corrosion resistance and electrical conductivity without precious metals

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The oxide film is designed as a composite structure containing multiple titanium oxide phases (TiO2 for corrosion resistance and TiOx for electrical conductivity). This composite approach allows simultaneous achievement of both protection and conductivity functions

Inventive Principle:

Principle #40Composite materials

2Reliability

If precious metals (Au, Pt) are plated on metal base to achieve both corrosion resistance and electrical conductivity, then both properties are improved, but cost increases and resource availability decreases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidcost and resource availability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces expensive precious metals with abundant titanium and its oxides. The titanium oxide film, while requiring careful control for optimal performance, uses only titanium-based materials that are significantly cheaper and more abundant than Au or Pt plating

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The titanium material itself serves dual functions: the base metal provides structural integrity and high conductivity, while the surface oxide film provides corrosion resistance. This self-sufficient system eliminates the need for additional precious metal plating layers

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If titanium oxide is synthesized to replace precious metal electrodes, then cost is reduced and corrosion resistance is improved, but mass productivity deteriorates

Engineering Contradiction:

Improvecost reductionVSAvoidmass productivity

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The conductive oxide phases (TiOx) are formed as an integral part of the material fabrication process through controlled oxidation and heat treatment, rather than as a separate post-processing step. This preliminary formation of the functional oxide structure enables scaling to mass production

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the need for complex precious metal plating processes with a simplified thermal oxidation process. This substitution of manufacturing methodology dramatically improves mass productivity while maintaining cost advantages

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 titanium material and separator achieve low contact resistance and high power generation efficiency, reducing costs and maintaining performance in corrosive environments without the need for precious metals.

Implementation Method 1

an oxide film primarily made of TiO2 is produced on the outer layer of the titanium material and protects the base metal thereof

Methodology Applied

Scientific EffectOxide film formation: Oxidation

Implementation Method 2

The oxide films are useful for improvement in the corrosion resistance but are poor in electrical conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11764368B2Titanium material, separator, cell, and polymer electrolyte fuel cell stack

Publication Date: 2023.09.19 NIPPON STEEL CORPORATION

AI summary

A titanium material including a base metal made of pure titanium or a titanium alloy and a titanium oxide film formed on the base metal. Peak intensities obtained by thin-film X-ray diffraction analysis performed on an outer layer of the titanium material using an incident angle of 0.3° satisfy (I(104)+I(200))/I(101)≥0.08−0.004×I(200), where I(104) is the peak intensity resulting from a plane (104) of a Ti2O3 phase, I(200) is the peak intensity resulting from a plane (200) of a TiO phase, I(101) is the peak intensity resulting from a plane (101) of an α-Ti phase, and 0<I(104), 0≤I(200), and 0<I(101). The titanium material is inexpensive and has both the electrical conductivity and corrosion resistance.