NiAl Protective Layer for Ammonia Handling Under Nitriding

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Solution Overview

Problem

Conventional ammonia handling devices using a Fe-Al alloy layer fail to sufficiently reduce nitriding in high ammonia concentration environments, leading to the formation of hard and brittle nitrogen compounds that degrade mechanical properties of metals.

Innovation Solution

The ammonia handling device incorporates a modified layer containing a β-phase NiAl intermetallic compound, which is formed by diffusing aluminum into a nickel or nickel alloy base material, to reduce nitriding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a Fe-Al alloy layer is used to handle ammonia, then ammonia can be handled, but nitriding occurs and reduces mechanical properties of metals

Engineering Contradiction:

Improveammonia handling capabilityVSAvoidmechanical properties

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent changes the material composition parameters by using Ni-Al intermetallic compound instead of Fe-Al alloy, and controls the aluminum content to be 25-30% to form the β-phase NiAl structure. This parameter change fundamentally alters the chemical reactivity with ammonia, preventing nitriding while maintaining ammonia handling capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite material structure consisting of a nickel base material with a formed Ni-Al intermetallic compound layer. This composite structure combines the properties of nickel (high temperature stability) with aluminum (ammonia resistance) to achieve both ammonia handling capability and prevention of nitriding.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If a Fe-Al alloy layer is used in high ammonia concentration environment, then ammonia handling is possible, but nitriding is not sufficiently reduced

Engineering Contradiction:

Improveammonia handling capabilityVSAvoidnitriding reduction effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a sacrificial protective layer of Ni-Al intermetallic compound that reacts with ammonia to form a stable barrier. This layer acts as a disposable protective barrier that consumes the harmful ammonia-metal interaction, preventing nitriding of the underlying metal structure.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If aluminum is diffused into nickel or nickel alloy to form modified layer, then nitriding is reduced, but manufacturing process becomes more complex

Engineering Contradiction:

Improvenitriding reductionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by forming the Ni-Al intermetallic compound layer on the nickel base material before the component is put into service. The aluminum diffusion is performed in advance during manufacturing, creating a pre-protective layer that prevents nitriding during subsequent ammonia handling operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent controls specific parameters during the aluminum diffusion process, including temperature (800-1100°C), time, and aluminum content (25-30%), to form the desired β-phase NiAl intermetallic compound. By precisely controlling these parameters, the manufacturing process achieves reliable nitriding prevention while maintaining feasibility.

Inventive Principle:

Principle #35Parameter changes

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 β-phase NiAl intermetallic compound effectively reduces nitriding, even at high temperatures, maintaining the mechanical integrity of metal components in ammonia-containing environments.

Implementation Method 1

forming the modified layer by diffusing aluminum into nickel or a nickel alloy

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentEP4703495A1Ammonia handling device and method for producing same

Publication Date: 2026.03.04 IHI CORP

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AI summary

An ammonia handling device (1) includes a modified layer (12) containing a β-phase NiAl intermetallic compound, and an ammonia contact part (10) configured so that ammonia contacts the modified layer (12). The ammonia contact part (10) may include a metal base material (11), and the modified layer (12) may cover the metal base material (11).