Al-Fe Intermetallic Thermal Spray Coating for Glass Rolls
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Solution Overview
Problem
Conventional Al-Fe based thermal spray coating films for glass-conveying rolls suffer from low hardness, hydrogen brittleness, and peeling due to differences in linear thermal expansion coefficients, and the calorizing treatment method is limited by batch processing, high-temperature requirements, and brittleness of the coating film.
Innovation Solution
A method for forming a thermal spray coating film with a multi-phase structure containing FeAl, FeAl2, and FeAl-FeAl2, using a mixture of Al-Fe based intermetallic compound powder and Fe-based metal powder, which is applied using high-velocity oxygen fuel or atmospheric plasma spraying, to achieve high hardness and toughness while matching the thermal expansion coefficient of the metal substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Al-Fe based thermal spray coating film is formed to provide corrosion resistance and non-adhesive properties, then the coating film achieves protective function, but the coating film exhibits low hardness and hydrogen brittleness
Solution Approach 1:
The patent applies composite materials by creating a multi-phase coating structure containing FeAl, FeAl2, and FeAl-FeAl2 intermetallic compounds. This composite intermetallic structure combines the corrosion resistance and non-adhesive properties of Al-Fe intermetallics with enhanced hardness and toughness through phase distribution control, resolving the contradiction between protective function and mechanical strength.
Solution Approach 2:
The patent changes the compositional parameters by controlling the Al/Fe weight ratio within 0.55-0.85 and adjusting the content of FeAl2 phase to 20-80%. These parameter changes transform the coating from a single-phase soft structure to a multi-phase composite structure with optimized hardness and toughness while maintaining corrosion resistance.
2Reliability
If a ceramic thermal spray coating film is applied to suppress deposit of glass residue and tin aggregate, then the coating provides non-adhesive properties, but the coating may peel due to difference in linear thermal expansion coefficient between ceramic and metal substrate
Solution Approach 1:
The patent changes the material parameters by selecting Al-Fe intermetallic compounds with thermal expansion coefficients matched to common metal substrates like stainless steel. By controlling the Al/Fe ratio and phase composition, the coating's thermal expansion properties are optimized to reduce thermal stress and prevent peeling while maintaining non-adhesive characteristics.
Solution Approach 2:
The patent uses composite intermetallic phases (FeAl, FeAl2, and FeAl-FeAl2) that provide both the non-adhesive properties needed for glass conveying and improved mechanical compatibility with metal substrates. The multi-phase structure offers a balance between chemical inertness and thermal-mechanical compatibility.
3Reliability
If calorizing treatment is used to form a diffusion coating film to improve oxidation and corrosion resistance, then the coating achieves protective function, but the treatment requires batch processing, high temperature, and produces brittle coating film
Solution Approach 1:
The patent replaces the thermal diffusion process (calorizing) with a mechanical deposition process (thermal spray). This substitution allows for continuous processing instead of batch treatment, reduces the required temperature exposure, and produces a coating with improved toughness by controlling the spray parameters and feedstock composition to create a multi-phase intermetallic structure.
Solution Approach 2:
The patent changes the processing parameters from high-temperature diffusion (calorizing at ~900-1100°C) to controlled thermal spray deposition. By adjusting spray temperature, particle velocity, and feedstock composition, the coating achieves similar protective properties with improved toughness and continuous processing capability.
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 resulting coating film exhibits high hardness, toughness, and resistance to peeling, with reduced hydrogen embrittlement and the ability to handle varying substrate sizes, maintaining integrity at high temperatures and resisting corrosion and wear.
Implementation Method 1
a method for forming a thermal spray coating film with a multi-phase structure containing FeAl, FeAl2, and FeAl-FeAl2, using a mixture of Al-Fe based intermetallic compound powder and Fe-based metal powder, which is applied using high-velocity oxygen fuel or atmospheric plasma spraying
Implementation Method 2
applied using high-velocity oxygen fuel or atmospheric plasma spraying
Implementation Method 3
applied using high-velocity oxygen fuel or atmospheric plasma spraying
Data Source
Figure 1~2(a)
Figure 2(b)~2(c)
Figure 2(d)~3(a)
AI summary
To provide a method for forming a thermal spray coating film, by forming a thermal spray coating film of an Al-Fe based intermetallic compound having a high hardness, on a metal substrate. A method for forming a thermal spray coating film, by forming a thermal spray coating film of an Al-Fe based intermetallic compound, from a mixture of an Al-Fe based intermetallic compound powder composed mainly of FeAl2 and a metal powder composed mainly of Fe, as feedstock, on the surface of a metal substrate.