Iron-Based Thermal Spray Coating Readability
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Solution Overview
Problem
Current thermal spray coatings based on iron are not readable with magnetic thickness gauges, limiting their use in corrosion and erosion environments, and existing nickel-based coatings are more expensive and less suitable for these applications.
Innovation Solution
Development of a thermal spray wire with a specific alloy composition that forms a coating with an FCC-BCC transition temperature below 950K, containing at least 10 wt.% solute elements, and maintaining a high austenite content after exposure to temperatures between 500-800°C, allowing for accurate measurement with magnetic thickness gauges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iron-based thermal spray coatings are used, then cost is reduced and performance in corrosion/erosion environments is improved, but the coating becomes magnetic and cannot be measured with magnetic thickness gauges
Solution Approach 1:
The alloy composition is specifically designed to control magnetic properties through parameter changes. By adjusting the content of austenite-forming elements (Ni: 15-20 wt.%, Mn: 10-15 wt.%, Cr: 15-20 wt.%) and controlling the FCC-BCC transition temperature below 950K, the coating maintains non-magnetic or low-magnetic properties at service temperatures while retaining iron-based corrosion resistance. This allows magnetic thickness gauges to read the coating accurately.
2Measurement precision
If nickel-based coatings are used to achieve readability with magnetic thickness gauges, then measurement capability is improved, but material cost increases significantly
Solution Approach 1:
The invention creates a composite alloy system combining iron (base metal providing cost-effectiveness and corrosion resistance) with nickel (15-20 wt.%) and manganese (10-15 wt.%) (austenite-forming elements). This composite composition achieves the non-magnetic properties needed for readability while using significantly less nickel than pure nickel-based coatings, thereby reducing material cost while maintaining both readability and performance.
Solution Approach 2:
By controlling the FCC-BCC transition temperature below 950K through specific alloy composition parameters, the coating maintains austenitic (non-magnetic) structure at service temperatures. This parameter control enables the use of iron-based materials at lower cost while achieving the magnetic properties needed for gauge readability.
3Measurement precision
If amorphous microstructure is used to maintain readability at low temperatures, then measurement capability is improved, but the coating loses readability when temperature exceeds 600°C due to devitrification
Solution Approach 1:
The alloy composition is designed with specific content ranges of austenite-forming elements (Ni: 15-20 wt.%, Mn: 10-15 wt.%, Cr: 15-20 wt.%) to control the FCC-BCC transition temperature below 950K. This parameter optimization ensures the coating maintains austenitic (non-magnetic) structure not only at low temperatures but also at high service temperatures up to 800°C, preventing devitrification and maintaining readability across the full temperature range.
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 solution enables the use of cost-effective iron-based coatings that remain readable and maintain high performance, including high abrasion resistance and adhesion strength, even after exposure to high temperatures, facilitating precise thickness measurement and extended service life.
Implementation Method 1
The voltage gap arcs the two wires at a connection point in the gun, melting the wire at the tip
Implementation Method 2
A gas stream is then applied behind the melt interface to atomize and spray the resultant liquid metal droplets onto a substrate
Implementation Method 3
The typical particle temperatures are between 1800-3500° C.
Implementation Method 4
the outer sheath and the powdered core combined comprise an alloy having an FCC-BCC transition temperature at or below 950K
Data Source
AI summary
Embodiments of an iron-based coating configured to be thermally sprayed are disclosed. The iron-based coatings can be fully readable, thus allowing for thickness measurements to be performed on the coating with standard magnetic measuring equipment. Further, the iron-based coating can have advantageous properties, such as high hardness, high wear resistance, and high adhesion strength.