Ni-Fe Alloy Susceptor for Inductive Heating
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Solution Overview
Problem
Multi-layer susceptor arrangements for inductively heating aerosol-forming substrates face issues with variations in magnetic properties due to internal mechanical stress and thermal expansion differences between layers, leading to inconsistent performance across different susceptor arrangements.
Innovation Solution
The use of an Ni—Fe-alloy with 75 wt %-85 wt % Ni and 10 wt %-25 wt % Fe for the second susceptor material, which exhibits weak or no magnetostriction, reduces variations in magnetic properties by minimizing the impact of thermal stress and expansion differences, ensuring consistent performance throughout the temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-layer susceptor arrangements are assembled by firmly bonding different susceptor material layers together, then temperature monitoring capability is improved through the second layer's Curie temperature marker function, but magnetic property variations occur due to internal mechanical stress and thermal expansion differences between layers
Solution Approach 1:
The patent changes the material parameter of the second susceptor layer to an Ni-Fe-alloy with specific composition (75-85 wt% Ni, 10-25 wt% Fe) that exhibits weak or no magnetostriction. This parameter change ensures that the layer's magnetic properties remain stable throughout the temperature range despite thermal stress and expansion differences, while still providing the Curie temperature marker function for monitoring.
2Ease of manufacture
If susceptor layers are processed by intimate connection and heat treatment, then manufacturing capability is improved, but thermal stress develops during cooldown due to different coefficients of thermal expansion between layers
Solution Approach 1:
The patent selects the second susceptor layer material (Ni-Fe-alloy) based on its specific physical parameters, particularly its weak or no magnetostriction property and compatible thermal expansion characteristics. This material parameter selection reduces the development of internal mechanical stress during heat treatment and cooldown processes, while still allowing standard manufacturing techniques to be used.
3Measurement precision
If the second susceptor material is chosen for strong magnetic properties to serve as temperature marker, then temperature detection accuracy is improved, but magnetostriction effects amplify variations in magnetic properties due to thermal stress
Solution Approach 1:
The patent changes the magnetic property parameters of the second susceptor layer by selecting an Ni-Fe-alloy with specific composition that exhibits weak or no magnetostriction. This allows the material to maintain stable magnetic properties throughout the temperature range while still providing the necessary Curie temperature marker function for accurate temperature detection.
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
This approach results in multi-layer susceptor arrangements with stable magnetic properties, maintaining heating efficiency and accuracy across different susceptor arrangements, reducing the risk of overheating and improving the reliability of aerosol generation.
Implementation Method 1
The device may comprise an induction source for generating an alternating magnetic field used to inductively heat a susceptor arrangement by inducing at least one of eddy currents and hysteresis losses in the susceptor material
Implementation Method 2
The device may comprise an induction source for generating an alternating magnetic field used to inductively heat a susceptor arrangement by inducing at least one of eddy currents and hysteresis losses in the susceptor material
Implementation Method 3
The device may comprise an induction source for generating an alternating magnetic field used to inductively heat a susceptor arrangement by inducing at least one of eddy currents and hysteresis losses in the susceptor material
Implementation Method 4
At its Curie temperature, the magnetic permeability of the second susceptor material drops to unity leading to a change of its magnetic properties from ferro- or ferrimagnetic to paramagnetic
Implementation Method 5
the variations of the magnetic properties observed with the multi-layer susceptor arrangements known from prior art are caused by a combination of magnetostriction properties and internal mechanical stress being present in the susceptor arrangement after its processing and throughout its temperature range of operation
Data Source
AI summary
A multi-layer susceptor arrangement for inductively heating an aerosol-forming substrate, the multi-layer susceptor arrangement including: a first layer including a first susceptor material; and a second layer including a second susceptor material, the second susceptor material including a Ni—Fe-alloy including one of: 79 wt %-82 wt % Ni and 13 wt %-15 wt % Fe, or 79 wt %-82 wt % Ni, 4 wt %-6 wt % Mo, less than 1 wt % of Si and Mn combined together, and 13 wt %-15 wt % Fe, or 77 wt % Ni, 16 wt % Fe, 5 wt % Cu, and 2 wt % of one of Cr and Mo, or 77 wt % Ni, 14 to 15 wt % Fe, 4 wt % Cu, and 4 wt % of Mo.