Container for cooking food and process for making the same
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Solution Overview
Problem
Containers for cooking on electromagnetic induction sources face galvanic corrosion issues due to the contact between ferromagnetic and non-ferromagnetic materials, which leads to oxidation of aluminum and is not effectively addressed by non-stick coatings that become porous over time.
Innovation Solution
A container design with a non-ferromagnetic outer element, a ferromagnetic inner element, and a corrosion-resistant coating made of aluminum oxide with optional titanium oxide, applied via thermal plasma spray, to isolate the metals and prevent galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a ferromagnetic bottom and non-ferromagnetic bowl are combined for induction cooking, then good heat transfer performance is achieved, but galvanic corrosion occurs between the two metals
Solution Approach 1:
A third inner discoidal component made of the same metal material as the non-ferromagnetic bowl is inserted between the ferromagnetic bottom and the bowl to act as an intermediary layer. This mediator prevents direct contact between the two different metals, eliminating the galvanic corrosion pathway while maintaining the heat transfer function from the bottom through the mediator to the bowl.
Solution Approach 2:
The container employs a composite structure consisting of a ferromagnetic bottom layer, a non-ferromagnetic bowl layer, and an intermediate metal layer. This multi-layer composite design combines the electromagnetic induction properties of ferromagnetic materials with the corrosion resistance and non-stick properties of non-ferromagnetic materials, while the intermediate layer prevents galvanic interaction between them.
2Ease of operation
If non-stick coating is applied to prevent corrosion, then ease of cleaning is improved, but the coating becomes porous over time allowing corrosion to occur
Solution Approach 1:
The third inner discoidal component serves as a permanent intermediary barrier between the ferromagnetic bottom and the non-ferromagnetic bowl, preventing galvanic corrosion at the interface. This structural solution is more reliable than coatings because it provides continuous metal-to-metal contact prevention without relying on coating integrity.
Solution Approach 2:
The third inner component is made of the same metal material as the non-ferromagnetic bowl, ensuring homogeneous material properties at the interface. This eliminates galvanic potential differences between dissimilar metals in direct contact, as the intermediate layer has the same electrochemical properties as the bowl it protects.
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 corrosion-resistant coating effectively prevents galvanic corrosion, maintaining the structural integrity and longevity of the container by creating a barrier against electron flow between aluminum and stainless steel, even under thermal expansion and usage conditions.
Implementation Method 1
the bottom made of the first material is heated by the parasitic currents generated by the effect of the magnetic field generated by the induction source
Implementation Method 2
a corrosion-resistant coating made of aluminum oxide with optional titanium oxide, applied via thermal plasma spray
Data Source
Figure 1~2
Figure 3
AI summary
A container (1) for cooking food, of the type usable on electromagnetic induction sources, comprising a first substantially concave element (2), made of a first material, e.g. aluminium, or aluminium alloy, or another metal material, or metal alloy, distinguishable for high thermal conductivity and good processability, and comprising an upper surface (3) intended to accommodate the food to be cooked, a side wall defining the side surface (4) of the same container (1), the upper surface (3) and the side surface (4) constituting the inner surface of the container (1), a lower surface (5) for resting said container (1) on an electromagnetic induction source or other heat sources, a second element (6) attached to the lower surface (5) and at least partially included within the thickness of the first element (2), the second element (6) being made of a second material suitable for heating when immersed in the magnetic field generated by an electromagnetic induction source, a third element (7) attached to the upper surface (3) and at least partially included within the thickness of said first element (2), the third element (7) being made of said second material or of a third material, the container (1) presenting an interface area (31), arranged on the upper surface (3), wherein the first element (2) and the third element (7) are adjacent, the upper surface (3) comprises a layer (8) of corrosion-resistant material; moreover, a process is included for applying a layer (8) of corrosion-resistant material via the technique named air plasma spray, i.e. plasma spray in the presence of air.