Silicon Electromagnetic Casting Crucible Hard Structure
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Solution Overview
Problem
The silicon electromagnetic casting process faces issues with crucible deformation due to the cubical expansion of silicon as it solidifies, leading to outward deflection and eventual cessation of ingot production as the ingot width increases, as the force from expansion exceeds the crucible's hardness.
Innovation Solution
A silicon electromagnetic casting apparatus with a conductive crucible and induction coil, where constant pressure is maintained using a prescribed gas, and a hard structure made from electrical insulating material is fitted onto the crucible's outer surface to prevent outward deflection by counteracting the expansion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the silicon ingot cross-section is increased to improve productivity, then the pushing force from cubical expansion increases cumulatively, but the crucible undergoes permanent deformation and outward deflection
Solution Approach 1:
A support structure is introduced as an intermediary element between the crucible and the external environment. This support structure bears the pushing force generated by cubical expansion of solidifying silicon, preventing the force from being transmitted to the crucible wall and causing deformation. The support structure acts as a mediator that protects the crucible while allowing continuous production of larger ingots.
Solution Approach 2:
The support structure is made from a composite material comprising a foam core and an outer layer. The foam core provides lightweight structural support, while the outer layer (made of insulating material) provides additional mechanical strength and thermal insulation. This composite construction allows the support structure to withstand the cumulative pushing force without excessive weight or heat loss.
2Strength
If the crucible hardness is increased to resist expansion force, then the pushing force can be balanced, but the ingot width increase still causes cumulative force that exceeds crucible hardness
Solution Approach 1:
The support structure serves as a mediator that intercepts the cumulative pushing force before it can act on the crucible wall. By placing the support structure against the inner wall of the crucible, the expansion force is transferred to the support structure rather than directly to the crucible, preventing the force from exceeding the crucible's hardness limit.
Solution Approach 2:
The support structure is positioned in advance within the crucible before the casting process begins. This preliminary placement ensures that as the silicon solidifies and generates expansion force, the support structure is already in position to counteract the force, preventing crucible deformation from the outset rather than attempting to correct it later.
3Productivity
If the casting process is continued to produce larger ingots, then productivity increases, but the outward deflection of the crucible increases and eventually prevents further ingot movement
Solution Approach 1:
The support structure acts as a permanent intermediary element that maintains the crucible's shape during continuous casting. By continuously bearing the expansion force, the support structure prevents the crucible from developing outward curvature, ensuring that the ingot can continue to move downward without obstruction throughout the entire casting process.
Solution Approach 2:
The support structure changes the mechanical parameters of the crucible system by adding structural reinforcement. This modification allows the crucible to maintain its original shape and dimensions even under the cumulative stress of prolonged casting operations, effectively changing the system's resistance to deformation parameter.
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 solution allows for stable and continuous manufacturing of silicon ingots by preventing crucible deformation, enabling the production of larger ingots without interruption, as the hard structure effectively manages the expansion force during solidification.
Implementation Method 1
a copper crucible in which a cooling water is circulated and an induction coil installed on the outer surface of the copper crucible are used. Levitation melting of the silicon mass is carried out in the copper crucible using electromagnetic force
Implementation Method 2
Levitation melting of the silicon mass is carried out in the copper crucible using electromagnetic force
Implementation Method 3
Cubical expansion took place during the solidification of this molten silicon which gained entry into the gap, thus generating a force pushing the inner surface of the crucible. Cubical expansion of approximately 9% takes place when silicon changes its state from liquid to solid.
Data Source
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AI summary
The present invention aims at providing a silicon electromagnetic casting apparatus which can prevent the outward deflection of a crucible 200 used in the apparatus. This apparatus has a reaction vessel 100, the conductive crucible 200 installed in the reaction vessel 100 and an induction coil 300 installed on the outer circumference of the crucible 200, wherein constant pressure is maintained in the reaction vessel 100 using a prescribed gas and the silicon inside the crucible 200 is solidified after melting it by induction heating by applying voltage on the induction coil 300. In the apparatus, a hard structure 810 made from electrical insulating material is fitted onto the outer peripheral surface of the crucible 200.