B4C/Al Neutron Absorbing Sheet via Electromagnetic Casting

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Solution Overview

Problem

Conventional methods for producing B4C/Al neutron-absorbing material sheets, such as stirring casting, face inefficiencies and defects due to slow cooling rates and poor dispersion of B4C particles in the aluminum matrix, leading to unsatisfactory uniformity and mechanical properties.

Innovation Solution

The method involves combining B4C particles with an aluminum matrix melt and applying an electromagnetic field and ultrasonic vibration during twin roll continuous cast rolling, which enhances particle dispersion and solidification structure, ensuring uniform distribution and refined grains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional stirring casting method is used to produce B4C/Al composite, then production efficiency is improved and process flow is simplified, but uniformity of B4C particles in the composite sheet deteriorates due to slow cooling rate

Engineering Contradiction:
Improveproduction efficiencyVSAvoiduniformity of B4C particles
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces the conventional mechanical stirring and slow cooling system with an electromagnetic field system. The electromagnetic field acts on the molten aluminum and B4C particles during casting, enhancing particle dispersion uniformity without compromising production efficiency. This substitution allows rapid solidification while maintaining particle uniformity through electromagnetic forces rather than mechanical means.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the cooling rate parameter from slow (conventional) to rapid by implementing continuous casting with electromagnetic field application. This parameter change enables the system to achieve both high production efficiency and uniform particle distribution by controlling the solidification process through electromagnetic parameters rather than traditional thermal parameters alone.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If aluminum matrix melt containing high mass content of B4C particles is used, then neutron-absorbing capability is improved, but viscosity increases and fluidity deteriorates, leading to casting defects

Engineering Contradiction:
Improveneutron-absorbing capabilityVSAvoidfluidity of aluminum matrix melt
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces conventional mechanical stirring with electromagnetic field application to handle the high-viscosity melt containing high B4C content. The electromagnetic field provides sufficient mixing and dispersion forces without requiring the melt to maintain low viscosity, enabling processing of high-B4C-content compositions that would otherwise be too viscous for conventional casting.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent applies periodic electromagnetic field action during the casting process to continuously disperse B4C particles and prevent aggregation. This periodic electromagnetic action maintains particle suspension and ensures uniform distribution even at high B4C concentrations, overcoming the viscosity and fluidity problems associated with high filler content.

Inventive Principle:
Principle #19Periodic action

3Reliability

If B4C particles are added to aluminum matrix, then neutron-absorbing performance is enhanced, but particle dispersion uniformity deteriorates due to poor wettability and crowding out effect during solidification

Engineering Contradiction:
Improveneutron-absorbing performanceVSAvoidparticle dispersion uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces conventional thermal solidification with electromagnetic field-assisted solidification. The electromagnetic field acts on both the molten aluminum and B4C particles during the solidification process, counteracting the crowding out effect and poor wettability. This enables uniform particle dispersion in the final composite structure while maintaining high B4C content for enhanced neutron-absorbing performance.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If conventional casting method is used, then production cost is reduced, but microstructure segregation occurs due to slow solidification rate

Engineering Contradiction:
Improveproduction costVSAvoidmicrostructure uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces conventional slow thermal solidification with rapid electromagnetic field-assisted solidification. This substitution eliminates microstructure segregation by achieving uniform cooling and solidification through electromagnetic field control, producing a homogeneous microstructure that would require expensive conventional processing to achieve similar quality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 improves processing efficiency, reduces defects, and achieves uniform particle dispersion, enhancing the mechanical properties and neutron-absorbing capabilities of the B4C/Al composite sheets.

Implementation Method 1

applying an electromagnetic field to the B4C particle-containing aluminum matrix melt passing through a headbox to achieve electromagnetic dispersion

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

Via applying ultrasonic vibration during cast rolling process, due to the acoustic cavitation and the acoustic streaming effect, air bubbles in the aluminum matrix melt can be reduced remarkably

Methodology Applied
Scientific EffectAcoustic cavitation: Acoustic Cavitation

Implementation Method 3

Via applying ultrasonic vibration during cast rolling process, due to the acoustic cavitation and the acoustic streaming effect, air bubbles in the aluminum matrix melt can be reduced remarkably

Methodology Applied
Scientific EffectAcoustic streaming:

Implementation Method 4

During twin roll continuous cast rolling, the cast rolls act as crystallizer and hot rolls. In casting rolling, the solidification rate of the liquid metal is very high (as high as 103-104°C/s), so that the reinforcement can distribute homogeneously in the matrix

Methodology Applied
Scientific EffectRapid solidification: Freezing

Data Source

PatentEP3112486B8Method of producing b 4c/al neutron absorbent material sheet by continuous cast rolling
Publication Date: 2019.09.18 CHINA NUCLEAR POWER ENGINEERING COMPANY LTD

AI summary

The present invention provides a method for producing B4C/Al neutron-absorbing material sheet by continuous cast rolling including the steps of: 1) providing B4C particles and aluminum matrix melt, adding the B4C particles into the aluminum matrix melt while stirring the composite of the B4C particles and the aluminum matrix melt; 2) applying an electromagnetic field to the B4C particle-containing aluminum matrix melt passing through a headbox; 3) applying an ultrasonic vibration to the B4C particle-containing aluminum matrix melt passing through a casting nozzle; and 4) conducing twin roll continuous cast rolling on the B4C particle-containing aluminum matrix melt from the casting nozzle to obtain B4C/Al neutron-absorbing material sheet. The method of the present invention uses twin roll continuous cast rolling under coupled ultrasonic and electromagnetic oscillation to rapidly cool and refine the grains of the solidified composite material and realize uniform distribution of B4C particles in the aluminum matrix.