Boron Carbide Neutron Detector Layer Adhesion
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Solution Overview
Problem
Conventional physical vapor deposition (PVD) methods for producing boron carbide layers with boron-10 face challenges such as poor adhesion to substrates, leading to spallation and contamination issues, especially when using temperature-sensitive substrates like aluminum, which affects the stability and neutron detection efficiency of neutron detectors.
Innovation Solution
A method involving physical vapor deposition using magnetron sputtering with a coating chamber evacuated to low pressure and heated to an elevated temperature, along with specific heating of the substrate and contaminant removal, to improve adhesion and reduce stress in the boron carbide layer, ensuring a continuous film with high boron-10 content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PVD methods are used to produce boron carbide layers with boron-10, then the neutron detection capability is achieved, but poor adhesion to substrates occurs leading to spallation and contamination
Solution Approach 1:
The patent applies parameter changes by heating the substrate to elevated temperatures (300-660°C) during the PVD process. This temperature parameter change improves the adhesion of the boron carbide layer to the substrate, preventing spallation and contamination while maintaining the neutron detection capability through boron-10 content of at least 60 at.%
Solution Approach 2:
The patent uses a vacuum environment (pressure of at most 6 mPa) during the PVD process to create an inert atmosphere. This prevents contamination of the boron carbide layer during deposition while enabling the physical vapor deposition process to proceed effectively, resulting in a clean layer with high boron-10 content and improved adhesion
2Ease of manufacture
If CVD techniques are used to produce boron carbide layers, then the boron carbide layer can be formed, but process risks and high material costs are associated with the use of gaseous materials
Solution Approach 1:
The patent replaces the chemical vapor deposition (CVD) process with a physical vapor deposition (PVD) process using magnetron sputtering. This substitution eliminates the need for gaseous materials and complex chemical reactions, reducing process risks and material costs while maintaining the ability to form boron carbide layers with high boron-10 content
Solution Approach 2:
The patent changes the deposition method from CVD to PVD with specific parameter control (pressure of at most 6 mPa, temperature of 300-660°C). This parameter change enables a more stable and cost-effective process without the hazards associated with gaseous materials in CVD techniques
3Reliability
If pure boron layers comprising boron-10 are used, then the theoretical neutron detection efficiency is higher, but such layers are difficult to produce with good adhesion and without contamination
Solution Approach 1:
The patent uses parameter changes (heating to 300-660°C, vacuum pressure of at most 6 mPa) during PVD to achieve both high neutron detection efficiency and manufacturing precision. The elevated temperature improves adhesion while the vacuum environment prevents contamination, enabling production of boron carbide layers with boron-10 content of at least 60 at.% and improved structural integrity
Solution Approach 2:
The patent uses composite materials by depositing boron carbide layers with controlled composition (boron content between 70 at.% and 85 at.% of total boron and carbon atoms) onto substrates. This composite approach maintains high boron-10 content for neutron detection efficiency while the carbide structure provides better adhesion and reduced contamination compared to pure boron layers
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 method enhances the adhesion of boron carbide layers to substrates, reduces contamination, and increases neutron detection efficiency, allowing for the production of stable and efficient neutron detector components, particularly suitable for large-area applications.
Implementation Method 1
evacuating the coating chamber to a pressure that is at most 6 mPa
Implementation Method 2
heating at least a coating surface of the substantially neutron transparent substrate in the coating chamber to an elevated temperature that is at least 300°C to about 660°C
Implementation Method 3
coating the neutron detecting boron carbide layer comprising boron-10 on the substantially neutron transparent substrate by means of physical vapor deposition in the form of magnetron sputtering
Data Source
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AI summary
Disclosed is a method for producing a neutron detector component (1 ) comprising a neutron detecting boron carbide layer (2) comprising boron-10 arranged on a substantially neutron transparent substrate (3). Disclosed is also a neutron detecting device (30) comprising a plurality of neutron detector components (1 ) arranged as a stack (32). The method comprising, placing (120) the substantially neutron transparent substrate (3) and at least one source of coating material (16) comprising carbon and boron-10 inside a coating chamber (10). The coating chamber (10) is then evacuated (146) to a pressure that is at most 6 mPa and at least a coating surface (3a) of the substantially neutron transparent substrate (3) is heated (144) to an elevated temperature that is at least 100°C. The method uses physical vapor deposition using the at least one source of coating material (16) when said pressure and said elevated temperature are reached, and coating (150) the neutron detecting boron carbide layer (2) comprising boron-10 to a desired thickness (t). The method enabling improved adhesion of the boron carbide layer to the substantially neutron transparent substrate.