Dense X-ray Target Cap via Hot Isostatic Pressing
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Solution Overview
Problem
Conventional X-ray targets produced by the PSF method have limited density, mechanical strength, thermal conductivity, and thermo-mechanical properties, leading to restricted operation at peak power, reduced X-ray output, and increased cooling periods between exposures, especially as target diameter increases, due to porosity variations and material property mismatches.
Innovation Solution
The development of X-ray targets with a target cap formed of dense substrate material and a focal track layer of dense emitting material, both exceeding 95% of theoretical density, using techniques like hot isostatic pressing and mechanical working to enhance mechanical strength, thermal conductivity, and durability, allowing for increased peak power operation and reduced cooling periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PSF method is used to produce X-ray targets, then manufacturing process is simple, but material density is limited to 90-95% of theoretical density with porosity variations
Solution Approach 1:
The manufacturing process is divided into distinct stages: initial forming (cold pressing), sintering to achieve intermediate density, and final hot isostatic pressing to achieve >95% theoretical density. This segmentation allows each stage to optimize for its specific function, achieving high density while maintaining manufacturing feasibility.
Solution Approach 2:
The process performs preliminary cold pressing and sintering to create a green body with intermediate density and porosity structure before applying hot isostatic pressing. This preliminary action prepares the material structure to accept the final densification treatment, enabling achievement of >95% theoretical density.
2Power
If X-ray target diameter is increased, then X-ray output capacity is improved, but mechanical strength and thermal conductivity decrease due to porosity variations
Solution Approach 1:
The process changes the density parameter from 90-95% to greater than 95% of theoretical density through hot isostatic pressing. This parameter change eliminates porosity variations that would otherwise limit mechanical strength in larger diameter targets, enabling increased X-ray output capacity without sacrificing strength.
3Power
If X-ray target diameter is increased, then X-ray output capacity is improved, but thermal conductivity decreases due to porosity variations
Solution Approach 1:
The process changes the density parameter to greater than 95% of theoretical density, eliminating porosity that would impede heat flow. This enables larger diameter targets to maintain high thermal conductivity despite increased size, supporting higher X-ray output capacity.
4Ease of manufacture
If conventional PSF method is used, then manufacturing cost is reduced, but thermal loading capacity and mechanical loading capacity are limited
Solution Approach 1:
The process segments manufacturing into cold pressing, sintering, and hot isostatic pressing stages. While more complex than simple PSF, this segmentation achieves the high density required for increased thermal and mechanical loading capacity, enabling targets to handle higher power loads.
5Power
If X-ray target operates at peak power, then X-ray output is maximized, but cooling periods between exposures must be increased
Solution Approach 1:
The process achieves greater than 95% theoretical density, creating a material with superior thermal conductivity and heat capacity. This allows the target to dissipate heat more efficiently during operation, enabling sustained peak power operation with shorter cooling periods between exposures.
6Strength
If material density is increased to greater than 95% of theoretical density, then mechanical strength and thermal conductivity are improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into standard, well-understood stages: cold pressing, sintering, and hot isostatic pressing. Each stage uses conventional equipment and parameters, making the overall complex process manageable and industrially viable while achieving greater than 95% theoretical density.
Solution Approach 2:
The process performs preliminary cold pressing and sintering to create a prepared green body before final hot isostatic pressing. This preliminary action reduces the complexity of the final densification step by pre-organizing the material structure, making the high-density achievement more manufacturable.
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 improved X-ray targets can operate at higher peak power with increased X-ray output, more frequent exposures, and shorter cooling periods, while maintaining mechanical integrity and thermal management, even at larger diameters, thus enhancing the performance and reliability of X-ray imaging systems.
Implementation Method 1
Heat is also conducted out of the focal track into the substrate, and then into the heat sink
Implementation Method 2
using techniques like hot isostatic pressing and mechanical working to enhance mechanical strength, thermal conductivity, and durability
Implementation Method 3
Interactions between the electrons and high atomic weight species in the focal track emit high frequency electromagnetic waves, or X-rays
Implementation Method 4
the electrical circuit energizes the cathode filament to generate high energy electrons which impinge upon the focal track of the X-ray target
Implementation Method 5
Heat dissipates from the heat sink through evacuated space in the chamber and into the housing
Data Source
AI summary
In some embodiments, an X-ray target includes a target cap formed of a substrate material and a focal track layer of emitting material, and at least one of the substrate material and the emitting material has a density greater than about 95.0% of theoretical density. In some embodiments, a method of manufacturing an X-ray target includes forming an intermediate target cap form of substrate material and a focal track layer of emitting material, and compacting the intermediate target cap form by application of gas pressure at elevated temperature to form a final target cap form, and at least the substrate material is dense substrate material having a final density greater than an intermediate density or the emitting material is dense emitting material having a final emitting material density greater than an intermediate emitting material density.