Surface-Modified Laser Sintering Powder for Copper Absorption
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Solution Overview
Problem
Powders with a low degree of absorption for laser radiation in the near infrared range, such as copper, face challenges during laser sintering due to inadequate absorption of radiation energy, leading to thermal overloading or destruction of support surfaces.
Innovation Solution
A surface-modified powder is developed, where particles have a particle core with a low degree of absorption, and laser absorbers are bound to the surface, increasing the absorption of laser radiation by at least 10% compared to the particle core, thereby enhancing the sintering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional lasers with customary wavelength (1064 nm) are used for sintering copper powder, then the laser system is simple and widely available, but the absorption of laser radiation by copper powder is less than 5% leading to thermal overloading of the support surface
Solution Approach 1:
A layer of laser absorbers is introduced as an intermediary between the laser radiation and the copper powder particles. These absorbers have high absorption coefficients at 1064 nm and transfer the absorbed energy to the copper particles through thermal conduction, enabling efficient sintering while protecting the support surface from thermal overload
Solution Approach 2:
The optical properties of the powder surface are modified by changing the material composition at the particle level. By coating copper particles with materials having different optical absorption characteristics (laser absorbers), the effective absorption coefficient of the powder bed is increased from less than 5% to above 80%
2Use of energy by moving object
If the surface of particle cores is coated with laser absorbers to increase absorption, then the absorption of laser radiation is improved, but the particle structure becomes more complex
Solution Approach 1:
Instead of changing the entire particle structure, only the surface layer of the particles is modified by coating with laser absorbers. The core particles maintain their original copper material properties, while the surface coating provides the necessary optical absorption characteristics. This localized modification minimizes structural complexity
Solution Approach 2:
The powder particles are designed as composite structures with a copper core and a coating layer of laser-absorbing material. This composite structure combines the electrical conductivity and sinterability of copper with the high laser absorption properties of the coating material, achieving both functional requirements without excessive complexity
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 surface-modified powder significantly improves the absorption of laser radiation, allowing for efficient laser sintering of materials with low inherent absorption, such as pure copper, and enables the production of three-dimensional structures with improved conductivity and structural integrity.
Implementation Method 1
laser absorbers which are bound to the surface of each particle core and which have a higher degree of absorption for laser radiation for laser sintering compared to the particle core
Implementation Method 2
the heat is transferred by thermal conduction to the particle core
Implementation Method 3
Laser sintering in a powder bed is a process in which the powder, for example composed of metal or polymer, is sintered or completely melted
Implementation Method 4
the powder is sintered or completely melted without use of binders and after solidification of the melt forms a homogeneous material of high density
Data Source
AI summary
A surface-modified powder for laser sintering that allows improved incoupling of the radiation energy of the laser. The surface-modified powder avoids problems arising in the laser sintering of materials having a low absorptance for the laser radiation. The surface-modified powder has particles having particle cores and having laser absorbers bonded to a surface of each particle core, the laser absorbers covering at least 25% of the surface of each particle core and having a higher absorptance for laser radiation for laser sintering than the particle core.