Surface-Modified Metal Powder for Low-Reflectivity Laser Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for surface modification of metal or metal alloy powders to reduce reflectivity and introduce alloying elements are costly, difficult to scale, and can introduce undesirable oxides, limiting their applicability and performance in laser additive manufacturing.
Innovation Solution
A method involving mixing metal or metal alloy powder with an alloying element powder, heating in a reducing gas atmosphere, and then switching to an inert gas at a controlled temperature to facilitate diffusion of the alloying element onto the surface, creating a thin, reduced-reflectivity layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxidation is used to enhance optical absorption of copper powder, then optical absorption increases, but oxygen is introduced into the final part which deteriorates corrosion resistance, mechanical strength, electrical and thermal conductivity
Solution Approach 1:
The invention changes the chemical composition parameters of the surface layer by controlling the diffusion of alloying elements (such as chromium, zinc, or tin) into the copper powder surface during heating in an inert atmosphere. This creates a surface layer with enhanced optical absorption properties without introducing oxygen, thereby resolving the contradiction between improving optical absorption and maintaining material reliability.
Solution Approach 2:
The invention uses an inert atmosphere (such as nitrogen or carbon dioxide) during the heating process to prevent oxidation of the copper powder surface. This allows the alloying elements to diffuse into the surface without introducing oxygen, thus maintaining both high optical absorption and good corrosion resistance in the final product.
2Adaptability or versatility
If electroplating or electrolysis is used to coat metal powder with alloying elements, then alloying element introduction is achieved, but the powder needs to be submerged into solvent and dried, requiring avoidance of air contact to prevent oxidation which is challenging and costly
Solution Approach 1:
The invention replaces the mechanical/chemical coating processes (electroplating, electrolysis) with a thermal diffusion process. By heating the metal powder in an inert atmosphere containing alloying elements, the alloying elements diffuse into the surface through atomic diffusion, eliminating the need for complex electrochemical equipment and solvent handling while avoiding oxidation issues.
Solution Approach 2:
The invention changes the process parameters from electrochemical (voltage, current density, electrolyte composition) to thermal (temperature, time, atmosphere composition). This parameter transformation simplifies the process by eliminating solvent handling and air contact requirements, while achieving the same alloying element introduction effect through controlled diffusion.
3Adaptability or versatility
If CVD or PVD is used to coat metal powder particles, then a wider range of materials can be coated, but the methods are very difficult to upscale to industrial level and can be very costly
Solution Approach 1:
The invention uses a self-service approach where the alloying elements are introduced through the heating process itself, and the diffusion occurs automatically based on temperature and time parameters. This eliminates the need for complex deposition equipment and manual coating processes, making the method inherently scalable to industrial production levels while maintaining versatility in coating material selection.
Solution Approach 2:
The invention transforms the coating mechanism from vapor-phase deposition (CVD/PVD) to solid-state diffusion controlled by temperature and time parameters. This parameter change simplifies the process for industrial scaling, as it eliminates the need for vacuum systems, complex gas delivery mechanisms, and expensive equipment, while still allowing a wide range of alloying elements to be introduced.
4Loss of energy
If high reflectivity powder is used in laser additive manufacturing, then less energy is absorbed by the powder, but higher laser power output is required increasing energy requirements and back-reflected laser light can cause damage to optical components
Solution Approach 1:
The invention changes the optical parameters of the powder surface by introducing alloying elements that alter the surface reflectivity. The surface-modified copper powder exhibits reduced reflectivity in the laser wavelength range, increasing energy absorption and reducing back-reflected light, thereby resolving the contradiction between energy absorption efficiency and harmful back-reflection.
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 allows for a wide range of alloying elements to be introduced without oxides, reducing reflectivity and enhancing optical absorption, making it scalable and cost-effective for laser-based additive manufacturing processes.
Implementation Method 1
heating the mixed powder in an atmosphere of reducing gas to a predetermined first temperature T1... after temperature T1 is reached, replacing the reducing gas atmosphere with an inert gas atmosphere and maintaining the temperature at a second temperature T2 for a predetermined time, wherein the alloying element is capable of diffusing in the metal or metal alloy element at the second temperature T2
Data Source
AI summary
A method of surface modification of a metal or metal alloy powder includes the steps of providing a metal or metal alloy powder including copper, gold, or silver and having an average diameter in the micron range; providing a powder having an alloying element to form an alloying element powder. The alloying element powder particles have an average diameter less than 10 micron and no more than half the average diameter of the metal or metal alloy powder particles; mixing the powders to form a mixed powder; heating the mixed powder in an atmosphere of reducing gas to a first temperature T1; after temperature T1 is reached, replacing the reducing gas atmosphere with an inert gas atmosphere and maintaining the temperature at a second temperature T2 for a predetermined time. The alloying element is capable of diffusing in the metal or metal alloy element at temperature T2.