Core-Shell Chromium Nanoparticles for Stable Aerosol Inks
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Solution Overview
Problem
Current methods for forming chromium metal nanoparticles are hindered by their susceptibility to aggregation, oxidation, and short shelf life, making them unsuitable for aerosol-based direct-write inks due to their high surface reactivity and limited availability in reduced states.
Innovation Solution
The development of core-shell microparticles with a chromium core and a less reactive metallic shell, formed through a process involving an acidic solution, reducing agents, and metallic acetate chelates, which are then dispersed in a solvent system to create stable aerosol inks for direct-write processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromium metal nanoparticles are used in aerosol-based direct-write inks, then the desired chromium content and functionality are achieved, but the particles aggregate, oxidize, and have prohibitively short shelf life due to high surface reactivity
Solution Approach 1:
The patent applies composite materials by creating core-shell structured nanoparticles where a chromium-containing core is encapsulated by a protective shell material. This composite structure allows the chromium core to maintain its functionality while the shell provides resistance to oxidation and aggregation, thereby extending shelf life and reducing surface reactivity issues.
Solution Approach 2:
The patent employs an inert atmosphere approach by using protective shell materials that create a chemically inert environment around the reactive chromium core. This shell acts as a barrier that prevents oxygen and other reactive species from reaching the chromium surface, effectively creating a protected micro-environment that prevents oxidation and extends particle stability.
2Quantity of substance
If chromium nanoparticles are formulated for aerosol-based direct-write, then the required chromium content is achieved, but the ink composition becomes unstable and particles aggregate
Solution Approach 1:
The core-shell composite structure allows high chromium content in the core while the shell material provides stabilization. This composite approach enables the ink to maintain both the required chromium quantity for functionality and the compositional stability needed for aerosol-based direct-write applications.
Solution Approach 2:
The protective shell acts as an intermediary between the chromium core and the surrounding ink matrix/environment. This intermediary layer prevents direct interaction between the reactive chromium surface and other ink components that would otherwise cause aggregation or instability, thereby maintaining both chromium content and ink stability.
3Reliability
If conventional metallization inks are used, then the ink has adequate shelf life and stability, but chromium-specific functionality and reduced state chromium content cannot be achieved
Solution Approach 1:
The core-shell composite structure resolves the manufacturing challenge by separating the chromium core formation from the stabilization function. The core provides the required chromium content and functionality, while the shell provides the stability and shelf life characteristics of conventional inks, making chromium-containing inks manufacturable with properties similar to conventional metallization inks.
Solution Approach 2:
The patent applies parameter changes by modifying the physical and chemical parameters of chromium nanoparticles through shell encapsulation. This changes the effective surface properties, reactivity, and stability parameters of the chromium particles, enabling them to achieve both the required chromium-specific functionality and the manufacturing ease and stability of conventional inks.
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 core-shell nanoparticles are more resistant to poisons and contaminants, extending their shelf life and enabling effective use in direct-write processes, particularly for chromium-containing alloys, while maintaining suitable processing properties like aerosol density and uniformity.
Implementation Method 1
adding a reducing agent to the dispersion including the plurality of chromium nanoparticles
Implementation Method 2
adding a metallic acetate chelate to the dispersion such that the metallic acetate chelate comprises a metallic material that surrounds the chromium nanoparticles
Implementation Method 3
dispersing the plurality of chromium nanoparticles within the acidic solution
Implementation Method 4
dispersed in a solvent system
Data Source
AI summary
Core-shell microparticles, along with methods of their fabrication and use, are provided. The core-shell microparticles may include a core comprising a first metallic material having a first chromium content, and a shell surrounding the core and comprising a second metallic material having a second chromium content, wherein the aerosol ink includes between 0.1% and 1% by weight of a radical scavenger and between 0.1% and 5% by weight of a dispersant.