Copper Nitrate Binder for 3D Printed Metal Strength
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Solution Overview
Problem
Current three-dimensional printing techniques face challenges in achieving sufficient strength for metal parts, particularly during the transition from green body objects to fused metal articles, as they often lack the necessary mechanical stability for handling and processing before sintering.
Innovation Solution
The use of copper nitrate as a binder in three-dimensional printing systems, which converts to copper hydroxynitrate upon heat curing, significantly enhances the flexural strength of green body objects from 3 MPa to over 13 MPa, allowing for improved stability and handling before fusing, by forming a strong bond between metal particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binding agents are used in three-dimensional printing, then the printing process can be completed, but the green body objects lack sufficient mechanical strength for handling and processing before sintering
Solution Approach 1:
The patent changes the chemical composition parameters of the binding agent by incorporating copper nitrate (20-60 wt%) combined with water and organic compounds. This parameter change transforms the binding agent's properties, enabling it to provide sufficient mechanical strength (flexural strength from 3 MPa to over 13 MPa) while maintaining ease of manufacture and handling capabilities during the 3D printing process.
Solution Approach 2:
The patent creates a composite binding agent system combining copper nitrate with water and organic compounds (surfactants, co-solvents). This composite material approach leverages the synergistic effects of each component: copper nitrate provides mechanical strength through conversion to copper hydroxynitrate, water provides fluidity for printing, and organic compounds enhance surface properties. The composite formulation resolves the contradiction by simultaneously achieving high strength and ease of handling.
2Strength
If heat curing is applied to increase binding strength, then flexural strength increases significantly, but the process time and energy consumption increase
Solution Approach 1:
The patent incorporates copper nitrate into the binding agent formulation before the 3D printing process, so that the strength-enhancing component is already in place. The copper nitrate begins converting to copper hydroxynitrate during the printing process itself, performing the strength-building action preliminarily before the final heat curing step. This preliminary action reduces the energy required for subsequent heat curing while still achieving the desired strength increase.
Solution Approach 2:
The patent optimizes the thermal parameters of heat curing by controlling temperature and time to achieve maximum strength with minimum energy input. The copper nitrate conversion to copper hydroxynitrate occurs within specific temperature ranges (typically 50-200°C), allowing the process to leverage thermal energy efficiently. By adjusting these parameters, the system achieves significant strength increase (from 3 MPa to over 13 MPa) while minimizing energy consumption.
3Strength
If copper nitrate is used as binding agent, then strong bonds form between metal particles, but the binding agent composition becomes more complex
Solution Approach 1:
The patent develops a composite binding agent where copper nitrate (20-60 wt%) is combined with water and organic compounds (surfactants, co-solvents). This composite formulation manages the complexity by assigning specific functional roles to each component: copper nitrate provides bond strength through conversion to copper hydroxynitrate, water provides fluidity and dilution, and organic compounds provide surface activity and stability. The composite approach organizes the complexity into functional categories, achieving strong bonds while keeping the composition manageable.
Solution Approach 2:
The patent applies different properties to different parts of the binding agent system: copper nitrate provides localized chemical bonding at metal particle interfaces, water provides bulk fluidity and transport, and organic compounds provide surface-level stabilization. This local quality differentiation allows each component to perform its specific function efficiently, achieving strong bonds without requiring all components to be complex. The binding agent composition becomes manageable when viewed through the lens of localized functional requirements.
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 method effectively increases the flexural strength of three-dimensional printed metal parts, enabling stable transport and processing, and subsequent sintering, with heat curing in the powder bed and/or a heating oven achieving part strengths suitable for automation and decaking.
Implementation Method 1
heat curing the green body object by heat soaking the green body object at a temperature within the range of about 70° C. to about 200° C. for about 30 minutes to about 8 hours
Implementation Method 2
copper nitrate acts as a binder, sticking together copper powder particles, but due to the heat curing that occurs, a large percentage of the copper nitrate may convert to copper hydroxynitrate, which can surface bind to the metal particles
Implementation Method 3
copper hydroxynitrate, which can surface bind to the metal particles of the particulate build material, thereby increasing the strength of the green body object
Data Source
AI summary
The present disclosure is drawn to a three-dimensional printing kit and can include a particulate build material including from about 80 wt % to about 100 wt % metal particles, and a binding agent including water, from about 0.01 wt % to about 5 wt % organic compounds, and from about 20 wt % to about 60 wt % copper nitrate.