Profiled Substrate Additive Manufacturing for Thick Metal Adhesion
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Solution Overview
Problem
Additive manufacturing techniques, such as cold spray deposition, face challenges with residual stress accumulation leading to delamination and cracking in metallic structures, especially when building thick layers on substrates with dissimilar thermal properties, as existing methods like pre-cooling or surface roughening are insufficient for large-scale structures.
Innovation Solution
A process involving a profiled substrate with recessed and protruding surface features having elongated non-vertical walls, which disrupts stress accumulation by ensuring each deposition layer conforms to the substrate profile, thereby reducing internal and interfacial stresses, allowing for thicker metallic structures without delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If cold spray deposition is used to build thick metallic structures, then the structure thickness increases, but residual stress accumulation causes delamination and cracking
Solution Approach 1:
The substrate surface is segmented into multiple recessed features (grooves, pits, or holes) that divide the continuous deposit-substrate interface into discrete segments. Each recessed feature creates independent bonding zones, so that stress accumulation in one region does not propagate continuously across the entire interface, thereby preventing delamination in thick structures
Solution Approach 2:
The substrate surface is pre-profiled with recessed features before deposition begins. This preliminary surface preparation creates a geometric structure that passively manages stress accumulation throughout the deposition process, eliminating the need for post-deposition stress relief operations or complex cooling systems
2Stress or pressure
If pre-cooling or cooling plates are used to reduce thermal stress, then stress build-up is mitigated, but process complexity and cost increase significantly
Solution Approach 1:
The substrate surface is pre-profiled with recessed features before deposition begins. This preliminary surface preparation creates a geometric structure that passively manages stress accumulation throughout the deposition process, eliminating the need for post-deposition stress relief operations or complex cooling systems
Solution Approach 2:
The invention replaces active thermal management systems (cooling plates, pre-cooling equipment) with a passive geometric surface structure. The mechanical profile of the substrate surface inherently manages stress distribution, substituting complex thermal control machinery with a simple geometric feature that achieves stress mitigation without additional equipment
3Strength
If substrate surface is roughened by grit blasting or micro-texturing, then bond strength improves, but stress disruption in thicker structures remains insufficient
Solution Approach 1:
The substrate surface is segmented into multiple recessed features (grooves, pits, or holes) that divide the continuous deposit-substrate interface into discrete segments. Each recessed feature creates independent bonding zones, so that stress accumulation in one region does not propagate continuously across the entire interface, thereby preventing delamination in thick structures
Solution Approach 2:
The recessed features introduce curvature and non-planarity to the substrate surface, creating three-dimensional geometric profiles. This curvature causes deposition layers to conform to the profiled surface, disrupting planar stress distribution and preventing the formation of continuous stress paths that lead to delamination in thick structures
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 approach effectively reduces the risk of delamination and cracking, enabling the production of thicker metallic structures on thermally dissimilar substrates by maintaining adhesion and cohesion through the propagation of the substrate's surface profile throughout the structure's thickness.
Implementation Method 1
The kinetic energy of the particles is utilised to achieve metallurgical bond formation between particles and mechanical interlocking of highly deformed particles (splats) that deposit under the supersonic shock load.
Implementation Method 2
mechanical interlocking of highly deformed particles (splats) that deposit under the supersonic shock load
Implementation Method 3
so that heat is inevitably transferred to the substrate and the deposited material
Implementation Method 4
maintaining adhesion and cohesion through the propagation of the substrate's surface profile throughout the structure's thickness
Implementation Method 5
maintaining adhesion and cohesion through the propagation of the substrate's surface profile throughout the structure's thickness
Data Source
AI summary
A process for producing a metallic structure by additive manufacturing comprises: providing a deposition-receptive substrate comprising a profiled surface, the profiled surface comprising a plurality of recessed and/or protruding surface features having elongated non-vertical walls and a depth of at least 0.5 mm relative to a base plane of the substrate; depositing metallic material on the substrate by an additive manufacturing technique to produce a first deposition layer which conforms to the profiled surface including the elongated non-vertical walls; and depositing successive deposition layers of the metallic material on the first deposition layer by the additive manufacturing technique to build up a metallic structure having a first thickness on the substrate, wherein each successive deposition layer conforms sufficiently to the profile of its preceding deposition layer to propagate a surface profile corresponding to the profiled surface of the substrate through the first thickness or a substantial portion thereof.