Additive Manufacturing Surface Smoothing via TLP Coating
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Solution Overview
Problem
Additively manufactured surfaces are rough, leading to turbulent fluid flow and reduced mechanical strength due to crevices, which affects performance and fatigue resistance in fluidic applications.
Innovation Solution
A method involving coating an additively manufactured article with a material comprising two constituents, where one is transient liquid phase (TLP) diffused into the base material at a specific temperature, while the other is not, followed by heating and hot isostatic pressing to create a smoother surface, using nickel alloys and processes like electroless plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additive manufacturing is used to create complex geometries, then manufacturing flexibility and design freedom are improved, but surface roughness increases creating crevices that reduce fluid flow performance and mechanical strength
Solution Approach 1:
A coating layer is applied to the additively manufactured surface before final processing. This preliminary coating fills in the surface crevices and irregularities, creating a smoother base surface that will become the final functional surface after selective removal, thereby pre-resolving the surface roughness issue before the component is put into service
Solution Approach 2:
After the coating is applied and bonded to the substrate, the excess coating material is selectively removed (etched away) to reveal the smoothed interface. This extraction process removes the harmful surface irregularities while preserving the beneficial coating layer that has already filled and smoothed the crevices
2Reliability
If conventional coating methods are applied to additively manufactured surfaces, then surface coverage is improved, but the rough crevices remain creating turbulence and reduced fatigue strength
Solution Approach 1:
The coating process utilizes phase transitions - the coating material is deposited in a controlled state, then heated to a diffusion temperature where it transitions to a liquid or semi-liquid state, allowing it to flow into and fill the surface crevices. Upon cooling, it solidifies, locking the smoothed surface geometry in place and eliminating the harmful irregularities that would reduce fatigue strength
Solution Approach 2:
Temperature is used as a critical parameter to control the coating behavior. By heating to a specific diffusion temperature range, the coating material's viscosity changes, enabling it to penetrate and fill surface irregularities. This parameter change allows the coating to adapt to the rough topology and create a smooth functional surface
3Manufacturing precision
If the coating material is heated to high diffusion temperatures, then transient liquid phase diffusion improves surface smoothness, but excessive heating may cause base material degradation
Solution Approach 1:
The coating material is formulated with specific compositional qualities that differ from the base material. It contains constituents designed to remain stable and non-diffusing at the intended service temperature, while being capable of controlled diffusion into the base material at the higher processing temperature. This local quality difference allows selective thermal processing without damaging the overall component
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
Results in smoother surfaces with improved fluid flow characteristics and enhanced high cycle fatigue resistance, aligning with the material properties.
Implementation Method 1
a first constituent of the at least two constituents is configured to be at least partially transient liquid phase (TLP) diffused from the coating material into the base material at a first constituent diffusion temperature
Implementation Method 2
heating the additively manufactured article to the first constituent diffusion temperature
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A method (100) can include coating a first surface of an additively manufactured article (200) made of a base material (201) with a coating material (203) comprising at least two constituents, wherein a first constituent of the at least two constituents is configured to be at least partially transient liquid phase (TLP) diffused from the coating material into the base material at a first constituent diffusion temperature, and a second constituent of the at least two constituents is configured to not diffuse from the coating material at the first constituent diffusion temperature, heating (103) the additively manufactured article to the first constituent diffusion temperature, TLP diffusing at least a portion of the first constituent from the coating and into the base material, leaving the second constituent of the coating material on the first surface, and forming a second surface that is smoother than the first surface.