LiquiEdge® Thermal Spray Shroud
Smoother, denser coatings and targeted deposition
All atmospheric thermal spray processes have overspray problems due to particles that do not deposit with acceptable properties. These unwanted particles are mostly located along the outer boundary of the plume.
The Progressive LiquiEdge® shroud combats these unwanted particles by injecting water into the plume boundary. This shroud of water around the plume core deflects unwanted particles, reduces unwanted particle adhesion, and impacts on the substrate to remove overspray particles that have settled on the surface. Through this combination of benefits the patented LiquiEdge can be used to produce denser, smoother coatings and provide better control of where coating is deposited.
Plume diameter and particle size distribution control
The LiquiEdge® is an attachment for thermal spray torches that can be used as an adjustable aperture to reduce the plume diameter. The powder particles within the plume tend to separate based upon size, so reducing the plume diameter also effectively narrows the particle size distribution (PSD) of the powder being sprayed. As a result, with the LiquiEdge® coatings can be produced from particles that have smaller differences in diameters, speeds, and temperatures, creating smoother, denser structures.
Wide, diverging plume with no water injection
Narrow, focused plume with water injection
The 100HE® torch gets even better
Injecting water does reduce the enthalpy content of the plume. Therefore, the LiquiEdge® works best with a torch like the 100HE® that can produce a high enthalpy plume.
LiquiEdge® (highlighted in orange in photo) is added to the front of the 100HE®.
APS microstructure control
Even with water injection from the LiquiEdge®, the 100HE® plume still contains enough enthalpy to deposit a dense, vertically cracked ZrO2 — Y2O3 thermal barrier coating (TBC) by the air plasma spray (APS) process. The narrowing of the particle size distribution provided by the LiquiEdge® reduced the surface roughness of the APS TBC by 55%.
APS coating ZrO2 — 8 wt% Y2O3
Without LiquiEdge® (cross section)
With LiquiEdge® (cross section)
Without LiquiEdge® (top surface)
With LiquiEdge® (top surface)
Surface roughness
Without LiquiEdge®
Ra 14.1 μm (553 μin)
Rz 101.4 μm (3987 μin)
With LiquiEdge®
Ra 6.3 μm (246 μin)
Rz 41.6 μm (1635 μin)
SPS microstructure control
The 100HE® with the LiquiEdge® can also be used to decrease the surface roughness and porosity of coatings made by the suspension plasma spray (SPS) process.
100HE® with the LiquiEdge® (below) spraying Y2O3 by SPS on a liner.
SPS coating Y2O3
Without LiquiEdge® (cross section)
With LiquiEdge® (cross section)
Without LiquiEdge® (top surface)
With LiquiEdge® (top surface)
Surface roughness
Without LiquiEdge®
Ra 12.3 μm (482 μin)
Rz 71.7 μm (2817 μin)
With LiquiEdge®
Ra 1.0 μm (40 μin)
Rz 6.5 μm (256 μin)
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LiquiEdge® Thermal Spray Shroud
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