Novel opportunities for thermal spray by PS-PVD

Mauer, Georg; Jarligo, Maria Ophelia; Rezanka, Stefan; Hospach, A.; Vaßen, Robert

doi:10.1016/j.surfcoat.2014.06.002

Cited by 89 publications

(35 citation statements)

References 16 publications

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“…The quasi-columnar structure, correlating with the nodules observed in plan view (Fig. 8) is reflective of the dendritic or columnar growth characteristic of EB-PVD coatings, and PS-PVD structures have been discussed at length in this regard [20,21]. Again, an adherent 20 μm Al 2 O 3 scale is apparent at the YSZ-Ti 2 AlC interface, but TiO 2 was not observed in the fields examined.…”

Section: Ps-pvd Ysz On Ti 2 Alcmentioning

confidence: 53%

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Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Smialek

Harder

Garg

2016

Surface and Coatings Technology

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Air plasma spray (APS) and plasma-spray-physical vapor deposition (PS-PVD) yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC),~80-100 μm thick, were produced on a commercial Ti 2 AlC MAX phase compound. They were oxidized in interrupted furnace tests for 500 h each, at five successive temperatures from 1100°-1300°C. The APS coating survived 2400 accumulated hours, failing catastrophically after 500 h at 1300°C. Porosity, large cracks, sintering, and high monoclinic YSZ phase contents were seen as primary degradation factors. The PS-PVD coating remained completely intact over 2500 total hours (65 cycles) including 500 h at 1300°C, exhibiting only fine porosity and microcracking, with less monoclinic. These Ti 2 AlC systems achieved a minimum α-Al 2 O 3 scale thickness of 29 and 35 μm, respectively, as compared to~6 ± 2 μm on average at failure for conventional bond coats on superalloys. Accordingly, times predicted from thermogravimetric analyses (TGA) of oxidation kinetics project an improvement factor of~25-50× for the time to achieve these scale thicknesses at a given temperature. Extreme oxidative TBC durability is achieved because the thermal expansion coefficient of Ti 2 AlC is only slightly different than those for α-Al 2 O 3 and YSZ. The strain energy term driving scale and TBC failure is therefore believed to be fundamentally diminished from the large compressive stress produced by higher expansion superalloys.Published by Elsevier B.V.

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Section: Ps-pvd Ysz On Ti 2 Alcmentioning

confidence: 53%

“…Dispersed porosity is known to at least decrease E and thus stress in the TBC. This is one mechanism by which PS-PVD coatings are expected to be more durable and strain-tolerant [20,21]. The polished crosssection displayed only minor amounts of interfacial porosity, minimal cracking, and YZTA reaction phase.…”

Section: Residual Stress and Strain Energy Factormentioning

confidence: 98%

Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Smialek

Harder

Garg

2016

Surface and Coatings Technology

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“…This process is very similar to standard APS or Low Pressure Plasma Spray (LPPS) methods, with the primary difference being that the pressure during deposition is in the range of 1x10 2 Pa compared to 1x10 6 Pa for APS and 8x10 4 Pa for LPPS. This facilitates vaporization of the molten particles [19,[22][23][24]. Tailoring the degree of vaporization enables deposition of splatlike lamellar morphologies at high feed rates to pseudo-columnar morphologies at (generally) low feed rates and high powers [23].…”

Section: Introductionmentioning

confidence: 99%

Process-structure-property relations for the erosion durability of plasma spray-physical vapor deposition (PS-PVD) thermal barrier coatings

Schmitt

Harder

Wolfe

2016

Surface and Coatings Technology

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New thermal barrier coating (TBC) materials and microstructures are under development to increase gas turbine operating temperatures beyond the ~1200°C threshold of standard 7 wt. % yttria stabilized zirconia (7YSZ). To deposit these advanced coatings, a new thermal spray deposition technique is used: Plasma Spray -Physical Vapor Deposition (PS-PVD). PS-PVD is capable of depositing from the vapor phase to yield strain tolerant columnar microstructures similar to Electron Beam -Physical Vapor Deposition (EB-PVD) or, alternatively, the traditional splat-like lamellar microstructure common to Air Plasma Spray (APS). This study investigates the process-structure relationships and resulting erosion response for plasma gas flow, amperage, and feed rate. It was found that in the selected design space, porosity and surface roughness vary © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ from ~12-26% and ~5-10 µm, respectively. Erosion behavior is discussed and the mechanism is identified to be heavily dependent upon the intercolumnar spacing. The lowest erosion rates are similar to EB-PVD, while the highest erosion rates were closer to APS. This is attributed to the hybrid nature of the PS-PVD process and provides an opportunity to tailor coatings with a wide range of properties, and thus performance.

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“…The presence of ZrO 2-x indicates that part of the oxygen content in the feedstock got lost during spraying [18]. Besides, small amount of monoclinic zirconia phase is detected, probably come from the insufficiently melted powder during spraying.…”

Section: Microstructure and Thermal Conductivitymentioning

confidence: 99%