NASA PS200 is the original self-lubricating high-temperature plasma-sprayed composite — the first coating in NASA Glenn's PS-series lineage. Nickel-cobalt-bonded chromium carbide carries the load; silver shears at low-to-intermediate temperatures; a barium-fluoride/calcium-fluoride eutectic softens and behaves plastically at high temperatures. The lubricant phases are dispersed through the wear-resistant matrix — no separate lubricant layer, no liquid oil.

Developed by Sliney and Dellacorte at NASA Lewis (now Glenn), PS200 was validated as a Stirling-engine cylinder coating at 760°C in hydrogen and as a foil gas-bearing journal coating to 650°C. The optimized PS212 variant — 70% metal-bonded Cr₃C₂, 15% Ag, 15% BaF₂-CaF₂ eutectic — cut foil wear in half through 9,000 start/stop cycles and lubricates to 900°C. A Cr₂O₃ seal coat, diamond-ground to a thin film, fills surface porosity and drops friction further. Friction coefficient sits in the 0.2-0.4 band across 25-760°C; wear factor ~10⁻⁵ mm³/N·m at elevated temperature. The coating runs best in hydrogen or inert gas — in moist air, chromic oxide accumulates at the interface and raises friction.

This is specialty duty: oil-free turbomachinery, foil bearings, Stirling cylinders, gas-turbine shaft seals — places where liquid lubrication can't survive. It's not a wear coating, not a bond coat. It requires qualified spray parameters, diamond grinding, and historically NASA licensing. The lineage evolved through PS300, PS304, and PS400 — PS400 is the current state of the art — but PS200 is where the story starts.

Send us the duty: temperature, atmosphere, counterface, cycle count. We'll tell you whether it's PS200, a newer PS-series variant, or a different solution entirely.

Technical data

Hardness: Plasma-sprayed composite — not a single-phase hardness; carbide matrix phase ~800-1,100 HV, softened by Ag and fluoride lubricant inclusions; bulk coating behaves as a wear-resistant composite that preferentially shears at the lubricant phases
Bond strength: Plasma-sprayed to Inconel X-750, Rene 41, and Inconel 718 turbine alloys (precipitation-hardened to Rockwell C-40); diamond-ground to spec — bond adequate for Stirling engine cylinder service at 760°C in H₂ and for foil-bearing journals through 9,000+ start/stop cycles
Max service temp: 1,200°F (650°C) continuous for foil gas-bearing service; 1,400°F (760°C) demonstrated as Stirling cylinder coating in H₂; PS212 variant lubricates to 1,650°F (900°C)
Max service temp: 650°C foil-bearing continuous; 760°C Stirling cylinder (H₂ atmosphere); PS212 lubricates to 900°C
As-sprayed porosity: Inherent plasma-spray porosity — Cr₂O₃ seal coat (applied then diamond-ground to a thin film) fills surface pits and measurably reduces friction and wear
Typical thickness: ~12 mils (300 µm) as-sprayed, ground to ~10 mils (250 µm) final (comparable PS400 variant spec); diamond-ground to final thickness and surface finish before service
Surface finish (Ra): Diamond-ground to low Ra for foil-bearing and cylinder service; PS200 chromium-carbide matrix requires diamond grinding (PS300/PS400 oxide variants polish with SiC — a key reason NASA evolved away from PS200)

Where it earns its keep

Self-lubricating solid coating — the Ag and BaF₂-CaF₂ phases exude at temperature and act as lubricant phases, eliminating any need for liquid lubrication where oil cannot survive
Wide temperature spectrum — Ag handles low-to-intermediate temperatures, fluoride eutectic handles high temperatures; PS200 covers ambient-to-760°C, PS212 extends to 900°C
Validated by NASA Glenn (originally Lewis) in flight-grade duty cycles — Stirling cylinder in H₂ at 760°C, foil-bearing journals through 9,000 start/stop cycles
Plasma-sprayed composite — no secondary impregnation, no bonded separate lubricant layer; the lubricant phases are dispersed throughout the wear-resistant carbide matrix
Backbone of the NASA PS-series lineage — PS200 → PS212 → PS300 → PS304 → PS400 — the published tribology record spans decades and covers every major heat-engine use case
NASA-developed and published — patent and literature trail (Sliney, Dellacorte, Edmonds) gives engineers a defensible specification basis for aerospace and advanced-machinery programs

Where it doesn't

Specialty coating — this is not a wear coating, not a bond coat, and not a corrosion coating; it is a high-temperature self-lubricating tribological coating for specific sliding-contact duty
Licensing and commercial status — NASA-developed; commercial application historically required licensing; PS/PM200 never reached wide commercialization (starting cobalt-bonded carbide powder is expensive)
Diamond-grinding finish is required for the chromium-carbide matrix — adds cost versus the later PS300/PS400 oxide-matrix variants that polish with SiC
Atmosphere-sensitive — best tribology in H₂ and inert gas; in moist air, Cr₂O₃ accumulates at the interface and raises friction/wear; applying a Cr₂O₃ seal coat mitigates surface porosity effects
Somewhat abrasive to counterface materials — a known characteristic that drove the PS300 reformulation with an oxide (already-oxidized) matrix
Not the current state of the art — NASA Glenn has evolved the lineage through PS300, PS304, and PS400; PS400 is the current NASA-published best-in-class for foil-bearing and oil-free turbomachinery duty
Plasma-spray parameters are specific to the powder blend (Cr₃C₂-NiCo-Ag-BaF₂-CaF₂) — qualified spray recipe, standoff, and powder-feed control are load-bearing; this is not a drop-in for a generic thermal-spray booth without a qualified procedure

Sources

Data points on this page draw on the following published references. Nothing here replaces a material-specific review by our process engineers — but it's the working starting point.

Sliney (NASA Lewis) — Self-Lubricating Coatings for High-Temperature Applications (NASA TM, 1988)
“PS200 was successfully tested as a cylinder coating in a Stirling engine at 760°C in a hydrogen atmosphere, and as a backup lubricant for gas bearings to 650°C; subsequent optimization (PS212) improved tribological properties by increasing the solid lubricant content to 15% Ag + 15% BaF₂-CaF₂.”
Sliney, Benoy, Korenyi-Both, Dellacorte — Tribology and Microstructure of PS212 with a Cr₂O₃ Seal Coat (NASA TM-106768, 1994)
“PS212 is a plasma-sprayed metal-bonded chrome-carbide coating with solid-lubricant additives with lubricating properties to about 900°C; a Cr₂O₃ seal coat diamond-ground to a thin layer fills the surface pits of the PS212 coating and reduces friction and wear.”
NASA CR-179649 — Composition Optimization of Chromium-Carbide Based Solid-Lubricant Coatings for Foil Gas Bearings at Temperatures to 650°C
“Optimum composition PS212: 70 wt% metal-bonded Cr₃C₂ / 15 wt% Ag / 15 wt% BaF₂-CaF₂ eutectic; plasma-sprayed on Inconel 718 journals, diamond-ground; reduced foil wear by a factor of two with coating wear well within acceptable limits through 9,000 start/stop cycles at 14 kPa.”
NASA — Effects of Atmosphere on the Tribological Properties of a Chromium-Carbide-Based Coating for Use to 760°C
“PS200 contains chromium carbide wear-resistant base with Ag and BaF₂-CaF₂ eutectic lubricants; pin-on-disk in helium, hydrogen, and moist air 25-760°C; specimens tested in hydrogen exhibited the best tribological properties; chromic oxide at the sliding interface correlates directly with friction coefficient.”
Dellacorte & Edmonds — Preliminary Evaluation of PS300: A New Self-Lubricating High-Temperature Composite Coating for Use to 800°C (NASA TM-107056, 1995)
“PS300 is a metal-bonded chrome-oxide coating with Ag and BaF₂-CaF₂ eutectic solid-lubricant additives; in pin-on-disk to 650°C, PS300 exhibits friction and wear properties comparable to PS200 while eliminating diamond grinding — PS200's chromium-carbide matrix required diamond finish, a major PS300 cost advantage.”
Sliney (NASA Lewis / DOE) — Composite Bearing and Seal Materials for Advanced Heat Engine Applications to 900°C (1990)
“Plasma-sprayed PS200 and PS212 and powder-metallurgy PM212 composites combine metal-bonded Cr₃C₂ with Ag and fluoride additives; lubrication from room temperature to 900°C in bench testing; PM variant enables bushings and cylinders that cannot be readily plasma-sprayed.”
Dellacorte & Edmonds — NASA PS400: A New High-Temperature Solid Lubricant Coating (NASA TM-2009-215678)
“The PS-series lineage (PS200 → PS212 → PS304 → PS400) originally developed to lubricate nickel-superalloy shafts operating against foil air bearings in oil-free turbomachinery; PS400 builds up ~300 µm as-sprayed, ground to ~250 µm final; friction coefficient 0.16 at 500°C for PS400 vs 0.23 for PS304.”
Sliney & Dellacorte — The Tribology of PS212 Coatings and PM212 Composites for Lubrication of Ti-6Al-4V Components of a Stirling Engine Space Power System (Tribology Trans., 1995)
“Plasma-sprayed PS212 and sintered PM212 composites lubricating Ti-6Al-4V Stirling-engine components for space-power applications; coatings prepared by powder blending, plasma-sprayed onto Inconel 718 journals, and diamond-ground to desired thickness and surface finish.”
NASA — Transition of PS300 Solid Lubricant Coating Technology to Field Aided by Demonstration on Key Substrate Alloys
“PS300 originally developed at NASA Glenn to lubricate nickel-based superalloy shafts operating against foil air bearings in oil-free turbomachinery; performance from below room temperature to over 650°C in both oxidizing and reducing environments; technology available for non-exclusive licensing.”
NASA Spinoff 2001 — Rotapower / PS200 Plasma-Applied Engine Coating
“The PS200 plasma-applied engine coating was developed at Glenn Research Center through SBIR funding; licensed to Moller International / Freedom Motors for rotary-engine housings — a representative commercial licensing path for NASA-developed PS-series coatings.”

Material data on this page is provided as a general reference and can vary by lot, substrate, and application. Contact HTS to confirm the right material and specification for your specific part.

PS 200

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Sources

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