PS 300 is NASA Glenn's self-lubricating composite coating for oil-free turbomachinery — the shaft coating that lets foil air bearings survive start-stop cycles before the air film develops. A specialty tribology solution licensed from NASA, built for a specific job.

The chemistry is a duplex microstructure: a NiCr matrix (~60 wt%) carrying Cr2O3 hard-phase particles (~20 wt%), silver (~10 wt%) as the low-temp startup lubricant, and a BaF2/CaF2 eutectic (~10 wt%) as the high-temp lubricant. Each phase engages at a different point on the temperature sweep — Ag from room temp up, fluorides above 400°C, Cr2O3 above 500°C — so friction actually drops as temperature climbs, from about 0.6 at 25°C to 0.2 at 650°C against Al2O3. Wear factors hold in the 10⁻⁵ mm³/N-m range. NASA testbeds have logged over 100,000 foil-bearing start-stop cycles on PS300 shafts without failure.

Versus the earlier PS200 (chromium carbide matrix), PS300 is denser as-sprayed, more stable through the temperature sweep, and polishes with silicon carbide — no diamond grinding. That's why it transitioned out of the lab.

Applications run narrow: foil-bearing journals, oil-free gas-turbine shafts, cryogenic compressor rotors, high-temp valve lift rods, sintering-furnace bearings. Tell us the shaft, the counterface, and the duty cycle — we'll tell you whether PS300 fits, or whether a Cr3C2-NiCr or Stellite makes more sense.

Technical data

Hardness: Composite microhardness typically 400-600 HV (matrix-dominated); NiCr matrix provides ductile binder while Cr2O3 hardener phase reaches ~900-1200 HV locally
Hardness (HRC): Not a primary spec — PS300 is a composite solid lubricant, not a wear-resistance-first coating; counterface hardness and tribofilm chemistry dominate behavior
Bond strength: Adhesion strength evaluated by NASA Glenn across nine substrate alloys; thermal-processing atmosphere and post-spray heat treatment are the primary levers on bond integrity
Max service temp: 1200°F (650°C) qualified service; preliminary evaluation extended to 1470°F (800°C) in oxidizing and reducing environments
Max service temp: 650°C qualified continuous; evaluated to 800°C per NASA TM preliminary work; stable across full temperature sweep below ambient to 650°C
As-sprayed porosity: Denser as-sprayed microstructure than PS200 (Cr3C2-matrix predecessor); duplex microstructure of hard NiCr/Cr2O3 phase + soft Ag and BaF2/CaF2 phases
Typical thickness: 10-30 mils (250-760 µm) typical for shaft and foil-bearing journal surfaces; thickness governed by post-spray grinding allowance
Surface finish (Ra): Chrome oxide matrix polishes readily with silicon carbide abrasives — no diamond grinding required, a major cost advantage over PS200

Where it earns its keep

Self-lubricating across the entire temperature sweep from below ambient to 650°C (qualified) / 800°C (evaluated) — Ag handles low-temp startup, BaF2/CaF2 eutectic engages above 400°C, Cr2O3 lubricates above 500°C
Lower manufacturing cost than predecessor PS200 — chrome oxide matrix polishes with silicon carbide abrasives, eliminating diamond grinding entirely
Denser, more dimensionally stable as-sprayed microstructure than PS200; duplex NiCr/Cr2O3 hard phase with Ag and fluoride lubricant phases
NASA-qualified for foil-bearing shaft service — demonstrated >100,000 start-stop cycles without failure in oil-free turbomachinery testbeds
Friction coefficient decreases with temperature (0.6 at 25°C → 0.2 at 650°C against Al2O3 at 1 m/s), and wear factor holds in the 10⁻⁵ mm³/N-m range
Operates in both oxidizing and reducing environments — rare combination for a solid lubricant coating

Where it doesn't

Licensed NASA Glenn technology (US Patent 5,866,518, 1999) — not a standard open-spec coating; commercial supply runs through ADMA Products and authorized licensees
Specialty R&D and niche commercial use — pricing and lead times reflect low-volume, high-precision powder blending (60 NiCr / 20 Cr2O3 / 10 Ag / 10 BaF2·CaF2 by wt%)
Composite solid lubricant, not a general-purpose wear coating — specify for oil-free, high-temperature sliding contact, not for abrasion or impact duty
Friction coefficient of ~0.2-0.6 is lubrication territory, not low-friction-bearing territory; it exists to prevent seizure and wear during start-stop, not to replace a lubricated rolling-element bearing
Thermal processing atmosphere matters — post-spray heat treatment and substrate chemistry directly affect adhesion strength; not a spray-and-ship coating
Successor materials (PS304, PS400) have extended the family to higher temperatures and cleaner processing; confirm PS300 is still the right point on the curve for the application

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.

NASA TM — Preliminary Evaluation of PS300: A New Self-Lubricating High Temperature Composite Coating for Use to 800°C
“PS300 is a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800°C, comprising a metal bonded chrome oxide coating with silver and BaF2/CaF2 eutectic solid lubricant additives.”
NASA — Tribological Evaluation of PS300: A New Chrome Oxide Based Solid Lubricant Coating Sliding Against Al2O3 From 25 to 650°C
“Friction ranged from 0.6 at 25°C to 0.2 at 650°C at 1 m/s sliding velocity. Al2O3 pin wear factors were in the 10⁻⁷ mm³/N-m range and PS300 coating wear factors were in the 10⁻⁵ mm³/N-m range.”
NASA — Industry Needs Fulfilled by Patented NASA PS300 Solid Lubricant Technology
“PS300 reduces friction and wear from below ambient to over 650°C. PS300 shaft coatings have successfully lubricated foil bearings for over 100,000 cycles without wearing out. NASA Glenn received patent #5,866,518 in 1999.”
NASA — Transition of PS300 Solid Lubricant Coating Technology to Field Aided by Demonstration on Key Substrate Alloys
“Nine different substrate candidate materials were tested including nickel-based superalloys, steels, stainless steels, aluminum alloys, and titanium alloys, evaluating coating strength and adhesion before and after exposure to high-temperature air.”
NASA Spinoff 2005 — Cost-Cutting Powdered Lubricant (PS300)
“ADMA Products licensed PS300 through GLITeC. Elliott Turbomachinery coated valve lift rods for steam turbine compressors operating up to 1,005°F — previously replaced every 2 years, PS300-coated rods projected to last 8 years, saving at least $3 million.”
NASA/TM—2009-215678 — NASA PS400: A New High Temperature Solid Lubricant Coating for High Temperature Wear Applications
“PS300 coatings are a series of self-lubricating composites with a duplex microstructure consisting of a hard nickel-chrome/chrome oxide phase with a soft noble metal and stable fluoride phases; PS400 succeeds PS300 with a denser, more dimensionally stable microstructure.”
US Patent 5,866,518 — Self-lubricating composite containing chromium oxide (DellaCorte / NASA)
“Self-lubricating composite containing a nickel-chrome binder, chromium oxide hardener, silver low-temperature lubricant, and barium fluoride/calcium fluoride eutectic high-temperature lubricant, for use in sliding bearing and seal applications to elevated temperature.”
A Systems Approach to the Solid Lubrication of Foil Air Bearings (DellaCorte, NASA Glenn)
“PS304 powder composition: 60 wt% NiCr + 20 wt% Cr2O3 + 10 wt% Ag + 10 wt% BaF2/CaF2 eutectic. NiCr acts as ductile binder, Cr2O3 as wear-resistant hardener, Ag and fluoride eutectic as low- and high-temperature solid lubricants respectively.”

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 300

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Sources

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