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Plasma Spray Coating

Thermal spray · Spray applied

Plasma spray propels molten or softened ceramic or metallic powder onto a grit-blasted substrate to build 50–500 µm coatings.

CNC machiningSheet metalCastingHigh cost $$$$Insulating
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Plasma Spray Coating on a machined part

What is Plasma spray?

It is chosen for thermal barriers, electrical insulation, wear, and dimensional restoration.

How it works

An electric arc ionizes process gas into a plasma jet that heats injected powder. Flattened droplets strike a roughened substrate and solidify as overlapping splats, mechanically interlocking with the surface. Bond coats are common beneath ceramics. The coating is usually sprayed oversize, then ground or lapped to final dimension; substrate bulk temperature can remain far below the plasma temperature.

Why specify it

  • 50–500 µm build capability
  • Ceramic and metallic feedstocks
  • Typical tensile bond strength about 20–70 MPa
  • Can be ground to final size

Where it falls short

  • Lamellar porosity is normal
  • Line-of-sight access
  • Grit blasting changes surface
  • As-sprayed tolerance and roughness are coarse

Plasma spray at a glance

Plasma spray is a middle-of-the-range finish; its best score is surface hardness (68 of 100), at a high cost.

Corrosion protectionGood60 / 100
Surface hardnessGood68 / 100
Cosmetic qualityLow30 / 100
LubricityLow20 / 100
Relative costHigh88 / 100
CorrosionHardnessCosmeticLubricityEconomy

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

Plasma spray key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among thermal spray finishes.

Thickness50–500 µm2–20 mil
Hardness500–900 HV
Max service temp.1,000 °C1,832 °F
Thickness
100–300 µm; thicker engineered systems require qualification
Hardness
500–900 HV — Alumina and alumina-titania topcoats commonly 500–900 HV as sprayed; zirconia TBCs are more porous and lower.
Electrical
Insulating
Colours
  • white
  • grey
  • black
  • feedstock-dependent
Appearance
Textured matte as sprayed; smooth ground finish on functional surfaces.

Where Plasma spray sits among all finishes

Surface hardness (Vickers, log scale) against corrosion protection (salt-spray hours, log scale) for every coating FabDigit offers, one cloud per finish group. Plasma spray is highlighted; hover a dot for its name or open the full map.

02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finisheshard, low corrosion protectionhard and protectiveprotective, softsoft, little protectionType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERHVOF coatingType II anodizePowder coatZinc plateZinc-nickelHard chromeDLCTiN PVDTin plateCadmium plateE-coatCerakoteWet paintHot-dip zincNitridingPlasma spray — corrosion 60, hardness 68Plasma spray
02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finishesType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27E-coat — corrosion 83, hardness 15Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERHVOF coatingPowder coatZinc platePlasma spray — corrosion 60, hardness 68Plasma spray
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for Plasma spray

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Drawing call-out

PLASMA SPRAY DESIGNATED SURFACE WITH NiCr BOND COAT 50–100 µm PLUS Al2O3-13TiO2 TOPCOAT 200–300 µm; GRIND TO Ø25.000 ±0.010 mm; BOND STRENGTH 35 MPa MIN PER ASTM C633

Which materials take Plasma spray?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material familyVerdictNotes
Nickel Alloy
YesStandard for thermal-barrier systems.
Stainless Steel
YesCommon substrate.
Steel
YesCommon after grit blast and optional bond coat.
Aluminum
With careUse compatible bond coat and low heat input.
Titanium
With careControl grit contamination and heat input.
Brass
LimitedGrit and jet heat readily distort low-melting brass.
Copper Alloy
LimitedSoft and heat-sensitive; use aggressive cooling and a qualified bond coat only.
Magnesium Alloy
NoGrit and spray heat readily ignite or distort magnesium.
Polymer
NoConventional plasma-spray heat and grit preparation are unsuitable.
Zinc Alloy
NoMelting point is too low for conventional HVOF or plasma spray.

How Plasma spray is applied, and what it does to the part

  1. 1Mask
  2. 2Grit blast
  3. 3Apply bond coat if required
  4. 4Plasma spray feedstock
  5. 5Seal if specified
  6. 6Grind or lap
  7. 7Inspect thickness and bond
DimensionsDo not tolerance the as-sprayed envelope as a precision surface; leave grinding stock and state final coating thickness after grinding.
Build-up per side50–500 µm — Spray oversize and grind designated functional surfaces to final dimension.
MaskingUsually needed. Mask threads, seal lands, bores, and all non-spray areas against grit and overspray.
ElectricalInsulating
Temperature limit1,000 °C (1,832 °F) continuous
AppearanceTextured matte as sprayed; smooth ground finish on functional surfaces.
Added lead time10–20 working days on top of the bare part

Design rules for Plasma spray

What to decide on the drawing before the part goes to the finisher.

  1. Specify feedstock composition.Plasma spray describes a process, not one material.
  2. State thickness after grinding.Finishing removes part of the sprayed build.
  3. Provide runouts beyond the finish area.Mask edges otherwise create weak feathered coating.
  4. Define bond-strength test and minimum.Bond depends on preparation and material system.

Plasma spray versus the alternatives

Finishes engineers weigh against Plasma spray, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
Plasma spray
this page
606830$$$$50–500 µm—
HVOF Carbide Coating
Plasma spray vs HVOF Carbide Coating →
787735$$$$50–500 µma denser carbide wear coating is required
CorrosionHardnessCosmeticLubricityEconomy
Plasma sprayHVOF Carbide Coating

The radar overlays Plasma spray with HVOF Carbide Coating, its most common alternative — chosen a denser carbide wear coating is required. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Plasma Spray Coating is a high-cost finish ($$$$): more expensive than about 93 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time10–20 working days
RoHSCompliant
NotesCompliance depends on feedstock; dust and fume extraction are required.

What Plasma spray is used for

  • Turbine thermal barriers
  • Electrical insulation
  • Pump sleeves
  • Roll restoration

Plasma spray — frequently asked

How thick is plasma spray coating?

Typical engineered coatings are 50–500 µm, often 100–300 µm. Thick builds need staged spraying and stress control.

How strong is plasma spray adhesion?

Tensile bond values often fall around 20–70 MPa when tested by ASTM C633. Feedstock, bond coat, grit profile, and test adhesive control the result.

Does plasma spray need grinding?

Precision wear surfaces are normally sprayed oversize and ground or lapped. As-sprayed texture and thickness variation are too coarse for close fits.

Plasma spray vs HVOF: what is the difference?

Plasma spray handles high-melting ceramics and thermal barriers. HVOF generally produces denser, lower-oxide carbide or metallic wear coatings.

Can aluminum be plasma sprayed?

Yes with controlled grit blasting, bond coat, and heat input. Thin walls need fixturing because local heating and residual stress can distort them.