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HVOF Carbide Coating

Thermal spray · Spray applied

HVOF accelerates WC-Co or Cr3C2-NiCr particles in a supersonic combustion jet to make dense 50–500 µm wear coatings.

CNC machiningSheet metalCastingHigh cost $$$$Conductive
Quote a part with HVOF coatingCompare thermal spray
HVOF Carbide Coating on a machined part

What is HVOF coating?

Aerospace WC systems are commonly qualified to AMS 2447 as hard-chrome replacements.

How it works

Fuel and oxygen burn at high pressure and accelerate heated powder toward a grit-blasted substrate. Particles deform and interlock as dense splats with lower oxide and porosity than many plasma-sprayed deposits. WC-Co suits lower-temperature severe wear; Cr3C2-NiCr retains properties at higher temperatures. Parts are sprayed oversize and diamond-ground to final size.

Why specify it

  • Dense carbide wear surface
  • 50–500 µm practical build range
  • Typical bond strength at least about 70 MPa for qualified systems
  • Avoids hexavalent-chrome plating baths

Where it falls short

  • Line-of-sight process
  • Requires aggressive grit preparation
  • Carbide coatings require diamond grinding
  • Geometry can shadow or overheat

HVOF coating at a glance

HVOF coating is strongest on corrosion protection (78 of 100) and surface hardness (77 of 100), at a high cost.

Corrosion protectionVery good78 / 100
Surface hardnessVery good77 / 100
Cosmetic qualityFair35 / 100
LubricityFair35 / 100
Relative costHigh94 / 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.

HVOF coating 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
Hardness1,000–1,400 HV
Max service temp.500 °C932 °F
Thickness
100–300 µm after grinding
Hardness
1,000–1,400 HV — WC-Co and WC-CoCr typically 1000–1400 HV; Cr3C2-NiCr is often slightly lower. Specify feedstock.
Electrical
Conductive
Colours
  • grey
  • dark grey
Appearance
Dense grey matte as sprayed; smooth metallic grey after grinding.

Where HVOF coating 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. HVOF coating 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 88Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERPlasma sprayHard chromeType II anodizePowder coatZinc plateZinc-nickelDLCTiN PVDTin plateCadmium plateE-coatCerakoteWet paintHot-dip zincNitridingHVOF coating — corrosion 78, hardness 77HVOF coating
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 88Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERPlasma sprayHard chromePowder coatZinc plateHVOF coating — corrosion 78, hardness 77HVOF coating
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for HVOF coating

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

HVOF SPRAY DESIGNATED JOURNAL WC-10Co-4Cr PER AMS 2447, 250–300 µm FINISHED THICKNESS; DIAMOND GRIND TO Ø50.000 ±0.008 mm, Ra 0.20 µm MAX; TENSILE BOND 70 MPa MIN

Which materials take HVOF coating?

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

Material familyVerdictNotes
Nickel Alloy
YesCompatible with suitable bond system.
Stainless Steel
YesCommon with qualified preparation.
Steel
YesCommon for shafts and landing gear.
Aluminum
With carePossible with low heat input and compatible bond coat.
Titanium
With careControl grit, bond coat, 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 HVOF preparation and heat are unsuitable.
Zinc Alloy
NoMelting point is too low for conventional HVOF or plasma spray.

How HVOF coating is applied, and what it does to the part

  1. 1Mask
  2. 2Grit blast
  3. 3Apply bond coat if specified
  4. 4HVOF spray carbide
  5. 5Diamond grind
  6. 6Superfinish if required
  7. 7Inspect
DimensionsState final thickness after grinding; provide grind stock and avoid feather edges by using runouts.
Build-up per side50–500 µm — Apply oversize and diamond-grind to final dimension and finish.
MaskingUsually needed. Protect threads, seal lands, bores, and non-coated areas from grit and overspray.
ElectricalConductive
Temperature limit500 °C (932 °F) continuous
AppearanceDense grey matte as sprayed; smooth metallic grey after grinding.
Added lead time12–25 working days on top of the bare part

Design rules for HVOF coating

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

  1. Specify WC-CoCr or Cr3C2-NiCr.Temperature and corrosion performance differ.
  2. Add coating runouts.Feather edges chip during grinding and service.
  3. State finished thickness and grind size.As-sprayed dimensions are not final.
  4. Define bond test and porosity limits.Process quality cannot be inferred from appearance.

HVOF coating versus the alternatives

Finishes engineers weigh against HVOF coating, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
HVOF coating
this page
787735$$$$50–500 µm—
Plasma Spray Coating
HVOF coating vs Plasma Spray Coating →
606830$$$$50–500 µmceramic or thermal-barrier feedstock is required
Hard Chrome Plating
HVOF coating vs Hard Chrome Plating →
407345$$$$10–500 µmlegacy drawing requirements cannot be changed
CorrosionHardnessCosmeticLubricityEconomy
HVOF coatingPlasma Spray Coating

The radar overlays HVOF coating with Plasma Spray Coating, its most common alternative — chosen ceramic or thermal-barrier feedstock is required. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

HVOF Carbide Coating is a high-cost finish ($$$$): more expensive than about 96 % 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 time12–25 working days
RoHSCompliant
NotesHVOF avoids hard-chrome plating baths, but cobalt/nickel/chromium-containing spray dust requires controlled collection.

What HVOF coating is used for

  • Landing-gear journals
  • Hydraulic rods
  • Pump shafts
  • Oil and gas valves

HVOF coating — frequently asked

HVOF vs hard chrome: which is better?

HVOF carbide is typically 50–500 µm and about 1000–1400 HV, and offers high wear resistance without a hexavalent-chrome bath. Hard chrome can be easier on some internal geometries but carries cracking and environmental constraints.

What does AMS 2447 cover?

AMS 2447 is the usual aerospace specification for HVOF tungsten-carbide coatings used as hard-chrome replacements. AMS 2437 is a plasma-spray ceramic specification, not an HVOF carbide document. State alloy, class, revision, and bond-test limits on the drawing.

How thick is HVOF coating?

Typical finished thickness is 50–500 µm, often 100–300 µm. The coating is sprayed oversize and ground back.

Does HVOF coating need grinding?

Yes for precision shafts, seal lands, and bearing surfaces. WC-based coatings usually require diamond grinding followed by optional superfinishing.

HVOF WC-Co vs Cr3C2-NiCr: which should I use?

WC-Co or WC-CoCr is favored for severe wear at moderate temperature. Cr3C2-NiCr retains wear and oxidation resistance at higher temperatures, commonly up to roughly 870 °C.