Tungsten Carbide · Cobalt (88/12)
88% WC, 12% Co
- HVOF
- HVAF
WC-12Co is the workhorse of the thermal-spray wear-coating world, and for good reason. Eighty-eight percent tungsten carbide grains locked into a twelve-percent cobalt binder, sprayed hot and fast onto your part, then ground and polished to whatever finish your seals need. When people say carbide coating, nine times out of ten this is the chemistry they mean.
We apply it by HVOF (high-velocity oxy-fuel) — the process that fires a supersonic flame at the part and shoots the powder through it. The result is a dense, well-bonded layer around 1050 to 1350 HV on the Vickers hardness scale, better than 10,000 psi bond strength, and under one percent porosity. Pick your surface finish: 2-4 microinch Ra off a diamond wheel, or down to 1 microinch if you superfinish.
This is the coating that put HVOF on hydraulic-rod shops and landing-gear cells. Paper mills rely on it for calendar rolls. Downhole tools, print rolls, valve seats, flap tracks, pump plungers — anywhere the enemy is abrasion, not acid, WC-12Co earns its keep.
When the service picks up salt spray, wet acid, or sour gas, step up to WC-10Co-4Cr. Above about 930°F, step over to a chromium carbide. For everything else in between — call us and tell us the part. We'll quote it.
Technical data
- Hardness
- 1050-1350 HV300 typical HVOF; up to 1600 HV300 with HVAF and fine powder
- Bond strength
- 10,000-12,000+ psi (69-83 MPa); HVAF routinely exceeds 12,000 psi glue-test limit
- Max service temp
- 930-1000°F
- Max service temp
- 500-540°C
- As-sprayed porosity
- <1% (HVOF); <0.1% (HVAF)
- Typical thickness
- 3-15 (75-380 µm)
- Surface finish (Ra)
- 90-120 as-sprayed; 2-4 diamond-ground; 1 superfinished
Where it earns its keep
- Highest hardness in the WC-Co family at 12% binder — maximum abrasion and sliding-wear resistance
- Very dense (<1% porosity) as-sprayed when applied by HVOF or HVAF; near-zero open porosity means the coating blocks liquid ingress at the surface
- Qualified, mature chrome-plating replacement with a 25-year aerospace and hydraulic-rod service record
- Lower cost per pound than WC-CoCr since no chromium is added — the workhorse choice when the duty is wear and the environment is not aggressively corrosive
- Grinds and superfinishes to mirror Ra (1-2 µin), so sealing surfaces against seals and packings live longer than on hard chrome
Where it doesn't
- Decarburization — WC dissociates to W₂C and W above ~500°C (930°F), which softens the coating and drops corrosion and wear life; keep service temperatures below that or step up to a Cr₃C₂-NiCr
- Corrosion — with no chromium in the binder, WC-12Co is not the pick for salt-spray, marine splash, wet acid, or sour-gas service; specify WC-10Co-4Cr when the environment turns chemically aggressive
- Impact loading — 12% cobalt is the sweet spot for hardness; for high impact or thermal shock, consider WC-17Co which trades some hardness for toughness
Typical applications
- Hydraulic cylinder rods (chrome-plating replacement)
- Aircraft landing gear inner cylinders and flap tracks
- Paper-mill calendar rolls and anilox/print-roll sleeves
- Steel-mill rolls and corrugating rolls
- Oil & gas downhole gate valves, ball valves, mud-motor rotors, sucker-rod couplings
- Pump plungers, pulp-pump and slurry-pump impellers
- Valve seats and plug valves in abrasive slurry service
Wear modes addressed
- Three-body abrasion
- Two-body abrasion against hard counterfaces
- Particle erosion (dry and low-angle)
- Adhesive sliding wear
- Fretting wear
Industries
- Aerospace (airframe, landing gear, actuation)
- Oil & gas (downhole, wellhead, completions)
- Pulp & paper (calendar and press rolls)
- Printing (anilox and impression rolls)
- Hydraulic manufacture (cylinder-rod OEMs)
- Steel and aluminum mills
- Mining and mineral processing
Substrates
- Low-alloy and medium-carbon steels (4140, 4340, 1045)
- Stainless steels (17-4 PH, 410, 316)
- Nickel-base superalloys (Inconel 718, Waspaloy)
- Titanium alloys (Ti-6Al-4V, per qualified process)
- Aluminum bronzes (select applications)
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.
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Cincinnati Thermal Spray — 88/12 Tungsten Carbide Cobalt
“Vickers hardness 1150-1350; bond strength >10,000 psi; porosity <1%; 90-120 Ra as-sprayed, 2-4 Ra ground, 1 Ra superfinished; service to 1,000°F.”
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Kermetico — HVAF & HVOF WC-Co Properties
“HVAF WC-12Co: 1150-1600+ HV300, bond >80 MPa (>12,000 psi), porosity <0.1%, max service 510°C (950°F).”
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Oerlikon Metco DSMTS-0044.7 — 88WC12Co (Metco 72F-NS)
“Nominal composition 81 min %W, 11.5-13.0% Co; -45 +11 µm; applied by HVOF/APS for very dense well-bonded coatings with excellent abrasive-wear resistance.”
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Höganäs AMPERIT 518 — WC 12Co
“Workhorse WC-12Co grade for HVOF and HVAF, delivering dense wear-resistant coatings for hydraulic rod, roll and valve service.”
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Surface & Coatings Technology — Oxidation of HVOF WC-12Co vs WC-10Co-4Cr
“At 700-800°C WC-10Co-4Cr shows markedly higher oxidation resistance than WC-12Co, consistent with a ~500°C practical service limit for unchromed WC-Co.”
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VAC AERO — HVOF Coatings for Chrome Replacement
“HVOF WC-Co and WC-CoCr are the qualified replacements for hard chromium on landing gear inner cylinders, flap tracks and actuator rods.”
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.
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