Metco 12C is the entry-tier self-fluxing Ni alloy — a classic workhorse powder in the Oerlikon Metco lineup that's been laying down restoration coatings on pump sleeves and printing rolls for decades. Nominal chemistry is Ni-balance with 7.5-11% Cr, 3-3.7% Si, 1.7-2.2% B, 2.5% Fe; the spec has drifted slightly across datasheet revisions but behavior is consistent: flame-spray it on, fuse at ~1,050°C, and you get a metallurgically bonded 35-40 HRC layer a shop can finish with carbide tooling rather than forcing a grind-only plan.

Where 12C earns its keep: general industrial wear restoration — pump sleeves, plunger pumps, shaft seals, printing rolls, ag components, boiler-feed pump parts — where moderate hardness is plenty and cost matters. It's meaningfully cheaper than a cobalt-base Stellite answer and easier to machine than the high-chrome self-fluxing grades.

When to step up: need 55+ HRC for heavier abrasion, go Colmonoy 6 or Metco 16C; impact or service above 1,000°F, go Stellite 6; fine-particle slurry erosion, Colmonoy 88. Also be aware 12C is crack-sensitive on thick deposits (~20% fuse shrinkage) and must be fused — as-sprayed flame coatings aren't service-ready.

Got a worn sleeve or plunger where machinability and cost both matter? Send us a drawing.

Technical data

Hardness: ~350-420 HV after fuse (derived from 35-40 HRC); as-sprayed unfused flame deposits are softer and porous and should not be run unfused in service
Hardness (HRC): 35-40 HRC after flame spray + fuse (per Oerlikon Metco DSMTS-0026.7); macrohardness target 40 HRC, microhardness floor 35 HRC
Bond strength: Metallurgically bonded after the fuse cycle — substrate-limited, not coating-limited; as-sprayed flame coatings are mechanical bond only (typical 4,000-6,000 psi per ASTM C633 on NiCrBSi family) and are expected to be fused before duty
Max service temp: ~1,000°F (540°C) continuous — above that, chromium boride network softens and oxidation accelerates
Max service temp: ~540°C continuous
As-sprayed porosity: Flame spray unfused ~5-10%; after fuse cycle <1-2%; HVOF + fuse ~1%
Typical thickness: Flame spray + fuse 15-40 mils typical; thicker sections risk shrinkage cracking (fuse cycle pulls ~20% linear shrink)
Melting range: ~1,915°F (1,046°C) melting; approximate fusing temperature ~1,920°F (1,050°C) per Oerlikon DSMTS-0026.7
Density: ~8.0 g/cc (typical for Ni-Cr-B-Si self-fluxing family; Oerlikon lists particle size -125 +45 μm or -120 +325 mesh depending on variant)

Where it earns its keep

Classic workhorse self-fluxing Ni alloy — one of the longest-running spray-and-fuse powders in the trade, with decades of field history
Self-fluxing chemistry: boron and silicon scavenge oxides during the fuse cycle, so the deposit finishes metallurgically bonded and dense with no separate flux
Machinable with carbide tooling at 35-40 HRC — finishes to print without forcing a grind-only strategy
Meaningfully cheaper per pound than cobalt-base Stellite alternatives — no cobalt premium
Moderate material cost plus forgiving flame-spray + fuse process makes it a go-to for straightforward restoration work
Well-documented application history across pumps, printing rolls, ag, and general MRO — easy to specify, easy to source

Where it doesn't

Lower hardness than Colmonoy 6 / Colmonoy 88 / Metco 16C — not the right pick when you need 55+ HRC wear life
Service temperature limited to ~1,000°F (540°C); above that, hardness and oxidation resistance both drop
Crack-sensitive on thick deposits — the ~20% linear shrink during fuse means multi-pass thick sections need careful thermal management
Flame-sprayed deposits must be fused before service — as-sprayed is porous and only mechanically bonded
Lower chromium than higher-grade Ni self-fluxing alloys means reduced corrosion resistance in aggressive chemistry
Not a fit for high-impact or high-shock service — cobalt-base Stellite 6 is the better answer there

Which process, when?

Flame spray + fuse is the traditional and most economical route for Metco 12C — apply a 15-40 mil coating with an oxyacetylene powder gun, then fuse with a neutral oxyacetylene flame at ~1,050°C (1,920°F) to drive the coating into a dense, metallurgically bonded layer. HVOF can be used to lay down a denser as-sprayed layer before fusing where part geometry benefits from the tighter initial deposit. PTA welding is also listed by Oerlikon Metco as acceptable for 12C on parts that can accept weld-overlay heat input and where precise placement matters. Regardless of route, the deposit needs the fuse/melt step to realize the self-fluxing chemistry's full benefit.

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.

Oerlikon Metco Joining & Cladding — Metco 12C Materials E-Guide
“Self-fluxing, alloy powder recommended where a hardness of HRC 35 to 40 with a shrink of approximately 20% during fusing is sufficient for wear resistance and where machinability of the coating is important. Chemistry: Ni / 7.5Cr / 3.5Si / 2.5Fe / 1.7B / 0.25C. Melting ~1046°C, approximate fusing temperature ~1050°C. Particle size -125 +53 μm. Applied via laser cladding, PTA, or spray and fuse powder welding.”
Oerlikon Metco DSMTS-0026.7 — Nickel and Cobalt Self-Fluxing Alloys (2016)
“Metco 12C: self-fluxing Ni-Cr-B-Si alloy. Fused hardness HRC 35-40. Approximate fusing temperature 1,046°C. Approximately 20% shrink during fusing. Maximum service temperature 540°C. Used where moderate hardness and coating machinability matter.”
Oerlikon Metco Thermal Spray Materials Guide
“Metco 12C chemistry listed as Ni / 11Cr / 3.7Si / 2.75Fe / 2.2B / 0.5C, particle size -125 +45 μm; classed with nickel-based self-fluxing alloys for spray-and-fuse applications requiring a machinable moderate-hardness coating.”
Thermal Spray Depot — Metco Powder Product Listing
“Metco 12C self-fluxing thermal spray powder, chemistry Ni-10Cr-3Si-3B-2.5Fe, particle size -120 +325 mesh; supplied for flame spray and fuse applications.”
Oerlikon Metco DSM-0263.6 — Nickel- and Cobalt-Based Self-Fluxing Alloys for Thermal Spray
“Nickel self-fluxing alloy powders are first applied via thermal spray and then fused to develop a fully dense microstructure that is free of oxides and porosity and metallurgically bonded to the substrate; used for wear restoration on pump components, shaft sleeves, and general industrial MRO parts.”
Welding in the World — Microstructural analysis of flame-sprayed and PTA-deposited nickel-based self-fluxing alloy coatings (2024)
“NiCrBSi self-fluxing coatings deposited by flame spray (with post-fuse) and PTA form dense, metallurgically bonded microstructures; lower-chromium grades in the family emphasize machinability and dimensional restoration rather than peak hardness.”
Powder Alloy Corporation — Self-Fluxing Powders
“Self-fluxing Ni-Cr-B-Si powders span a hardness range from ~20 HRC up through 60+ HRC depending on chromium, boron, and tungsten-carbide loading; lower-chrome grades are chosen where machinability and cost govern the selection.”
HTS Coatings — Metco 16C Material Information
“Metco 16C is a nickel-based self-fluxing alloy with 16% chromium, 4% silicon, 4% boron, 3% copper, 3% molybdenum, 2.5% iron, 0.5% carbon, and nickel balance; coating hardness in the 60 HRC range and capable of thick coatings up to ~3 mm without cracking — the higher-hardness, higher-corrosion step up from entry-tier 12C.”

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.

Metco 12C

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Which process, when?

Sources

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