Aluminum bronze is the marine go-to for shaft-sleeve and bearing restoration — nominal 91% Cu / 9% Al laid down by twin-wire arc, flame wire, or HVOF on worn propeller shafts, pump bushings, valve trim, and seawater hardware. Chemistry matches Oerlikon Metco Sprabronze AA, TAFA 10T, and 10E Aluminium Bronze — three names for the same family. Hardness ~150-220 HV (roughly twice standard tin bronze), density ~7.06 g/cc, tensile ~29,000 psi, bond from 4,000-8,000 psi on arc up to >11,000 psi on HVOF per A&A and Kermetico. Machines cleanly with carbide tooling to ~32 Ra.

Two properties earn its keep. First: the aluminum forms a self-healing Al2O3 film that shrugs off seawater — the reason naval architecture and CDA Pub 222 spec it across submarine seawater piping, valves, low-noise propellers, and rudder bearings. Second: it is genuinely non-galling against steel. Where stainless-on-stainless cold-welds under boundary lubrication, copper-aluminum slides. The as-sprayed porosity is a feature — it holds oil at bearing interfaces longer than solid bar. Thermal limit ~260°C continuous; not a heavy-abrasion coating (step up to carbide for that).

HTS applies aluminum bronze by twin-wire arc, flame wire, and HVOF — one alloy, three routes, same seawater-ready finish. Got a worn shaft sleeve or pump bushing? Send a sketch.

Technical data

Hardness: ~150-220 HV as-sprayed across the aluminum-bronze thermal-spray family — softer end (~150 HV) for twin-wire arc and flame-wire deposits, harder end (~200-220 HV) for HVOF and HVAF variants; roughly twice the hardness of standard tin-bronze coatings per Oerlikon Metco Sprabronze AA literature
Bond strength: Tensile bond typically 4,000-8,000 psi for arc-spray and flame-wire on grit-blasted steel (ASTM C633); HVOF aluminum bronze reports >11,000 psi (>75 MPa) on carbon steel per HVAF/HVOF aluminum-bronze studies — higher than conventional bronze deposits and sufficient for pump, bearing, and shaft-sleeve service
Max service temp: ~400-500°F (200-260°C) continuous — aluminum bronze loses hardness above this band and the protective Al2O3 film degrades in oxidizing service above ~600°F
Max service temp: ~200-260°C continuous
As-sprayed porosity: Twin-wire arc and flame-wire ~3-8% (characteristic of the process — the porosity is functional, holding lubricant at bearing interfaces); HVOF ~1-3%; HVAF <1% per Kermetico data
Typical thickness: Twin-wire arc 10-60 mils on bearing surfaces and shaft-sleeve restoration; flame-wire 5-40 mils; HVOF 5-30 mils; single deposits up to 100+ mils practical on propeller-shaft journals with controlled pass sequencing
Melting range: 1,615-1,900°F (A&A Company metallized aluminum bronze datasheet)
Density: 7.06 g/cc sprayed deposit (A&A Company); bulk wrought aluminum bronze ~7.5-7.8 g/cc

Where it earns its keep

Excellent seawater corrosion resistance — the aluminum content forms a passive Al2O3 film that self-heals in chloride environments; standard material for marine propeller-shaft work
Outstanding anti-galling behavior against mating steel shafts — the inherent lubricity of copper-aluminum prevents cold welding, the common failure mode of stainless-on-stainless pairs
Porous as-sprayed structure is a feature, not a bug — the micropores hold oil and hold onto lubricant longer than a solid-bronze bushing, giving boundary-lubricated bearing surfaces real margin
Roughly twice the hardness and strength of standard tin-bronze coatings (Oerlikon Metco Sprabronze AA literature) while retaining machinability
Moderate cost — materially cheaper than cobalt-base Stellite or tungsten-carbide alternatives and far cheaper than machining a bearing from solid aluminum-bronze bar stock
Easily machined, tapped, drilled, and milled with standard carbide tooling — finishes to ~32 Ra without needing diamond grinding
Effective bond coat layer for subsequent harder thermal-spray deposits on difficult substrates
Non-ferrous, non-sparking, tarnish-resistant — qualified for food-industry and explosive-atmosphere service
Applied by every wire-fed thermal-spray process HTS runs: twin-wire arc, flame wire, HVOF

Where it doesn't

Not a hard-wear coating — ~150-220 HV is modest; for heavy abrasion or severe erosion step up to chromium carbide, tungsten carbide, or Colmonoy family
Service temperature capped at ~200-260°C continuous — the Al2O3 protective film degrades and the deposit softens above that
Galvanic couple: aluminum bronze is cathodic to aluminum and zinc; isolate from anodic structures or accept the galvanic budget
Arc- and flame-wire deposits are porous and must be sealed (epoxy, silicone, or specialty sealers) when used in aggressive aqueous service where through-porosity would let corrodent reach the substrate
Oxidation of copper during spray — deposits contain Cu2O and Al2O3 inclusions; this is characteristic and generally acceptable but does reduce conductivity vs wrought bar
Not the right choice in ammonia or ammonia-bearing environments — copper alloys stress-corrode
For naval nickel-aluminum-bronze requirements (submarine seawater systems), a higher-alloy Ni-Al-bronze wire may be specified — confirm the exact marine spec before substituting

Which process, when?

Twin-wire arc spray is the workhorse for aluminum bronze — the fastest, most economical way to lay down 10-60 mil bearing surfaces on shaft sleeves, pump bushings, and propeller journals. Arc-spray deposits are moderately porous, which is a feature for boundary-lubricated bearing interfaces. Flame wire spray gives a slightly finer splat structure and is the right pick on thin-walled or thermally sensitive parts where arc-spray heat input would distort geometry. HVOF aluminum bronze produces the densest (>95% theoretical) and highest-bond (>11,000 psi) deposits, recommended where cavitation resistance, higher hardness, or a seal-ready surface matters from the gun. HVAF pushes porosity below 1% with bulk-like deposit properties per Kermetico data. For most marine and pump shaft-sleeve work, twin-wire arc at 10-60 mils is the standard and cost-optimized call; reserve HVOF for performance-critical impellers, cavitation-exposed surfaces, and food-grade machinery where a tight finish matters.

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.

A&A Thermal Spray Coatings — Material Spotlight: Aluminum Bronze
“HVOF Aluminum Bronze composition 9.5% Al, 1% Fe, balance Cu. HVOF Sprayed Aluminum Bronze coatings exhibit higher tensile bond strength than conventional aluminum bronze deposits. Metallized variants have twice the hardness and strength of other standard bronze alloys. Recommended for soft bearing applications, cavitation, hard surfaces, fretting — easily tapped, drilled, milled, and machined.”
A&A Company — Metallized Aluminum Bronze Datasheet
“Composition Cu 90% / Al 9% / Fe 1%. Hardness Rb 82. Density 7.06 g/cc. Tensile strength 29,000 psi. Melting 1,615-1,900°F. Coating weight 0.045 lb/ft² per 0.001 in. Applications: bearings in steel industry, reclaiming aluminum/bronze components, propeller shafts for seawater operation, pump impellers, bronze castings, plungers, armature bushings. Can be ground or machined at low speed with carbide tools. Extremely effective bond coat.”
Oerlikon Metco — Sprabronze AA Wire Material
“Produces dense, moderately wear-resistant coatings with as much as twice the strength and hardness of other bronzes; easily machined; produces excellent surface finishes. Very good corrosion resistance — aluminum forms a protective oxide surface. Suitable for machine element restoration on bronze or brass components and bearing surfaces, with corrosion resistance in neutral to mildly oxidizing atmospheres and sea water environments.”
Hayden Corp. — Thermal Spray Materials: Aluminum Bronze
“A high-density, moderate-hardness metallic aluminum and copper; self-lubricating characteristics; excellent resistance to adhesive wear; non-galling and non-seizing; suitable for bearing applications and metal-to-metal contact where seizure is a concern; used for restoration of dimensional tolerances in bronze, copper, and aluminum components and as a bond coat layer.”
Astro Alloys — TAFA Arc Spray Wires (10T Aluminum Bronze)
“Aluminum bronze alloy produces high tensile strength, low shrink, wear-resistant, dense coatings that are easily machinable and good for bearing surfaces and machine element work. TAFA 10T is equivalent to Sulzer Metco Sprabronze AA and 10E Aluminium Bronze.”
Kermetico — HVAF Aluminum Bronze Coating Data
“HVAF aluminum-bronze deposits bulk-like materials characterized by less than 1% porosity, bond strength over 11,000 psi (>75 MPa) on carbon steel, and very dense, very wear-resistant coatings that machine easily to an excellent finish.”
Copper Development Association — Guide to Nickel Aluminium Bronze for Engineers (Pub 222)
“Large naval market for nickel aluminium bronze, particularly submarine fleets. Applications include seawater piping, valve systems, weapons handling, flexible couplings, sonar equipment, seawater external hatches, hydraulic valves and bearings, fasteners and sealing flanges, low-noise propellers, propulsion equipment, and periscope assemblies.”
Copper Development Association — Guidelines for Copper Alloys in Seawater
“Aluminum bronze resistance to corrosion results from the aluminium in the alloy reacting with atmospheric oxygen to form a thin, tough surface layer of alumina (aluminium oxide) which acts as a barrier to corrosion of the copper-rich alloy; the film is self-healing in seawater.”
VIIPLUS — Marine Propeller Bearing Sleeves: Aluminum Bronze Self-Lubricating Materials
“C95800 specified for seawater corrosion resistance, non-magnetic properties, and anti-galling characteristics against steel propeller shafts. Under boundary lubrication, the inherent lubricity of bronze prevents the bushing from galling (cold welding) to the steel shaft — a common failure mode in stainless-on-stainless setups.”
American Welding Society — Top Four Reasons to Use Arc Thermal Spray for Machine Components
“Arc spray applies aluminum bronze for bearing surfaces — more economical than making entire parts from these materials, with the added benefit of porosity. The porous surface more readily accepts lubricants and holds onto them longer.”

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.

Aluminum Bronze

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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