What Tin Bronze 10-1 Is
Tin bronze 10-1 is a cast copper alloy whose designation reads as the two controlling alloying additions: nominally 10 % tin and 1 % phosphorus. In the Chinese national standard system the grade is written ZCuSn10P1, where the leading Z marks a casting alloy, CuSn identifies the copper tin base and the trailing figures record the nominal additions. The phosphorus addition is a deliberate deoxidiser and hardener: it refines the cast structure and raises wear resistance, which is why this grade is treated as a bearing and bushing material rather than a general purpose bronze.
The alloy is characterised by high hardness, excellent wear resistance, a low tendency to seize against a steel counterface, good casting performance, good machinability and good corrosion resistance in the atmosphere and in fresh water. Those properties are obtained directly in the as cast condition, without the need for heat treatment.
Designation and Standard Basis
| Item | Designation |
|---|---|
| Material family | Cast copper alloy, continuously cast or sand cast tin bronze |
| Chinese grade | ZCuSn10P1 |
| Chinese national standard | GB/T 1176-2013 |
| Corresponding American grade | C90700 |
| Shorthand used in trade | 10-1 tin bronze, tin bronze 10-1 |
C90700 is the closest American designation for a cast tin bronze of this composition type. Where a drawing quotes either designation, the controlling documents remain the composition limits and mechanical property minima rather than the name, so the tables below should be checked against the purchase specification before the alloy is ordered.
Chemical Composition
| Element | Content (%) |
|---|---|
| Copper (Cu) | Balance |
| Tin (Sn) | 9.0–11.5 |
| Phosphorus (P) | 0.5–1.0 |
| Zinc (Zn) | 0.05 max |
| Lead (Pb) | 0.25 max |
| Nickel (Ni) | 0.10 max |
| Iron (Fe) | 0.1 max |
| Aluminium (Al) | 0.01 max |
| Manganese (Mn) | 0.05 max |
| Silicon (Si) | 0.02 max |
| Antimony (Sb) | 0.05 max |
| Sulphur (S) | 0.05 max |
| Total impurities | 0.75 max |
The tin range is deliberately wide because tin is the main solid solution strengthener and controls the amount of hard, tin rich phase that carries the load in service. Phosphorus must stay inside its window: below the minimum the casting is inadequately deoxidised, while above it the alloy becomes too hard and brittle for bushings that must conform to a shaft.
Mechanical Properties
| Property | Minimum value |
|---|---|
| Tensile strength | 360 MPa |
| Yield strength | 170 MPa |
| Elongation | 6 % |
| Brinell hardness | 88 HB |
These minima describe a material that is strong enough to carry bearing loads but retains enough ductility to be pressed or shrink fitted into a housing without cracking. Hardness above 88 HB is the property that most directly translates into wear life on a lubricated shaft.
Service Performance
Wear resistance: the hard tin bearing phase supports the load while the softer matrix runs in against the shaft, giving a low wear rate on both members.
Anti-seizure behaviour: the alloy resists local welding to steel, so a brief loss of lubrication is less likely to score the journal.
Casting performance: good fluidity and a narrow freezing range allow sound, dense castings to be produced in sand, permanent mould and continuous casting routes.
Machinability: good, with the alloy breaking into short chips so that bearing bores, oil grooves and tolerance fits can be finished accurately.
Corrosion resistance: good in the atmosphere and in fresh water, which suits pump, valve and marine machinery parts.
Typical Applications and Working Limits
The alloy is specified for wear resistant parts working under high load and high sliding speed, in particular:
Connecting rods and rod end bushings
Sleeve bearings and wrapped bushings for pumps, compressors and gearboxes
Thrust washers and bearing shells
Gears and worm wheels in slow and medium speed drives
Valve guides, trunnion bearings and slide blocks
The recognised working window for these components is a contact pressure below 20 MPa combined with sliding speeds up to about 8 m/s. Within that envelope the alloy develops a stable lubricating film and delivers a long service interval. Above it, friction heat rises faster than the lubricant can remove it and the bearing film breaks down, which is the usual cause of premature failure attributed to the material itself.
Frequently Asked Questions
Q: What does the 10-1 in tin bronze 10-1 mean?
The figures are the nominal alloying additions: about 10 % tin and 1 % phosphorus. The standard grade designation for this composition is ZCuSn10P1.
Q: Which standard covers this alloy?
GB/T 1176-2013 covers cast copper alloys in the Chinese system and lists ZCuSn10P1. The closest American cast tin bronze designation of the same composition type is C90700.
Q: What are the minimum mechanical properties?
360 MPa tensile strength, 170 MPa yield strength, 6 % elongation and 88 HB hardness.
Q: What load and speed can a bearing in this material carry?
It is intended for wear resistant parts under high load and high sliding speed, typically up to about 20 MPa contact pressure with sliding speeds up to roughly 8 m/s.
Q: Does the alloy need heat treatment?
No. The properties come from the cast structure, so parts are used in the as cast condition, optionally stress relieved if machining stability demands it.
Q: How does it perform in water and in the atmosphere?
Corrosion resistance is good in the atmosphere and in fresh water, which is why it is common in pump and valve components handling these media.
