These aluminum alloys, doped tin, specially developed for bearings. Quality bearings main criteria are the load-bearing capacity, fatigue and corrosion resistance in lubrication conditions in internal combustion engines. Aluminum Alloy Bearings, tin alloyed, unsurpassed among other types of bearing materials.
Aluminum tin phase diagram
Aluminum-tin alloys contain about tin 6 %, as well as small amounts of copper and nickel to increase strength. They are used for cast bearings.. It is tin that provides very good glide in these alloys..
American aluminum-tin alloys
American Tin Aluminum Alloys 850.0, 850.1 and 852.0 can be cast as in sand, so in the chill mold. However alloys 850.0 (6,3Sn-1Cu-1Ni) and 852.0 (6,3Sn-2Cu-1,2Ni-0,8Mg) is usually poured only into permanent forms. Sand casting is used for large rolling mill bearings, which are usually made of alloy 851.0 (6,3Sn-2,5Si-1Cu-0,5Ni).
The “bearing” properties of aluminum-tin alloys are highly dependent on the casting method. Finely dispersed tin distribution is essential for optimum bearing properties.. This requires a small interdendritic distance., and such a distance can only be obtained with fast cooling casting methods.
Long cure interval
In terms of the casting process, the aluminum-tin alloy system is unique. The solidification of the alloy in the mold begins at a temperature of about 650 oC, and the tin remains liquid somewhere up to the temperature 225 oC. Such a too large temperature hardening range presents difficulties for casting. High solidification rates of castings are recommended to avoid excessive macrosegregation..
A casting aluminum alloy 850.0
- copper: 0,7-1,3 %;
- magnesium: 0,10 Max.;
- silicon: 0,7 % Max.;
- iron: 0,7 % Max.
- lead: 5,5-7,0 %;
- nickel: 0,7-1,3 %;
- titanium: 0,20 % Max.;
- others: 0,30 % Max.;
- aluminum: rest.
Influence of impurity content:
- high iron content, manganese or magnesium reduces plasticity and increases hardness;
- high silicon improves slip characteristics.
Typical mechanical properties in T5 condition:
- tensile strength: 160 MPa;
- yield point: 75 MPa;
- relative extension: 10 %;
- hardness: 45 NV;
- Poisson's ratio: 0,33;
- elastic modulus: 71,0 GPa.
- density: 2,880 g / cm3;
- liquidus temperature: 650 ºS;
- solidus temperature: 225 oC.
- melting point: from 650 to 730 ºS;
- temperature spills: from 650 to 705 ºS;
- aging temperature: 230 oC, excerpt - 8 hours.
Источник: Aluminum and Aluminum Alloys, ASM International, 1996