Silicon tombac
Silicon Tombac (also Siliciumtombak , silicone tombac , Olkusil ) is an alloy consisting of copper (main component 80%), zinc (16%) and silicon (4%). The designation according to EN 1982 is CuZn16Si4-C.
properties
| Melting range | 950 ... 1000 ° C |
| Tensile strength Rm | 500 N / mm² |
| Yield strength Rp 0.2% | 300 N / mm² |
| Hardness HB | 130 |
| density | 8.3 kg / dm³ |
| Elongation at break A | 8th % |
| Electric conductivity | 3 MS / m |
The silicon content leads to a solidification of the structure . The external appearance is similar to that of brass . Silicon tombac is not resistant to ammonia , but has good sliding bearing properties and is corrosion-resistant . Silicon tombac is a special brass, i.e. a multi-material alloy based on copper and zinc, which is characterized by good castability and increased strength compared to brass. The strength properties are largely retained even at temperatures of up to 200 ° C. Compared to many cast iron materials, the almost constant toughness with a slightly increasing strength at low temperatures down to −200 ° C is advantageous.
use
Silicon tombac is used as a construction material wherever high strength is required in connection with the dimensioning of mechanically stressed construction parts . The production takes place by gravity casting (see also: die casting process ) or in the die casting process . The heavy metal castings thus competes with the steel casting (see also: lost wax ).
metallurgy
Silicon has a very strong influence on the Cu-Zn alloy. Silicon limits the solubility of zinc in copper in the α range. In α-brass, up to 4% silicon can be dissolved in the mixed crystal . As the zinc content increases, the solubility of silicon in the α mixed crystal decreases. With the alloy CuZn16Si4-C, the maximum amount of silicon has been added with the highest possible zinc content. Therefore, the rapid cooling rate of die and permanent mold casting is important. The α-phase crystallizes supersaturated with silicon. This effect is of practical importance: The higher mechanical values in chill and die casting compared to sand casting can be explained by the oversaturation of the primary, non-disintegrated α-mixed crystal.
literature
- Catrin Kammer, Hans Krämer, Volker Läpple: Materials science for practitioners. 5th edition, Europa-Lehrmittel, 2000, ISBN 3-8085-1325-X (influence of silicon as an alloying element).
- E. Paul DeGarmo, JT Black, Ronald A. Kohser: DeGarmo's Materials and Processes in Manufacturing . 10th edition. John Wiley & Sons, 2007, ISBN 978-0-470-05512-0 (section: copper-zinc alloys ).
- Kurt Dies: Copper and copper alloys in technology . Springer, B., 1967, ISBN 3-540-03759-4 .
Individual evidence
- ↑ a b c silicon tombac . Breuckmann GmbH & Co. KG
- ↑ DIN EN 1982: 2008-08: Copper and copper alloys - ingots and castings; German version EN 1982, Beuth Verlag, August 2008.