Material

Cuphin is a newly developed copper-zinc alloy with a copper content of 76 %, a zinc content of 21 %, a silicium content of 3 % and a phosphorus content of 0.05 %. The chemical formula is CuZn21Si3P.

Cuphin is free of lead, nickel and other harmful substances and therefore, particularly suitable for drinking water applications. Due to its high copper content Cuphin has a positive effect on drinking water hygiene because copper surfaces can effectively stop the multiplication of bacteria and other microorganisms.

Cuphin is characterised by high strength, reliability, good processing properties and good corrosion resistance. Cuphin is completely reusable due to its already well-operating recycling system and therefore has a very favourable energy balance compared to other metals.

A summary of the technical data of Cuphin is available from the material data sheet .

Dezincification and stress corrosion cracking — the two corrosion types — may particularly occur in drinking water installations.

Dezincification

Dezincification is selective leaching of zinc characterised by the red colour of the dezincified areas. A dezincification depth of < 100 µm can generally be regarded as non-critical. However, dezincification in standard brass often exceeds these values.

Dezincification-resistant brasses such as CuZn36Pb2 can reduce dezincification substantially. However, these materials show a critical level of lead reaching into drinking water. Cuphin is superior in its dezincification resistance.

Stress corrosion cracking resistance

In the determination of stress corrosion cracking resistance according to DIN 50930 / Part 1 and ISO 6957 no stress corrosion cracking can be provoked in components made of Cuphin even by applying stricter test conditions when quadrupling the exposure time of the test medium.

Processing properties

Lead-containing materials often have very good machining properties. However, in particular for drinking water applications there is an increasing demand for lead-free materials. It is technically difficult to manufacture lead-free materials with good machining properties because lead acts as a chip breaker and results in the desired short and homogeneous chip shapes. With Cuphin it has been possible to develop a lead-free material with excellent machining properties. The silicium content of Cuphin leads to the formation of a silicium enriched phase acting as chip breaker and resulting in good machining properties. In addition, Cuphin has very good hot working and casting properties, thus offering the manufacturer various production possibilities for a wide range of components. Good weldability, solderability and a certain cold workability make Cuphin an innovative, yet reliable alternative for drinking water installations.

Result

In addition the the very good corrosion resistance of Cuphin’s high strength makes the material a reliable alternative for drinking water installations. Cuphin has a tensile strength of more than 700 Mpa, whereas CuZn40Pb2 lies within a range of 430 – 540 Mpa. With Cuphin being highly resistant to dezincification as well as to stress corrosion cracking and at the same time exhibiting high strength it is possible to install drinking water applications in a very reliable and durable quality. This covers almost all components of domestic installation, manufactured by casting, forming or machining technologies.