Everyone knows the beautiful green roofs on historic buildings. The longevity of copper is proverbial. Not least for this reason, architects and builders have increasingly used this beautiful utility metal in recent years in the implementation of modern buildings as well as modernisation and renovation – not least because of its special sustainability and importance for the Circular Economy. And “Green Building” is also not feasible without copper.
Today it plays a significant role in roofing, exterior wall cladding and roof drainage. The interest in copper in today’s architecture is based on economic and design considerations and also, in combination with other natural building materials, on an increasing sensitivity towards the built environment.
Copper materials can be used to realise exciting architectural applications that give every building an individual character.
The outstanding properties that copper naturally brings with are essentially:
- Long service life due to extraordinary corrosion resistance against atmospheric influences and against condensation water.
- Good workability when designing difficult construction details
- No impairment of formability even at low temperatures
- Harmonious adaptation to other building materials due to a natural material surface. The patina makes the copper more beautiful with age
- Economic efficiency, low maintenance costs, no cleaning
- Copper is 100% recyclable. Its high degree of purity guarantees reuse of the same quality. Downcycling, as occurs with other materials, does not happen with copper.
- The joining technique of hemming allows for a high degree of flexibility in cuts and difficult construction details. With the further development of old handicraft techniques and the addition of modern manufacturing and processing methods, a high technical and design standard has been achieved.
- Copper is not endangered by other metals due to its position on the positive side of the electrochemical voltage series.
- Copper is a sustainable material due to its economic and ecological properties.
Assembly with other metals
Copper is not endangered by other metals due to its position on the positive side in the electrochemical voltage series. However, if combined incorrectly with other metals, they can be endangered. In the electrochemical voltage series, the redox pairs are indicated with the corresponding voltage differences to hydrogen. Since the redox potential of hydrogen to water is almost zero, all other redox potentials are related to this pair. According to this, aluminium has a standard potential of -1.6 V and copper a standard potential of 0.337 V. Metals with a negative potential above hydrogen (e.g. aluminium) can give electrons to the H3O+ ions. In the process, hydrogen develops and the metal dissolves and goes into solution as an ion: these metals are called base metals. Metals with a positive potential below the hydrogen (e.g. copper) cannot react with the H3O+ ions. It follows that they are insoluble in acids (e.g. hydrochloric acid) because the H3O+ ion cannot do anything. These metals are called noble.
Copper and stainless steel assembly
The assembly of copper with stainless steel is considered harmless according to the current state of knowledge. Stainless steel refers to the stainless steels of material numbers 1.4301 (chrome-nickel steel) and 1.4401 (chrome-nickel-molybdenum steel) and 1.4571 that are commonly used in construction.
Assembly of copper and aluminium
In the past, the assembly of copper and aluminium was generally not considered permissible due to the potential difference in the electrochemical voltage series described above. According to more recent investigations, anodised pure aluminium (oxide layer thickness 20 μm) is only slightly affected by copper-containing water in its decorative appearance, but not in its function. Direct contact between these two materials should still be avoided. Today, aluminium components are usually provided with coloured coatings. These components can of course be combined with those made of copper without any problems. A slight attack can then only occur under unfavourable conditions at the unprotected cut edges of the aluminium parts.
Behaviour in the atmosphere
Especially under today’s environmental conditions, copper is an extraordinarily durable building material with a technical life expectancy of over 200 years. This durability is based on its ability to form a weather-resistant, adherent and non-toxic protective layer in the atmosphere. This oxide layer is inherently stable and self-healing. Regardless of its composition, it provides optimum protection against further corrosion attacks and thus guarantees high durability. Copper has a good resistance to building materials such as gypsum, lime and cement and is not endangered by condensation.
Outside temperatures during copper processing
Plumbers and installers appreciate the easy formability of copper during processing. The versatile material can be installed regardless of the outside temperatures, as copper is temperature-stable, does not age and does not become brittle. As there is no impairment of the formability of this material even at low temperatures, there are no restrictions in the processing temperatures.
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