It delivers electricity and clean water into our homes and cities and makes an important contribution to sustainable development. More than that, it is essential for life itself. The following describes different properties of copper, divided by type (chemical, mechanical and physical).
Chemical properties of copper
All common metals and alloys react with a moist atmosphere and corrode. Only in hot/dry (deserts) and cold/dry environments do metals resist corrosion. However, due to the chemical properties of copper, the corrosion process is very slow. The corrosion resistance of copper and copper alloys is based on their ability to form stable compounds that provide some protection from corrosive attack. When exposed to the atmosphere, protective layers of oxides and poorly soluble basic salts form on the surface of copper and copper alloys. Suitable alloying elements can positively influence the formation of these coatings.
The copper element is in the same periodic table group as silver and gold. Therefore, it is relatively inert against chemicals. In most of its compounds it can have the valency (oxidation state) of +I or the valency state +II. The aqueous solutions of copper ions in the oxidation state +II have a blue colour, whereas copper ions in the oxidation state +I are colourless. Copper and copper compounds give a greenish color to a flame.
Physical properties of copper
Mechanical properties of copper
The primary mechanical properties of copper—hardness, strength and ductility—determine its condition. The material condition (alternative term: temper) is designated in standards either by the letter H, representing a minimum hardness, or the letter R, representing a minimum tensile strength.
Copper can be supplied in a range of conditions from annealed (soft) to fully hard, which is obtained by cold working.
Annealed copper (H040) has a minimum hardness of 40HV, a minimum tensile strength 200 N/mm2(R200) with fully cold worked copper (H110) having a hardness of 110HV minimum and tensile strength of 360 N/mm² ( R360) minimum.
The ductility of fully cold worked copper is much less than in the annealed condition with a value of 2% elongation.
The strength and hardness of copper can also be increased by alloying, but this results in a decrease in electrical conductivity. The strongest copper alloy of all is produced by alloying with beryllium, followed by an age hardening heat treatment resulting in a tensile strength of up to 1500 N/mm².