What are the characteristics of copper and copper alloys

Bronze originally refers to copper alloys with tin as the main additive element. In modern times, all copper alloys except brass are included in the category of bronze, such as tin bronze, aluminum bronze, and beryllium bronze. It is also customary to divide bronze into two categories: tin bronze and Wuxi bronze. It is mainly used to manufacture corrosion-resistant and wear-resistant parts, such as shaft sleeves, thrust bearing pads, etc. Due to the limited resources of tin, some other alloying elements have been widely used in the industry recently to replace tin. The more common ones are aluminum bronze, lead bronze and beryllium bronze. Aluminum bronze has better corrosion resistance than tin bronze, and is often used to manufacture corrosion-resistant and wear-resistant parts, such as gears, worm gears, bushings, etc. Beryllium bronze is mainly used for important springs and elastic parts, as well as electrical contactors, electrodes for electric welding machines, clocks and clock parts, etc.

Many methods have been used to protect copper, the most important of which is the great progress in research and development using various corrosion inhibitors. At present, Japan has more and more extensive research on copper and copper alloy surface protection technology, especially in the aspect of building decoration materials, and has achieved a lot of successful experience. Domestic work mainly focuses on surface polishing and anti-discoloration treatment of copper products, and some progress has also been made.

The process flow of copper and copper alloy surface passivation is: degreasing – hot water washing – cold water washing – pickling (concentrated hydrochloric acid or mass fraction of 10%, room temperature 30s) – machine washing – strong acid washing – water washing – surface conditioning (30-90g /LCrO3, 15-30g/LH2S04, 15-30s)->washing-pickling (112804 with a mass fraction of 10%)->washing-passivation-washing-drying. Unqualified passivation films of copper and copper alloys can be removed by soaking in H2S04 solution with a hot mass fraction of 1,000, concentrated hydrochloric acid or 300g/L sodium hydroxide solution.