Materials

Bronze is a Copper-Tin alloy. The casting alloy has tin content between 9-12%. Increasing Tin content decreases conductivity but increases the hardness. Bronze also form protecting layer on the surface of Copper oxide and Copper carbonate which protects underlying alloy from further corrosion. This makes bronze resistant to corrosion, wear, and seawater and offers good fatigue strength and excellent material for spring and sliding components. Bronze alloys with about 0.4 – 1 % Phosphorous are harder and usually called Phosphorous Bronze.

Gunmetal is a Copper-Tin-Zinc alloy. Gunmetal alloys approximately contain Tin 2-11% and Zinc 1-10%. Modified alloys of Gunmetal, Leaded gunmetal and Nickel gunmetal, contains Lead up to 7% and Nickel up to 6% respectively. Gunmetal alloys are frequently used for bearings with moderate speed and load and specially where pressure tight castings required for valves, pipe fittings and pumps.

Leaded Bronze is a Bronze alloy with a higher Lead contents. It has very good sliding and emergency running properties and being used in mechanical engineering. Leaded bronze alloys offer excellent wear resistance (also against not perfectly smooth and soft shaft) and machineability therefore used for manufacturing of bearings and bushes-plain bearings.

Aluminium Bronze is Copper-Aluminium alloy where Aluminium (5-11%) is the main alloying element added to Copper. Aluminium bronze alloy has higher strength and corrosion resistant compare to other bronze alloys. They form tough layer of Aluminium oxide on the surface which gives them higher corrosion resistance. It makes them preferable to other engineering materials and their applications includes Bushes (plain bearings), valve components, underwater fastenings, ship propellers and also used in engine components because of their low reactivity to sulphurous compounds and other combustion exhaust products.