Question

Which of these, when added to copper increases its tensile strength by 50%?
1. Boron
2. Cadmium
3. Silicon
4. Rhodium

Answer 1

Correct Answer - Option 3 : Silicon

Explanation:

• Silicon is added to strengthen the copper.
• Phosphorus is often used to deoxidize copper, which can increase the hardness and strength, but severely affect the conductivity.  Silicon can be used instead of phosphorus to deoxidize copper when conductivity is important.
• In copper, boron also slows grain growth during heating. In addition, boron facilitates pouring and filling operations. In brasses, boron behaves as a strong grain refiner. 
• Rhodium is one of the six platinum group metals: platinum, palladium, rhodium, osmium, iridium and ruthenium. It is also classified as a noble metal, meaning that it does not react to oxygen easily, acts as a fantastic catalyst and is resistant to corrosion and oxidation in copper.
• When cadmium is added to copper the material becomes more resistant to softening at elevated temperatures. The more cadmium that is added the more heat resistant the material becomes. Small additions of cadmium do not affect the thermal and electrical conductivities, and room temperature mechanical properties of cadmium copper.