Chemistry
Answer
An alloy is a homogeneous mixture of two or more metals or of one or more metals with certain non-metallic elements.
The properties of alloys are often greatly different from those of the components.
- Gold is too soft to be used without a small percentage of copper.
- The corrosion and oxidation resistance of steel is markedly increased by adding 15 to 18% of chromium and often a few percent of nickle (stainless steel).
- The presence of carbon up to 1.5% greatly affects the properties of steel.
- A low percentage of molybdenum improves the toughness and wear resistance of steel.
Alloys are made to change the property of their major constituent to achieve a specific objective.
Related Questions
With respect to the Hall Heroult process, justify the following:
(a) Powdered coke is sprinkled over the electrolytic mixture undergoing electrolytic reduction.
(b) Graphite anodes are continuously replaced during the electrolysis.
(c) Cryolite and fluorspar must be added to the electrolytic mixture.
(d) Along with cryolite and alumina, another substance is added to the electrolyte mixture. Name the substance and give one reason for the addition.
Explain the following:
(a) Zinc is used to cover iron so as to prevent rusting of iron. Why?
(b) In construction work, why is the alloy of aluminium–duralumin used rather than pure aluminium?
Both Brass and bronze contain copper as major constituents. Name other elements in these alloys.
Name an alloy of:
(a) Aluminium used in aircraft construction.
(b) Lead used in electrical wiring or electrical work in joining metals.
(c) Copper in electrical appliances or household vessels.
(d) Zinc used in naval ships.