3. NON-FERROUS METALS AND ITS ALLOYS
Non-ferrous metals are metals that do not contain iron as a primary component. These metals tend to have superior properties such as better corrosion resistance, lower density, and higher conductivity compared to ferrous metals (iron-based alloys). Some of the most common non-ferrous metals include copper, aluminum, nickel, and zinc, among others.
3.1 Properties of Non-Ferrous Metals
Non-ferrous metals exhibit several distinct properties that make them highly useful for various applications. These properties include:
- Corrosion Resistance: Many non-ferrous metals (like aluminum and copper) are highly resistant to rust and corrosion, making them suitable for outdoor and marine environments.
- Light Weight: Non-ferrous metals are generally lighter than ferrous metals, which is why they are preferred for industries like aerospace and transportation (e.g., aluminum alloys).
- Electrical Conductivity: Copper, for example, has excellent electrical conductivity and is used in electrical wiring.
- Malleability and Ductility: Many non-ferrous metals, such as copper and aluminum, can be easily shaped and drawn into wires.
- Non-Magnetic: Most non-ferrous metals do not exhibit magnetic properties, making them useful for certain electrical and electronic applications.
- Good Strength-to-Weight Ratio: Many non-ferrous metals have a good balance of strength and lightness, ideal for structural applications.
Examples of Non-Ferrous Metals:
- Aluminum: Low density, excellent corrosion resistance.
- Copper: High electrical conductivity, corrosion-resistant.
- Lead: Soft, dense, and corrosion-resistant.
- Nickel: Corrosion-resistant, used in alloys.
3.2 Copper Alloys: Brasses, Bronzes – Composition, Properties, and Uses
Copper alloys are metals made by combining copper with other elements like zinc, tin, and aluminum. The two most common types of copper alloys are brasses and bronzes.
Brasses (Copper-Zinc Alloys):
- Composition: Brass is primarily composed of copper and zinc. The percentage of zinc typically varies from 5% to 45%.
- Properties: Brasses are characterized by good corrosion resistance, high strength, excellent machinability, and good electrical conductivity. They can be easily cast and forged.
- Uses: Brasses are used in applications requiring low friction and good wear resistance, such as in coins, musical instruments, electrical connectors, and plumbing fittings.
Example: Naval Brass (Copper-30% Zinc) – Known for its excellent resistance to seawater corrosion.
Bronzes (Copper-Tin Alloys):
- Composition: The primary alloying element in bronze is tin, with copper as the base. Other elements like phosphorus, aluminum, or silicon can be added for improved properties.
- Properties: Bronzes are strong, wear-resistant, and have good corrosion resistance, especially in marine environments. They are less brittle than cast iron.
- Uses: Bronzes are used in marine hardware, bearings, sculptures, and electrical connectors due to their resistance to corrosion and high durability.
Example: Phosphor Bronze (Copper-5-10% Tin, and a small amount of Phosphorus) – Used for electrical connectors, springs, and bearings due to its high strength and resistance to fatigue.
3.3 Aluminium Alloys: Properties and Uses
Aluminum alloys are composed primarily of aluminum and small amounts of other elements such as copper, magnesium, silicon, and zinc. Aluminum is one of the most versatile and widely used non-ferrous metals.
Properties:
- Lightweight: Aluminum has a low density (about 1/3 that of steel), making it ideal for applications where weight is a critical factor.
- Corrosion Resistance: Aluminum naturally forms a protective oxide layer, which makes it highly resistant to corrosion, especially in marine environments.
- Good Electrical and Thermal Conductivity: Aluminum is a good conductor of electricity and heat, though not as good as copper.
- Malleability and Ductility: Aluminum is easily shaped into thin sheets and wires, which makes it highly versatile in manufacturing.
- Strength-to-Weight Ratio: It has an excellent balance of strength and lightness, making it ideal for aerospace, automotive, and construction applications.
Uses:
- Aerospace: Lightweight and high-strength aluminum alloys are used in the manufacturing of aircraft bodies and wings.
- Transportation: Aluminum is used in car parts, trucks, and rail vehicles to reduce weight and improve fuel efficiency.
- Packaging: Aluminum foil and cans are commonly used in food packaging due to aluminum's resistance to corrosion and its ability to be easily shaped.
- Construction: Window frames, roofing, and cladding materials are often made from aluminum alloys.
3.4 Nickel Alloys: Properties and Uses
Nickel alloys are composed primarily of nickel and other metals such as iron, chromium, and copper. Nickel has excellent resistance to corrosion and high temperatures.
Properties:
- Corrosion Resistance: Nickel alloys are highly resistant to corrosion, even in extreme environments such as high-temperature and acidic conditions.
- High-Temperature Strength: Nickel alloys maintain their strength and toughness at elevated temperatures, making them suitable for high-temperature applications.
- Good Ductility: Nickel alloys can be easily fabricated and welded, which is important for many industrial applications.
- Magnetic Properties: Some nickel alloys are magnetic, and this property can be leveraged in certain applications.
Uses:
- Aerospace: Nickel-based superalloys are commonly used in turbine blades and other high-performance components due to their ability to withstand high temperatures.
- Chemical Processing: Nickel alloys are used in reactors, piping, and heat exchangers in the chemical industry because of their excellent resistance to corrosion and heat.
- Electronics: Nickel is used in rechargeable batteries (like nickel-cadmium batteries) and in various electronic components.
- Marine: Nickel alloys are used for marine applications such as in shipbuilding and underwater equipment due to their resistance to seawater corrosion.
3.5 Types of Anti-Friction/Bearing Alloys
Anti-friction and bearing alloys are designed to minimize friction between moving parts and to provide smooth, efficient operation. These alloys are used in bearings, gears, and other applications where high wear resistance is required.
- Lead-Based Alloys: These alloys are typically composed of lead combined with tin and other elements. They are often used in engine bearings due to their excellent conformability and resistance to wear.
- Babbit Metal: Babbit alloys are typically composed of tin, copper, and antimony and are widely used in bearing applications. These alloys have excellent wear resistance and low friction properties.
- Aluminum Alloys: Aluminum-based bearing alloys are used in lightweight applications like automotive engines due to their strength and resistance to corrosion.
3.5.1 Standard Commercial Grades as per BIS/ASME
BIS (Bureau of Indian Standards): The BIS specifies grades of anti-friction alloys such as:
- IS 1706: This standard specifies the requirements for cast bronze bearing alloys.
- IS 318: This standard specifies the composition for babbit bearing alloys.
ASME (American Society of Mechanical Engineers): ASME also sets standards for bearing materials, often focusing on the properties like strength, wear resistance, and thermal conductivity of bearing materials.
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