Aluminum, Copper, Polymers, and Ceramics: Properties and Uses

Aluminum

Aluminum is used in telescopes. Tempered powder paint is used in metal protection and the preparation of alloys. Aluminum forms alloys with other metals. Duralumin, an aluminum alloy, is used in aeronautics because it is very lightweight and has great resistance.

Aluminothermy

Aluminothermy is a metal extraction procedure that reduces metal oxides using aluminum powder. Metals such as chromium, manganese, and molybdenum are obtained using this method.

Salts of Aluminum

Important industrial salts are called alum (double salts).

Natural Aluminum

Aluminum is not found free in the Earth's crust. It is named after these characteristics:

1. Alumina
2. Hydroxide
3. Silicates

Obtaining Aluminum

Aluminum is extracted using the electrolytic method. Bauxite and cryolite are melted in a kiln. An anode current is passed through the mixture. The oxygen in the bauxite decomposes, and aluminum accumulates at the bottom of the kiln.

Properties of Aluminum

Aluminum is a white metal that melts at 660°C. It is ductile, malleable, and resistant to corrosion. It is also a good conductor of heat and electricity.

Copper Alloys

Aluminum Bronze

Aluminum bronze is a copper alloy used in parts that require resistance to mechanical stress, tenacity, impact, or fatigue.

Beryllium-Copper Alloys

Beryllium-copper alloys have excellent properties when subjected to thermal treatment (aging). They have high resistance to fatigue. Aging increases hardness and resistance to distraction.

Brasses: Copper and Zinc Alloys

The most common types of brass are alpha, beta, and gamma.

• Dutch metal: Malleable brass with high tensile strength (alpha).
• Brass: High mechanical strength (alpha + beta).
• Muntz metal: Contains 30-49% zinc.

Aluminum Alloys

• Casting alloys: Physicochemical properties vary depending on the casting method. They allow for welding.
• Wrought alloys: Lose hardness with annealing and are machinable.

Uses of Aluminum Alloys

Magnesium alloys are the most important aluminum alloys. Al-Zn-Mg alloys are the most used. Other alloys include Mg-Mn, Mg-Al, Al-Mg-Ag, and Mg-Al-Cd.

Beryllium Alloys

Beryllium alloys are obtained through electrolysis. Impurities can cause fragility. They have a high elastic modulus but limited use.

Copper Alloys

Copper alloys are used in sheets, tubes, rods, and wires. They have a resistance of 12-14 kg/mm². The properties of bronze vary.

Copper and Tin Alloys

Currency metal contains 96% copper and 8% nickel. Gun metal composition varies between 92-88% copper.

Polymers

Polymers cover materials such as plastics, rubber, and adhesives. They are giant organic chain molecules.

Polymerization

Polymerization is the process by which small molecules bind to create giant molecules.

Uses of Polymers

Polymers are used in toys, household items, coatings, paints, adhesives, binders, and foams.

Classification of Polymers

• Thermoplastics: Consist of long chains produced by combining small molecules. They behave in a ductile and plastic manner and are easily recycled.
• Thermosets: Long-chain compounds with molecular cross-links, forming three-dimensional networks. They are more resistant and more fragile than thermoplastics. The cross-linking makes them difficult to process.
• Elastomers: Have the capacity to be elastically deformed without a permanent change. They are used in hoses and electrical insulation.

Additives

• Fillers: Increase resistance to wear.
• Pigments: Produce colors in polymers and paints.
• Stabilizers: Prevent polymer degradation due to environmental effects.
• Flame retardants.
• Plasticizers.
• Reinforcements.

Ceramics

Ceramics are chemical compounds that contain metallic and non-metallic elements.

Uses of Ceramics

Ceramics are used in pottery, bricks, tiles, kitchenware, magnets, and electrical devices. They are hard, fragile, have a high melting point, and have low electrical and thermal conductivity. They have high compressive strength but lower fracture toughness than some non-metals. Their use in high-resistivity applications is very limited due to their electrical insulation properties.