Which of the following is a characteristic of crystalline materials?
A Brittleness
B Regular pattern
C Random arrangement
D High thermal conductivity
Crystalline materials have atoms arranged in a highly ordered, repeating pattern. This regular arrangement results in distinct properties like higher strength and better thermal and electrical conductivity.
What is the main effect of increasing carbon content in steel?
A Increase ductility
B Increase conductivity
C Increase hardness
D Decrease hardness
Increasing the carbon content in steel increases its hardness and strength, but it reduces its ductility. This is why high-carbon steels are used for tools and cutting instruments.
What does the term “creep” refer to in materials?
A Slow deformation over time
B Quick hardening
C Instantaneous breaking
D Rapid fracture
Creep refers to the gradual and permanent deformation of materials when subjected to constant stress over time, typically occurring at high temperatures, and can lead to failure in structural components.
Which material undergoes phase transformation at the eutectoid point?
A Copper
B Aluminum
C Zinc
D Steel
In steel, the eutectoid point is where the phase transformation from austenite to pearlite occurs at a specific composition and temperature, influencing its mechanical properties.
What is the role of annealing in metal treatment?
A To soften and relieve stress
B To increase brittleness
C To harden the material
D To increase corrosion resistance
Annealing is a heat treatment process used to soften metals, relieve internal stresses, and improve ductility by heating the material and then cooling it slowly.
Which of the following is a typical property of ceramics?
A High toughness
B Good electrical conductivity
C High melting point
D High ductility
Ceramics typically have high melting points and are resistant to heat and wear. They are used in high-temperature applications like engine components and heat shields due to these properties.
Which process involves heating a material to a high temperature and then cooling it slowly in air?
A Welding
B Tempering
C Annealing
D Quenching
Annealing involves heating a material, usually metal, to a high temperature and then cooling it slowly to reduce hardness, increase ductility, and relieve internal stresses.
What does the term “fracture toughness” refer to?
A Material’s resistance to crack growth
B Material’s ability to conduct electricity
C Material’s resistance to corrosion
D Material’s resistance to wear
Fracture toughness is a material’s ability to resist crack propagation under stress. It is an essential property for materials used in critical structures where cracks could lead to failure.
What does the term “alloy” refer to?
A Pure metal
B Non-metallic material
C Mixture of metals
D Plastic material
An alloy is a mixture of two or more metals, or a metal and a non-metal, designed to improve certain properties, such as strength, hardness, or corrosion resistance.
Which material is commonly used in bearings for its low friction?
A Cast iron
B Bronze
C Steel
D Brass
Bronze, an alloy of copper and tin, is commonly used for bearings because of its low friction properties, making it ideal for applications where smooth movement is required.
Which welding process uses an electric arc to melt and join metals?
A Brazing
B Forging
C MIG welding
D Soldering
MIG (Metal Inert Gas) welding uses a continuously fed wire electrode and an electric arc to melt the metal at the joint, making it ideal for joining thin metals with high precision.
Which of the following materials is a typical example of a composite?
A Concrete
B Aluminum
C Iron
D Copper
Concrete is a composite material made from cement, water, and aggregates like sand or gravel. It is strong in compression but weak in tension, often reinforced with steel.
Which type of polymer is used to make rubber products?
A Thermoplastic
B Composite
C Thermoset
D Elastomer
Elastomers are polymers that exhibit rubber-like elasticity. They are used to make items such as tires, seals, and gaskets due to their ability to stretch and return to their original shape.
Which steel is known for its ability to resist corrosion?
A Cast iron
B Stainless steel
C Tool steel
D Carbon steel
Stainless steel contains chromium, which forms a protective oxide layer that prevents corrosion, making it ideal for applications in harsh environments like kitchen appliances and medical instruments.
What is the primary characteristic of smart materials?
A High hardness
B Inert
C Change properties with stimuli
D High electrical conductivity
Smart materials are capable of changing their properties in response to external stimuli, such as temperature, pressure, or electric fields, making them ideal for applications in sensors, actuators, and adaptive structures.