What is the primary reason for using non-ferrous alloys in marine applications?
A Corrosion resistance
B Low cost
C High density
D High strength
Non-ferrous alloys, such as bronze and brass, are used in marine applications for their resistance to corrosion from saltwater. This makes them ideal for components exposed to harsh marine environments like ship parts and fittings.
Which process is used to change the microstructure of steel to improve hardness?
A Forging
B Quenching
C Casting
D Welding
Quenching involves heating steel to a high temperature and then rapidly cooling it, usually in water or oil. This process transforms the steel’s microstructure, increasing its hardness and strength, making it ideal for tools and machinery parts.
Which material is commonly used for high-temperature applications such as turbine blades?
A Copper
B Steel
C Titanium alloys
D Aluminum
Titanium alloys are used for high-temperature applications, such as turbine blades, due to their excellent high-temperature strength, low density, and resistance to oxidation. They maintain performance at elevated temperatures, which is critical in aerospace and power generation industries.
Which of the following is most commonly used for coating materials to prevent corrosion?
A Lead
B Zinc
C Brass
D Copper
Zinc coatings, especially through galvanizing, are commonly used to protect steel and iron from corrosion. Zinc acts as a sacrificial anode, corroding in place of the underlying metal, which extends the material’s lifespan in corrosive environments.
What is the most significant advantage of powder metallurgy over traditional casting?
A Less material wastage
B Increased ductility
C Better hardness
D Higher strength
Powder metallurgy produces less material wastage compared to casting by directly forming parts from metal powders. This method is more efficient and is ideal for creating parts with complex shapes and high precision, reducing the need for further machining.
What is the main characteristic of smart materials?
A High electrical conductivity
B Low cost
C Ability to respond to stimuli
D High strength
Smart materials can change their properties in response to external stimuli such as temperature, pressure, or magnetic fields. This adaptability is beneficial in applications like sensors, actuators, and responsive structures.
Which phase transformation occurs during the quenching of steel?
A Precipitation
B Austenitic transformation
C Solidification
D Martensitic transformation
During quenching, steel undergoes martensitic transformation, where the high-temperature austenite phase is rapidly cooled, forming martensite. This phase is hard but brittle, which can be modified further by tempering to improve toughness.
Which of the following materials is most commonly used for electrical conductors?
A Steel
B Copper
C Zinc
D Brass
Copper is widely used for electrical conductors due to its excellent electrical conductivity. It is an ideal choice for wiring and cables in electrical systems because it allows for efficient current flow with minimal resistance.
Which material property is tested using the Rockwell hardness test?
A Toughness
B Strength
C Hardness
D Ductility
The Rockwell hardness test measures the resistance of a material to indentation. The test uses a diamond or steel ball indenter to press into the material, and the depth of indentation is used to calculate the hardness value.
What is the main effect of increasing carbon content in steel?
A Increased strength
B Decreased hardness
C Increased ductility
D Decreased corrosion resistance
Increasing the carbon content in steel generally increases its strength and hardness, making it more suitable for applications that require high strength. However, higher carbon content can reduce ductility, making it more prone to brittleness.
What is the purpose of adding alloying elements like chromium and nickel to steel?
A To lower cost
B To increase ductility
C To reduce hardness
D To improve corrosion resistance
Alloying elements like chromium and nickel are added to steel to improve its corrosion resistance, creating stainless steel. This type of steel is used in environments that require resistance to rust and other forms of corrosion, such as in medical equipment and kitchen appliances.
What is the main purpose of heat treatment processes like tempering?
A To increase hardness
B To relieve stresses and improve toughness
C To increase brittleness
D To decrease strength
Tempering is a heat treatment process used to reduce brittleness in steel after hardening. It involves reheating the steel to a lower temperature to relieve internal stresses and improve the material’s toughness while maintaining its strength.
What is the effect of using polymers in composite materials?
A Decreased cost
B Increased hardness
C Decreased corrosion resistance
D Increased strength and flexibility
Polymers are commonly used in composite materials to provide flexibility, strength, and resistance to environmental factors. When combined with fibers like glass or carbon, they create materials that are strong yet lightweight and highly durable.
Which of the following is an important characteristic of biomaterials?
A Low cost
B High corrosion resistance
C Biocompatibility
D High strength
Biocompatibility is crucial for biomaterials, ensuring that they do not cause harmful reactions in the body when used in medical devices, implants, or prosthetics. Materials like titanium and certain polymers are chosen for their compatibility with human tissues.
What is the key benefit of using nanomaterials in industrial applications?
A High conductivity
B High surface area
C High strength
D Low cost
Nanomaterials have a high surface area relative to their volume, which enhances their chemical reactivity and makes them suitable for applications such as catalysts, drug delivery systems, and advanced coatings. Their small size also provides improved mechanical properties.