Two mark Questions and Answers

TWO MARK QUESTIONS AND ANSWERS

1. What is diffusion welding?

Diffusion welding is a solid state joining process in which the strength of the joint results primarily from diffusion. Diffusion means movement of molecules or atoms from wenst high concentration region to low concentration region. In this welding process both the welding plates are placed one over other in high pressure and temperature for a long period of time. This high pressure force starts diffusion between interface surfaces.

2. Write down the stages involved in diffusion welding.

Stage 1: Deformation and interfacial boundary formation. 

Stage 2: Grain boundary migration and pore elimination. 

Stage 3: Volume diffusion pore elimination.

3. What are the advantages of diffusion welding?

1. Plastic deformation at surface is minimal.

2. There is no limitation in the thickness of workpieces.

3. The bonded surface has the same physical and mechanical properties as the base but material.

4. The diffusion bonding is able to help us to build high precision components with complex shapes. Also, the diffusion is flexible.

4. Mention the limitations of diffusion welding.

1. It is a time consuming process due to low productivity.

2. Very thorough surface preparation is required prior to welding process.

3. *The mating surfaces must be precisely fitted to each other

4. It is relatively high initial investments in equipment.

5. List down the applications of diffusion welding.

1. It is used in joining of high-strength and refractory metals based on titanium in aerospace and nuclear industries.

2. Diffusion welding is usually used on sheet metal structures such as nuclear and electronics industries.

6. What is adhesive bonding?

Adhesive Bonding is the process of joining two surfaces together, usually with the creation of a smooth bond. This may involve the use of glue, epoxy, or one of a wide range of plastic agents which bond either through the evaporation of a solvent or through curing via heat, time, or pressure.

7. Define adhesive.

Adhesive is a filler material that binds parts together. It is a non-metallic substance, mostly a polymer. The parts being joined are called “adhenands”.

8. List the advantages of adhesive bonding.

1. Plastic deformation at surface is minimal.

2. There is no limitation in the thickness of workpieces.

3. The bonded surface has the same physical and mechanical properties as the base material.

4. The diffusion bonding is able to help us to build high precision components with ant complex shapes. Also, the diffusion is flexible.

9. Write the disadvantages of adhesive bonding.

1. They are not suitable for high temperature services.

2. Bonding and curing is a lengthy process.

3. Self-life of the adhesives is short and some may require special storage conditions such as refrigeration.

4. Surface preparation is essential.

10. What are the applications of adhesive bonding?

1. Adhesive bonding is used across many industries including automotive, air aerospace, medical and even textiles.

2. Bonding of metal to non-metals especially plastics is the major application of adhesive bonding.

3. Bonded joints are used as an alternative to riveting for aircraft structures.

4. Widely applicable in fastening of stiffeners to the aircraft skin and in assembling honeycomb structures in aircraft.