SURFACE ENGINEERING
2 MARKS
1. What is the purpose of surface modification?
To improve surface properties like hardness, wear resistance,
corrosion resistance, or biocompatibility without changing the
bulk properties of the material.
2. What is the difference between adhesive wear and
abrasive wear?
• Adhesive wear: Occurs when two surfaces slide and
material transfers due to adhesion.
• Abrasive wear: Happens when hard particles or asperities
scratch or cut a softer surface.
3. Name some self-lubricating nanocomposite coatings.
• MoS₂-based nanocomposites
• WS₂-based nanocomposites
• TiN/Ag nanocomposites
• TiAlN/Ag coatings
4. Differentiate CVD and PVD process.
• CVD (Chemical Vapor Deposition): Uses chemical
reactions from gaseous precursors to form coatings.
• PVD (Physical Vapor Deposition): Uses physical processes
like evaporation or sputtering to deposit thin films.
5. What is the use of XPS and calotest in surface
characterization?
• XPS (X-ray Photoelectron Spectroscopy): Analyzes
surface chemical composition and bonding.
• Calotest: Measures the thickness of thin films or coatings.
6. What are the applications of surface coated materials?
Used in cutting tools, biomedical implants, aerospace
components, automotive parts, and electronics for enhanced
durability and performance.
7. Name the different types of wear.
• Adhesive wear
• Abrasive wear
• Erosive wear
• Corrosive wear
• Fatigue wear
8. Compare Nitriding and Carbonitriding.
• Nitriding: Diffusion of nitrogen into the surface.
• Carbonitriding: Diffusion of both carbon and nitrogen into
the surface for hardening.
9. Differentiate evaporation and sputtering process.
• Evaporation: Material is heated to vapor phase and
condensed on substrate.
• Sputtering: Energetic ions bombard a target material,
ejecting atoms onto the substrate.
10.How are XPS and EDS used for surface characterization?
• XPS: Identifies elemental composition and chemical states
on the top few nanometers.
• EDS (Energy Dispersive X-ray Spectroscopy): Detects
elemental composition, typically coupled with SEM.
11. Why is surface engineering of nanomaterials required?
To control surface interactions, enhance mechanical, electrical,
and catalytic properties, and improve performance at the
nanoscale.
12. Differentiate aluminizing and calorizing.
• Aluminizing: Diffusion of aluminum onto the surface.
• Calorizing: Diffusion of aluminum plus other alloying
elements (like iron) to form a protective layer.
13. What is the use of corrosion inhibitor?
It slows down or prevents the corrosion process by forming a
protective film on the material surface.
14. Differentiate evaporation and sputtering technique.
(Repeated from Q9, but summarized)
• Evaporation: Thermal method, less energetic, directional
deposition.
• Sputtering: Physical bombardment, more energetic, better
adhesion.
15. What are the factors that affect super-hard
nanocomposite coatings?
• Grain size
• Layer architecture
• Residual stress
• Interface bonding
• Composition and phase distribution
16. Name the methods to change the surface chemistry of the
materials.
• Ion implantation
• Plasma treatment
• Laser surface treatment
• Chemical coatings
• Electrochemical modification
17. What are the factors affecting corrosive wear?
• Material composition
• Surface roughness
• Environmental factors (pH, temperature)
• Velocity of corrosive fluid
• Type and concentration of corrosive agents
18. Compare Carburizing and Nitriding processes.
• Carburizing: Adds carbon into the surface; requires high
temperature.
• Nitriding: Adds nitrogen; can be done at lower
temperatures, less distortion.
19. Differentiate Electrolysis coating and Electroless coating.
• Electrolysis coating: Needs external electric current.
• Electroless coating: Chemical reaction-based, no external
current required.
20. How is surface roughness quantified, and why is it
essential in coating applications?
Measured using Ra (average roughness) or Rz (peak-to-valley
height); it affects coating adhesion, wear resistance, and surface
performance.
21. Name the different types of wear.
• Adhesive wear
• Abrasive wear
• Erosive wear
• Corrosive wear
• Fatigue wear
22. How to control wear of materials?
• Apply surface coatings
• Use lubricants
• Select wear-resistant materials
• Optimize surface finish
• Reduce operational loads
23. Name some corrosion prevention methods.
• Protective coatings (paints, platings)
• Cathodic protection
• Use of corrosion inhibitors
• Material selection (corrosion-resistant alloys)
24. What is pitting corrosion?
A localized form of corrosion that leads to small holes or pits in
the metal surface, often hard to detect and very damaging.
25. Why is surface engineering of nanomaterials required?
To enhance mechanical strength, electrical properties, chemical
stability, and surface functionality at the nanoscale.
26. Name the techniques to change the surface chemistry of
the materials.
(Same as Q16, but listed again)
• Ion implantation
• Plasma treatment
• Laser treatment
• Chemical coatings
• Electrochemical methods
27. Name some important techniques for surface analysis.
• XPS (X-ray Photoelectron Spectroscopy)
• SEM (Scanning Electron Microscopy)
• EDS (Energy Dispersive X-ray Spectroscopy)
• AFM (Atomic Force Microscopy)
• FTIR (Fourier Transform Infrared Spectroscopy)
28. Differentiate carburizing and nitriding.
• Carburizing: Carbon diffuses into the surface.
• Nitriding: Nitrogen diffuses into the surface.
29. Differentiate aluminizing and calorizing.
• Aluminizing: Applies aluminum to the surface.
• Calorizing: Applies aluminum with iron or nickel to form
protective layers.
30. What is the purpose of surface modification?
To improve surface-specific properties like wear resistance,
corrosion resistance, biocompatibility, or electrical behavior
without altering bulk material.
31. What is shot peening?
A cold working process where small spherical media (shots)
bombard a surface to introduce compressive stresses, improving
fatigue strength.
32. Differentiate shot peening and shot blasting.
• Shot peening: For strengthening surfaces via compressive
stress.
• Shot blasting: For cleaning or preparing surfaces by
removing contaminants.
33. Name some evaporative type material deposition
methods.
• Thermal evaporation
• Electron beam evaporation
• Laser evaporation
34. Classify the physical vapour deposition (PVD) methods.
• Evaporation methods (thermal, electron beam)
• Sputtering methods (magnetron, RF sputtering)
• Arc deposition methods (cathodic arc)
35. Differentiate reactive and activated reactive electron
beam evaporation.
• Reactive evaporation: Reactive gas forms compound
coatings.
• Activated reactive evaporation: Includes plasma or ion
sources to enhance reactivity.
36. Differentiate evaporation and sputtering technique.
• Evaporation: Material heated and evaporated onto
substrate.
• Sputtering: Ions bombard target, ejecting atoms onto
substrate.
37. List the applications of pulsed laser deposition (PLD)
technique.
• Thin-film fabrication
• Superconducting films
• Optical coatings
• Semiconductor device layers
38. What is the use of corrosion inhibitor?
To slow down or prevent metal corrosion by forming a protective
layer or altering the corrosion process.
39. List the applications of the CVD technique.
• Semiconductor device fabrication
• Hard coatings on tools
• Protective coatings on turbine blades
• Optical fiber production
40. What is cathodic protection?
A technique where the metal surface is made the cathode of an
electrochemical cell to prevent corrosion.
41. List the materials that can be deposited via CVD.
• Silicon nitride (Si₃N₄)
• Titanium nitride (TiN)
• Diamond-like carbon
• Silicon carbide (SiC)
42. List the different types of CVD process.
• Thermal CVD
• Plasma-enhanced CVD (PECVD)
• Low-pressure CVD (LPCVD)
• Metal-organic CVD (MOCVD)
43. List the materials that can be deposited using atomic
layer deposition (ALD).
• Al₂O₃ (aluminum oxide)
• TiO₂ (titanium dioxide)
• HfO₂ (hafnium oxide)
• ZnO (zinc oxide)
44. Name some self-lubricating nanocomposite coatings.
• MoS₂-based composites
• WS₂-based composites
• TiN/a-C (titanium nitride/amorphous carbon)
45. What are the factors that affect super-hard
nanocomposite coatings?
• Composition and phase structure
• Grain size
• Interface bonding strength
• Deposition parameters
46. What is the use of XPS and calotest in surface
characterization?
• XPS: Determines surface elemental composition and
chemical states.
• Calotest: Measures coating thickness and wear resistance.
47. What makes nanomaterials innovative for tribological
advancement?
Their ultra-small grain sizes, high surface area, and unique
mechanical and chemical properties enhance wear resistance,
friction reduction, and self-healing abilities.
