1. Please mention the layers of organic paints and shortly describe them

• Organic paints Consist of several layers:

• Priming paints

• Interlayers paints

• Topcoats paints

Priming paints

• We divided priming paints for:

• Insulating

• Pasivating

• Protectoring

• Reactive

Interlayers paints

• They are designed to:

• Sealing the coating

• Giving it a proper thickness

• Reducting the permability

Topcoats paints

• Contain components which give special properties:

• Prevent fouling algae

• Increase resistance to abrasion

• Increase resistance to high temperature

1. Mentioned the advantages and disadvantages of metallic coatings

   Advantages

• Many of them are quite cheap

• Similar values of the coefficient of thermal expansion

• They are resistivity for electrochemical and high-temeprature corrosion

• Easy methods of application

• Easier production of multilayers coatings

  disadvantages

• Not used over 1600-1700 ○C

• Sometimes very expensive (gold , platinum)

1. Mentioned the advantages and disadvantages of ceramic coatings

   Advantages

• Better resistivity in agressive environment like high temperaure, acids, alkalines, water

  Disadvantages

• Worse resistivity for thermal shocks

• Complex chemical composition

• They are quite expensive

1. Mentioned methods of preparations for TBC

   In industry, thermal barrier coatings are produced in a number of ways:

1. Electron Beam Physical Vapor Deposition

2. Air Plasma Spray

   c) High Velocity Oxygen Fuel

   d) Electrostatic Spray Assisted Vapour Deposition

   e) Direct Vapor Deposition

1. Please mention required properties of coatings

• Resistance of coating in a given agressive environment and working conditions of construction

• Appropriate melting points of coating and the substrate and phases presents in diffusion layer

• Similar values of the coefficients of thermal expansion with substrate

• Good adhesion properties between coating , diffusion layer and substrate

• Coating’s resistance for erosive effects of gas