Aviation Corrosion

CORROSION ENGINEERING Assignment IIShreyas Patwardhan2012A1PS036U

4th November, 2014Room no: 105

Which factors promote Corrosion ?

1. Moisture Content

2. Salt Content

3. Dissimilar Metals

4. Stress

5. High Velocity of surrounding fluids

6. High Friction

7. High Temperature

8. Fatigue

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

CORROSION IN THE

MODERN AVIATION INDUSTRY

14

3

2

6

5

1. Aircraft Body-Uniform, Galvanic

2. Joints- Stress

3. Avionics- Galvanic, Uniform, Surface

4. Aircraft Engine- High temperature, Galvanic, Stress

5. Brakes – Erosion Corrosion

6. Wings- Composite, Bacterial

VARIOUS COMPONENTS UNDERGOING COROSSIONAtmospheric

and Operating factors affect the degree of corrosion

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Composites are materials made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components.

Advantages of using Composites:

• Typically are 20 per cent lighter than aluminum

• More reliable

• Added strength and superior durability

• Lower maintenance costs

• Corrosion Free (?)

Why more aircrafts are built using composites ?

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Structure of compositesComposites are mainly fabricated with 3 main types of structures:

• Fiber Reinforced Polymers• Matrix Composites• Sandwich Structure Composites

In aircrafts we mainly use FRP’s and SSC’s

Carbon fibers are set into a thermoplastic polymer or resin.

These composites are allowed to harden on thin sheet of metal, or onto a metallic mesh.

With advent of newer polymers are relatively cheaper availability of carbon nanotubes, even stronger CFRP are possible to fabricate

Does anything come to your mind having a combination ofCARBON and METAL CONTACTS separated by a MEDIUM ?Alkaline dry cell

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

What is the Faudree Effect ?Bismaleimide (BMI) is a polyimide resin and is favored as material of construction for aircraft components because:• Greater Toughness• High Operating Temperatures (175 – 205 degree C)• Simplifies parts fabrication• 15% lighter than other composites known to withstand high

operating temp.

BISMALEIMIDE (BMI)

In presence of the following conditions BMI undergoes galvanic corrosion:• A conductive fiber• Contact with metal• Electrolyte solution with Oxygen present• Stagnant conditions at interface

This effect was first discovered by accident by Process Engineer, Michael C. Faudree

The corrosion is said to be catalyzed by dense concentration of hydroxyl ions at metal/water interface with pH up to 13-14. Research is still under way to better understand the phenomenon.

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Trade offs when constructing with composites

Corrosion resistance for composites by

avoiding/minimizing metal contacts which

initiate galvanic corrosion

Safety for aircraft by allowing electricity to be conducted through

the aircraft body by addition of metal

contacts

Lightning does strike twice, and in case of aircrafts its multiple times

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

Further Discussion• Bacterial Corrosion

Questions & Answers ?ReferencesWill be mailed after the presentation to common email for access to all.

Corrosion Engineering, Assignment II Shreyas Patwardhan, 2012A1PS036U

THANK YOU !

For your attention