Sustainability and Enviromental Degradation Flashcards
What are the characteristics of eco-friendly Materials
From renewable source, Bio-degradable, durable, locally sourced, embodied energy
Define corrosion in metals
Electron transfer involving both oxidiation and reduction
Define photo-degradation in polymers
When polymers are exposed to light and oxygen causing loss of strength, toughness and de-colouration.
What are corrosion control measures?
good design, coatings, inhibitors, monitoring
What is designing by alloying
Changing electrode potential and addition of a protective surface film
What is pitting corrosion
localised form of corrosion when cavities or holes are produced
What is green shipping
Eco-friendly packaging materials such as poporn, wood shavings, nut shells etc.
Define durability in materials
A function of a material and the environment it operates in
Factors that affect durability
industries, materials, protection, environments, design, Mechanisms
How does design (geometry/configuration) help avoid degradation?
Allow uniform corrosion, supress galvanic attack, avoid crevices, consider cathodic protection, be aware of stress corrosion and fatigue, design for inspection and maintenance
What is Galvanic Corrosion
when two dissimilar metals are electrically connected in electrolyte. The > difference in oxidation potential, the > galvanic corrosion. occurs at the contact point of two metals/alloys with different electrode potentials.
What is the difference between passive and active elements?
passive elements will not corrode, they act as a cathode. Active elements will corrode, they act as an anode.
Name types of coatings
Passive coatings - separate the material from the corrosive environment.
Active Coatings - Sacrificially corrode to protect metal
Self-generated coatings - rely on alloying to produce protective film
Examples of galvanic corrosion coatings
Paint Spraying, hot dip galvanising, electroplating, metal flame spraying, polymer powder spraying, enamaling.
What are corrosion inhibitors
Reduce rate of attack when dissolved in a corrosive medium by lowering the Ph or suppressing the anodic/cathodic steps
