Surface treatments Flashcards
What should learners understand about surface treatment processes?
How surface treatment processes affect the properties of materials.
What effect can painting have on a material surface?
Can alter the manner in which the material reacts to external forces and can protect the material from oxidation and corrosion.
What adverse effect can solvent-based paints have on thermoplastics?
Can break down the polymer chains in thermoplastics.
What is the process of plastic coating?
Involves immersing a preheated part into liquid plastisol to form a plastic coating.
What benefits does plastic coating provide to metal parts?
- Enhances appearance
- Provides a soft grip
- Protects from chemicals and abrasion.
What are special purpose additives used for in coatings?
To provide specific characteristics such as fungal resistance, dielectric strength, and flame retardancy.
What does galvanising refer to?
The application of a zinc coating to the surface of a metal, usually steel or iron.
What is the main purpose of galvanising?
To prevent corrosion and increase the serviceable life of the protected metal component.
What are the two main types of protection offered by zinc coatings?
- Barrier protection
- Galvanic protection.
What is barrier protection in galvanising?
Forms a protective zinc oxide layer that is impervious to air and moisture.
How does barrier protection prevent corrosion?
Eliminates contact between underlying steel substrate and external air or moisture.
What is galvanic protection also known as?
Cathodic protection.
How does galvanic protection work?
Protects the underlying steel substrate by corroding preferentially.
What role does zinc play in galvanic protection?
Assumes the role of the anode and corrodes first if the adjacent steel is unprotected.
Fill in the blank: Zinc will continue to offer galvanic protection until the coating is entirely _______.
consumed.
True or False: Zinc coatings only provide barrier protection.
False.
