Surface conversion coatings on steel The process used to form a thin, adherent phosphate coating on steel surfaces for corrosion protection and paint adhesion is called “parkerising.” State whether this is correct.

Introduction / Context:
Surface treatments prepare steel for service and finishing. Phosphate coatings improve corrosion resistance and paint bonding on automotive and machinery components. The trade name “Parkerising” is widely used for manganese or zinc phosphate processes.

Given Data / Assumptions:

• Base metal: carbon or low alloy steel.
• Chemical bath contains phosphate salts with accelerators.
• Typical thin crystalline coating.

Concept / Approach:
Parkerising (phosphating) chemically converts the steel surface into insoluble phosphate crystals. It is distinct from galvanising (zinc metal coating), anodising (oxide growth on aluminum/titanium), and bluing (oxide layer on steel). Phosphate layers also provide a good substrate for oils and paints.

Step-by-Step Solution:
Identify the stated coating: thin phosphate layer on steel.Relate to process names: parkerising is phosphating.Therefore, the statement is correct.

Verification / Alternative check:
Process datasheets specify weight per unit area and crystal morphology; salt spray tests show improved paint adhesion on phosphated steel.

Why Other Options Are Wrong:
Anodising targets aluminum, not steel; galvanising deposits metallic zinc rather than a phosphate conversion layer; stainless steels are less commonly parkerised due to chromium oxide passivation.

Common Pitfalls:
Poor cleaning before phosphating causes patchy coatings; incorrect bath control (pH/temperature) yields weak layers.

Final Answer:
Correct