Understanding Parkerising and Phosphating

The question asks for an alternative name for the process known as Parkerising. To answer this, we need to understand what Parkerising is and how it relates to the given options.

What is Parkerising?

Parkerising is a specific type of surface treatment applied primarily to steel surfaces. Its main purposes are to provide increased corrosion resistance and to create a porous surface layer that acts as a good base for subsequent painting or oiling.

Comparing Parkerising with the Options

Let's examine each option provided:

1. Dipping: This is a very general term referring to the act of immersing something into a liquid. While Parkerising involves dipping metal parts into a chemical solution, dipping itself is not synonymous with Parkerising.
2. Galvanizing: Galvanizing is a process of applying a protective zinc coating to steel or iron to prevent rusting. This is usually done by hot-dip galvanizing, where the metal is dipped in molten zinc. Galvanizing is a different chemical process than Parkerising.
3. Anodizing: Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. It is most commonly associated with aluminum and its alloys, although other nonferrous metals like titanium, zinc, magnesium, and tantalum can also be anodized. This process is different from the treatment applied in Parkerising.
4. Phosphating: Phosphating, also known as phosphate conversion coating or phosphatizing, is a chemical process for treating a metallic surface. It involves applying a phosphate chemical to the surface of the metal, which reacts to form a protective, crystalline coating of metal phosphates. This coating is porous and provides excellent adhesion for paints and reduces friction for moving parts. Parkerising is indeed a trade name for a specific type of phosphating process, particularly iron or manganese phosphating.

The Relationship: Parkerising is a Type of Phosphating

Based on the analysis, Parkerising is a proprietary name for a process that falls under the broader category of phosphating. Specifically, it is a type of chemical conversion coating where metal surfaces are treated with a phosphoric acid solution containing various phosphates and other chemicals.

Therefore, Parkerising is otherwise known as Phosphating, as it is one form of this chemical surface treatment process.

Summary Comparison

Hence, the process known as Parkerising is essentially a form of Phosphating.

Revision Table: Surface Treatments

Additional Information: Types of Phosphating

Phosphating processes can be categorized based on the type of phosphate used. Common types include:

• Iron Phosphating: Provides a relatively thin coating, often used as a paint base on steel, zinc, or aluminum.
• Zinc Phosphating: Creates a thicker, more crystalline coating than iron phosphating. Used for corrosion resistance, as a paint base, or for cold forming (like drawing).
• Manganese Phosphating: Produces the heaviest coating, primarily used for anti-galling and wear resistance, especially on moving parts like gears and bearings, often combined with oiling. Parkerising typically refers to either iron or manganese phosphating processes developed by the Parker Rust-Proof Company.

Understanding these different types helps clarify why Parkerising is considered a specific application within the broader field of phosphating.