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The differences between electroplated nickel and electroless nickel plating

Electroless nickel plating is increasingly being applied in industrial production and has several significant advantages compared to electroplating nickel,

they can be used for some precision cnc machining shaft, sheet metal stamping bracket.

Mainly reflected in the uniformity of coating, substrate adaptability, environmental friendliness, and performance characteristics.

The core advantage of electroless nickel plating is that the coating thickness is extremely uniform and the imitation is good

electroless nickel plating relies on self catalytic chemical reactions and does not require external current, so the thickness of the coating is not affected by the shape of the workpiece or the distribution of current. No matter how complex the workpiece structure is (such as deep holes, grooves, internal threads, etc.), as long as the plating solution can come into contact, a uniformly thick coating can be formed. In contrast, electroplated nickel has uneven current density distribution, resulting in excessive coating on the edges and protrusions of the workpiece, while the coating on the inner cavity, deep holes, and other areas is too thin or even unable to deposit.

Can be deposited on non-conductive substrates

electroless nickel plating does not require the workpiece itself to be conductive, so it can directly deposit a nickel layer on the surface of non-conductive materials such as plastics, ceramics, glass, and semiconductors, greatly expanding its application range. Nickel electroplating must be carried out on a conductive substrate.

Excellent coating performance and strong adhesion

electroless nickel plating layers are usually amorphous or microcrystalline structures (especially high phosphorus coatings), with dense structure, low porosity, and higher microhardness (up to 550HV in the plated state and 1200HV after heat treatment), and better wear resistance than electroplated nickel. Meanwhile, the adhesion between the electroless nickel plating layer and the substrate is generally higher than that of the electroplated nickel layer.

No risk of hydrogen embrittlement, no need for dehydrogenation treatment

During the electroplating process, the cathodic reaction produces hydrogen atoms, and some of the hydrogen will penetrate into the base metal, causing hydrogen embrittlement. Therefore, high-temperature dehydrogenation treatment must be carried out after electroplating. The deposition mechanism of electroless nickel plating is chemical reduction, which basically does not produce hydrogen gas. Therefore, the coating has no risk of hydrogen embrittlement and does not require subsequent hydrogen removal processes. It is particularly suitable for high-strength steel and other components that are sensitive to hydrogen embrittlement.

The process is more environmentally friendly and has high safety

Modern environmentally friendly electroless nickel plating solutions usually do not contain toxic substances such as cyanide and hexavalent chromium. The concentration of nickel ions is only about 1/10 of that of electroplating processes, and the plating solution can be recycled and reused. The amount of waste liquid discharged is less, making it easier to handle and meet environmental standards, and complying with environmental directives such as ROHS.

Simple equipment with low energy consumption

electroless nickel plating does not require a direct current power supply, anodes, or complex electrical control equipment. It only requires a heating tank and a general plastic or stainless steel container to operate. The equipment investment and operating energy consumption (without electricity consumption) are much lower than electroplating.

‌There are significant differences in uniformity, hardness, and corrosion resistance between electroplated nickel and electroless nickel surfaces, as follows:

1. Uniformity of coating

Electroplated nickel plating: Due to the influence of current distribution, the coating on the edges and corners of the workpiece is thicker, and complex structures (such as pipeline walls and gear teeth) are prone to thin or uneven coating.

electroless nickel plating: deposited through chemical reactions, as long as the plating solution can come into contact, the coating thickness is uniform, with a deviation generally not exceeding 5%, especially suitable for irregular parts.

2. Hardness and wear resistance

Electroplated nickel: Low hardness (HV150-300), average wear resistance.

electroless nickel plating: High hardness (HV450-600, can reach HV1000 or more after heat treatment), far superior wear resistance to electroplated nickel.

3. Corrosion resistance

Electroplated nickel plating: The coating has small pores, and its corrosion resistance is average when used alone. It is usually necessary to combine multiple layers of coating such as chrome plating to enhance the protective effect.

electroless nickel plating: The coating contains phosphorus (2% -15%), with a dense structure and low porosity. Its corrosion resistance in acidic, alkaline, seawater and other environments is much better than that of electroplating nickel plating.

4. Bonding force

Electroplated nickel plating: The adhesion depends on the quality of the pre-treatment, and may cause peeling or detachment due to incomplete oil removal.

electroless nickel plating: Through chemical bonding and mechanical fitting, the bonding force is stronger and more firm.

5. Surface structure

Electroplated nickel: a typical crystalline structure with crystal gaps.

electroless nickel plating: The high phosphorus coating is amorphous, without crystal gaps, and denser.

6. Process and Application

Electroplated nickel plating: requires an external current and is suitable for simple structural components with regular shapes, decorative features (such as mirror gloss), or basic rust prevention.

electroless nickel plating: No current required, suitable for precision parts with complex structures, high wear resistance, and high corrosion resistance (such as molds, aerospace components).

electroless nickel plating is afraid of copper pollution because the high potential of copper ions will preferentially displace nickel, damaging the continuity and lattice structure of the coating, resulting in increased internal stress and decreased corrosion resistance. Electroplating nickel does not have this problem, but it is necessary to ensure the conductivity of the substrate.

electroless nickel plating has outstanding advantages in uniformity, complex component coverage, non-conductive coating, no hydrogen embrittlement, environmental friendliness, and equipment simplicity. It is particularly suitable for precision parts, complex structural components, non-metallic materials, and fields with high environmental and performance requirements. Its main disadvantages are slow deposition rate, high plating solution cost, and strict maintenance requirements