ZINCROLYTE® Sprint™ High-Performance Alkaline Zinc-Nickel Process

In the corrosion-resistant coatings market, demand for zinc-nickel alloy coating has increased. Behind this rise in demand lies not only extended warranty periods but also higher quality expectations. The advantages of zinc-nickel alloy coating create a marked difference when compared with zinc and other zinc alloy coatings. Chief among these advantages is, without question, the advanced corrosion resistance that zinc-nickel alloy coating possesses even when subjected to mechanical damage and/or high temperatures. ZINCROLYTE Sprint contains all the advantages of zinc-nickel alloy coating while also delivering increased coating speed.

Figure 1: Demonstrates corrosion resistance performance of fasteners coated with zinc and zinc-nickel alloy (14% Nickel). Tests were conducted in accordance with ISO 9227.

ZINCROLYTE Sprint is a zinc-nickel alloy coating process designed specifically for coating complex parts frequently used in automotive and other high-value-added applications to continuously provide optimal efficiency. Zinc-nickel coating possesses exceptional corrosion resistance and provides unparalleled protection on steel materials. Passivations produced by MacDermid Enthone (TriPass ELV) and lacquers (ENSEAL/TNT) are applied to further enhance optical appearance (black/bright silver) or to meet predetermined coefficient of friction values. ZINCROLYTE Sprint is a γ-phase zinc-nickel (12–15% Ni) alloy coating process that meets the most demanding corrosion resistance requirements of the automotive industry. The process enables smooth and even coating through homogeneous alloy composition and exceptional throwing power in both low and high current density areas.

Increased Coating Speed

The ZINCROLYTE Sprint process offers higher coating speed compared to conventional alkaline zinc-nickel coating. High loading capacity and high coating speed are maintained throughout the entire bath life. With its new addition systems, this high performance can be sustained without any auxiliary equipment.

Figure 2: Example showing thickness, distribution and homogeneous Ni % in parts processed under identical conditions.

Conclusion:

ZINCROLYTE Sprint delivers high performance by enabling coating in significantly less time than required by conventional alkaline zinc-nickel processes.

Smooth and Fine Appearance

Conventional alkaline zinc-nickel has good brightness and the spherical nodules formed on the part surface are visible in electron microscope images (SEM). To achieve a smooth surface appearance, these nodules must be closely spaced, and to ensure this, special maintenance procedures are typically required. ZINCROLYTE Sprint naturally produces a smoother and finer surface that provides a brighter appearance.

Figure 3: ZINCROLYTE Sprint surface characteristics, bright silver-colored, homogeneous appearance.

Furthermore, this achieves a brighter appearance, facilitating passivation of the surface and ensuring a narrow coefficient of friction range.

Figure 4: Comparison of surface characteristics of ZINCROLYTE Sprint and conventional alkaline zinc-nickel.

High Efficiency

The ZINCROLYTE Sprint process has a 30% higher coating rate compared to conventional processes. High current efficiency is continuously maintained throughout the entire bath life.

Figure 5: Comparison of ZINCROLYTE Sprint process efficiency at 1 A/dm² with conventional alkaline zinc process efficiency

 

Wide Operating Window & Low Maintenance Requirements

ZINCROLYTE Sprint requires less maintenance compared to conventional processes due to characteristics such as not requiring any freeze-out operation like carbonate crystallization and not forming deposits on anodes and other equipment. High conductivity is achieved with reduced cooling. ZINCROLYTE Sprint provides smooth and even coating with high burn resistance in areas of low and high current density. This enables faster coating of parts with complex geometries.

Figure 6: ZINCROLYTE Sprint demonstrates consistently high efficiency even at increased salt concentrations compared to conventional alkaline zinc-nickel.

Summary

The ZINCROLYTE Sprint process offers manufacturers more advantages when compared with conventional zinc-nickel alloy coating processes.

* For drum applications, does not require extra dilution and feeding; standard handling will normally be sufficient. Figure 7: Comparison of ZINCROLYTE SPRINT characteristics with conventional processes

It is important that the coating line equipment be capable of handling this much more efficient process. When installing ZINCROLYTE Sprint, rectifiers and other control systems should be evaluated to ensure the operation can accommodate the additional capacity. The ZINCROLYTE Sprint process is designed to achieve profitability in high-volume operation. • Faster coating rates even at high production volumes, • High conductivity – lower bath voltage, • Excellent metal distribution – homogeneous appearance, • High burn resistance – capability to operate at higher currents, • No sediment formation in tanks or pipes, no scale formation on anodes, • No freezing of required salts – lower maintenance requirements. High productivity = high efficiency + high applicable current (enhanced burn resistance feature). Productivity is achieved without the need for specialized equipment.   Mehmet Eren Technical Sales Engineer MacDermid Enthone Industrial Solutions