Nickel-Chrome Composite Coating
Bi-Protec® nickel-chrome composite coating gives custom CNC parts dual protection against corrosion and wear.
When corrosion and wear attack the same component
In pumps, compressors, food-processing equipment and automation systems, CNC machined parts rarely face wear alone — moisture, cleaning chemicals, process fluids and galvanic reactions often attack the surface at the same time as sliding contact. A coating chosen only for hardness may lack corrosion resistance, and one chosen only for corrosion resistance may not survive repeated friction.
JF Precision can provide Bi-Protec® nickel-chrome composite coating as part of a custom CNC machining and surface-finishing project — a high-phosphorus electroless nickel barrier under a thin dense chrome working surface, managed from drawing review through final dimensional inspection.
Why the dual-layer structure matters
Bi-Protec® is an industrial composite system, not decorative nickel-chrome plating. A high-phosphorus electroless nickel layer is deposited on the substrate first, followed by a thin dense chrome layer — either a nodular NTDC structure or a diamond-enhanced XADC® layer for more severe wear conditions.
The high-phosphorus electroless nickel layer
Creates a corrosion-resistant barrier between the substrate and the operating environment.
Provides more conformal coverage over complex geometry, grooves and section changes than many line-of-sight plating processes, and supports aluminum substrates.
The thin dense chrome working layer
Adds a hard surface for sliding, contact and abrasive wear, and improves resistance to galling and fretting.
Protects the nickel barrier from mechanical damage; a nodular surface can also help retain lubricants.
Typical Bi-Protec® coating data
The values below are typical published ranges and should be confirmed for each substrate and operating condition.
| Property | Typical Published Value | Design Consideration |
|---|---|---|
| Electroless nickel thickness | 5.1–76.2 μm (0.0002–0.003 in) | Selected by corrosion exposure and geometry |
| Thin dense chrome thickness | 2.5–12.7 μm (0.0001–0.0005 in) | NTDC or XADC® selected by wear demand |
| Maximum combined deposit | Up to 88.9 μm (0.0035 in) | Requires deliberate pre-coating planning |
| Surface hardness | Up to ~78 HRC | Depends on coating system and specification |
| Processing temperature | Below ~88°C (190°F) | Reduces heat-related distortion risk |
Ni + NTDC or Ni + XADC®: which system should be used?
The outer chrome layer is selected according to the dominant failure mode — we review material, geometry and operating environment before confirming the specification. Our side-by-side comparison of Ni + NTDC and Ni + XADC® walks through the selection in detail, and the outer layer of the second system is our XADC® diamond thin dense chrome.
| System | Main Strength | Selection Focus |
|---|---|---|
| Ni + NTDC | Balanced corrosion and wear protection | General machinery, aluminum parts, moderate sliding conditions |
| Ni + XADC® | Enhanced wear resistance plus corrosion protection | Severe sliding or abrasive wear, low-lubrication contact |
Why it's useful for aluminum CNC components
Aluminum is widely used for custom CNC parts for its weight and machinability, but an unprotected surface may not resist wear or corrosion well enough for demanding service — particularly where it contacts steel, process fluids or humid environments. A properly engineered nickel-chrome system builds a more durable working surface while keeping the aluminum substrate's weight advantage. See our full Available Materials list. Coating suitability depends on alloy grade, heat treatment, geometry and operating environment, and is reviewed before the process is selected.
Complex geometry and conformal nickel coverage
Pump bodies, valve components and tooling often have grooves, bores and irregular surfaces. Electroless nickel is deposited by chemical reduction and can cover complex geometry more conformally than line-of-sight electroplating, creating a continuous corrosion barrier before the chrome layer is applied. Final coverage still depends on part design, masking and drainage — deep blind holes and trapped volumes should be reviewed at the drawing stage.
Coating thickness and final dimensional control
Because Bi-Protec® combines nickel and chrome, its total deposit can be considerably thicker than a standalone chrome coating, so the coating allowance must be planned before machining begins. An outside diameter increases, an inside diameter decreases, and a coated flat surface shifts the stack height — threads, sealing lands and bearing fits may need selective masking.
Reviewing the 3D model and drawing for final fit and functional dimensions
Identifying surfaces to coat and surfaces to mask
Selecting Ni + NTDC or Ni + XADC® for the corrosion and wear conditions
Confirming target nickel and chrome thickness ranges
Calculating pre-coating dimensions for diameters, bores and mating features
Machining and inspecting the component before coating
Completing the coating process and inspecting the finished surface
Measuring final dimensions and preparing inspection records when required
Custom CNC parts that may benefit from this coating
Bi-Protec® is most relevant when a component must tolerate corrosive exposure and mechanical wear at the same time. We apply it to custom CNC machined parts produced to your own drawing.
FAQ: Nickel-chrome composite coating
Questions about ordering, lead times or shipping? Our FAQ page answers the most common questions.
No. It's an engineered industrial composite coating using high-phosphorus electroless nickel beneath a thin dense chrome working layer, for corrosion and wear protection rather than appearance.
Ni + NTDC gives balanced corrosion and wear protection. Ni + XADC® uses a diamond-enhanced chrome layer and is generally chosen for more severe wear or sliding conditions.
Yes, including drawing review, machining allowance planning, coating coordination and final inspection.
It can be suitable for selected aluminum alloys and applications; alloy, geometry and service environment are reviewed before the process is confirmed.
Yes. Both layers add thickness — outside diameters increase, inside diameters decrease, and coated flat surfaces change in height. Pre-coating dimensions are planned around the specified coating thickness.
A 3D model, 2D drawing, material, quantity, coating areas, operating environment, target coating system and final dimensional requirements.
Continue reading
Ni + NTDC vs Ni + XADC®
Which nickel-chrome composite system fits your part: balanced protection or maximum wear resistance.
Read article →
Coating Allowance for Precision CNC Parts
How coating thickness changes diameters, bores, threads and fits — and how to plan the pre-coating dimensions.
Read article →
Diamond Thin Dense Chrome Coating
XADC® diamond thin dense chrome for shafts, bushings and tooling exposed to severe wear.
Read article →