Composite Diamond Coating®

CDC results in a unique and attractive matte gray finish. When the coating is used or polished, it transforms into a shinier, more metallic appearance.

Thanks to the electroless chemical deposition method, CDC uniformly covers all surfaces of the substrate, regardless of geometry. The coating does not build up on edges, corners, inner diameters, or any other unwanted surfaces. Unlike other coating processes, such as electroplating and spray coatings, Composite Diamond Coating® does not require a line-of-sight for application.

CDC thickness can be tailored to the specific needs of each application, ranging from 0.0002” (5 microns) to over 0.025” (625 microns). Although a standard coating thickness of 0.001 (25 microns) is commonly used in most applications, any thickness can be produced with a tolerance of about +/- 2 microns.

On average, the density of diamond particles within Composite Diamond Coating® is around 40% by volume. This ensures a balanced composition for optimal performance. However, both higher and lower densities can be produced as needed. With too little diamond, the coating will not have sufficient diamond properties. Too much diamond leads to a lack of enough metal matrix necessary for proper adhesion to the substrate, and can jeopardize the structural integrity of the coating.

The most popular version of Composite Diamond Coating® is CDC-2 featuring diamond particles with a mean size of 2 microns for maximum diamond density, hardness and wear resistance. Other sizes can also be employed, with particles of about 20 or 40 microns for high-friction applications.

We also offer the Nano-Plate™ version of CDC, with nanometer-sized particles. This version increases the diamond surface area within the composite coating, but with few automorphic or cleavage faces because the particles are generally rounded.

Nano-Plate™ is compatible with a wide range of mating materials, such as textiles, paper, seals, metals, plastics, and alloys. In some cases, this version of the coating demonstrates lubricating properties along with exceptional wear resistance.

The diamond used in Composite Diamond Coating® is meticulously specified for composition, size, and shape. The interaction of a large surface area of diamond particles with the reactive electroless nickel bath requires exceptional purity. High quality, precisely sized and shaped diamonds are essential to ensure the optimal density and surface characteristics of the coating.

Our Composite Diamond Coating® services employ finely graded diamond particles with rigid sizing specifications, resulting in uniform coatings without variations in roughness. For specific applications requiring a rougher texture for increased friction and grip, we also offer alternative coatings.

In delicate applications that require greater smoothness, other options include:

• Lightly sandblasting, polishing, or tumbling the Composite Diamond Coating® before use.
• Applying an electroless nickel overcoat to create a break-in layer for the initial use of the substrate.
• Applying the Nano-Plate™ version of CDC, which uses smaller diamond particles.

CDC combines the hardness of heat-treated electroless nickel, which is approximately 950 Vickers, with the extraordinary hardness of diamond at 10,000 Vickers. This results in an average hardness of about 1,200 – 1,500 Vickers. While this is significantly higher than other materials, such as tool steel at around 400 Vickers, it is difficult to determine absolute hardness on composite materials like CDC. What really makes Composite Diamond Coating® shine is its superior wear resistance and durability.

There are various standardized tests available that have demonstrated the outstanding wear resistance of CDC and other coatings. One of the most common test methods is the Taber abrasive wear test, in which a coated panel rotates under two abrasive wheels that are also rotating. Wear is measured according to the panel’s weight loss after a specific number of rotations under a fixed load. The lower the wear determined by this test, the lower the wear to the coating.

The following coatings and materials were tested by going through 1,000 cycles on the Taber test device.

The following table represents the Nano-Plate™ and hard chrome plating Taber abrasion test results, based on 10,000 cycles on the device.

Another common testing method is the Yarnline abrasive wear test. This involves a yarnline that is under constant tension being drawn across a test piece, and maintained at a constant speed and force against the test material. The wear is measured in the amount of material removed over time as mil3 per hour. The following results are from Yarnline abrasive wear testing of various coatings.

The abrasive slurry test program is another important testing method. In this program, an abrasive slurry is constantly applied to steel panels, some with the coating applied and others without it. The following results are from an abrasive slurry test in which an Alumina slurry of 5-micron powder was applied to the panels. Wear is measured as the volume of material that was lost (microns3) per unit force applied (Newton) for unit length (mm). The following table shows how Composite Diamond Coating® compares to electroless nickel and bare steel.

The pricing of Composite Diamond Coating® is determined based on factors such as the size of the substrate, amount of masking or fixturing necessary, coating thickness, material, and quantity. However, the cost of CDC is surprisingly economical for several reasons:

• All plating components used in the process are manufactured on-site, reducing costs and ensuring high quality results
• The long-term cost of CDC is reasonably low when you factor in the benefits of its longevity and exceptional wear resistance
• The base material used with the coating can be swapped for one that is less expensive, lighter, or easier to produce
• We can chemically remove and recoat CDC, eliminating the need for replacing parts entirely

Composite Diamond Coating® can enhance virtually any metal or alloy, including carbon and tool steels, aluminum alloys, copper, brass, bronze, stainless steel, and titanium. However, stainless steel and titanium require extended pretreatment, making the coating process slightly more expensive for these materials. Luckily, the superior properties of CDC allow for the substitution of costly materials like titanium and carbide with more affordable ones, such as aluminum and steel.

Selective deposition of CDC is achievable based on specific requirements. Understanding which critical areas need treatment, and which areas should avoid treatment for particular reasons is crucial for ensuring a quick and economical process. Typically, it’s faster and less expensive to coat the non-critical areas, rather than mask them off.

A post-coating heat treatment, typically around 750°F, is beneficial for improved adhesion, increased matrix hardness, and optimal wear resistance. Other temperature ranges can be used as needed.

Composite Diamond Coating® offers significant environmental benefits, including:

• No use of chrome, minimizing the environmental impact of the coating.
• The reduced nickel usage due to codeposition of particles conserves resources.
• Thinner coatings compared to conventional options result in less material use.
• Extended lifespan of coated parts, meaning less frequent replacements.
• Longer bath life leads to less waste.
• Chemical stripping and recoating allow for the recycling of nickel.

CDC is protected by one or more U.S. patents, including but not limited to patents 4,997,686, 5,145,517, 5,300,330, 5,863,616, 6,306,466, 7,744,685, 8,147,601, 8,598,260, 9,096,924 and 10,006,126, with additional patents pending.