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COMPOSITE DIAMOND COATING is a unique, patented coating with ultra-fine diamond particles contained within hard electroless nickel metal. The uniformity of the dispersion of diamond particles within Composite Diamond Coating makes the coating consistent and regenerative in use. This proprietary process offers a practical and economical opportunity to provide the properties of diamond to the surface of parts.

The synergy of the electroless nickel matrix and the unsurpassed properties of diamond in Composite Diamond Coating provides numerous benefits including:

• Exceptional wear resistance
• Excellent hardness
• Enhanced corrosion resistance
• Perfect conformity to complex geometries
• Increased thermal transfer
• Applicability to all common metals and alloys
• Coverage of entire surfaces or selected critical areas

1000x Cross Section of Composite Diamond Coating	Photograph of the surface of Composite Diamond Coating

These features allow increased lifetime and minimize maintenance related downtime due to the replacement of high wear parts. In addition, any process parts enhanced by Composite Diamond Coating will produce more consistent product over an extended period of time. The presence of this unique coating may also allow new materials with other performance or cost advantages to be utilized.

Prospective users of Composite Diamond Coating often ask questions about one or more of the following topics. Below, you will find each of these topics briefly discusses.

What is the appearance?
Composite Diamond Coating is a unique and attractive matte gray color. When used or polished the coating becomes shinier and more metallic in appearance. The Nano-Plate version of Composite Diamond Coating is inherently a shinier nickel colored coating. The color of these coatings cannot be changed. They can however be subsequently coated with other materials if an alternate final appearance is desired.

How perfect is the uniformity?
Because of the electroless chemical method of deposition, Composite Diamond Coating covers all surfaces of the work piece with essentially perfect uniformity. There is no build up on edges, corners, inner diameters, or any other surface. Another significant advantage of Composite Diamond Coating over other coating processes such as electroplating, spray, and other types coatings is that Composite Diamond Coating can be applied with uniformity to all surfaces of parts regardless of geometry. Recesses, holes, inner diameters of any size; there is no " line of sight "  requirement for Composite Diamond Coating.

What thicknesses are possible?
The thickness of Composite Diamond Coating can be customized according to the requirements of each specific application. Any thickness from 0.0005" (12 microns) to over 0.01" (250 microns) can be produced with Composite Diamond Coating, although most applications use a standard coating thickness of 0.001" (25 microns). Any thickness can be applied to a tolerance of about +/- 5 microns.

How high is the diamond density?
The density of diamond particles within Composite Diamond Coating is typically 25-35% by volume. Higher and lower densities can be produced as needed, but the standard range serves well in virtually all applications. Too little diamond in the coating will not sufficiently provide the properties of diamond desired in the coating. Too much diamond in the coating creates the risk that there will not be enough of the metal matrix required for adhesion to the part and structural integrity of the coating itself.

What is the surface finish?
Dura-Tech Processes, Inc. uses only finely graded diamond within rigid sizing specifications for Composite Diamond Coating. This produces a very smooth coating without sandpaper like roughness.

In certain especially delicate applications where even greater smoothness is required, there are three main options to consider:

1. The standard Composite Diamond Coating can be lightly sandblasted, polished, or tumbled before use.
2. An electroless nickel overcoat may also be applied to provide an even smoother surface for parts upon initiation of their usage.
3. The Nano-Plate version of Composite Diamond Coating that employs smaller diamond particles can be applied.

If a rough surface is desired, larger particles of about 8-10 microns can be used in the coating. Alternatively, the substrate should be made rough before the standard Composite Diamond Coating is applied which will replicate and preserve the exact roughness profile. This latter approach is generally preferable as it replicates the roughness profile of the substrate, and also provides the greater wear resistance inherent in the high density of smaller particles employed in the standard Composite Diamond Coating.

How hard?
As you know, Composite Diamond Coating is made up of two materials: electroless nickel and diamond. The hardness of heat-treated electroless nickel is about 950 Vickers, while diamond is an extraordinary 10,000 Vickers. Combined, the hardness of Composite Diamond Coating is about 1,200 Vickers. While significantly high in comparison to other materials such as tool steel (400 Vickers) and chrome plating (1,000 Vickers), it is complicated to establish absolute hardness readings on composite materials such as Composite Diamond Coating; and it is in its tremendous wear resistance and other properties that Composite Diamond Coating really shines.

What is the wear resistance?
Various standardized test methods have been employed to evaluate wear resistance of different materials and coatings. Perhaps the most common test method is the Taber abrasive wear test. In the Taber test method, a coated panel turns under two rotating abrasive wheels. Wear is measured as the weight loss of the panels following a specified number of rotating cycles. The lower the wear index, the lower the wear to the coating. The coatings and materials in the following table were tested by 1,000 cycles on the Taber test device.

Following are Taber abrasion test results for Nano-Plate and hard chrome plating. These results are based on a more extensive test of 10,000 cycles.

Many other test methods have been used to demonstrate the exceptional wear resistance of Composite Diamond Coating over other coatings and materials. For example, in the Yarnline Abrasive Wear Test where an abrasive yarnline under constant tension is drawn across a material sample at a constant speed and force against the test piece. Results are measured in material removal over time as mil³ per hour. The following are results from this testing:

In an Abrasive Slurry test program, steel panels with and without coating were wear tested by an Alumina slurry of 5 micron powder contacting the panel surface under a constant load. The wear data was converted to a new constant equating the volume of material lost (microns³) per unit force (Newton) for unit length (mm). The following results show the advantage of Composite Diamond Coating over conventional electroless nickel and bare steel.

What does it cost?
The cost of Composite Diamond Coating is surprisingly economical for a number of key reasons.

1. Dura-Tech Processes, Inc. has been supplying composite electroless composites for over a quarter of a century and has recently expanded modern production facility to produce this and its other coatings on daily basis.
2. Surface Technology, Inc. uses only chemicals it manufactures itself for the Composite Diamond Coating process, thereby making the product at a further reduced cost and optimal quality.
3. The cost of Composite Diamond Coating is relatively low when consideration is given to its outstanding wear life and the savings that can be realized from extending use and greater reliability.
4. Given the unique properties of Composite Diamond Coating, many customers are able to change the base material of their parts to one that is less expensive, lighter, or easier to manufacture, thereby creating an additional cost saving.

In general, the price to coat parts with Composite Diamond Coating is determined based on the size of the parts (both overall size and the area to be coated), amount of masking or fixturing required, coating thickness, base material, and quantity of parts.

What substrates can be coated?
Essentially any metal or alloy can be enhanced by Composite Diamond Coating. The most common materials coated are carbon or tool steels and aluminum alloys. Copper, brass, bronze, stainless steel and titanium are also regularly treated with Composite Diamond Coating. It should be noted, however, that the extended pretreatment process required for stainless steel and titanium make the coating onto these materials more expensive than common steels or aluminum. Fortunately, the exceptional wear and corrosion resistance properties of Composite Diamond Coating allows the substitution of these more expensive materials such as titanium and carbide with less expensive alternatives like aluminum and steel.

Is selective coating or masking possible?
Selective deposition of Composite Diamond Coating is certainly achievable when required. It is important to know for each part which critical areas must be treated, which areas may not be treated for specific reasons, and which areas may or may not be treated depending on the greatest economy and expediency of the coating process. Often it is less expensive and faster to coat "non-critical" areas than to mask off these areas.

What post-treatment may be done?
After coating, a heat treatment step is generally desirable to provide improved adhesion of the coating, greater hardness of the matrix, and maximum wear resistance. A heat treatment of up to 750 Degrees Fahrenheit is normally preferred. Other temperatures can be implemented as needed for specific applications.

What are the environmental benefits?
Composite Diamond Coating offers a number of important environmental benefits in comparison to alternative coating technologies:

1. Composite Diamond Coating uses no chrome. The environmental problems inherent with plating and using chrome are therefore entirely eliminated.
2. Composite Diamond Coating can be routinely produced with up to 35% by volume of codeposited particles. This means that at least 35% less nickel is required to produce composite coatings of equal thickness to a conventional coating without such particles.
3. Given the greater wear resistance of Composite Diamond Coating versus conventional coatings, the deposit thickness of Composite Diamond Coating can be significantly less than conventional electroless nickel coatings. This means even less nickel needs to be used.
4. Composite Diamond Coating last longer, and parts will need to be recoated or replaced less frequently. Again, resulting in even less nickel used.
5. The less nickel the plating shop uses, the longer their baths will last. This means less baths required, less waste treatment and less waste.
6. Greater wear resistance of the Composite Diamond Coating reduces the release of the coating into the environment.