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Ion Bonded Diamond Like Coating (DLC) | Bolt Carrier Groups

Posted by Jose Rueda on

Ion Bond Diamond like Carbon (DLC) Explained...

DLC is a superb coating for ferrous alloys (8620, 9310, c158 etc..) and stainless steels (1740, 415R and 416R etc..) is the plasma assisted vapor deposition coating called Tungsten Diamond Like Carbon. One of the best selling points of the Diamond-Like Coating in that the parts are never heated over 300 degrees Fahrenheit, so there's no need to worry about the parts losing their temper, softening, or becoming brittle. Two microns of the material is deposited on the surface during the DLC Process. 2 microns amounts to about 80 millionths of an inch-far too little to affect any parts' function or fit. DLC is a thoroughly impressive treatment. Not only does it perform its intended task of coloring the bright steel to a matte, non-reflective greyish black, it also provides a tough, corrosion-proof coating that is virtually scratch proof. DLC will not wear even when subjected to extensive use. Our DLC BCG uses a high quality ion-bonded first layer followed by a Physical Vapor Deposition process to harden the parts to superior Rockwell hardness ratings yo see below.

See our Premium Match Grade DLC Carrier Groups Now!


Quality DLC Deposition

DLC coatings can be deposited using a variety of deposition methods such as sputtering, ion beam, cathodic arc, electron beam, lasers and PACVD. Cobratac deposits our diamond like carbon coatings using a patented technology combining PVD (Physical Vapor Deposition) and PACVD/Ionbond (Plasma Assisted Chemical Vapor Deposition) which deposits some of the highest quality, most consistent DLC coatings available to industry today. 

This technology allows the DLC coatings to be deposited in large production machines without sacrificing film quality. With this patented technology, we have the ability to deposit PVD layers as well as dense, uniform PACVD layers in the same system. Our process will transition from PVD layers to DLC layers seamlessly producing films that exhibit excellent interlayer adhesion as well as excellent adhesion to the substrate.  

Coating Process

Diamond Like Carbon Coating Coating ProcessThe Bolt Carrier Gorup parts are placed into the stainless steel vacuum chamber on a fixturing carousel and the chamber is evacuated. The product is preheated to a low processing temperature that will not exceed (150 c) 300 F. The preheating phase of the process conditions the substrate for the coating and will ensure that all of the moisture absorbed by the material has been outgassed before the Ionbonding deposition process begins.

After the preheat cycle is complete, the process transitions into the ion etching phase where product is bombarded with ions from argon gas to scrub or sputter clean the surface and remove micro oxides. This scrubbing of the surface with ions cleans the surface and improves the adhesion of the coating to the substrate.

After the substrate has been sputter cleaned, the process transitions into the coating phase. If an initial layer(underlayer) is needed to improve the performance of the product in the final use, the high energy sputtering process is used to deposit a dense well adhered smooth underlayer. As the underlayer coating reaches the proper thickness, the process transitions into the DLC coating step which deposits a dense, smooth amorphous carbon hydrogenated(a-C:H) layer onto the BCG surface. 

Coating Phase

During the DLC coating phase of the process, a carbon carrying gas is introduced into the chamber. This gas is the source for the amorphous carbon DLC coating. The carbon carrying gas introduced into the chamber is ionized by auxiliary anodes and undergoes what is referred to as “cracking” or separating of the hydrogen and carbon in the gas. The ionized hydrogen and carbon atoms in the gas are drawn to the surface of the product with an electrical charge that is applied to the fixture carousel.




Final Steps

Diamond Like Carbon Coating ChartThe carousel that has the electrical charge applied and is carrying the product to be coated is also rotating in the chamber and draws the ionized carbon/hydrogen ions to the surface of the product forming the amorphous carbon or diamond like carbon (DLC) film.

The rotation of the carousel carrying the product in the chamber can be a single, double or triple axis rotation depending on the complexity of the product geometry and the coating uniformity required. This allows a scratch proof uniform film to be deposited on the surface of the product unlike conventional plating processes (NiB) that can flake or chip.

Film properties, structure, hardness and underlayers can all be tuned to produce a coating optimized for the firearms industry.

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