Detailed Product Description:

Chromium Nitride (CrN) is not as well known as Titanium Nitride but is also a Physical Vapor Deposition (“PVD”) hard coating.   It finds specific applications under conditions of high load.  It is a single phase coating with an exceptionally low residual stress level which results in the best adhesion and ductility of any of the PVD coatings.  These characteristics allow this coating to be applied in thicker film layers while still maintaining ductility and hardness without chipping or flaking during use.

Here is a coating that won’t chip, peel, or flake.  It has a hardness of about 2000 Vickers—just under

That of Titanium Nitride (equivalent to about 85 Rockwell C, still harder than tungsten carbide).  It has the beautiful appearance of shiny gun metal gray. 

It is self-lubricating with a coefficient of friction of about 0.5.   Because of its greater thickness and high surface load resistance, empirical data shows it to outlast Titanium Nitride coatings in deep drawing dies, extrusion dies and plastic molds.

Chromium Nitride is applied in a vacuum in a plasma field and forms a metallurgical bond with the substrate.  Its film thickness can range from 2 microns up to 6 microns.  Most applications use about 5 microns.  Inherent in the process is coating thickness uniformity.  No buildup occurs in corners yet the coating throws well into complex geometric features.

Key Features/Benefits:

Resistant to nearly all chemicals (acids, bases, solvents, saltwater, etc.)

Temperature resistant—begins to oxidize at 600ºC 

Non-stick/non-galling surface—perfect for titanium fasteners

Specifications:

Surface Micro-Hardness:                                    2,000 Vickers (equivalent to 85 Rc)

Thermal Stability:                                 up to 1,300ºF

Coefficient of Thermal Expansion:                    9.4 ppm/ºC  (9.4 microinches/inch/ºC)

Thermal Conductivity:                                        0.046 Calories/second-cm-ºC

Density:                                                                 5.22 grams/cm3

Crystalline Structure:                                           Face centered cubic

Modulus of Elasticity:                                         600 GigaPascals

Coating Thickness:                                              5 microns typical (range from 2 to 6 microns)

Deposition Temperature:                                    can range from 200ºC up to 400ºC

Electrical Resistivity:                                           25 micro-Ohm-cm

Substrate Selection:

PVD coatings are applied to many different materials.  Materials coated include most metals, ceramics, and some plastics.  Substrates must be compatible with a high vacuum environment and must be able to withstand the deposition temperatures of the process. 

The most common materials successfully coated with CrN are the tool steels, stainless steel, mild steel, titanium alloys, carbides, Inconel, Hastelloy, the copper alloys and the aluminum alloys.

Avoid metals containing significant amounts of Cadmium (Cd), Tin (Sn) or Lead (Pb) and materials that can outgas in the vacuum chamber. Assemblies and press fit parts can also create an out-gassing situation. 

Substrate Preparation:

Proper adhesion of the coating requires a pristine surface of the part.  The surface must be free of paint, glue, rust, oxidation, etc.  Grit blasting after heat treating and before finish grinding has been found the best approach.  Areas that are not important for coating still must not have a contaminant on the surface that could outgas, as this material will migrate throughout the chamber and contaminate all of the coating.

We clean the parts immediately before coating them.  They should be ready for coating, and cleaned of foreign material, then coated with a light rust-preventive oil for shipment to us.  Parts that do not require oil may be wrapped in a suitable material to prevent contamination and/or prevent oxide buildup.

Coating Services:

Please contact our Technical Support department via phone or e-mail to discuss your needs and to obtain a quotation.  Pricing is based on minimum lot charge.  Thus piece part cost is dependent upon size and quantity per lot.