A USERS GUIDE TO FENCR

 

   This is a non-technical explanation of the SEA coating called “FENCR”, which covers the process, the usefulness of this product, its distinguishing characteristics, materials to avoid, and some of our successful applications.

   The process begins with using immersion in a molten salt bath to drive elemental carbon and nitrogen into the surface of ferrous metal parts. This process takes place at about 1000 deg F., which means that the distortion commonly associated with conventional heat treatments does not occur. Parts can be finish machined beforehand, with no allowance necessary for final grinding.

   The diffused layer is a carbon rich zone of iron nitride, only about .001” thick, which has a very high hardness, about 68-72 Rc depending on materials used,  and excellent surface wear properties. In addition to the hardness, this outer layer has superior fatigue resistance, improved strength, improved corrosion resistance, and a lower coefficient of friction, as compared to the parent metal. While often referred to as a coating, the FENCR process is actually a “conversion coating” meaning the parent material has been changed, not just covered with some foreign material. This diffusion layer can eventually be worn off, or it can be physically pushed into the parent metal under high load, but it will not chip or spall, which is a failure mode common to plating or thermal spray.

   Another comparison to the thermal spray process, which is a “line-of sight” coating deposition method, is that FENCR is a total coating, meaning that every surface of a part is treated, including tapped holes, id surfaces etc..

  The final step in the FENCR process involves the application and curing of a resin bonded dry film lubricant, which seals the surface and provides an additional layer of self-lubrication. This layer is about .001” thick but because it is polymeric in nature and embedded in the pores of the diffusion layer we seldom incur any fitting or geometry problems at assembly. Dry film lubes in general have been shown to be effective at thicknesses a thousand times thinner than this, so the “as applied” coating can survive for a long time under very high loads.

  When completed, the FENCR process converts the surface of any steel or alloy part into an extremely hard, corrosion resistant, and self-lubricating platform, with excellent durability in both lubricating/rolling contact.

 

   The FENCR process is limited to ferrous parts and does not like bronze, copper, aluminum, etc.. So any fittings, inserts, bushings, etc., made from these materials must be removed before processing. Cast and alloy irons, as well as iron based stainless steels can be treated successfully. Because this is a time at temperature process any thinned edges or sharp points should be handled with care because they could become over-treated. All ferrous materials can benefit from this process but tool steels and nitriding steels are most suitable because their tempering temperatures are above the FENCR processing temperatures.