We have developed a novel method, dubbed thermal processing & coating (TP&C), for manufacturing surface coatings that can replace the traditional hard chrome plating. The TP&C surface treatment allows one to combine exceptional mechanical properties obtained due to heat treatment with an enhanced tribological performance and corrosion resistance.

Hard chrome plating has been the standard solution for manufacturers for more than six decades to increase the hardness, abrasion resistance and corrosion resistance various components. Common applications include hydraulic cylinders and pistons, piston pins, valves, rolls, molds, dies, press punches, shafts and rotors for pumps, etc. However, there are well known health and environmental hazards associated with the chrome plating processes. Conventional hard chrome electroplating process known as hex-chrome or chrome (VI) plating generate hexavalent chromium ion which is a known carcinogen. In the European Union, the use of hexavalent chromium is prohibited by REACH. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coatings with an environmentally benign, non-carcinogenic coating having characteristics similar or superior to those of hard chrome. Several alternative technologies have been developed, among which various thermal spray, PVD and CVD coatings should be mentioned. Known commercial products are Hardide® CVD coatings, Duralar PACVD coatings, InnerArmor plasma spray coatings, Tribond™ PVD and PACVD coatings, etc. There has been a major paradigm shift from universality to specialization - rather than striving to find a one-fits-all direct replacement for hard chrome, which proved to be very challenging, engineers are now trying to find individual solutions for specific applications. For instance, nickel-tungsten coatings can match hard chrome in terms corrosion resistance, wear and hardness, being non-toxic at the same time. Nickel-tungsten coatings can be produced using selective plating, when localized areas are selectively coated without the use of an immersion tank. There are an increasing number of industry standards that include this technology, for example AMS2451C and MIL-STD-865D. Metal matrix composites such as cobalt/chromium carbide, nickel/chromium carbide and nickel/ tungsten carbide can also be used as a replacement for hard chrome in a number of applications where good tribological properties and oxidation resistance are needed.

Thermal spray hard coatings of chromium carbide, tungsten carbide, aluminum oxide and the like, such as Tribaloy™, using plasma spray, high-velocity oxyfuel (HVOF), high-velocity air fuel (HVAF) and other similar processes are currently being used. However, these processes have not been able to be used for non-line of sight (NLOS) applications, such as the inner diameter (ID) of cylinders, bearing cavities and the like. For NLOS applications, a number of electroplated coatings have been evaluated. These include electroplated Ni—P and Ni—W alloy coatings, Ni—SiC electrocomposite and other similar coatings.

The novel CorroNite technology developed by Tribonex allows one to produce a durable coating with enhanced corrosion resistance and tribological properties closely matching those of hard chrome plating, as demonstrated by extensive testing carried out by our industrial partners - Volvo Construction Equipment and Trelleborg Sealing Solutions.