Diamalloy 5849 is an economical tungsten-carbide 10% cobalt 4% chromium powder. Diamalloy 5849 is especially suited for applications where simultaneous wear and corrosion resistance is required. Chromium in the matrix improves the corrosion resistance while maintaining the abrasive, erosive, and fretting wear properties of tungsten carbide-cobalt based materials.
Process rolls of all types are hardfaced with Cobalt-Chromium-Carbide for original equipment manufacturing and overhaul of components. These thermal coatings offer an environmentally safer, cleaner, and less expensive alternative to chromium plating.
| PHYSICAL COMPARISON | TUNGSTEN-CARBIDE | CHROME | |
| Macrohardness (Rc) | 65-70 | 60-70 | |
| Microhardness (DPH 300) | > 1050 | 750-850 | |
| Bond strength *Results exceed strength limit of epoxy needed for tensile test |
> 12,000* | 6,000 | |
| Porosity | < 1% | Inherently cracked | |
| >Coating thickness typical (in) | .003-.012 | less than .005 | |
| Surface finish (Ra) | < 4 | < 4 | |
| Corrosion Test – ASTM B117 (hours) | 720 | 55 | |
| Surface temperature limits (F) | 1025 | 750 |
In this process ionized gas is used to heat and propel the tungsten-carbide at moderate speeds ( typically Mach I ) Operating costs are lower than HVOF and the bond strengths and overall densities are reduced. Higher cobalt content (17%) is used to create a tougher coating with some flexibility. Hardness is slightly reduced due to reactance in the heat of the plasma. This is often the most economical process to deposit Tungsten-Carbide.
In this process the powder is accelerated to trans-sonic speeds by the rapid combustion of fuel and large quantities of oxygen. The coating is extremely dense and the carbides are left unreacted by the heat and extremely hard. This is the hardest of the carbide coatings and will take moderate loads or impact. The system has high operating costs but HVOF is finding acceptance in roll facing and chrome plating replacement. The consumable is usually tungsten-carbide in a 12% cobalt matrix. Common powders are Metco Diamalloy 2005, Eutectic 19910, Praxair WC 489.
Pratt and Whitney Aircraft PWA 36332
Detroit Diesel Allison EMS 39660A
Society of Automotive EngineersAMS 7879C
General Electric Company B50TF167-S4
Rolls Royce Specification MSRR 9507/60