How does the cobalt binder content affect a tungsten carbide nozzle's lifespan and performance? The cobalt percentage is critical because it controls the trade-off between wear resistance and impact toughness. For high-velocity abrasive blasting (such as silica sand or steel grit at 100 psi and above), a lower cobalt content of 6% to 8% with fine grain carbide produces maximum hardness and erosion resistance. This grade will hold its bore diameter stable the longest. However, for applications with larger, heavier abrasive particles or where the nozzle may experience accidental impacts against hard objects, you need a tougher grade with 10% to 15% cobalt and a coarser grain structure. This tougher grade will resist chipping at the inlet and outlet edges. For waterjet mixing tubes, where the abrasive is fine garnet at extremely high pressure (60,000 psi or more), a medium cobalt content around 8% to 10% with submicron grain size gives the best combination of wear life and structural integrity. Picking the wrong grade will cause either rapid bore erosion or premature edge chipping. https://www.xymjcarbide.com/products/tungsten-carbide-nozzle