The spray-and-fuse process
Fused coatings, also called spray-and-fuse or diffusion-bonded coatings, start as self-fluxing alloy powder, typically nickel- or cobalt-based. The powder is flame-sprayed onto the part with an oxy-fuel torch. The part is then heated to 1,800–2,200 °F (1,000–1,200 °C) by torch, furnace or induction, so atoms diffuse between coating and substrate.
The result is a seamless, dense coating that is metallurgically bonded to the base metal.
Advantages of fused coatings
- Impact resistance: the metallurgical bond adheres more strongly than HVOF or plasma coatings, so the coating withstands moderate impact loads without delaminating.
- Hardness and corrosion resistance: 600–800 HV (roughly 55–64 HRC), extending component life in harsh environments.
- Typical parts: pump sleeves, rollers and other components that take impact.
Self-fluxing alloys
| Alloy | Properties | Hardness after fusing |
|---|---|---|
| Ni-Cr-B-Si | Corrosion resistance and hardness | 50–60 HRC |
| Ni-Cr-Mo-B-Si | Enhanced corrosion resistance | 58–63 HRC |
| Ni-Cr-B-Si-WC | High wear resistance from added tungsten carbide particles | 60–65 HRC |
Many other self-fluxing alloys are available, including cobalt-based Co-Ni-Cr-W-B-Si.
Finished in-house
Grinding, CNC machining, precision flat lapping and super finishing all happen in our Allentown facility, so fused parts leave at final tolerances.
