Two-step method in which a nickel- or cobalt-based self-fluxing alloy is sprayed, usually by flame spray, then heated to about 1,000 to 1,150 °C until it melts and wets the substrate. The result is a dense, pore-free coating with a true metallurgical bond, often loaded with tungsten carbide for abrasion. The part gets hot enough to distort and change its heat treatment, and the coating shrinks noticeably during fusing.
Sucker rod couplings are spray and fuse, shoot the NiCrBSi then hit it with the torch till it goes glassy.
Watch for the surface to turn shiny and wet as it fuses; stopping early leaves a porous layer, while going long makes it sag and run.
Also heard as
- spray-fuse
- fused coating
- fusing
Related terms
Self-fluxing alloy
Nickel or cobalt alloy with boron and silicon that fluxes its own oxides when fused after spraying.
Flame spray
The simplest thermal spray process: powder or wire melted in an oxy-fuel flame and blown onto the part.
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.
Thermal spray
Family of coating processes that melt or soften material and propel it onto a surface to build a layer.