Saint-Gobain Ceramic Materials, Boron Nitride Products, based in Amherst, NY, USA, has announced that its Combat Boron Nitride Grade ZSBN has found successful use in specialty molten metal atomisation.
ZSBN is a unique composite of boron nitride and zirconia, a hot-pressed solid that combines the best thermal performance and machinability of hot-pressed boron nitride with the strength and wear-resistance of zirconia. ZSBN nozzles are made by machining solids of hot pressed micron-size particles, giving a very smooth finish and tight tolerances. Such precision in nozzle formation leads to a more controlled atomisation and a tight particle size distribution.
Commonly used nozzles for powder metal atomisation of common alloys of nickel, copper and aluminium are made by pressing and sintering large or coarse particles of alumina, zirconia or other refractories. These nozzles lack both tight tolerances and clean edges, causing unpredictable atomisation and uneven yields. The result is a wide particle size distribution.
Additionally, since these cheaper materials are easily wetted by metals, nozzles frequently clog, further adding to the unpredictable particle sizes or even shutdowns. Because of this uncontrolled atomisation, the distribution of the powder is not known until the run is over and the powder has been classified. This ultimately results in lower yields, higher scrap rate and additional costly runs.
“A wide particle size distribution may be acceptable for high-volume steel and ferrous powder applications where the breadth of markets and applications accommodates all particle sizes,” stated Steve Lyle, Product Manager for Combat® Boron Nitride components at Saint-Gobain Ceramic Materials.
“However, for specialty powder metals, such low yields, high scrap rates, and frequent clogging add to an already expensive process. ZSBN provides a stable and predictable particle size distribution and 30% higher yields than zirconia nozzles,” added Lyle.
With non-wetting properties, sharp edges, and minimised clogging and metal-creep, ZSBN nozzles offer an ideal solution for specialty powder metal atomization.