Thermal conductivities of WC-Ni cermet powders for powder bed additive manufacturing

The thermal conductivities of WC-Ni 10 and WC-Ni 17 cermet powders used in powder bed additive manufacturing processes were measured using the transient hot wire method. The 10 % and 17 % Ni by weight powders have measured thermal conductivities of 0.13 ± 0.02 Wm −1 K −1 and 0.15 ± 0.02 Wm −1 K −1 respectively at a temperature of 295 K and a pressure of 101 kPa – more than 25 % lower than common metal powders used in additive manufacturing. The WC-Ni powder grains are irregularly shaped and have a low average circularity, which causes a lower packing fraction and different contact geometry compared to a spherical powder bed. This results in reduced heat transfer through the gas assisted solid pathway of the powder bed and a lower overall powder thermal conductivity. The pressure dependence on the powder bed thermal conductivity was measured from 1 kPa to 101 kPa with both N 2 and He used as infiltrating gases. The powder bed thermal conductivity increased as the ambient pressure increased, and the magnitude of this pressure dependence was found to be a function of the infiltrating gas, not the powder composition. At 101 kPa infiltrating N 2 pressure, the WC-Ni 10 (WC-Ni 17 ) powder bed thermal conductivities increased from 0.13 (0.15) Wm −1 K −1 at 295 K to 0.17 (0.19) Wm −1 K −1 at 435 K. With this knowledge, thermal management of WC-Ni powder bed additive manufacturing techniques can be more accurately addressed. • Thermal conductivities of WC-Ni powders are measured with the transient hot wire method. • Pressure and temperature dependence of powder thermal conductivity are studied. • Gas pressure and composition significantly impact WC-Ni powder thermal conductivity. • WC-Ni powders exhibit high void fractions, low circularity, and irregular morphologies. • WC-Ni powders have lower thermal conductivities than commonly used metal powders.