Refractory sintering talcum powder

Talc refractory powder is a material used in the sintering process of parts printed with Filamet Copper and Filamet Bronze metal filaments. These metal filaments consist of a very high percentage of metal (80 % - 95 %) and the rest of PLA. This high metal content does not increase the complexity of printing, as all Filamet filaments are used with the same printing configuration as PLA, making them ideal materials for any type of FDM 3D printer (industrial or domestic).

The function of the refractory powder during the thermal debinding and sintering process is to act as a support for the parts, preventing their deformation during the different heat treatments.

Image 1: Sintering process. Source: The Virtual Foundry.

The most common material is alumina powder, due to its excellent resistance to high temperatures. However, its low mobility means that during the shrinkage of the parts during sintering, hollow spaces can remain in some areas of the part, which can damage the surface finish or create small defects on the surface. For this reason, with materials with low sintering temperatures, such as copper or bronze, it is advisable to use other refractory powders with greater mobility to accompany the shrinkage of the parts.

	Bronze	Copper	316L	Inconel	17-4
Crucible Alumina
Crucible Graphite
Crucible Stainless steel
Refractory powder Debinding	Alumina + Sintering carbon	Alumina + Sintering carbon	Steel mix powder + Sintering carbon	Steel mix powder + Sintering carbon	Steel mix powder + Sintering carbon
Refractory powder Debinding	Alumina + Sintering carbon or Talc + Sintering carbon	Alumina + Sintering carbon or Talc + Sintering carbon	Steel mix powder + Sintering carbon	Steel mix powder + Sintering carbon	Steel mix powder + Sintering carbon
Max. temp. Sintering	871 ºC	1074 ºC	1260 ºC	1260 ºC	1232 ºC

Table 1: Products for sintering FVL metal filaments. Source: The Virtual Foundry.

Talc refractory powder has a very small particle size (11 - 15 microns) which causes it to flow more easily than alumina powder during the sintering process. This high fluidity allows the powder block to accompany the part during shrinkage, minimising the risk of surface defects and improving the finish of the part.

Talc powder optionally replaces alumina during the sintering treatment of copper and bronze in order to improve the finish of the parts and is used as a refractory material in both thermal debinding and sintering of Pyrex glass.