As explained in SPD method description iro3d printer is material agnostic. But post-processing (baking) for some materials is easier than others because they require different baking temperatures and atmospheres. For example, glass can be baked in an oxidizing atmosphere, such as air. But most metals require a reducing atmosphere to prevent oxidation. Most commonly used reducing atmospheres are hydrogen, carbon monoxide, and hydro-carbons. Hydrogen can be supplied from an external bottle or generator. Carbon monoxide can be produced in-situ by placing some metallurgical coke (carbon) into the crucible or furnace. Hydro-carbons can be either supplied externally (methane, propane, butane, ...) or produced in-situ, by tar, asphalt, polylactide (PLA), polypropylene (PP), acrylonitrile butadiene styrene (ABS), etc.
Generally, non-reactive metals, such as iron, copper, nickel, tin, lead, bismuth, antimony, molybdenum, cobalt, tungsten, palladium, cadmium, silver, gold, and platinum are easy to reduce. Reactive metals, such as aluminum, chromium, beryllium, etc, are difficult to reduce, so, you shouldn't use them in the powder in large concentrations. You can use them in the infill if the atmosphere is not too oxidizing. To help you decide which metals need which atmosphere, see Ellingham diagram or interactive Ellingham diagram. The tables below show some of the materials and atmospheres we have researched or tried so far.
| SPD variant | Powder | Infill | Atmosphere | Result |
|---|---|---|---|---|
| infilling | copper | copper + tin | carbon monoxide (from coke) | bronze |
| infilling | copper | copper + silver | carbon monoxide (from coke) | copper + silver |
| infilling | copper | zinc vapor | carbon monoxide (from coke) | porous brass |
| infilling | iron | copper | carbon monoxide (from coke) | iron + copper |
| infilling | iron | bronze | carbon monoxide (from coke) | iron + bronze |
| infilling | iron | iron + carbon | carbon monoxide (from coke) | high carbon steel, or cast iron, or malleable iron |
| infilling | nickel | copper | carbon monoxide (from coke) | Monel |
| infilling | tungsten | copper | carbon monoxide (from coke) | tungsten + copper (good for radiation shielding) |
| infilling | alumina coated with silver | bronze | carbon monoxide (from coke) | alumina + bronze (composite) |
| infilling | alumina | aluminum | hydrogen or argon | alumina + aluminum (composite) |
| infilling | copper | copper + aluminum | hydrogen + argon | aluminum bronze |
| infilling | copper | copper + beryllium | hydrogen + argon | beryllium bronze |
| infilling | iron | iron + chromium + nickel | hydrogen + argon | stainless steel |
| infilling | copper | zinc | borax | brass |
| infilling | sand | polymer | air | mold for metal casting |
| sintering | shell sand | air | mold for metal casting | |
| sintering | glass | air | porous glass | |
| sintering | glass | vacuum, then air | solid glass |