Above roughly 1000 °C a graphite hot zone stops being inert: it becomes a carbon source, and the part picks up carbon whether the recipe asks for it or not. This 60-second explainer covers the all-metal alternative on the HAOYUE V series — tungsten elements rated 1800/2000 °C, molybdenum 1000/1300 °C, 0.2–0.5 mm radiation shields instead of hygroscopic graphite felt, and 6.7×10-3 Pa high vacuum from a diffusion or molecular pump. It also states where the platform stops: above 2000 °C, with oxygen-releasing loads, or wherever the process needs pressure assistance.
Read the full process and specification detail in our tungsten and molybdenum vacuum furnace guide.
