While SPS is highly effective for densifying powders into bulk materials, it has limitations when manufacturing complex geometries. The primary challenge arises from the nature of the process, which relies on uniaxial pressure and a mold to shape the material. This constraint limits the ability to produce intricate or highly detailed parts directly.

To address this limitation, hybrid manufacturing approaches are increasingly employed. Additive manufacturing (AM) techniques, such as Laser Powder Bed Fusion (LPBF), can be used to fabricate near-net-shape preforms from ultra-high-temperature ceramics (UHTCs), refractory metals, and composite materials, which are then consolidated and refined using SPS. This combination allows for the efficient production of intricate structures while taking advantage of the rapid densification and superior material properties enabled by SPS.

Additionally, the need for high-temperature-resistant dies and the challenge of achieving uniform heating and pressure distribution can further complicate the sintering of complex geometries. Innovations in tooling design, including multi-part molds and advanced die materials, are helping to expand the design possibilities for SPS applications.

However, preparing high-quality powder feedstock for SPS can pose significant challenges. Traditional mechanical alloying methods, such as planetary ball milling, often suffer from small batch sizes, unacceptably long processing times, and contamination risks from milling media. Additionally, achieving tight control over particle size distribution and morphology is difficult, resulting in potential inhomogeneities and reduced repeatability during sintering. Furthermore, working with milled powders presents risks due to exposure to very fine, micron-sized or sub-micron particles, which can reduce the flowability of the powder, lower its apparent and tap density, and pose significant health and safety risks, including fire hazards. Proper handling precautions are necessary to mitigate these concerns.