BN Crucibles, Setter Plates and Supports: What Are Their Roles in AlN Ceramic Processing?
Aluminum nitride (AlN) ceramics undergo multiple thermal processing steps from raw powder synthesis to high-temperature sintering. These processes rely heavily on the internal furniture and fixtures of high-temperature vacuum or atmosphere furnaces. Depending on workpiece geometry and thermal cycles, different ceramic structures—including crucibles, setter plates, support blocks, and electrical insulators—are required inside the hot zone. Boron nitride (BN) exhibits exceptional thermal shock resistance, excellent electrical insulation, high sublimation temperatures, and a very low coefficient of thermal expansion (CTE). Crucially, BN does not wet or easily react with most molten materials and nitride green bodies. However, each furnace component serves a distinct mechanical and thermal role: crucibles hold loose materials, setter plates provide planar support for flat substrates, fixtures maintain multi-layer stacking, and insulators isolate high-voltage heating circuits....