| 摘要 |
PROBLEM TO BE SOLVED: To provide the subject implement in the form of a boron nitride sintered plate with porous structure having each specific porosity, flexural strength and air permeability coefficient and enabling through operation to burning process including uniform degreasing step. SOLUTION: This degreasing/burning implement is made of boron nitride sintered compact in the form of a porous hexagonal sintered plate, having a porosity of 40-60 vol.%, flexural strength of >=20 MPa, air permeability coefficient of 1.1 to 2.0×1.0-9 mol.m/m2.s.Pa, and the average pore size of its through hole of pref. <=1 μm. The porous hexagonal sintered plate is produced by the following process: hexagonal boron nitride set in order with an average particle size of <=10 μm, oxygen content of 1.5-3 wt.% and boron oxide content of <=0.3 wt.% is molded under a molding pressure so as to afford the porosity of the final sintered compact to a specified value and then burned at 1,800-2,300 deg.C in an inert atmosphere under normal pressures. The porous hexagonal sintered plate thus obtained can be used as this degreasing/burning implement for large-sized/thick-walled aluminum nitride molded forms which prevents to-be- burnt objects from cracking and enables the binder in such objects to be subjected to uniform decomposition/elimination treatment. |
