POROUS SI3N4 AND PREPARING METHOD THEREOF WITH HIGH POROSITY AND HIGH ASPECT RATIO FOR FILTERING

摘要

PURPOSE: Provided are a porous Si3N4 with high porosity and a high aspect ratio for filtering by using inexpensive metal silicon as starting materials, and preparing method thereof. CONSTITUTION: The porous Si3N4 is prepared by the steps of: (a) mixing Si powder with as a first sintering agent, powder of at least one compound of the rare earth element in an amount of 7.5-4.5 parts by weight, based on 100 parts by weight of Si powder calculated as the oxide to obtain mixed powder; (b) adding a binder to the mixed powder; (c) molding the mixture into a molded body; (d) heating the molded body to 300-500 deg.C in a nitrogen atmosphere to remove the binder to form a binder-free body; (e) heating the binder-free body to 1350-1500 deg.C in a nitrogen atmosphere to form a nitrided body; and (f) sintering the nitrided body at 1750-1900 deg.C under nitrogen pressure of 0.1-1 atmospheric pressure.