Silicon nitride sintered material method for manufacturing the same molten-metal-resistant member and wear resistant member formed from the same

A silicon nitride sintered material comprising a silicon nitride crystal and a grain boundary layer that contains at least two of first through third metal silicides selected from the group consisting of a first metal silicide, a second metal silicide and a third metal silicide,

• wherein said grain boundary layer has a neighboring phase where at least two of said first through third metal silicides exist in contact with each other;
• wherein said first metal silicide is a metal silicide comprising, as a first metal element, at least one selected from the group consisting of Fe, Cr, Mn and Cu;
• where said second metal suicide is a metal silicide comprising, as a second metal element, at least one of W or Mo;
• and
• wherein said third metal silicide is a metal silicide comprising a plurality of metal elements including said first metal element and said second metal element.

A method for manufacturing a silicon nitride sintered material comprising:

• preparing a material powder by mixing a preliminarily mixed powder that has been made by wet mixing and drying materials including a Si powder or a mixture of a Si powder and a silicon nitride powder;
• a compound of first metal element having a mean grain size in a range from 0.1 to 20 μm and having at least one selected from the group consisting of Fe, Cr and Mn;
• and a compound of second metal element having a mean grain size in a range from 0.1 to 30 μm and having at least one of W or Mo;
• forming a compact including said material powder and an organic binder;
• degreasing said organic binder in an atmosphere substantially consisting of nitrogen gas, argon gas or a mixed gas thereof to form a degreased compact;
• transforming said degreased compact to a nitride material in a substantially nitrogen gas atmosphere;
• and
• firing said nitride material in a non-oxidizing atmosphere that contains nitrogen gas to form a sintered material.