Laminated ceramic cutting tool

In a laminated ceramic cutting tool having a flank face, the improvement comprising:

• a core layer having a thickness within a range of from about 0.1375 inch to about 0.1675 inch and whose composition comprises one or more of the group consisting of alumina, silicon carbide, silicon nitride, titanium carbide, titanium nitride, cemented tungsten carbide and boron carbide;
• at least two outer layers, one on each side of said core layer, each of said outer layers having a thickness within a range of from about 0.0050 inch to about 0.0250 inch;
• each of said outer layers having a composition different from said core layer and which comprises one or more of the group consisting of alumina, cemented tungsten carbide, boron carbide, titanium carbide, silicon carbide, titanium nitride and silicon nitride;
• said outer layers including a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement having a composition which comprises one or more of the group consisting of silicon carbide, silicon nitride, titanium carbide and titanium nitride;
• each of said at least two outer layers having the same thickness and composition;
• and
• each of said at least two outer layers having a compressive residual stress state relative to said core layer.

In a laminated ceramic cutting tool having a flank face, the improvement comprising:

• a core layer having a thickness within a range of from about 0.1375 inch to about 0.1675 inch and whose composition comprises one or more of the group consisting of alumina, silicon carbide, silicon nitride, titanium carbide, titanium nitride, cemented tungsten carbide and boron carbide;
• at least two outer layers, one on each side of said core layer, each of said outer layers having a thickness within a range of from about 0.0050 inch to about 0.0250 inch;
• each of said at least two outer layers having a composition different from said core layer and which comprises one or more of the group consisting of alumina, cemented tungsten carbide, boron carbide, titanium carbide, silicon carbide, titanium nitride and silicon nitride;
• said core layer including a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement having a composition which comprises one or more of the group consisting of silicon carbide, silicon nitride, titanium carbide and titanium nitride;
• each of said at least two outer layers having the same thickness and composition;
• and
• each of said at least two outer layers having a compressive residual stress state relative to said core layer.

A reinforced, laminated ceramic cutting tool having a flank face, said cutting tool further comprising:

• a core layer;
• at least two outer layers symmetrically arranged about said core layer and spaced along an axis which is perpendicular to said core layer;
• and
• a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement present in said cutting tool in an arrangement selected from the group consisting of said core layer, said core layer and said at least two outer layers, and said at least two outer layers;
• each outer layer having a first residual stress in a direction perpendicular to said flank face and a second residual stress in a direction parallel to said flank face;
• said at least two outer layers having the same thickness, composition, and residual stresses;
• wherein the coefficient of thermal expansion for said core layer is about 7.92.times.10.sup.-6 /.degree. C. and the coefficient of thermal expansion of each of said outer layers is in a range of from about 7.16.times.10.sup.-6 /.degree. C. to about 8.10.times.10.sup.-6 /.degree. C.

A reinforced, laminated ceramic cutting tool having a flank face, said cutting tool further comprising:

• a core layer;
• at least two outer layers symmetrically arranged about said core layer and spaced along an axis which is perpendicular to said core layer;
• and
• a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement present in said cutting tool in an arrangement selected from the group consisting of said core layer, said core layer and said at least two outer layers, and said at least two outer layers;
• each outer layer having a first residual stress in a direction perpendicular to said flank face and a second residual stress in a direction parallel to said flank face;
• said at least two outer layers having the same thickness, composition, and residual stresses;
• and
• an unreinforced layer on an outward side of each of said outer layers, said unreinforced layer selected from the group consisting of alumina and mullite.

A reinforced, laminated ceramic cutting tool having a flank face, said cutting tool further comprising:

• a core layer;
• at least two outer layers symmetrically arranged about said core layer and spaced along an axis which is perpendicular to said core layer;
• and
• a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement present in said cutting tool in an arrangement selected from the group consisting of said core layer, said core layer and said at least two outer layers, and said at least two outer layers;
• each outer layer having a first residual stress in a direction perpendicular to said flank face and a second residual stress in a direction parallel to said flank face;
• said at least two outer layers having the same thickness, composition, and residual stresses;
• wherein the coefficient of thermal expansion of each of said outer layers is lower than the coefficient of thermal expansion of said core layer.

A reinforced, laminated ceramic cutting tool having a flank face, said cutting tool further comprising:

• a core layer having a thickness within a range of from about 0.1375 inch to about 0.1675 inch and whose composition comprises one or more of the group consisting of alumina, silicon carbide, silicon nitride, titanium carbide, titanium nitride, cemented tungsten carbide and boron carbide;
• at least two outer layers, one on each side of said core layer, each of said outer layers having a thickness within a range of from about 0.0050 inch to about 0.0250 inch;
• each of said outer layers having a composition which comprises one or more of the group consisting of alumina, cemented tungsten carbide, boron carbide, titanium carbide, silicon carbide, titanium nitride and silicon nitride;
• said outer layers including a reinforcement selected from one or more of the group consisting of reinforcement particles, reinforcement whiskers oriented so that a longitudinal dimension of substantially all of said whiskers is aligned substantially perpendicular to said flank face and reinforcement platelets oriented so that a basal plane of substantially all of said platelets is in a plane substantially perpendicular to said flank face;
• said reinforcement having a composition which comprises one or more of the group consisting of silicon carbide, silicon nitride, titanium carbide and titanium nitride;
• each of said at least two outer layers having the same thickness and composition;
• each of said at least two outer layers having a compressive residual stress state or a neutral residual stress state, relative to said core layer;
• and
• an unreinforced layer positioned outwardly of each of said at least two outer layers, said unreinforced layer selected from the group consisting of alumina and mullite.

A laminated ceramic cutting tool made according to a process comprising the steps of:

• (a) preparing a slurry comprising a matrix powder and a reinforcement;
• (b) depositing the slurry on a carrier film using a spreading blade to form a tape, said carrier film moving relative to said spreading blade in a casting direction;
• (c) drying the tape;
• (d) cutting the tape into sections of predetermined shape and dimensions;
• (e) removing the carrier film from the tape;
• (f) stacking a first portion of said tape sections in a die so that a casting direction for each section is parallel to the casting direction of its adjacent sections;
• (g) inserting a dry powder in said die on top of said first portion of said tape sections and inserting a second portion of said tape sections, equal to said first portion, into said die on top of said dry powder to form a symmetric sandwich arrangement;
• and
• h) pressing said tape sections and said dry powder in said die under conditions of elevated temperature and pressure.