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US 6,124,225 AGranted
Cutting tools and wear resistant articles and material for same
AssigneeThe Regents of the University of Michigan
InventorsTseng-Ying Tien, Zhen-Kun Huang
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Abstract
A ceramic having a relatively high proportion of an alpha prime SiAlON phase and exhibiting high hardness and toughness. In a particularly preferred embodiment, a cation of Gd is used as a modifying cation.
Claims32
A method for cutting an article, the method comprising:
- (a) contacting a workpiece with a cutting tool, said cutting tool having a surface for contacting the workpiece, said surface including a ceramic material having:
- (i) an alpha prime SiAlON phase present in an amount greater than any other phase in said ceramic material and prepared from an alpha silicon nitride starting material present in a starting material in a major amount;
- (ii) a hardness (Vickers) of at least about 19 GPa;
- (iii) an indentation toughness of at least about 5 MPa.cndot.m0.5;
- said alpha prime SiAlON phase including a plurality of elongated rod shape .alpha.'(R)-SiAlON grains having an average grain diameter of approximately 0.5 to about 2.5 microns and an average aspect ratio of at least about 6:1, where R is a modifying cation selected from the group consisting of Nd, Sm, Gd, Dy, Yb, Y, and mixtures thereof and said grains have the formula R.sub.m/3 Si.sub.12-(m+n) Al.sub.(m+n) O.sub.n N.sub.16-n, where m ranges from about 0.9 to about 3.2 and n ranges from about 0.4 to about 1.8;
- and
- (b) removing material from the workpiece with the cutting tool.
4 more elements
A method for making a ceramic article, the method comprising:
- (a) providing starting materials, including:
- (i) silicon nitride;
- (ii) aluminum nitride;
- (iii) alumina;
- and
- (iv) Gd.sub.2 O.sub.3 ;
- and
- (b) applying heat and pressure to said starting materials for forming a resulting material having:
- (i) alpha prime SiAlON present in an amount greater than 45% by weight of the overall material, and having the formula Gd.sub.m/3 Si.sub.12-(m+n) Al.sub.(m+n) O.sub.n N.sub.16-n, with m ranging from 0.9 to about 1.35, 1.6 to about 2.4 or mixtures thereof and n ranging from about 0.9 to about 1.2;
- a hardness (vickers) of at least about 19.0 GPa;
- (iii) a toughness (K.sub.IC) of at least about 5.0 MPa.cndot.m0.5;
- (iv) a room temperature strength of greater than about 500 MPa.
9 more elements
A method for making a ceramic article, the method comprising:
- (a) providing an alpha silicon nitride starting material in a major amount of the overall starting materials;
- (b) densifying said starting material to form a ceramic body having:
- (i) a first phase present in an amount of at least about 45% by weight of said material, including a plurality of alpha prime SiAlON elongated grains having a majority of said grains present with an average grain diameter of at least about 0.5 microns and an aspect ratio greater than about 6:1;
- (ii) a second phase including a phase selected form the group consisting of glass phase, beta SiAlON, AlN polytypoids, melilite, garnet and mixtures thereof;
- said alpha prime SiAlON grains having the formula R.sub.m/3 Si.sub.12-(m+n) Al.sub.(m+n) O.sub.n N.sub.16-n, with m ranging from about 0.9 to about 3.2 and with n ranging from about 0.4 to about 1.8, and where R is a cation of an element selected from the group consisting of Nd, Sm, Gd, Dy, Yb, Y, and mixtures thereof.
2 more elements
Dependencies are inferred from the claim text.