Ceramic particulate material and processes for forming same

Abstract

Ceramic particulate material includes alumina particles, the particles having a specific surface area (SSA) not less than 15 m 2 /g and not greater than 75 m 2 /g and a sphericity quantified by at least one of (i) a mean roundness not less than 0.710 as measured by Roundness Correlation Image Analysis, and (ii) a concavity less than 20%, wherein concavity is the percent of alumina particles based on a sample of at least 100 particles, which have a concave outer peripheral portion that extends along a distance not less than 10% of d 50 by TEM inspection, the concave outer peripheral portion having a negative radius of curvature as viewed from an interior of the particle

1 . Ceramic particulate material, comprising:
 alumina particles, the particles having a specific surface area (SSA) not less than 15 m 2 /g and not greater than 75 m 2 /g and a sphericity quantified by at least one of (i) a mean roundness not less than 0.710 as measured by Roundness Correlation Image Analysis, and (ii) a concavity less than 20%, wherein concavity is the percent of alumina particles based on a sample of at least 100 particles, which have a concave outer peripheral portion that extends along a distance not less than 10% of d 50  by TEM inspection, the concave outer peripheral portion having a negative radius of curvature as viewed from an interior of the particle.   
     
     
         2 . The ceramic particulate material of  claim 1 , wherein the SSA is not greater than 60 m 2 /g. 
     
     
         3 . The ceramic particulate material of  claim 2 , wherein the SSA is not greater than 50 m 2 /g. 
     
     
         4 . The ceramic particulate material of  claim 3 , wherein the SSA is not greater than 40 m 2 /g. 
     
     
         5 . (canceled) 
     
     
         6 . The ceramic particulate material of  claim 1 , wherein the alumina particles are comprised of alpha phase alumina. 
     
     
         7 . (canceled) 
     
     
         8 . The ceramic particulate material of  claim 6 , wherein the alumina particles are comprised of at least 85 wt % alpha phase alumina. 
     
     
         9 . The ceramic particulate material of  claim 8 , wherein the alumina particles are essentially entirely alpha phase alumina. 
     
     
         10 . The ceramic particulate material of  claim 9 , wherein the alumina particles are single crystal alpha phase alumina. 
     
     
         11 . The ceramic particulate material of  claim 1 , wherein the alumina particles have a concavity less than 15%. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . The ceramic particulate material of  claim 1 , wherein the alumina particles have said mean roundness not less than 0.710. 
     
     
         15 . The ceramic particulate material of  claim 14 , wherein the mean roundness is not less than 0.720. 
     
     
         16 . Ceramic particulate material, comprising:
 alumina particles, the particles having an average primary particle size less than 135 nm as measured by TEM, and a sphericity quantified by at least one of (i) a mean roundness not less than 0.710 as measured by Roundness Correlation Image Analysis, and (ii) a concavity less than 20%, wherein concavity is the percent of alumina particles based on a sample of at least 100 particles, which have a concave outer peripheral portion that extends along a distance not less than 10% of d 50  by TEM inspection, the concave outer peripheral portion having a negative radius of curvature as viewed from an interior of the particle.   
     
     
         17 . The ceramic particulate material of  claim 16 , wherein the average primary particle size is less than 125 nm. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . Ceramic particulate material, comprising:
 alumina particles, the particles having an average primary particle size not greater than 135 nm as measured by TEM, a secondary particle size characterized by a d 85  not less than 150 nm as measured by photon correlation spectroscopy, and a sphericity quantified by at least one of (i) a mean roundness not less than 0.710 as measured by Roundness Correlation Image Analysis, and (ii) a concavity less than 20%, wherein concavity is the percent of alumina particles based on a sample of at least 100 particles, which have a concave outer peripheral portion that extends along a distance not less than 10% of d 50  by TEM inspection, the concave outer peripheral portion having a negative radius of curvature as viewed from an interior of the particle.   
     
     
         21 . The ceramic particulate material of  claim 20 , wherein the d 85  is not less than 155 nm. 
     
     
         22 . The ceramic particulate material of  claim 21 , wherein the d 85  is not less than 160 nm. 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . The ceramic particulate material of  claim 20 , wherein the secondary particle size is further characterized by a d 50  not greater than 135 nm. 
     
     
         26 . The ceramic particulate material of  claim 25 , wherein the secondary particle size is further characterized by a d 50  not greater than 120 nm. 
     
     
         27 . (canceled) 
     
     
         28 . Ceramic particulate material, comprising:
 alumina particles, the particles having a specific surface area (SSA) not less than 15 m 2 /g and not greater than 75 m 2 /g, an average primary particle size less than 135 nm as measured by TEM, a secondary particle size characterized by a d 85  not less than 150 nm as measured by photon correlation spectroscopy, and a sphericity quantified by at least one of (i) a mean roundness not less than 0.710 as measured by Roundness Correlation Image Analysis, and (ii) a concavity less than 20%, wherein concavity is the percent of alumina particles based on a sample of at least 100 particles, which have a concave outer peripheral portion that extends along a distance not less than 10% of d 50  by TEM inspection, the concave outer peripheral portion having a negative radius of curvature as viewed from an interior of the particle.   
     
     
         29 . A method for forming ceramic particulate material, comprising:
 providing a loose powder into a heat treatment chamber, the loose powder comprising particles; and   hot isostatic pressing (HIPing) the loose powder at a pressure not less than about 0.1 ksi, wherein the particles are individually isostatically pressed to effect phase transformation of the loose powder.   
     
     
         30 - 55 . (canceled)