Good evening (here anyway) all. I followed Scott from Cliff's forum.
Ceramics are a huge variety of materials. The abrasive in basically any sharpening stone can be considered a ceramic. Aluminum oxide, silicon carbide, zirconium oxide, cubic boron nitride (CBN), and a handful of others are all ceramics.
Solid ceramic stones like Spyderco and some others, and the ceramic rods people used in various V sharpeners are generally aluminum oxide (Al2O3). This is by far the most common form, and as far as I know is generally referred to as alumina. I am not familiar with the softer version Mark speaks of above, but aluminum oxide has more than the Al2O3 form, though I don't know what applications use them. Various forms of abrasive have different concentrations and quality of aluminum oxide. Emory and corundum are both aluminum oxide with various other materials mixed in with it in different amounts. Corundum works well as a sharpening abrasive, but I cannot recommend emory from my few experiences with it.
These types of stones and rods are sintered solid aluminum oxide with no binder, and the bonds between the particles are very strong, similar to the bonds between powder particles in CPM type steels. I have found them to be useful as finishing stones, thought they are not typically coarse enough to remove enough metal to be useful for rebeveling or sharpening really dull knives. I sharpen using the Spyderco Sharpmaker fairly often, and find the standard white stones to provide a very sharp edge and fine finish, though I typically stop at the brown stones, just out of saving a step.
Most stones use aluminum oxide or silicon carbide as an abrasive, combined with some form of binder/filler. These can be seen in micrographs of stones from Leonard Lee's book on sharpening. The resin and vitrified bond of water and oil stones, respectively, are quite different under magnification. Grinding/sanding belts use a larger variety of ceramics as abrasives. I use zirconium oxide (zirconia) belts for 40 and 80 grit rough grinding, then switch to aluminum oxide belts for finishing/polishing. CBN and diamond are both ceramics, and are both used in belts or on wheels. I have not tried any of these, and likely won't due to cost and my low grinding/sharpening volume.
The various oxides and other compounds used as abrasives in polishing compounds would also be considered ceramics. Chromium oxide, cerium oxide, iron oxide (for softer metals), diamond, and cbn buffing/polishing compounds are ceramics. It's really bewildering, and the imprecise use of the names by various industries/suppliers doesn't help.
Ceramics are a huge variety of materials. The abrasive in basically any sharpening stone can be considered a ceramic. Aluminum oxide, silicon carbide, zirconium oxide, cubic boron nitride (CBN), and a handful of others are all ceramics.
Solid ceramic stones like Spyderco and some others, and the ceramic rods people used in various V sharpeners are generally aluminum oxide (Al2O3). This is by far the most common form, and as far as I know is generally referred to as alumina. I am not familiar with the softer version Mark speaks of above, but aluminum oxide has more than the Al2O3 form, though I don't know what applications use them. Various forms of abrasive have different concentrations and quality of aluminum oxide. Emory and corundum are both aluminum oxide with various other materials mixed in with it in different amounts. Corundum works well as a sharpening abrasive, but I cannot recommend emory from my few experiences with it.
These types of stones and rods are sintered solid aluminum oxide with no binder, and the bonds between the particles are very strong, similar to the bonds between powder particles in CPM type steels. I have found them to be useful as finishing stones, thought they are not typically coarse enough to remove enough metal to be useful for rebeveling or sharpening really dull knives. I sharpen using the Spyderco Sharpmaker fairly often, and find the standard white stones to provide a very sharp edge and fine finish, though I typically stop at the brown stones, just out of saving a step.
Most stones use aluminum oxide or silicon carbide as an abrasive, combined with some form of binder/filler. These can be seen in micrographs of stones from Leonard Lee's book on sharpening. The resin and vitrified bond of water and oil stones, respectively, are quite different under magnification. Grinding/sanding belts use a larger variety of ceramics as abrasives. I use zirconium oxide (zirconia) belts for 40 and 80 grit rough grinding, then switch to aluminum oxide belts for finishing/polishing. CBN and diamond are both ceramics, and are both used in belts or on wheels. I have not tried any of these, and likely won't due to cost and my low grinding/sharpening volume.
The various oxides and other compounds used as abrasives in polishing compounds would also be considered ceramics. Chromium oxide, cerium oxide, iron oxide (for softer metals), diamond, and cbn buffing/polishing compounds are ceramics. It's really bewildering, and the imprecise use of the names by various industries/suppliers doesn't help.