An abrasive article comprising: a body comprising abrasive grains contained within a bond material comprising a metal or metal alloy, wherein the body comprises a ratio, (V.sub.AG/V.sub.BM), of volume of abrasives (V.sub.AG) to volume of bond (V.sub.BM), of between about 0.127 and about 1.27, wherein (V.sub.AG) is a volume percent of abrasive grains within the total volume of the body, (V.sub.BM) is the volume percent of bond within the total volume of the body, wherein the body could have about 15% to about 55% porosity, more preferably about 20% to about 55% and most preferably 25% to 55% porosity, wherein the bond material comprises at least 1% of an active bond composition of the total volume of the bond, a portion of which is at the interface of the abrasive grains and the bond material.

A coated abrasive article comprises a backing having first and second opposed major surfaces. A make layer is bonded to the first major surface. Agglomerate grinding aid particles are directly bonded to the make layer. At least a portion of the agglomerate grinding aid particles comprise grinding aid particles retained in a binder, and are arranged according to an open predetermined pattern. Abrasive particles are directly bonded to the make layer in spaces between the agglomerate grinding aid particles. A size layer is directly bonded to the make layer, agglomerate grinding aid particles, and abrasive particles. A method of making a coated abrasive article, in which the agglomerate grinding aid particles are deposited onto a curable make layer precursor prior to depositing abrasive particles onto the curable make layer precursor in spaces between the agglomerate grinding aid particles is also disclosed.

A method of producing a boron nitride polycrystal includes: a first step of obtaining a thermally treated powder by thermally treating a powder of a high pressure phase boron nitride at more than or equal to 1300 C.; and a second step of obtaining a boron nitride polycrystal by sintering the thermally treated powder under a condition of 8 to 20 GPa and 1200 to 2300 C.

An abrasive article includes a body having abrasive grains contained within a bond material comprising a metal or metal alloy, wherein the body comprises a ratio of V.sub.AG/V.sub.BM of at least about 1.3, wherein V.sub.AG is the volume percent of abrasive grains within the total volume of the body and V.sub.BM is the volume percent of bond material within the total volume of the body.

A sheet of coarse sandpaper includes a backing layer having opposed first and second major surfaces, an adhesive make coat on the second major surface, coarse abrasive particles at least partially embedded in the make coat, thereby defining a coarse abrasive surface, and an exposed non-slip coating layer on the first major surface. Methods of making and using such coarse sandpaper are also provided.

The invention relates to a method for producing an alumina based abrasive particle (1), comprising at least the following steps: forming a sol as a solution or dispersion of alumina particles, gelling the sol by adding gelling agents, forming shaped bodies from the gel using an additive procedure, drying and firing the shaped bodies while retaining the previously achieved geometry of the abrasive particles.

Hereby, it is provided that an optically binding binder is added to the sol and/or the gel, the gel is applied additively layer by layer and the binder is set using electromagnetic radiation so as to form the shaped bodies.

The produced abrasive particle may be formed, in particular, by six intersecting or overlapping triangular volume regions.

The invention relates to a method for producing an alumina based abrasive particle (1), comprising at least the following steps: forming a sol as a solution or dispersion of alumina particles, gelling the sol by adding gelling agents, forming shaped bodies from the gel using an additive procedure, drying and firing the shaped bodies while retaining the previously achieved geometry of the abrasive particles.

Hereby, it is provided that an optically binding binder is added to the sol and/or the gel, the gel is applied additively layer by layer and the binder is set using electromagnetic radiation so as to form the shaped bodies.

The produced abrasive particle may be formed, in particular, by six intersecting or overlapping triangular volume regions.

An abrasive article can include a body including a bond material and abrasive particles contained within the bond material. The bond material can include an organic material including a resin, particularly a phenolic resin. A methylene bridge can be present at para or ortho sites of aromatic phenolic rings. The bond material can include an average ortho to para substituent ratio for the methylene bridge within a range including at least 1.5:1 and not greater than 9:1, particularly, within a range including at least 3 and not greater than 6.9.

A PCD structure comprises a first region and a second region adjacent the first region, the second region being bonded to the first region by intergrowth of diamond grains; the first region comprising a plurality of alternating strata or layers, each stratum or layer having a thickness in the range of around 5 to 300 microns. The second region comprises a plurality of strata or layers, one or more strata or layers in the second region having a thickness greater than the thicknesses of the individual strata or layers in the first region. The alternating layers or strata in the first region comprise first layers or strata alternating with second layers or strata, the first layers or strata being in a state of residual compressive stress and the second layers or strata being in a state of residual tensile stress.

A PCD structure comprises a first region and a second region adjacent the first region, the second region being bonded to the first region by intergrowth of diamond grains; the first region comprising a plurality of alternating strata or layers, each stratum or layer having a thickness in the range of around 5 to 300 microns. The second region comprises a plurality of strata or layers, one or more strata or layers in the second region having a thickness greater than the thicknesses of the individual strata or layers in the first region. The alternating layers or strata in the first region comprise first layers or strata alternating with second layers or strata, the first layers or strata being in a state of residual compressive stress and the second layers or strata being in a state of residual tensile stress.