Various embodiments disclosed relate to an abrasive article (10). The abrasive article (10 includes a backing (12) defining a major surface. The abrasive article (10) includes an abrasive layer including a plurality of tetrahedral abrasive particles (16) attached to the backing (12). The tetrahedral abrasive particles (16) include four faces joined by six edges terminating at four vertices (40, 42, 44, 46). Each one of the four faces contacts three of the four faces, and a major portion of the tetrahedral abrasive particles (16) have at least one of the vertices (40, 42, 44, 46) oriented in substantially a same direction.

A method of making shaped abrasive particles including forming an abrasive flake comprising a plurality of precursor shaped abrasive particles and a frangible support joining the precursor shaped abrasive particles together; transporting the abrasive flake through a rotary kiln to sinter the abrasive flake; and breaking the sintered abrasive flake into individual shaped abrasive particles. The method is useful to make small shaped abrasive particles having insufficient mass to be efficiently individually sintered in a rotary kiln without joining two or more of the shaped abrasive particles together.

A cubic boron nitride particle population having highly-etched surfaces and a high toughness index is produced by blending a reactive metal powder with a plurality of cubic boron nitride particles to form a blended mixture. The blended mixture is compressed to form a compressed mixture. The compressed mixture is subjected to a temperature and a pressure, where the temperature is controlled to cause etching of the plurality of cubic boron nitride particles by reaction of cubic boron nitride with the reactive metal powder, thereby forming a plurality of etched cubic boron nitride particles. Also, the temperature and pressure are controlled to cause boron nitride to remain in a cubic boron nitride phase. Afterwards, the plurality of etched cubic boron nitride particles is recovered from the compressed mixture to form the particle population. Preferably, the particle population contains no hexagonal boron nitride.

A sintered vitrified superfinishing grindstone is provided which is a sintered product which is obtained by compression molding of a mixed powder of: a sinterable vitrified binder composed of a powder of a borosilicate glass composition; hard abrasive grains; and soft abrasive grains; and which includes bonded portions formed by necking due to heat compression, between particles of the powder of the borosilicate glass composition which are in contact with each other; and wherein the sinterable vitrified binder contains from 94 to 100% by mass of a powder composed of a low-melting-point borosilicate glass composition containing from 35 to 55% by mole of SiO.sub.2; from 3 to 5% by mole of Al.sub.2O.sub.3; from 10 to 35% by mole of B.sub.2O.sub.3; and from 25 to 30% by mole of R.sub.2O+RO.

A particulate material having a body including a dopant contained in the body, the dopant is non-homogenously distributed throughout the body and the body has a maximum normalized dopant content difference of at least 35%.

An abrasive grain includes a surface having at least a first face with a first outline, and at least one second face with a second outline. The first outline does not contain any vertices, but the second outline contains at least one vertex. The abrasive grain may include a ceramic material, especially polycrystalline -Al.sub.2O.sub.3.

A method of forming polycrystalline diamond comprised placing a plurality of graphene nano-platelets into a capsule; and subjecting the platelets to a pressure of around 10 GPa to around 20 GPa and a temperature of around 1600 degrees Celsius to around 3000 degrees Celcius to convert the graphene platelets to nano-polycrystalline diamond. There is also disclosed a polycrystalline super hard construction comprising a polycrystalline diamond region comprising polycrystalline diamond material formed according to said method.

An abrasive grain is disclosed and may include a body. The body may define a length (l), a height (h), and a width (w). In a particular aspect, the length is greater than or equal to the height and the height is greater than or equal to the width. Further, in a particular aspect, the body may include a primary aspect ratio defined by the ratio of length:height of at least about 2:1. The body may also include an upright orientation probability of at least about 50%.

The invention relates to sintered abrasive particles of which the chemical composition comprises the weight concentration ranges indicated in the table, to give a total of 100%.

TABLE-US-00001 % Fe.sub.2O.sub.3 % TiO.sub.2 % CaO % MgO % SiO.sub.2 % Al.sub.2O.sub.3 0.5-2.5% 0-2% 0.5-2.5% 0.5-3% 0.5-3% 93-96.5%

Provided are electrofused alumina grains excellent in grinding performance and a production method of such electrofused alumina grains, and a grinding stone and a coated abrasive using the electrofused alumina grains. The electrofused alumina grains of the present invention contain titanium and magnesium. The production method for the electrofused alumina grains includes the steps of: preparing a mixture material by mixing an alumina material, a titanium compound and a magnesium compound, forming an ingot from the mixture material according to an electrofusing process, grinding the ingot to prepare a ground powder, size-regulating the ground powder to have a predetermined grain size to prepare size-regulated grains, and heating the size-regulated grains at a heating temperature of 1,000 C. or higher to give electrofused alumina grains. The grinding stone contains the electrofused alumina grains. The coated abrasive contains the electrofused alumina grains.