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 α-Al.sub.2O.sub.3.

Shaped ceramic abrasive particles include a first surface having a perimeter having a perimeter comprising at least first and second edges. A first region of the perimeter includes the second edge and extends inwardly and terminates at two corners defining first and second acute interior angles. The perimeter has at most four corners that define acute interior angles. A second surface is disposed opposite, and not contacting, the first surface. A peripheral surface is disposed between and connects the first and second surfaces. The peripheral surface has a first predetermined shape. Methods of making the shaped ceramic abrasive particles, and abrasive articles including them are also disclosed.

A method of forming a shaped abrasive particle including extruding a mixture into a form, applying a dopant material to an exterior surface of the form, and forming a precursor shaped abrasive particle from the form.

A method of producing high strength shaped alumina by feeding alumina power into an agglomerator having a shaft with mixers able to displace the alumina power along the shaft, spraying a liquid binder onto the alumina power as it is displaced along the shaft to form a shaped alumina, and calcining the shaped alumina. The shaped alumina produced having a loose bulk density of greater than or equal to 1.20 g/ml, a surface area less than 10 m.sup.2/g, impurities of less than 5 ppm of individual metals and less than 9 ppm of impurities in total, and/or crush strength of greater than 12,000 psi.

Various embodiments disclosed relate to a partially shaped abrasive particle. The partially shaped abrasive particle includes a shaped portion, engineered to have a polygonal shape, and an irregular portion. The irregular portion is coupled to a base of the shaped portion, forming a single partially shaped abrasive particle.

Shaped ceramic abrasive particles include a first surface having a perimeter having a perimeter comprising at least first and second edges. A first region of the perimeter includes the second edge and extends inwardly and terminates at two corners defining first and second acute interior angles. The perimeter has at most four corners that define acute interior angles. A second surface is disposed opposite, and not contacting, the first surface. A peripheral surface is disposed between and connects the first and second surfaces. The peripheral surface has a first predetermined shape. Methods of making the shaped ceramic abrasive particles, and abrasive articles including them are also disclosed.

A sintered rod-shaped proppant and anti-flowback agent possesses high strength and high conductivity. The sintered rods comprise between about 0.2% by weight and about 4% by weight aluminum titanate. In some embodiments, the sintered rods are made by mixing bauxitic and non-bauxitic sources of alumina that may also contain several so-called impurities (such as TiO.sub.2), extruding the mixture, and sintering it. The starting material may optionally be milled to achieve better compacity and crush resistance in the final sintered rod. A fracturing fluid may comprise the sintered rods alone or in combination with a proppant, preferably a proppant of a different shape.

An abrasive particle having a body including a first major surface, a second major surface opposite the first major surface, and a side surface extending between the first major surface and the second major surface, such that a majority of the side surface comprises a plurality of microridges.

Ceramic particles for use in a solar power tower and methods for making and using the ceramic particles are disclosed. The ceramic particle can include a sintered ceramic material formed from a mixture of a raw material and MnO. The sintered ceramic material can include about 0.01 wt % to about 10 wt % MnO, about 0.1 wt % to about 20 wt % Fe.sub.2O.sub.3, and about 0.01 wt % to about 10 wt % Mn.sub.2O.sub.3. The ceramic particle can have a size from about 8 mesh to about 170 mesh.

The present invention relates to sintered platelet-like randomly shaped abrasive particles based on alpha alumina having a hardness H.sub.V of at least 20 GPa and a crystal structure with an average crystal size between 100 nm and 300 nm, whereby the abrasive particles comprise a body having a first surface and a second surface opposite to the first surface, both surfaces are separated from each other by a randomly shaped sidewall having a thickness (T) between 20 μm and 500 μm.