A precursor of an alumina sintered compact including aluminum, yttrium, and at least one metal selected from iron, zinc, cobalt, manganese, copper, niobium, antimony, tungsten, silver, and gallium. The aluminum content is 98.0% by mass or more as an oxide (Al.sub.2O.sub.3) in 100% by mass of the precursor of an alumina sintered compact; the yttrium content is 0.01 to 1.35 parts by mass as an oxide (Y.sub.2O.sub.3) based on 100 parts by mass of the content of the aluminum as an oxide; the total content of the metals selected from the foregoing group is 0.02 to 1.55 parts by mass as an oxide based on 100 parts by mass of the content of aluminum as an oxide; and the aluminum is contained as α-alumina. Also disclosed is an alumina sintered compact, and a method for producing an alumina sintered compact and for producing abrasive grains.

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.

A slurry scraping mechanism and an applying and scraping device used in an SG abrasive production process includes a scraping master support; a scraper, wherein the scraper is connected with the scraping master support through a suspension component such that the scraper is suspended, and a damping spring is arranged in the suspension component; and a torsion spring adjusting component, wherein the torsion spring adjusting component includes a plurality of torsion springs supported by a torsion spring support shaft, the torsion spring support shaft is fixed to the scraping master support, the torsion spring support shaft is movable up and down relative to the scraping master support, the torsion springs are clamped in a V-shaped plate, an end side of the V-shaped plate is connected with the scraping master support, and a side surface of the V-shaped plate is connected with the scraper.

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 provides a method for making agglomerate particles, said method comprising: (a) forming by mixing at high speed a slurry of mineral agglomerate components in a polymerizable liquid resin carrier; (b) mixing said slurry with a non-miscible fluid to form discrete dispersed droplets; (c) exposing the discrete dispersed droplets to UVA radiation; (c) solidifying said droplets to form a multitude of solid particles; (d) isolating said solid particles and then firing said particles. The resulting size of the fired particles of the invention are estimated to be in the range from approximately 20 μm to approximately 500 μm.

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%.

A titanium carbonitride powder for use as a starting material for a hard material satisfies a D50 of from 2.0 μm to 6.0 μm and a D10/D90 of from 0.20 to 0.50, wherein D50 is a particle size at a cumulative percentage of 50% of a particle size distribution by volume, D10 is a particle size at a cumulative percentage of 10% of the particle size distribution by volume, and D90 is a particle size at a cumulative percentage of 90% of the particle size distribution by volume.

A process for solid lubricant filler powder used in abradable coating manufacture comprising mixing a bentonite clay and a hexagonal boron nitride powder to form a mixture of the bentonite clay and the hexagonal boron nitride powder; consolidating the bentonite clay and the hexagonal boron nitride powder to form a composite material; heat treating the composite material to at least 500 degrees centigrade; breaking up the composite material into a variety of sizes; and segregating the composite material to produce a final product of free flowing, low dust powder of composite hexagonal boron nitride and calcined bentonite.

The invention relates to a method of separating and extracting rare-earths from rare-earth polishing powder waste and regenerating rare-earth polishing powder, which is characterized by: firstly, process the waste powder with first acid leaching, alkali roasting, and second acid leaching to separate and extract rare-earths from rare-earth polishing powder waste to obtain the leaching solution of rare-earth chloride; secondly, precipitate from the leaching solution with ammonia to remove impurities and hydrochloric acid solution to obtain the purified solution of rare-earth chloride; thirdly, co-precipitate from the solution acquired in the second step with hydrofluoric acid, ammonium bicarbonate, and dispersant to obtain the lanthanum cerium fluoro-carbonate; and finally, after drying, two-stage high-temperature calcination, and ball milling, the regenerated rare-earth polishing powder with decent polishing performance can be obtained. The total leaching efficiency of rare-earths in the rare-earth polishing powder waste of the present invention reaches more than 95%, and the total recovery efficiency of rare-earths reaches more than 93%, which realizes the efficient separation, extraction, and regeneration of rare-earths in the rare-earth polishing powder waste.

The invention relates to a method of separating and extracting rare-earths from rare-earth polishing powder waste and regenerating rare-earth polishing powder, which is characterized by: firstly, process the waste powder with first acid leaching, alkali roasting, and second acid leaching to separate and extract rare-earths from rare-earth polishing powder waste to obtain the leaching solution of rare-earth chloride; secondly, precipitate from the leaching solution with ammonia to remove impurities and hydrochloric acid solution to obtain the purified solution of rare-earth chloride; thirdly, co-precipitate from the solution acquired in the second step with hydrofluoric acid, ammonium bicarbonate, and dispersant to obtain the lanthanum cerium fluoro-carbonate; and finally, after drying, two-stage high-temperature calcination, and ball milling, the regenerated rare-earth polishing powder with decent polishing performance can be obtained. The total leaching efficiency of rare-earths in the rare-earth polishing powder waste of the present invention reaches more than 95%, and the total recovery efficiency of rare-earths reaches more than 93%, which realizes the efficient separation, extraction, and regeneration of rare-earths in the rare-earth polishing powder waste.