Mitsui Minings & Melting Co., Ltd.

Naoyoshi Mochizuki

Kenzo Hanawa

Terunori Ito

Hiroyuki Watanabe

Yoshitsugu Uchino

Naruo Ueda

Kazuhiko Kato

Hidehiko Yamasaki

Kazuya Ushiyama

Akira Shimogawara

The object of the present invention is to provide a powder cerium-based abrasive which enables the preparation of a cerium-based abrasive slurry, in which the dispersed state of the abrasive particles is maintained for a long period of time, simply by blending it with a dispersion medium such as water and which makes easier the after-treatment of the abrasive slurry having been used. The cerium-based abrasive of this invention is a cerium-based abrasive including chlorine-containing compounds in which chlorine (element) is contained in amounts, in terms of total mass, equivalent to 0.05% to 5.0% of the mass of the total rare earth oxide contained therein. An abrasive slurry including the abrasive of this invention as a solid content is superior in dispersion maintaining properties of its abrasive particles. Accordingly, an abrasive slurry having a stable concentration of the solid content can be supplied continuously. Further, the abrasive requires no dispersant for maintaining its dispersed state, and hence separation treatment for a dispersant is unnecessary after the abrasive has been used. Thus, the abrasive according to the present invention makes simpler the after-treatment of the abrasive slurry after use.

Cerium-based abrasive material and method for preparation thereof

There is provided a cerium-based abrasive containing cerium oxide as a main component, in which the abrasive particles composing the abrasive are coated with a coating layer containing at least either one of a silicon component of silicon or a silicon compound and an aluminum component of aluminum or an aluminum compound. The cerium-based abrasive can be produced by wet-dispersing the cerium-based abrasive in a dispersion medium to obtain a slurry and carrying out surface treatment by adding a treatment solution containing at least either one of the silicon compound and the aluminum compound to the slurry. Further, the cerium-based abrasive can be produced by carrying out surface treatment by adding a treatment solution containing at least either one of the silicon compound and the aluminum compound to the slurry during the pulverization step or after the pulverization step in the conventional cerium-based abrasive production process and after that roasting and classifying the obtained cerium-based abrasive.

Cerium-based abrasive material and abrasive material slurry, and method for producing cerium based abrasive material

A cerium-based abrasive and a production method of the cerium-based abrasive excellent in polishing properties of a high polishing speed and scarce formation of polishing scratches are provided by keeping the color of the abrasive in specified ranges or stably making fluorine be contained in the abrasive. For example, as such a cerium-based abrasive, examples include a cerium-based abrasive containing cerium oxide as a main component and having an L* value in a range not lower than 65 and or lower 90, an a* value in a range 0 or higher but 15 or lower, and a b* value in a range 10 or higher but 30 or lower in the case the color is expressed by an L*a*b* color system.

Regarding a cerium oxide-based abrasive containing cerium oxide as a main component and abrasive particles with an average particle diameter of 0.2 to 3.0 &mgr;m, the present invention provides a cerium-based abrasive containing coarse particles of 10 &mgr;m or larger in a concentration of 1000 ppm or lower (by weight) or magnetic particles in a concentration of 1000 ppm or lower (by weight). The coarse particles or the magnetic particles are particularly preferable to exist in a concentration of 300 ppm or lower (by weight). Further, by controlling an average value of the specific surface area of the abrasive particles to be within 0.5 to 30 m /g, the resulting abrasive is provided with a high cutting property and is capable of forming a polished face with high precision. The production method of such cerium-based abrasives comprises control being the concentration of the coarse particles and the classification point and repeated classification. The control of the magnetic particle concentration is made possible by utilization of a filter of a magnetic material and alteration of pulverization media, which are either solely or properly combined with each other to be performed.

Cerium based abrasive material and method for producing cerium based abrasive material

Black ultrafine magnetite particles and process for preparing the same

A fine particulate polishing agent comprises fine particles of a solid solution composed of single-crystal ceric oxide and silicon dioxide and fine particles of silicon dioxide. A slurry polishing agent comprising the fine particulate polishing agent can be prepared by a method which comprises the steps of mixing, with stirring, single-crystal ceric oxide fine particles, silica sol and a liquid; drying the mixture; subjecting the dried particulate material to a thermal treatment at a high temperature and then cooling the solid solution powder formed by the thermal treatment and composed of single crystal ceric oxide and silicon dioxide; again mixing the powder with silica sol and a liquid; and then subjecting the mixture to deagglomeration using a wet pulverizing mill to give a slurry.

Fine particulate polishing agent, method for producing the same and

Cerium oxide ultrafine particles consist essentially of cerium oxide single crystal grains having a grain size ranging from 10 to 80 nm and the cerium oxide ultrafine particles can be prepared by a method which comprises the steps of mixing, with stirring, an aqueous solution of cerous nitrate with a base in such a mixing ratio that the pH value of the mixture ranges from 5 to 10, then rapidly heating the resulting mixture up to a temperature of 70 to 100.degree. C. and maturing the mixture at that temperature. The cerium oxide ultrafine particles not only have an average particle size ranging from 10 to 80 nm, but also are uniform in the particle size and in the shape.

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Tokyo, Japan

Naoyoshi Mochizuki