In order to use less cerium oxide and achieve higher durability and polishing speeds, these abrasive particles used in an abrasive have: a shell layer (3) which is the outermost shell layer of the abrasive particles and is formed with cerium oxide as the main component; and a middle layer (2) which contains cerium oxide and an oxide of at least one element selected from Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, In, Sn, Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Bi, Th, and the alkali earth metals, and which is formed closer to the center of the abrasive particles than the shell layer (3).

A coupling mechanism which enables a rotating body to follow an undulation of a polishing surface without generating flutter or vibration of the rotating body, and can finely control a load on the rotating body on a polishing surface in a load range which is smaller than the gravity of rotating body is disclosed. The coupling mechanism includes an upper spherical bearing and a lower spherical bearing disposed between a drive shaft and the rotating body. The upper spherical bearing has a first concave contact surface and a second convex contact surface which are in contact with each other, and the lower spherical bearing has a third concave contact surface and a fourth convex contact surface which are in contact with each other. The first concave contact surface and the second convex contact surface are located above the third concave contact surface and the fourth convex contact surface. The first concave contact surface, the second convex contact surface, the third concave contact surface, the fourth convex contact surface are arranged concentrically.

To provide modified colloidal silica capable of improving the stability of the polishing speed with time when used as abrasive grains in a polishing composition for polishing a polishing object that contains a material to which charged modified colloidal silica easily adheres, such as a SiN wafer, and to provide a method for producing the modified colloidal silica.

Modified colloidal silica, being obtained by modifying raw colloidal silica, wherein

the raw colloidal silica has a number distribution ratio of 10% or less of microparticles having a particle size of 40% or less relative to a volume average particle size based on Heywood diameter (equivalent circle diameter) as determined by image analysis using a scanning electron microscope.

A polishing system performs chemical-mechanical polishing of an object to be polished using an abrasive slurry. The polishing system includes a polishing amount calculator that measures an amount of free metal ions of a metallic element derived from the object to be polished in a processed slurry and calculates a polishing amount of the object to be polished from the amount of the free metal ions. The object to be polished is a glass containing the metallic element of Group 1 or Group 2 of a periodic table.

Provided is a polishing composition that is produced at low cost and can impart high-grade mirror finishing to ceramic. The polishing composition includes abrasives, has a pH of 6.0 or more to 9.0 or less, and is used for polishing ceramic.

Provided is a polishing composition that is produced at low cost and can impart high-grade mirror finishing to ceramic. The polishing composition includes abrasives made of carbide, and is used for polishing ceramic.

Letting a particle diameter be Dx (μm) when a cumulative particle volume cumulated from the small particle diameter side reaches x (%) of the total particle volume in a particle size distribution obtained regarding cerium oxide included in a polishing liquid using a laser diffraction/scattering method, D5 is 1 μm or less, and a difference between D95 and D5 is 3 μm or more.

A lapping device for gear helix artifact with equal common normal by rolling method, use the rotary table to accurately control the angle between the lapping surface of whetstone and the axis of the base-circle cylinder to control the helix angle of base-circle about the involute helicoid. Use the whetstone driven component to drive the whetstone to make a high-precision linear motion in the vertical direction to adjust the position of the lapping surface of whetstone. The distance between the two lapping surface of whetstone is precisely adjusted by the gauge block to control the processing length of the three tooth common normal of the gear helix artifact. The invention provides a lapping device for gear helix artifact with equal common normal by rolling method, it conforms to the generation principle of the involute helicoid, and there is no machining principle error.

A method of manufacturing a glass substrate having a penetrating structure, the method includes: (1) preparing a glass substrate that has a first surface and a second surface opposite to each other, and includes 3 mol % to 30 mol % of B.sub.2O.sub.3 in terms of oxide; (2) having the glass substrate irradiated with a laser from a first surface side, to form an initial penetrating structure; (3) wet etching the glass substrate having the initial penetrating structure formed; (4) polishing the wet-etched glass substrate from the first surface side, by using an abrasive including acid-soluble abrasive grains; and (5) cleaning the glass substrate with an acid solution.

A method for raising a polishing pad for polishing a silicon wafer, wherein a polishing pad made of foamed urethane resin is attached to a polishing machine, after dressing is performed, dummy polishing is performed, after processing to remove the polishing residues that have built up in the polishing pad by the dummy polishing is then performed, an amount of polishing residues in the polishing pad is measured, and a rise of the polishing pad subjected to the dummy polishing is judged based on the measured amount of polishing residues. As a result, a method for raising a polishing pad can improve the particle level in the polishing pad life early stage.