Abstract: The present invention relates to a silicon substrate 10 for a solar battery, wherein the silicon substrate 10 comprises: a plurality of curves 13 constituted by concave parts 11 and convex parts 12 to absorb sunlight; and planes 14 connected to both edges of the curves to absorb sunlight and to be connected to other silicon substrates. Each of the curves 13 and each of the planes 14 have a thickness of 100 to 300 ?m, and each of the concave parts 11 or each of the convex parts 12 has a semi-circular shape. The curves 13 occupy 90% or more of the total area.

Abstract: A grinding wheel has a disc having a connection hole formed at a center thereof, to which a rotation axis of a grinder is connected, and a plurality of abrasive segments detachably connected to a surface of the disc. A plurality of fixing recesses are radially formed on the surface of the disc at an interval and fixing protrusions having a shape corresponding to the fixing recess are formed on bottom surfaces of the abrasive segments, so that the abrasive segments are connected to the disc by inserting the fixing protrusions into the fixing recesses. According to the grinding wheel, when the abrasive segment is worn away or inferior as it is used for a long time, it has only to replace the corresponding abrasive segment only. Accordingly, an economical efficiency is high.

Abstract: A manufacturing method of a diamond cutting tool is characterized in that the metal coated diamond particles are arranged on a region of a steel body portion intended to be used as a cutting edge, and then adhered to the body portion through the electro-deposition whereby the manufacturing time is reduced, the diamond particles are securely adhered to the body portion, and the lifetime of the cutting tool is prolonged as well.