Abstract: A drill bit includes a cutting head and a bit body. The cutting head has a tip and cutting parts. The bit body is connected to the cutting head and has a longitudinal axis extending through the tip. The bit body has chip discharge flutes. The cutting parts are disposed at different angular positions around the longitudinal axis. Each cutting part is concaved inwardly and bounds one of the chip discharge flutes. Each of the cutting parts includes a rake face that has a corner edge adjacent to a respective one of the chip discharge flutes. When a bottom of the cutting head is viewed in a direction parallel to the longitudinal axis of the bit body, the corner edge has an obtuse included angle.

Abstract: The invention provides an electrically conductive composite having high conductivity, hermeticity, high mechanical strength, low surface roughness, lightweight, and thin profile. The composite comprises a rubber modified with vinyl ester resin. After curing in mold, the composite may serve as a bipolar plate in a fuel cell. For example, the bipolar plate is combined with a membrane electrode assembly (MEA) to form a proton exchange membrane fuel cell (PEMFC).

Abstract: The invention provides an electrically conductive composite having high conductivity, hermeticity, high mechanical strength, low surface roughness, lightweight, and thin profile. The composite comprises a rubber modified with vinyl ester resin. After curing in mold, the composite may serve as a bipolar plate in a fuel cell. For example, the bipolar plate is combined with a membrane electrode assembly (MEA) to form a proton exchange membrane fuel cell (PEMFC).

Abstract: A heat dissipation device for an electronic device includes a first heat dissipation element contacting the electronic device, wherein the material of the first heat dissipation element includes a composite material with high thermal conductivity comprising carbon fiber or porous graphite. The material with high thermal conductivity includes a fibrous structure and a matrix.