Korea Atomic Energy Research Institute

Korea Electric Power Corporation

Other

Il Hiun Kuk

Yong Hwan Jeong

Kyeong Ho Kim

Youn Ho Jung

Jong Hyuk Baek

Sun-Jae Kim

Byong Kwon Choi

Soon Dong Park

Sun Jae Kim

Joung Soo Kim

Yeon Sang Ahn

Whung Whoe Kim

Thak Sang Byun

Hong Deuk Kim

Chang Kyu Rhee

Jun Wha Hong

Jeong Hun Suh

The present invention relates to titanium dioxide powder with a large specific surface area, a method for preparing thereof, and a use of the titanium dioxide as a photocatalyst, and more particularly, discloses a method for the preparation of titanium dioxide powder comprised of the steps of adding ice pieces or icy distilled water to pure titanium tetrachloride (TiCl ) to give an aqueous titanylchloride solution of 1.5 M or higher; diluting the aqueous titanylchloride with distilled water; obtaining precipitates from the diluted aqueous titanylchloride solution by standing for 2-20 hours at 15-70&deg; C.; and filtering, washing and drying the above precipitates to give downy hair-shaped TiO powder with a specific surface area of 130-200 m /g. The titanium dioxide powder of the present invention shows high photocatalytic activity, so that it can be used to decompose environmental organic pollutants by taking advantage of an advanced oxidation process (AOP) in which pollution-free energy, such as solar energy is utilized as a driving force. The method allows the formation of a crystalline phase of titanium dioxide at room temperature without a high temperature and high pressure process and enjoys an economical advantage of being low in production cost.

TiO2 ultrafine powder, and process for preparing thereof

The present invention relates to the heat treatment processes for manufacturing high toughness SA 508 Gr.3 steels including the intercritical heat treatment step in addition to the conventional heat treatment process, wherein the intercritical heat treatment(IHT) is added between the quenching step and the tempering step and is performed at 680&deg; C. to 750&deg; C., which is the ferrite/austenite two phase region, for 1 hour to 8 hours. When compared with the conventional heat treatment process the room temperature impact energy and the upper shelf energy of the steels manufactured by the invention increase significantly and the ductile-to-brittle transition temperature decreases. Also the present invention relates to the modified tempering processes for manufacturing high toughness SA 508 Gr.3 steels, wherein the tempering after the intercritical heat treatment is performed at the temperature lower than 635&deg; C. The modified tempering is performed to compensate the decrease of strength due to the intercritical heat treatment and to additionally increase the toughness of the intercritically heat treated SA 508 Gr.3 steels.

Intercritical heat treatment process for toughness improvement of SA 508 GR.3 steel

The present invention is related to the method for surface-alloying comprising the steps of: (a) plating alloying ingredients on the surface of metal or alloy substrate to form plated layer, and (b) melting this surface using a laser beam to form an alloyed layer of which composition is different from that of base material. And, the method of this invention may further include surface-reforming method of metal or alloy substrate. And the method of this invention may further include surface-repairing method of damaged metal or alloy substrate. Using the method of this invention, an alloyed layer, which has improved resistance to grain boundary related material degradation phenomena, e.g. stress corrosion cracking, abrasion, fatigue, erosion, and so on, can be formed.

Method for surface-alloying on metal or alloy substrates, or for

A method for production of mono-dispersed and crystalline titanium dioxide ultra fine powders comprises preparing an aqueous titanyl chloride solution, diluting the aqueous titanyl chloride solution to a concentration of between about 0.2 to 1.2 mole and heating the diluted aqueous titanyl chloride solution and maintaining the solution in a temperature range of between 15 to 155.degree. C. to precipitate titanium dioxide. The aqueous titanyl chloride solution is prepared by adding ice pieces of distilled water or icing distilled water to undiluted titanium tetrachloride.

Method for production of mono-dispersed and crystalline TiO.sub.2

The present invention is directed to an advanced zirconium alloy having superior corrosion resistance and high strength suitable for fuel rod cladding, spacer grids and other structural components in a reactor core of nuclear power plants.

Composition of zirconium alloy having low corrosion rate and high

The invention presented herein relates to a zirconium alloy with superior corrosion resistance and high strength for use in fuel rod claddings, spacer grids and structural components as used in reactor core of light water and heavy water nuclear power plant. The zirconium alloy of this invention with superior corrosion resistance and high strength comprises an alloy composition as follows:

Composition of zirconium alloy having high corrosion resistance and high

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Taejon-si, South Korea

Il Hiun Kuk