National Science Council

Taiwan Power Company

Jiann-Kuo Wu

Fu-Der Lai

Tair-I Wu

San-Der Chyou

Ran Huang

Wen-Chi Chiang

An anti-biofouling system adapted to be used for an underwater structure immersed in seawater is disclosed. The anti-biofouling system includes a conductive layer, comprising carbon fiber, graphite powder and binder, formed on a surface of the underwater structure for serving as an anode, a cathode, and a power supply for providing a current, thereby performing an electrolytic reaction for the anti-biofouling system such that a fouling organism is prohibited from attaching on the surface of the underwater structure.

Anti-biofouling system

The adhesive strength and hardness of chromium nitride(CrN) film deposited on SKD 61 tool steel was significantly enhanced by a nitriding process on the surface the tool steel before coating with a CrN film. These nitriding processes included nitrocarburing, gas nitriding, and plasma nitriding, respectively. After nitriding, the surface of tool steel was repolishing with grits #600, #1000, #1800 of SiC grinding paper, as well as #1000 grinding paper and diamond paste, respectively. After repolishing, the CrN film was deposited by the cathodic arc ion plating deposition process at low temperatre of 200.degree. C. The present invention was related to the process modification for enhancing the adhesive strength and surface hardness of CrN film deposited on tool steels. This method included a nitriding process and a repolishing followed by the cathodic arc ion plating deposition.

Method of surface modification for tool steels

A cyaniding process, operating in a molten cyanide salt, and a nitriding process, operating in a Tufftride salt bath, can be utilized to modify the near-surface microstructure of Ti-6Al-4V alloy. The surface-hardened layers have been characterized with respect to their hardness and microstructure. The corrosion and wear performance can be both improved by cyaniding and nitriding.

Method of surface modification of titanium alloy

Disclosed is a process of surface hardening for titanium alloys comprising .alpha. phase by carburization in a molten salt which consists of carbonate as the carbon-yielding agent with electrolysis within 790.degree. C. to 930.degree. C. The hardness within the effective carburizing layer is influenced by bath temperature, applied current density and carburizing period. The major hardening effect is due to the formation of solid solution of carbon in .alpha.-Ti.

Process of surface hardening for titanium alloy by molten salt

Disclosed is a process of surface hardening of Ti-6A1-4V alloy that can be performed by electrolytic charging in an acid solution, subsequent solution treatment, followed by dehydrogenation to obtain an equiaxed alpha grain in transformed beta matrix. Surface hardnesses of the processed specimens are better than that of the mill-annealed specimen. The depth of hardened layer depends on the charging time.

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Taipei, Taiwan

Jiann-Kuo Wu