New Way to Cut down Metal Corrosion

A senior Chinese engineer has developed a new diffusion metallizing method which increases the resistance of metal parts to high temperatures, erosion and abrasion.

Using the method, one machine part had its working life increased by 14 times. 

Through repeated experiments, Engineer Li Zhongjun discovered a new electrode discharge phenomenon of the second current in cylinder cathodes, which formed a high-temperature and high-energy ion zone. The temperature would reach 800 to 1000 degrees Centigrade, at which metal atoms of the diffusion materials such as chromium, cobalt, molybdenum, copper and gold, would be fully ionized and rapidly penetrate the parts.

Li works for a technology research institute under the Ministry of Machinery and Electronics Industry. He began his research in 1983, and discovered the method purely by accident.

With Li's new diffusion metallizing method by cylinder cathode's, one or several metals can be diffused simultaneously into steel parts. The diffused layer becomes an alloy structure with a penetration depth of up to 300〜900 micrometres. Moreover, the depth of diffusion can be controlled, thus creating the ability to withstand high temperatures, erosion and abrasion.

The new method can be widely applied to aircraft manufacture, and the electronic, machinery and chemical industries.

It can also diffuse a weldable layer to some electronic materials that are difficult to weld, which scientists consider of great importance.

The ion-plating technique was first introduced by American scientists in 1963. However, before Li's discovery, the technique could only coat and toughen the surface of the metal parts. Now, for the first time, Li has strengthened the inner metal structure.

Studies showed that for lack of an effective way to toughen the surface of metal parts, great losses had been suffered in using steel worldwide. Some four per cent of the GNP was lost annually in some countries through the corrosion of machine parts. In China, an estimated 20 billion yuan, was corroded away each year.

It is hoped that this new easy-to-manage technique, will help prevent further losses.

Trials carried out in recent years have proven the technique to be of remarkable economic value. In one case, it prolonged a part's service life by 14 times.

Last year, Li was awarded a national invention prize for his breakthrough.