Study On Oxidation Resistance Of Ultrafine Ni-Ag Bimetallic Powders

With the rapid increase of precious metals?price, people have to use base metals Ni, Cu, which can replace precious metals for reducing chip components? cost. But the base metals oxidate easily at high temperature in the atmosphere. So it?s necessary to prevent base metals?oxidation at high temperature. The silver–plated Ni powder is a new material. Through chemical reduction method in aqueous solutions, Ag nanoparticles strew nickel powder, so silver–plated Ni powder has good antioxidation property.Adopted Ni powders in this research , whose average diameter are 25 nm, 200 nm and 2μm respectively, were mainly prepared in the lab. Ag nanoparticles , whose average diameter was 40 nm, were also prepared by ourselves. The influences of different technology conditions about the properties of superfine metal powders were investigated respectively.Ultrafine Ni-Ag bimetallic powders were prepared by chemical reduction method in aqueous solutions. The influences of different technology conditions on the properties of ultrafine Ni-Ag bimetallic powders were investigated, and the oxidation resistance of bimetallic powders were also investigated. XRD and TEM were used to analyse the properties of the samples. The particle diameter ratio of Ni to Ag and the content of silver in the Ni-Ag bimetallic powders, were the main factors on bimetallic powder antioxidation property. At last we chose the best process of fabricating coating bimetallic powder after doing a lot of experiments. The results indicate that: The particle diameter ratio is 5:1, and the content of silver in the Ni-Ag bimetallic powders is 40 percent, the oxidation resistance temperature of bimetallic powders is 800℃. Electrical paste, which was composed of bimetallic powder, glass powder and organic binder, was sintered in the atmosphere. The average resistance is 97 m?/□.