無電解ニッケル-リン合金めっき皮膜の耐食性に及ぼす上層スズめっきの影響 [in Japanese] Tin Overlayer Fffect on Corrosion Resistance of Electroless Nickel-Phosphorus Alloy Plating Films [in Japanese]
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Electroless nickel-phosphorus alloy was plated on steels, and tin plated on top of these. Double-plating films were analyzed by glow discharge emission spectrometry (GDS) before and after heat treatment. Effects of heat treatment on X-ray diffraction patterns, anodic polarization curves, and corrosion resistance were investigated compared to electroless nickel-phosphorus alloy films. Anodic polarization currents for tin/electroless nickel-phosphorus alloy double-plating films were greatly suppressed by heat treatment at 400°C. X-ray diffraction measurements confirmed the formation of intermetallic tin-nickel compounds after heat treatment. Current values were assumed suppressed due to formation of these compounds.<br>GDS results showed that film surfaces were blue due to nickel oxides forming on them in heating electroless nickel-phosphorus alloy films at 400°C in an atmosphere. Electroless nickel-phosphorus alloy films with a tin overlayer did not show this color, however, because intermetallic tin-nickel compounds formed on the film surface. CASS tests showed that electroless nickel-phosphorus alloy films with a tin overlayer were superior in corrosion resistance to films without this overlayer.
- Jitsumu Hyomen Gijutsu
Jitsumu Hyomen Gijutsu 49(6), 613-617, 1998-06-01
The Surface Finishing Society of Japan