Electroless Ni–P coating of different magnesium alloys

Surface Treatment of Magnesium Alloys by Electroless Ni –P Plating Technique with Emphasis on Zinc Pre-Treatment: A Review

“…64, a relatively smooth Ni-P surface was obtained in all samples with R a of less than 1 µm in most samples and an R z value of 3.4 to 5.8 µm.…”

“…The results indicated that bright electroplating gave the least surface roughness, mirror-like which could be used for decorative purpose, followed by Ni electroplated, then electroless plated with stabilizer. Additionally, the surface roughness tended to decrease after the heat treatment process [64].…”

“…A comparison was made between the surfaces obtained by: 1) electroless Ni-P plating, 2) same then followed by Ni electroplating, and 3)same as in 2) then followed by bright Ni electroplating [62]. The results indicated that bright electroplating gave the least surface roughness, mirror-like which could be used for decorative purpose, followed by Ni electroplated, then electroless plated with stabilizer.…”

“…Electroless plating technique was developed and optimized for wrought AZ31 magnesium alloy [62] and modified recently to improve the quality of the coat and to apply it on several wrought magnesium alloys [63][64], namely AZ31B, AE42 and ZRE1. The procedure includes mechanical polishing, ultrasonic cleaning, alkaline cleaning, acid pickling, acid activation, zinc immersion, then electroless Ni-P plating.…”

“…The surface preparation and pre-treatment prior to electroless coating was found to be of prime importance for a successful coat [63][64][65][66]. It is to be noted that some defects in the coat were found such as micropores, blistering and cracking and that these defects disappeared after careful surface preparation and bath optimization applying the modified plating procedure shown in Table 1.…”