AZ31 Magnesium Alloy Electroless Ni-P Amorphous Plating and Its Crystallization
|Keywords||AZ31 magnesium alloy Electroless nickel plating Heat treatment Hardness Corrosion resistance|
Magnesium alloy is the lightest metal in the practical application of structural materials , in addition to have high specific strength and specific stiffness , electromagnetic shielding , damping , damping , cutting , or a , in the aerospace , automotive, electronics and other areas are being increasingly wide range of applications . However , the chemical properties of magnesium alloys is very lively , and lower corrosion resistance can become constraints to further obstacle to the development of magnesium alloy . Accordingly, the magnesium alloy workpiece after a certain surface treatment step before use to provide protection . The electroless plating is one effective way of protection of the magnesium alloy workpiece , magnesium alloy after the electroless nickel plating process , and not only the corrosion resistance and abrasion resistance is improved , but also to obtain a uniform coating thickness in the complex shape of the castings . AZ31 magnesium alloy surface plating , prepared by the appearance of smooth , bright , good binding capacity Ni-P coating . Optimization of the electroless plating pre-treatment process , the main salt , a reducing agent , pH and temperature and other factors on the deposition rate . Metallographic observation , SEM observation , EDS analysis , XRD analysis , DSC analysis test method coating surface morphology , structure , composition , and crystallization transition point were measured and analyzed . Last test method by the salt spray test , polarization curves of the coating as well as coating heat treated after the performance . Magnesium alloy surface by electroless plating Ni-P treatment , its hardness has been greatly improved , nearly ten times the magnesium alloy matrix coating with excellent corrosion resistance in 3.5% NaCl solution , resulting Ni-P coating the corrosion potential relative to the matrix by nearly 800mV electroless plating samples in the salt spray chamber continuous spray 72h no peeling , flaking , magnesium alloy electroless plating corrosion resistance has been greatly improved . Electroless plating Ni-P coating the surface hardness of the coating after annealing crystallization has been greatly improved , but the corrosion resistance decreased .