DefinePK

Abstract

An electroless Ni-P deposition procedure has been advanced to treat the AZ91D magnesium alloy surfaces against corrosion. Magnesium alloy AZ91D became first sulfated in a nickel sulfate bath containing thiourea-molybdate. Then an electroless Ni-P deposition became performed on the sulfate coating from a sulfate answer. The stages in the sulfate coatings had been analyzed by way of XRD. Microstructures of sulfate coatings and electroless Ni-P depositions have been located by using SEM and EDS. It was located that there has been metal nickel inside the sulfate coating and the addition of thiourea-molybdate in the sulfating bathtub resulted within the boom of nickel in the coating. Quite a few disperse steel nickel particles acted because the catalyst nuclei for the succeeding Ni-P deposition. Therefore, the Ni-P depositions with dense and first-rate microstructure have been acquired on the sulfate coatings received from the sulfating bath in which 10.0~12.5g/l thiourea molybdate turned into introduced. The Ni-P plus nickel sulfate coatings at the AZ91D magnesium alloy exhibited ideal corrosion resistance as proven via the effects of the salt spray corrosion test.