An Assessment on the Corrosion Behavior of Ni-P Electro less Coatings Consisting of MoS2, PTFE, Duplex Ni-P-SiC/N i-P-MoS2 and N i -P-SiC/N i-P-PTFE

Electro less nickel coatings due to their good resistance to wear and corrosion have been widely used in many industries such as oil. automotive. space. etc. In order to increase their coating properties, simultaneous precipitation of different particles into the coating structure is advised by many workers. For example, the use of SiC particles has been suggested to increase the wear resistance and hardness of these coatings. In addition, the use of some lubricants such as PTFE and MOS2 has shown to improve the tnbological properties of these coatings. Ahhough these lubricant materials have been used to improve the wear properties of these coatings, but since they are normally subjected to a harsh environmental condition or corrosive media, hence it is important to investigate their corrosion behavior. In this paper a single layer of Ni-P-PTFE and Ni-P-MoS2. together with double layers of Ni-P-SiCINi-P-PTFE and Ni-P-SiClNi-P-MoS2 were applied on plane carbon steel and their corrosion behavior prior and after heat treatment were investigated, using potentiostatic polarization tests in 3.5% NaCI solutions. The results show that these coatings have different corrosion behavior to that of electro less Ni-P base coating and it can be deduced that by introducing secondary phase particles, corrosion resistance ofNi-P (composite I double layer) coatings reduces, substantially.

An Assessment on the Corrosion Behavior of Ni-P Electro less Coatings Consisting of MoS2, PTFE, Duplex Ni-P-SiC/N i-P-MoS2 and N i -P-SiC/N i-P-PTFE Keywords:

electro less coating , Ni-P , electro less composite coatings , wear resistance , corrosion resistance