The effect of heat treatment on Ni–B–Ce electroless coatings

We successfully obtained sonicated Ni-B-Ce coating on the surface of low carbon steel (Q235) through ultrasonic-assisted electroless plating with the deposition time of 60 minutes. The coatings were heat treated at 300, 500 and 800 degrees C for 2 hours. The results showed the Ni-B-Ce coating changed from amorphous to crystallised and produced Ni3B and Ni2B phases after heat treatment. The addition of Ce changed the crystallisation temperatures of Ni-B-Ce coating after heat treatment to 562 and 692 degrees C, which differed from those of Ni-B coating (298, 371 and 411 degrees C). It also improved the activation energy to 156.85 and 214.11 kJ mol(-1), which was much higher than those of Ni-B coating (32.23, 25.80 and 50.69 kJ mol(-1)). In addition, the 800 degrees C annealed coatings showed notable improvement in hardness (1212 HV10) and corrosion properties (3.01 mu A cm(-2)) which could be ascribed to the formation of Ni3B and Ni2B phases.