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

Abstract

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°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°C, which differed from those of Ni–B coating (298, 371 and 411°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°C annealed coatings showed notable improvement in hardness (1212 HV10) and corrosion properties (3.01 μA cm−2) which could be ascribed to the formation of Ni3B and Ni2B phases.