Effect of zwitterionic surfactant on tribological behaviour of electroless plating

Abstract

Zwitterionic surfactant consisting of positive and negative charges on its head is introduced in electroless alkaline bath to reduce the cost of electroless plating in industrial applications. The concentration of surfactant varied from 0 to 0·030 g L⁻¹ insteps of 0·006 g L⁻¹. The surfactant exhibits attractive and repulsive forces in the electrolyte used, and their corresponding influence on coating thickness, surface structure, adhesion, specific wear rate and microhardness was studied. The results indicated that there was an improvement in the properties of coated substrate. Scanning electron microscope image showed a unique blackberry shaped surface structure after adding the surfactant. Without zwitterionic surfactant, the coating thickness was 44·31 μm, and with surfactant at 0·018 g L⁻¹, it was increased to 98·03 μm. The wear resistance of coated substrate was improved to 54% when compared with the substrate coated without surfactant. Without addition of surfactant, the microhardness was 432 HV, and with zwitterionic surfactant at critical micelle concentration, it was improved to 680 HV.