Measuring the Covering Power of a Tin Plating Bath Using Scanning Electron Microscopy

For electroplating articles with a complex shape, it is essential that the plating bath should (1) cover the contoured surface in a short time and (2) produce a uniform thickness preferably over the entire surface or at least over the significant surfaces. The former is decided by the covering power of the bath and the latter by the13; throwing power of the bath. Throwing power refers to the thickness distribution of the deposit, whereas covering power is concerned with the ability of the bath to cover the entire cathode surface in the least possible time, even in low current density areas. Though quantitative methods (Haring and Blum cell, Hull cell, etc.)are available for measuring the throwing power of the bath, there are no such methods for covering power. In our laboratory, we examined the feasibility of measuring the covering power of a tin plating bath with the help of13; scanning electron microscopy (SEM).This article describes an approach for quantitative estimation of covering power of a tin plating bath

Structure and properties of electrodeposited Ni-Co-YZA composite coatings

The aim is to develop an economical composite coating with high thermal stability. Ni-Co alloys are found to possess better thermal, physical and mechanical properties compared to Ni. Also, oxide particles as distributed phase can impart better thermal stability. Hence, particulates of composite Yttria stabilised zirconia, a commonly used high temperature material and alumina (YZA) were reinforced in various Ni-Co alloy matrices through electrodeposition. The influence of YZA on the microhardness, tribology and corrosion behaviour of Ni-Co alloys with Co contents of 0 wt.%, 17 wt.%, 38 wt.% and 85 wt.% was evaluated. Optical and Scanning Electron Microscopy (SEM) confirmed the presence of YZA particles and Energy Dispersive X-ray Analysis (EDX) revealed the composition. Tribology testing showed that composite containing 38 wt.% Co displayed better wear resistance. It was found from the immersion corrosion studies that Ni-17Co-YZA coating displayed improved corrosion resistance. Thermal stability studies showed that Ni-85Co-YZA coating retained its microhardness at temperatures of 600oC. Thus, these coatings can be tailored for various applications by varying the cobalt content