Bubble‐Free Aqueous Electrophoretic Deposition (EPD) by Pulse‐Potential Application

Abstract

A novel method based on the application of a square‐wave pulse potential of 50% duty cycle has been demonstrated to obtain dense bubble‐free deposits of alumina by constant voltage electrophoretic deposition (EPD) from an aqueous suspension. Application of continuous dc voltage invariably resulted in the incorporation of bubbles in the deposits. Bubbles in the deposit decreased progressively with decrease in the size of pulse width during the pulse potential EPD. A unique and narrow band of pulse width exists for each voltage within which a bubble‐free deposit is obtained. The band is wider at low applied voltages than at higher voltages. Such bands of pulse width were found to be independent of substrate material and occurred at the same range for stainless steel and nickel substrates, suggesting that the process may be generic and applicable to any conductive substrate. The green density of deposits obtained by pulse EPD has been found to be the same as those obtained by continuous dc voltage EPD. The cathodic pulse EPD produced uniform and homogeneous deposits and was more convenient and amenable to better control than anodic pulse EPD.

Functionalizing Ti-Surfaces through the EPD of Hydroxyapatite/NanoY2O3

“…Manipulation of the porosity in green compacts during the EPD process has been previously reported in the literature for other materials. 27,34 Sintered Coatings on Titanium Substrates. Titanium and titanium alloys are the most commonly employed bioinert material for implants due to their good mechanical properties and biocompatibility.…”

Graphene Coating on Copper by Electrophoretic Deposition for Corrosion Prevention

“…Coatings 2017, 7, 214 3 of 13 suspending medium because of their higher density, good chemical stability, and low conductivity [29]. But, the use of aqueous system has more advantages as they need much lower voltage, lower cost, has less risk of fire, and is more environmental friendly than the hazardous organic liquids [30].…”

“…A constant dc voltage (10 V) was applied to the suspension for an optimized time of 1 s, using a source meter (Model 2410, Keithley Instruments Inc., Cleveland, OH, USA). The coated green samples were dried overnight at room temperature [29]. The GO coated on copper was then reduced chemically by dipping it in sodium borohydride (NaBH 4 ) solution as the reducing agent [41].…”

“…A constant dc voltage (10 V) was applied to the suspension for an optimized time of 1 s, using a source meter (Model 2410, Keithley Instruments Inc., Cleveland, OH, USA). The coated green samples were dried overnight at room temperature [29].…”

“…It is a very versatile, fast, and cost effective technique because it can be modified easily for specific applications, and it is easy to control the deposition rate, thickness, and uniformity of coating. Generally, EPD involves organic liquids as the suspending medium because of their higher density, good chemical stability, and low conductivity [29]. But, the use of aqueous system has more advantages as they need much lower voltage, lower cost, has less risk of fire, and is more environmental friendly than the hazardous organic liquids [30].…”