This is where brazing neither using electroplated nickel becomes a potential jointing technique. Chen et al. [2] jointed WC-Co to stainless steel by a brazing process using nickel interlayer between the two metals and found that fracture of the brazed joints occurred in the bulk WC-Co substrates, indicating the success of the jointing nickel interlayer.In other applications requiring extreme wear resistance, cemented carbide properties are still insufficient, and coating it with harder and stronger substances such as diamond or diamond-like carbon is applicable. Electroplated nickel interlayer is explored for this purpose where adhesion between the two substances is the main issue.

Common diamond coating technique, that is, chemical vapor deposition, requires high temperature in which the cobalt binder within cemented carbide favors reaction towards graphitic phase, an unexpected interlayer during diamond deposition process which leads to deleterious effect to the diamond coating [3, 4]. There is also problems related to residual stress at the interface caused by mismatch in thermal expansion coefficients between the two substances. These issues make pretreatments on the hard metal substrate prior to diamond deposition required. Introducing intermediate layer between the cemented carbide substrate and the diamond coating is a way for this purpose. The use of electroplated nickel as the interlayer is of interest in this study considering nickel’s thermal expansion coefficient which is close to that of hard metal, and that diamond can deposit and grow on nickel substrate [3, 5, 6].

Electroplating for nickel deposition uses an electrolytic path. This method has advantages of having low reaction temperature which avoids residual stress caused by mismatch in thermal expansion coefficient, being economically viable, and being easy to control by manipulating the deposition parameters [7�C9]. Thickness and uniformity are some of quality measures of electroplating results. This study attempts to improve the quality of electroplated nickel on hard metal substrate by selecting proper deposition parameters combination. Intensity of electric field and electrolyte resistance between anode and cathode are affected by the gap between electrodes [10]. Also, considering kinetics of reaction, electroplating is affected by the duration of reaction.

Accordingly, in this study the electroplating time and the gap between electrodes varied, GSK-3 and their influence on the quality of deposited nickel layer is quantified by empirical models using design of experiment (DOE) so that the result could be objectively analyzed [11].2. Experimental2.1. Sample PreparationA WC-6%Co rod of size 5mm diameter �� 150mm length was cut using a precision cutter machine into moderate thin samples.