Mechanism of Nickel-Tungsten Alloy Electrodeposition From Pyrophosphate Electrolyte

The Mechanical Properties and Rate of Electrodeposition of Co−W Alloys from a Boron−Gluconate Bath: Impact of Anodic Processes

“…2 can explain the nature of the size effect in the microhardness of the deposited coatings, along with the role the anodic processes play during electrodeposition of alloys between iron group metals and refractory metals [10,[12][13][14]. The results of this study can also be considered as indirect experimental proof of the validity of the electrodeposition mechanism proposed in [21][22][23].…”

“…We note that the mechanism as it is given in [21][22][23] cannot explain the role of anodic processes that was evident from the findings shown in Fig. 1.…”

“…If we assume that the electrodeposition mechanism follows the reaction scheme presented in Fig. 2, which is based on works [21][22][23], the results discussed above can be considered as experimental proof of the validity of this mechanism.…”

“…1 can be explained based on the mechanisms for electrodeposition of similar alloys (i.e., alloys between iron group metals and refractory metals), which is known as induced codeposition [1,2,[19][20][21][22][23]. Depending on where the mixed metal complex that is immediately involved in the formation of an alloy is formed (in our case, it would be a cobalt−tungsten complex), in the bulk of solution [2] or directly at the electrode surface [1,[19][20][21][22][23], all the proposed mechanisms of the induced codeposition can be divided into two large categories. The findings reported in our previous experimental study [24], in particular, suggested that a relevant mixed metal complex was formed at the electrode's surface; however, it was not that unambiguous.…”

“…In a number of studies, it was proposed that the reduction of a multivalent metal anion (tungstate or molybdate) at the cathode was the first stage in the formation of the intermediate [1,19,20], whereas the other authors showed that the process started with the partial reduction of the metal component inducing the codeposition (a nickel or cobalt complex) to an intermediate degree of oxidation (see reaction (1) in Fig. 2) [21][22][23]. If we assume that the electrodeposition mechanism follows the reaction scheme presented in Fig.…”