Effects of Co content and heat treatment on mechanical properties of electrolessly deposited Ni‐Co‐P alloys

Abstract

The effects of cobalt content and heat treatment temperature on hardness and wear resistance of nickel-cobalt-phosphorus (Ni-Co-P) are systematically investigated on the electroless alloy deposits composing of cobalt with contents up to 45%. The increase of the cobalt content leads to improved stabilization of grain size and crystallographic structure upon thermal annealing. A moderate annealing temperature of 300°C applied on Ni-45Co-2.6P deposits grants optimum hardness of 959 Hv and relatively low wear loss of 8.85 mg/1000 cycles in abrasive mode, as assessed by Taber abraser wear test. An exclusion of cobalt, however, shows benefit in wear resistance enhancement under the ball-on-disc wear test, where a combined abrasive and adhesive wear is induced in this class of nickel-based alloys.

Effects of cobalt content on mechanical and corrosion properties of electroless Ni‐Co‐P/TiN nanocomposite coatings

“…, the wear loss of the coating diminishes with Co content, which indicates that cobalt acts as a significant role to enhance the wear resistance. The relationship between wear loss and hardness is well stated by the Archard's law that abrasive wear loss ( V ) is inversely proportional to hardness ( H ) but directly proportional to the normal load ( P ) and sliding distance . In the present measurement, the load and distance remain consistent.…”

“…In the forementioned discussion of XRD patterns, it is found that cobalt can cause refinement of microstructure of the samples, so the micro‐hardness of composite coatings increases with the cobalt content. Another reason proposed here, the improvement of the hardness is probably ascribed to solid solution strengthening mechanism of cobalt element in nickel matrix . Besides, the micro‐hardness of the TiN‐Ni‐Co13‐P coating (414 HV) is higher than that of TiN‐free Ni‐Co‐P coating (391 HV).…”

“…It is obvious that the micro‐hardness of the composite coatings is in the range of 390–500 HV, considerably higher than that of bare aluminum alloy (210 HV), and increases prominently with cobalt content in the coatings. According to the classical Hall‐Petch effect : where δ y refers to yield limit, d refers to crystal grain size, δ x and K are constant, the hardness gets larger in the case of smaller average grain size ( d ). In the forementioned discussion of XRD patterns, it is found that cobalt can cause refinement of microstructure of the samples, so the micro‐hardness of composite coatings increases with the cobalt content.…”

“…It is obvious that the micro-hardness of the composite coatings is in the range of 390-500 HV, considerably higher than that of bare aluminum alloy (210 HV), and increases prominently with cobalt content in the coatings. According to the classical Hall-Petch effect [11]:…”

Cu/Ni/Au multilayers by electrochemistry: A crucial system in electronics - A critical review

“…those that can be deposited individually and those that can be only codeposited. The former group consists of metals that are much nobler than Ni, like Ag [54][55][56][57] and Cu [58][59][60][61][62][63][64][65][66][67][68]; metals that have similar standard potentials, such as Co [69][70][71][72][73][74][75][76] and Sn [77][78][79][80][81][82][83][84][85]; and metals that are more cathodic, like Cr [86,87], Zn [88][89][90][91][92][93][94][95][96][97][98][99][100] and Mn [101]…”