Investigation of Wear Behavior of Electroless Ni-P-W Coating under Dry and Lubricated Conditions Using RSM and Fuzzy Logic

Abstract

The present work aims to investigate and correlate the wear behavior of electroless NiP -W coating under dry and lubricated conditions with the tribological testing parameters. A pin-on-disc configuration test setup is used for the same. Taguchi's orthogonal design of experiments technique is used to carry out the experiments. Both response surface and fuzzy rule based models are seen to be effective in determining the complex interrelationship between the wear depth of the coatings and the test parameters, namely applied normal load, sliding speed and sliding duration. The coefficient of determination for fuzzy logic based predictions is seen to be higher than the regression predicted ones, indicating better modeling capabilities of the artificial intelligence technique. ANOVA results reveal that the wear depth is mostly influenced by sliding speed followed by applied normal load and sliding duration for both dry and lubricated conditions. Coating composition, phase transformation and microstructure studies are undertaken to analyze their effects on the wear behavior. Abrasive wear mechanism is seen to be the predominating under both dry and lubricated condition. The coatings are seen to suffer more wear under dry sliding condition compared to lubricated environment.

Evaluation of Tribological Properties and Optimization of Electroless Ni-P-W Coating Under Dry Condition Using Grey Fuzzy Analysis

“…For the deposition of coating, the chemicals given in Table 1 are mixed appropriately and in proper sequence. The bath composition is decided after a lot of trials and literature review and is kept constant so that all the specimens are uniformly coated [20,21]. The role of each chemical and operating conditions are also enlisted in Table 1.…”

“…The wear resistance of electroless nickel (EN) coatings shows a remarkable improvement on addition of hard particles such as diamond, Al2O3 and TiO2 [13][14][15]. The addition of a third element to the binary Ni-P and Ni-B coating leads to the formation of a ternary alloy such as Ni-P-W and Ni-P-Cu [16][17][18][19][20][21][22][23], which again leads to an enhanced wear resistance. Softer particles incorporated with EN coatings such as PTFE, MoS2, graphite and CNTs [24][25][26][27] promote self lubricity and finds their applications in the reduction of friction.…”

“…Laser treatment increases the wear resistance of electroless Ni-P-W coating further, than obtained by furnace annealing [34]. The wear mechanism of the deposits is observed to be adhesive and in some cases to be abrasive depending on the test conditions and sliding environment [16,[18][19][20][21]34].…”

“…This happens due to the precipitation of phosphides and solid solution strengthening of the nickel matrix due to dissolved tungsten [17]. The wear resistance also depends on the tribological testing conditions such as the applied normal load, test speed, sliding time as well as test environment [18][19][20][21]. With the increase in applied normal load, the specific wear rate of heat treated Ni-P-W coating increases though it is lower than Ni-P deposits or Ni-P-W coating in its as-plated condition [16].…”

“…Exhaustive review of the literature reveals that most of the studies related to electroless Ni-P-W coating are directed mainly towards effect of heat/mechanical treatments of the deposits on its tribological properties, corrosion resistance and coating characterization under different deposition conditions [16][17][18][19][20][21][29][30][31][32][33][34]. Due to the broad industrial usage of EN coatings in industries, their investigation and optimization is gaining immense importance [35][36][37][38].…”