Arkadeb Mukhopadhyay

EFFECTS OF HEAT TREATMENT ON TRIBOLOGICAL BEHAVIOR OF ELECTROLESS Ni–B COATING AT ELEVATED TEMPERATURES

The present work investigates the effects of heat treatment on friction and wear behavior of electroless Ni–B coatings at elevated temperatures. Coating is deposited on AISI 1040 steel specimens and subjected to heat treatments at 350∘C, 400∘C and 450∘C. Coating characterization is done using scanning electron microscope, energy dispersive X-Ray analysis and X-Ray diffraction analysis. Improvement in microhardness is observed for the heat treated deposits. Further, the effect of heat treatment on the tribological behavior of the coatings at room temperature, 100∘C, 300∘C and 500∘C are analyzed on a pin-on-disc setup. Heat treatment at 350∘C causes a significant improvement in the tribological behavior at elevated temperatures. Higher heat treatment temperatures cause deterioration in the wear resistance and coefficient of friction. The wear mechanism at 100∘C is observed to be predominantly adhesive along with abrasion. While at 300∘C, abrasive wear is seen to be the governing wear phenomenon. Formation of mechanically mixed layers is noticed at both the test temperatures of 100∘C and 300∘C for the coatings heat treated at 400∘C and 450∘C test temperature. The predominant wear mechanisms at 500∘C are abrasive and fatigue for as-deposited and heat treated coatings, respectively.

Effect of Operating Temperature on Tribological Behavior of As-Plated Ni-B Coating Deposited by Electroless Method

ABSTRACT The present work investigates the tribological behavior of electroless Ni-B coating in its as-plated condition at elevated operating temperatures. Ni-B coating is deposited using an electroless method on AISI 1040 steel specimens. Coating characterization is done using scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction techniques. Vickers microhardness and surface roughness are measured. Friction and wear tests are carried out on a pin-on-disc tribological test setup at room and elevated temperatures of 100, 300, and 500°C. The tribological behavior deteriorates at 100°C compared to room temperature. Electroless Ni-B coating shows excellent wear resistance at 300°C, which again degrades at 500°C due to severe oxidation and softening of the deposits. The worn surface of the coatings is analyzed using optical microscopy and scanning electron microscopy. Within the temperature range considered, the wear mechanism changes from adhesion to a combination of adhesion and abrasion as the temperature rises from ambient condition to 100°C, following which the wear mechanism is predominantly abrasive. The formation of a tribochemical oxide film also affects the tribological behavior of the coatings at high temperature.

Investigation of Friction and Wear Properties of Electroless Ni–P–Cu Coating Under Dry Condition

This study presents the deposition and tribological characterization of electroless Ni–P–Cu coatings deposited on AISI 1040 steel specimens. After deposition, coatings are heat treated at 500∘C for...

Effect of heat treatment on microstructure and corrosion resistance of Ni-B-W-Mo coating deposited by electroless method

The present work reports the deposition of a quaternary Ni-B-W-Mo coating on AISI 1040 medium carbon steel and its characterization. Quaternary deposits are obtained by suitably modifying existing ...

Tribology of Electroless Ni-P Coating Under Lubricated Condition: An RSM and GA Approach

Friction and wear behavior of electroless Ni-P coating under lubricated condition is studied on a block – on – roller type tribo – tester by varying applied normal load, sliding speed of the roller and sliding time. Electroless Ni-P coating is deposited on AISI 1040 steel substrates. Surface morphology, phase transformation, composition and analysis of wear mechanism are done using scanning electron microscope, X-ray diffraction techniques and energy dispersive X-ray analysis respectively. Based on Taguchi experimental data, a multiple regression model is fitted to relate the coefficient of friction and wear depth with the tribo – testing parameters. Three dimensional surface and contour plots are generated to analyze the trends in variation of the response variables with the interaction of the process parameters (load, speed and time). Significant improvement in wear depth and COF of electroless Ni-P coating is observed under lubrication. Optimization of wear depth and coefficient of friction is conducted using genetic algorithm. KEywoRdS Friction, Genetic Algorithm, Lubrication, Ni-P Coating, Regression, Taguchi, Wear

Wear behavior of electroless Ni-P-W coating under lubricated condition - a Taguchi based approach

The present study aims to investigate the tribological behavior of electroless Ni-P-W coating under engine oil lubricated condition to ascertain its suitability in automotive applications. Coating is deposited onto mild steel specimens by the electroless method. The experiments are carried out on a pin - on - disc type tribo tester under lubrication. Three tribotesting parameters namely the applied normal load, sliding speed and sliding duration are varied at their three levels and their effects on the wear depth of the deposits are studied. The experiments are carried out based on the combinations available in Taguchis L27 orthogonal array (OA). Optimization of the tribo-testing parameters is carried out using Taguchis S/N ratio method to minimize the wear depth. Analysis of variance carried out at a confidence level of 99% indicates that the sliding speed is the most significant parameter in controlling the wear behavior of the deposits. Coating characterization is done using scanning electron microscope, energy dispersive X-ray analysis and X-ray diffraction techniques. It is seen that the wear mechanism under lubricated condition is abrasive in nature.

Effect of Heat Treatment on Tribological Behavior of Electroless Ni-B-Mo Coatings at Different Operating Temperatures

The present work aims to characterize the tribological behavior of electroless Ni-B-Mo coatings in their as-plated and heat treated conditions deposited on AISI 1040 steel. Heat treatment temperatures considered are 350 °C, 400 °C and 450 °C. Friction and wear tests are carried out at room (25 °C) and elevated temperatures of 100 °C, 300 °C and 500 °C. The as-deposited Ni-B-Mo coatings show a high wear rate compared to the heat treated ones at room as well as elevated temperatures. The wear rate of the heat treated coatings at high temperatures does not show a significant variation which is indicative of their high thermal stability. A similar result is also observed for the coefficient of friction of the heat treated Ni-B-Mo coatings. Analysis of worn specimens at 500 °C indicates the formation of protective tribo-oxide layers and occurrence of microstructural changes due to the in-situ heat treatment effect resulting from the high operating temperatures. The wear debris also significantly affects the tribological mechanisms of the coatings at high operating temperatures.

Friction and Wear Performance of Electroless Ni-B Coatings at Different Operating Temperatures

Electroless Ni-B coatings are deposited on AISI 1040 steel specimens and heat treated at 350 ∘C for 1 h to improve their properties. Coating characterization is done using energy dispersive X-ray analysis, scanning electron microscope and X-ray diffraction techniques. The as-deposited coatings are amorphous and become crystalline on heat treatment. Microhardness of the coatings improves significantly on heat treatment due to the precipitation of boride phases. The tribological behavior of the heat treated coatings is observed on a pin-on-disk tribological test setup by varying the applied normal load, speed of the counterface material and the test temperature. The wear and coefficient of friction of the coatings are significantly affected by the load, speed and test temperature which in turn control the in-situ oxide formation and microstructural changes during the wear process. This is further confirmed by examining the worn specimens using scanning electron microscope and energy dispersive X-ray analysis.

Tribological behavior of electroless Ni–B–W coating at room and elevated temperatures

Sodium borohydride reduced electroless Ni–B coatings possess high hardness, wear resistance, and low coefficient of friction. They are found to be suitable candidates for wear reduction of mechanical components. In a quest to achieve enhanced tribological behavior and high thermal stability, the present work reports the inclusion of W to Ni–B coatings. Electroless method is employed for Ni–B–W coating deposition on AISI 1040 steel specimens. Post deposition, the coatings are heat treated at 350 ℃, 400 ℃, and 450 ℃. Deposit characterization is carried out using energy-dispersive X-ray analysis, X-ray diffraction, and scanning electron microscopy. Inclusion of W leads to an increase in microhardness and thermal stability of Ni–B coatings. The tribological behavior of as-deposited and heat-treated Ni–B–W coatings are investigated at room and elevated temperatures (100 ℃, 300 ℃, and 500 ℃). Heat-treated coatings show lower wear rate at room temperature compared to as-deposited ones but the coefficient of friction increases. Tribological test results at elevated temperatures suggest an improvement in the wear resistance and coefficient of friction at 300 ℃ and 500 ℃ in comparison with 100 ℃. Phase transformation study post wear test indicate microstructural changes in the coating due to the in situ heat treatment at high temperature. The tribological behavior of the coatings at 100 ℃ and 300 ℃ is mainly governed by the loose wear debris and formation of debris patches, respectively. Whereas at 500 ℃, formation of protective tribo-oxide patches is also observed.