Tapan Kumar Barman

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.

Tribological Behavior of Al-SiC Metal Matrix Composite Under Dry, Aqueous and Alkaline Medium

The present study considers friction and wear behavior of aluminum matrix composites reinforced with SiC particles under three different working environments, viz., dry condition, aqueous medium and alkaline medium. The experiments are conducted with a pin-on-disk tribotester where the composite specimen slides against an alumina disk under the application of varying normal load and sliding speed. It is observed that wear increases with increase in applied load and sliding speed for all three working environments and the maximum wear occurs in the case of the alkaline medium followed by the aqueous medium and the dry condition. In general, the friction coefficient decreases with increase in applied normal load. The microstructure analysis of the worn sliding surface is done with the help of a scanning electron microscope and energy dispersive X-ray analysis. It is seen that the wear mechanism in dry condition is dominated by adhesive and abrasive wear while both mechanical and corrosive wear occur in corrosive environments.

Optimization of Material Removal Rate in EDM Using Taguchi Method

This paper presents an investigation on the effect and optimization of machining parameters on material removal rate (MRR) in electrical discharge machining (EDM) of EN31 tool steel. For the experiment, four process parameters viz. pulse on time, pulse off time, discharge current and voltage are considered. The settings of machining parameters are determined by using Taguchis orthogonal array (OA). L27 orthogonal array (OA) is considered for the study. The level of importance of the machining parameters on MRR is determined by analysis of variance (ANOVA) test. The optimum machining parameter combination is obtained by the analysis of signal-to-noise (S/N) ratio. The analysis shows that discharge current has the most significant effect on MRR followed by pulse off time and voltage. It is seen that with an increase in discharge current and pulse off time, MRR increases in the studied range. The methodology described here is expected to be highly beneficial to manufacturing industries.

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 ...

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.

Optimization of Tribological Properties of Electroless Ni-P Coatings under Lubrication Using WPCA

This work presents an experimental study of tribological performance of electroless Ni-P coating under lubricated condition. Mild steel specimens are used as the substrate material for the deposition of Ni-P coating. Tribological tests are carried out based on L27 orthogonal array (OA) varying three test parameters viz. normal load, sliding speed and sliding time in a multi-tribotester using block-on-roller configuration in lubricated condition. The experimental results for friction coefficient and wear are analysed using weighted principal components analysis (WPCA). An optimal test parameter combination is found out for minimum wear and friction coefficient. It is seen that the optimum combination of parameters are found at higher level of normal load, sliding speed and sliding time at 99% confidence level. Finally, a confirmation test is carried out to validate the analysis.

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.

Fractal Analysis in CNC End Milling

This chapter deals with the fractal dimension modeling in CNC end milling operation. Milling operations are carried out for three different materials viz. mild steel, brass and aluminium work-pieces for different combinations of spindle speed, feed rate and depth of cut. The generated surfaces are measured with Talysurf instrument and analyzed to get fractal dimension. The experimental results are further processed to model fractal dimension using response surface methodology (RSM). It is seen that spindle speed and depth of cut are the significant factors affecting fractal dimension for mild steel. For brass material, the significant factors are spindle speed and feed rate but for aluminium the significant factor is depth of cut. In general, for mild steel and brass, with increase in spindle speed, D increases. Comparing the developed response surface models, it is concluded that the models are material specific and the tool-work-piece material combination plays a vital role in fractal dimension of the generated surface profile.

Effect of Process Parameters on MRR and Surface Roughness in ECM of EN 31 Tool Steel Using WPCA

WeightedprincipalcomponentanalysisisusedtopredicttheoptimalmachiningparametersforEN 31toolsteelinelectrochemicalmachiningforminimumsurfaceroughnessandmaximummaterial removalratebasedonL27Taguchiorthogonaldesign.Forthis,multi-responseperformanceindexis calculatedtoderiveanequivalentsingleobjectivefunctionandthenTaguchimethodisusedtooptimize theprocessparameters.Theseparableinfluenceofindividualmachiningparametersandtheinteraction between theseparameters arealso investigatedbyusinganalysisofvariance (ANOVA).Results showthatthemainsignificantfactoronMRRandsurfaceroughnessiselectrolyteconcentration. Theeffectsofprocessparametersviz.electrolyteconcentration,voltage,feedrateandinter-electrode gaponMRRandsurfaceroughnessarealsoinvestigatedusing3Dsurfaceandcontourplots.Finally, thesurfacemorphologyisstudiedwiththehelpofscanningelectronmicroscopy(SEM)images. KEyWoRdS ECM, MRR, Optimization, Surface Roughness, WPCA