The present experimental investigation deals with the deposition of electroless Ni-P-W coating on mild steel substrate and optimization of tribological parameters for better tribological behaviour like minimization of wear depth and coefficient of friction. Three tribological test parameters, namely, load, speed, and time, are optimized for minimum friction and wear of the coating. Friction and wear tests are carried out in a multitribotester using block on roller configuration under dry conditions. Taguchi based grey relational analysis is employed for optimization of this multiple response problem using L27orthogonal array. Analysis of variance shows that load, speed, time, and interaction between load and speed have significant influence on controlling the friction and wear behavior of Ni-P-W coating. It is observed that wear mechanism is mild adhesive in nature. The structural morphology, composition, and phase structure of the coating are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD), respectively.
The present paper considers the comparative study of tribological characteristics of various electroless alloy coatings viz. Ni-P, Ni-P-W and Ni-P-Cu. The tribological behavior of these coatings depends on various parameters like load, speed, lubricant, chemical compositions and heat treatment temperature to a great extent. One of the main effects of heat treatment on these coatings is phosphide precipitation, which makes them suitable for anti-wear applications. The property of binary Ni-P can be further improved by depositing third particles electrolessly. The phase structure of the coatings depends on the amount of phosphorous and heat treatment temperature. The tribological behavior of heat treated samples reveals that Ni-P-W deposit shows higher coefficient of friction and lowest wear among these three types coatings. Very high tungsten concentration retard the phosphide precipitation, thus low concentration of tungsten and low heat treatment temperature produce better coating. In case of Ni-P-Cu, medium concentration of copper and medium heat treatment temperature produces better coating.
Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites were characterized for mechanical properties using destructive and non-destructive ultrasonic testing methods. The physical properties of the composite were determined and compared with those of cortical bone.
Submerged arc welding (SAW) is one of the chief metal fabrication processes in industry. It works with high current density and can affect high metal deposition rate. The present work emphasizes the influence of process parameters on quality and performance of submerged arc weldment by incorporating one of the traditional methods of statistical data analysis i.e. ANOVA. This approach aims to reveal the main and interactive effects of process parameters on different response variables associated with the weldment. Based on factorial design without replication, experiments were conducted with three different levels of process parameters like voltage, welding current and electrode stick out to obtain butt joints from mild steel plates. Experimental results were examined by exploring Analysis of Variance Method, using statistical software package MINITAB. liased on ANOVA, several graphical plots are shown-histogram of residuals, normal plot of residuals, residual verses order and residual verses specified variables etc. ANOVA delivers feasible data to justify the significance of process parameters on different response variables of submerged arc weldment in terms of their main effects and interactive effects. The effects due to variation of process parameters on (i) bead geometry in terms of bead width, depth of penetration, reinforcement, and (ii) bead quality as well as performance of the welded joint in terms of hardness, impact value and tensile strength are represented graphically. Graphical representations of the experimental data are supposed to contribute 149 Brought to you by | Western University Authenticated Download Date | 6/9/15 10:39 AM Vol. 17, No. 3, 2006 Effect of Process Parameters on Submerged Arc Weldment valuable information for quality control of submerged arc welding process, which would help to obtain superior quality weld and also to achieve high productivity.
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