There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Intermolecular And Surface Forces

Nonlinear Oscillations: Exact Solutions and their Approximations

https://pureadmin.qub.ac.uk/ws/files/126683921/Edited_sudagar_R1.pdf

Electroless nickel, alloy, composite and nano coatings – A critical review

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings...

Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior:

Electroless nickel coating is a novel method of coating which can be developed in various combinations of alloys and composites each having its unique set of characteristics. Electroless nickel coatings are mainly used for wear and corrosion resistant properties. However, additional characteristics like smoothness of deposit, low friction, descent plating rate, electrical and magnetic properties also make them suitable for a host of applications. The properties of electroless nickel coatings depend mainly on the electroless solution ingredients as well as deposition conditions. Important deposition parameters include bath temperature, concentration of nickel source, concentration of reducing agent, pH of the solution, concentration of surfactants, and so on. Moreover, heat treatment is found to modify the microstructure of the coating and influence certain properties viz. hardness, wear resistance, corrosion resistance, etc. A large number of works have been published by the researchers on the evaluation of electroless nickel coating performance on the basis of hardness, roughness, corrosion resistance, friction and wear resistance for various types of coatings and substrates. Several approaches are proposed in the literatures to solve the problems related with optimization of these parameters. It is felt that a review of the various approaches developed would help to compare their main features and their relative advantages or limitations which will enable to choose the most suitable approach for a particular application and also throw light on aspects that needs further attention. In this regard, the present paper presents a review on the developments done on the optimization of electroless nickel coatings to increase its efficiency.

Optimization Studies on Electroless Nickel Coatings: A Review

Electroless Ni-P coatings have shown tremendous potential as tribology material at room temperature. However, the performance of the same in high temperature field needs to be evaluated as investigation reveals the softening of most of the coating materials. In the current study, both as-deposited as well as heat treated samples are developed for the performance evaluation. Coatings are tested under different loads with a constant speed and at temperatures ranging from room temperature (R.T.) to 500°C. Tribological tests are carried out on a pin-on- disc tribotester by selecting a wear track diameter of 60 mm for 5 minutes. Wear is reported in the form of wear rate by following Archard's equation. The microstructure characterization of the coating is performed using SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray Analysis) and XRD (X-Ray Diffraction Analysis). Coating is developed with phosphorous weight percentages around 9% on cylindrical mild steel samples and the deposition thickness is observed to be around 50 μm. The as-deposited coating is found to be amorphous in nature and hardness of the as-deposited coating is found to be around 585HV01. Friction coefficient increases initially with the increase in temperature from room temperature up to 100°C but thereafter gradually decrease with the increase in temperature. Initial increase in temperature (up to 100°C) provides higher rate of wear compared to room temperature but with further increase it drops in most of the cases. Wear rate increases with the increase in temperature but as it crosses or nears the phase transformation temperature (around 340°C), the scenario gets reversed. From X-ray diffraction analysis, it is found that coating is amorphous in as-deposited condition but transforms into a crystalline structure with heat treatment.

http://iopscience.iop.org/article/10.1088/1757-899X/149/1/012046/pdf

Influence of load and temperature on tribological behaviour of electroless Ni-P deposits

Electroless Ni-P-W coating has enhanced tribological properties compared to the conventional binary alloys. Hence, electroless Ni-W-P, which is a ternary alloy, is synthesized on mild steel substrates. The coatings are heat treated at 400 °C for 1 hr to obtain a high hardness. Their tribological behavior is investigated on a pin–on–disc tribo–tester under dry condition. Three test parameters which include the applied normal load (L), sliding speed (S) and sliding time (T) are varied and their effects on wear depth and coefficient of friction are analyzed. An attempt is made to ascertain the optimum combination of the parameters that would minimize the coefficient of friction and wear depth of the deposits simultaneously using Grey Fuzzy logic. Optimum tribological behavior of the deposits is obtained at an applied normal load of 10 N, sliding speed of 80 rpm and sliding duration of 5min. Load and time are seen to be the most significant factors in influencing the friction and wear of the deposits. The variation of coefficient of friction and wear depth considering the combined effect of the aforesaid parameters is analyzed from three dimensional surface plots. The wear mechanism is found to be predominantly abrasive in nature. © 2017 Published by Faculty of Engineering Corresponding author: P. Sahoo Department of Mechanical Engineering, Jadavpur University, Kolkata 700032, India. E-mail: psjume@gmail.com

/pdf/evaluation-of-tribological-properties-and-optimization-of-4nrva5f3p2.pdf

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

A dynamic analysis of a hemispherical and cylindrical contact, material properties of which are graded elastically and plastically along the radius, is presented. The static force–displacement beha...

Prasanta Sahoo

Papers

Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior:

Optimization Studies on Electroless Nickel Coatings: A Review

Influence of load and temperature on tribological behaviour of electroless Ni-P deposits

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

Dynamic analysis of elastically and plastically graded spherical and cylindrical contact