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

Magnetron sputtering: a review of recent developments and applications

The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulse ...

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High power impulse magnetron sputtering discharge

A Review on Biomedical Titanium Alloys: Recent Progress and Prospect

Diamond-like carbon (DLC) films combine several excellent properties like high hardness, low friction coefficients and chemical inertness. The DLC coating material can be further classified in two main groups, the hydrogenated amorphous carbon (a-C:H, ta-C:H) and the hydrogen free amorphous carbon (a-C, ta-C). By adding other elements like metals (a-C:H:Me) or non-metal elements like silicon, oxygen, fluorine or others (a-C:H:X), several modifications of the properties can be adjusted according to application requirements. First reports on hard amorphous carbon films were published in the 1950s and about 20 years later there began worldwide intensive research activities on DLC. In the following years the number of publications increased continuously and the importance for industrial applications became more and more evident. Several deposition techniques were applied to prepare a-C:H, ta-C, metal containing a-C:H:Me and non-metal containing a-C:H:X coatings. In parallel the structure and deposition mechanisms of DLC coatings were extensively studied. An essential obstacle for a broad industrial application was the high compressive stress level in a-C:H films causing delamination and limiting the film thicknesses. With metal based intermediate layer systems most adhesion problems could be solved satisfactorily and thus from the mid-1990s the pre-conditions for a broad application especially in the automotive industry were given. With modified a-C:H:X and a-C:X coatings a considerable friction reduction or surface energy adjustments could be achieved.

History of diamond-like carbon films — From first experiments to worldwide applications

Amorphous hydrogenerated carbon films containing a small amount of metal (Me:C-H) have been deposited by closed field unbalanced magnetron sputter ion plating. The films have graded film compositions to optimise the adhesion to the substrates, and multilayer TiC/Ti:C-H films have also been deposited. The films have excellent properties: very high measured microhardness (more than 4000 H v ), excellent adhesion ( L c 115–125 N), coefficients of friction against WC of less than 0.2, and volumetric wear rates one fifth that of titanium nitride. The coating procedure is ideally suited to the system used, and many applications for the films are already realised.

Deposition of wear resistant coatings based on diamond like carbon by unbalanced magnetron sputtering

Wear and corrosion behaviour of various surface treated medical grade titanium alloy in bio-simulated environment

The development of a deposition system based on closed field unbalanced magnetron sputter ion plating (uniform deposition and plasma), has greatly increased the number of complex nitrides that it is possible to routinely deposit. The new alloy nitrides can increase the hardness of standard TiN by a factor of 2, and can consequently result in longer tool life. In order to maintain high levels of coating to substrate adhesion, it is necessary to gradually grade the composition of the film in the interface region. Grading of an alloy nitride such as TiZrN will ensure minimum Lc scratch adhesion levels of 75 N. The technique can be closely controlled and is very flexible, enabling the changes in composition to be attained with precision.

Deposition of graded alloy nitride films by closed field unbalanced magnetron sputtering

Aluminum alloys are becoming increasingly important, especially in the automotive and aerospace industries. However, these materials tend to have poor wear resistance at atmospheric and high temperature conditions. Aluminum oxide layers are potentially very effective in developing hard, wear-resistant surfaces. The aim of present study was to evaluate the high temperature wear behavior of aluminum oxide layers at different temperatures by using high temperature pin-on-disc tribo tester and alumina balls as counterfaces. The aluminum oxide layers were produced by AC micro arc oxidation (MAO). The structural analyses of the layers were performed using XRD and SEM techniques. The hardness was measured using microhardness tester. The wear rates and friction coefficient was decreased with increasing wear test temperature. The lowest wear rate and friction coefficient, narrow and smooth wear tracks are obtained at 200 °C.

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Ihsan Efeoglu

Papers

Deposition of wear resistant coatings based on diamond like carbon by unbalanced magnetron sputtering

Wear and corrosion behaviour of various surface treated medical grade titanium alloy in bio-simulated environment

Deposition of graded alloy nitride films by closed field unbalanced magnetron sputtering

High temperature wear behavior of aluminum oxide layers produced by AC micro arc oxidation

The effect of deposition parameters and Ti content on structural and wear properties of MoS2Ti coatings