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Lin J.,Southwest Research Institute | Sproul W.D.,Reactive Sputtering Inc. | Wei R.,Southwest Research Institute | Chistyakov R.,Zpulser LLC
Surface and Coatings Technology | Year: 2014

Diamond like carbon films were deposited by sputtering a graphite target using deep oscillation magnetron sputtering (DOMS). DOMS is an alternative high power impulse magnetron sputtering technique that uses large voltage oscillation packets to achieve high power pulses for sputtering. The deposition variables include negative substrate bias voltage, working pressure and peak target current density (J). In this study, the deposition rate was varied from 23nm·min-1 to 70nm·min-1 by changing the above variables. The peak substrate current density during high power pulses was measured up to 50mA·cm-2. The microstructure of the films was characterized using scanning electron microscopy and Raman spectroscopy. Higher J, lower working pressure, and properly controlled bias voltage promoted sp3 bond formation and increased the density of the films. Super dense DLC films were obtained by increasing J above 0.75A·cm-2 at 0.13Pa with a substrate bias voltage of -60V. The surface of the films became smoother as the J was increased. The adhesion and mechanical and tribological properties of the films were measured using HRC tests, nanoindentation and ball on disk wear tests. The films exhibited excellent adhesion on stainless steel. The films exhibited the maximum hardness value of 35GPa, the lowest dry sliding COF of 0.09 and the lowest wear rate of 1.5×10-8mm3N-1m-1. © 2014. Source


Lin J.,Colorado School of Mines | Sproul W.D.,Colorado School of Mines | Sproul W.D.,Goya Inc | Moore J.J.,Colorado School of Mines | And 2 more authors.
Surface and Coatings Technology | Year: 2011

The paper presents the results on the deposition of nanoscale structurally laminated CrN films using a novel multi pulse modulated pulsed power (MPP) magnetron sputtering technique. With the multi pulse MPP approach, thin films with a structural modulation in the nanometer range are obtained by alternately switching two (or even more) high power MPP pulses on the same target, which have different pulse lengths, frequencies and powers. Each pulse was turned on for a pulse repeat duration during which this given pulse shape was repeated. In this study, CrN films have been deposited in a closed field unbalanced magnetron sputtering system using the multi pulse MPP technique by varying the pulse repeat duration of two different pulses. The CrN films were also deposited by dc magnetron sputtering (dcMS) and single pulse MPP techniques for comparison. The microstructure and properties of the films were characterized using glancing incident X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nanoindentation, and ball-on-disk wear tests. The structure and properties of the multi pulse MPP CrN films depended on the pulse repeat duration. The highest hardness of 30.5. GPa and an H/E ratio of 0.9 have been achieved in the multi pulse MPP CrN films. The wear rate of the single pulse MPP and multi pulse MPP CrN films decreased by a factor of 5.8-17 as compared to the dcMS CrN films. © 2011. Source


Lin J.,Colorado School of Mines | Sproul W.D.,Colorado School of Mines | Sproul W.D.,Reactive Sputtering Inc. | Moore J.J.,Colorado School of Mines | And 5 more authors.
JOM | Year: 2011

Over the past 10 years, the development of high-power pulsed magnetron sputtering (HPPMS) has shown considerable potential in improving the quality of sputtered films by generating a high degree of ionization of the sputtered species to achieve high plasma density by using pulsed, high peak target power for a short period of time. However, the early HPPMS technique showed a significantly decreased deposition rate as compared to traditional magnetron sputtering. Recently, an alternative HPPMS deposition technique known as modulated pulsed power (MPP) magnetron sputtering has been developed. This new sputtering technique is capable of producing a high ionization fraction of sputter target species and while at the same time achieving a high deposition rate. This paper is aimed at giving a review of recent advances in the MPP technique in terms of the plasma properties, the improvements in the structure and properties of the thin films, and the important advances in the high rate deposition of high quality thick coatings on the order of 20-100 μm in thickness. Source


Liebig B.,University of Liverpool | Braithwaite N.S.J.,Open University Milton Keynes | Kelly P.J.,Manchester Metropolitan University | Chistyakov R.,Zpulser LLC | And 2 more authors.
Surface and Coatings Technology | Year: 2011

Time-resolved Langmuir probe measurements have been employed to investigate the temporal development of the plasma properties, such as electron and ion density, electron temperature as well as the floating and plasma potential, during Modulated Pulsed Power Magnetron Sputtering (MPPMS). A chromium target was sputtered with an average power of 650W in an argon atmosphere (0.53Pa) employing two steps of excitation of the discharge which was realised by altering the modulation frequency of the voltage supplied to the target. The overall pulse duration was kept at 750μs and a repetition frequency of 100Hz was used. Three distinct stages of the discharge, namely the initial and the second step of excitation as well as the transition region which connects both stable states, were found. Maximum electron densities up to 7×1011cm-3 were obtained during the transient phase. © 2011. Source

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