Influence of pulse frequency and bias on microstructure and mechanical properties of TiB2 coatings deposited by high power impulse magnetron sputtering

Nedfors, Nils; Mockuté, Aurelija; Pališaitis, Justinas; Persson, Per O. Å.; Näslund, Lars-Åke; Rosén, Johanna

doi:10.1016/j.surfcoat.2016.06.086

Cited by 71 publications

(34 citation statements)

References 32 publications

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“…A common issue in sputter-deposited group-IV TM diborides is that the films often contain excess B. 33,34 However, it is important to be able to control the B/TM ratio, and hence film properties, during deposition. The underlying mechanism leading to the incorporation of excess B in sputter-deposited TM diboride films is the difference in TM and B preferential-ejection angles resulting from mass-mismatch differences between the sputtering gas and the two target constituents.…”

Section: Introductionmentioning

confidence: 99%

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

Bakhit

Engberg

et al. 2019

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Refractory transition-metal (TM) diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, we demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 °C. ZrB2.4 layers are

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Section: Introductionmentioning

confidence: 99%

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

Bakhit

Engberg

et al. 2019

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

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“…Coatings deposited by 1f rotation presented uniform, featureless, and dense structures, while coatings deposited in a 3-fold rotation set-up showed a comparatively facetted growth with visible columns, as illustrated in Figure 2. This is related to the arrival rate of film-forming species as well as their energy during coating growth, where samples mounted in the 1f rotational set-up are exposed to more and higher energetic film forming species per time unit [39][40][41].…”

Section: Discussionmentioning

confidence: 99%

Towards Functional Silicon Nitride Coatings for Joint Replacements

et al. 2019

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Silicon nitride (SiNx) coatings are currently under investigation as bearing surfaces for joint implants, due to their low wear rate and the good biocompatibility of both coatings and their potential wear debris. The aim of this study was to move further towards functional SiNx coatings by evaluating coatings deposited onto CoCrMo surfaces with a CrN interlayer, using different bias voltages and substrate rotations. Reactive direct current magnetron sputtering was used to coat CoCrMo discs with a CrN interlayer, followed by a SiNx top layer, which was deposited by reactive high-power impulse magnetron sputtering. The interlayer was deposited using negative bias voltages ranging between 100 and 900 V, and 1-fold or 3-fold substrate rotation. Scanning electron microscopy showed a dependence of coating morphology on substrate rotation. The N/Si ratio ranged from 1.10 to 1.25, as evaluated by X-ray photoelectron spectroscopy. Vertical scanning interferometry revealed that the coated, unpolished samples had a low average surface roughness between 16 and 33 nm. Rockwell indentations showed improved coating adhesion when a low bias voltage of 100 V was used to deposit the CrN interlayer. Wear tests performed in a reciprocating manner against Si3N4 balls showed specific wear rates lower than, or similar to that of CoCrMo. The study suggests that low negative bias voltages may contribute to a better performance of SiNx coatings in terms of adhesion. The low wear rates found in the current study support further development of silicon nitride-based coatings towards clinical application.

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“…16 However, a common issue in sputter-deposited TiBx is that the films contain excess B with x ranging from 3.5 to 2.4. [16][17][18][19] While excess B can lead to the formation of interesting nanostructures with enhanced hardness, 17,20,21 it is important to be able to control the B/Ti ratio, and hence film properties, during deposition.…”

Section: Introductionmentioning

confidence: 99%

“…High-power impulse magnetron sputtering (HiPIMS) 24,25 has also been used to grow TiBx films. 17 In HiPIMS, relatively high power is applied to the target in short pulses in order to increase the plasma density and, thus, the ionization efficiency of sputter-ejected atoms. At constant average power, the HiPIMS pulse length and frequency are the primary parameters that influence the peak target current density which, in turn, determines the degree of plasma ionization.…”

Section: Introductionmentioning

confidence: 99%

Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering

Bakhit

Petrov

Greene

et al. 2018

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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TiBx thin films grown from compound TiB2 targets by magnetron sputter deposition are typically highly over-stoichiometric, with x ranging from 3.5 to 2.4, due to differences in Ti and B preferential-ejection angles and gas-phase scattering during transport from the target to the substrate. Here, the authors demonstrate that stoichiometric TiB2 films can be obtained using high-power impulse magnetron sputtering (HiPIMS) operated in power-controlled mode. The B/Ti ratio x of films sputter-deposited in Ar is controllably varied from 2.08 to 1.83 by adjusting the length of HiPIMS pulses ton between 100 and 30 µs, while maintaining average power and pulse frequency constant. This results in peak current densities JT,peak ranging from 0.27 to 0.88 A/cm 2. Energy-and time-resolved mass spectrometry analyses of ion fluxes incident at the substrate position show that the density of metal ions increases with decreasing ton due to a dramatic increase in JT,peak resulting in strong gas rarefaction. With ton < 60 µs (JT,peak > 0.4 A/cm 2), film growth is increasingly controlled by ions incident at the substrate, rather than neutrals, as a result of the higher plasma dencity and, hence, electronimpact ionization probablity. Thus, since sputter-ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the Ti concentration in as-deposited films increases with decreasing

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Influence of pulse frequency and bias on microstructure and mechanical properties of TiB2 coatings deposited by high power impulse magnetron sputtering

Abstract: Influence of pulse frequency and bias on microstructure and mechanical properties of TiB2 coatings deposited by high power impulse magnetron sputtering, Surface &

Cited by 71 publications

References 32 publications

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

Towards Functional Silicon Nitride Coatings for Joint Replacements

Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering

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