http://www.mdpi.com/journal/coatings Latest open access articles published in Coatings at http://www.mdpi.com/journal/coatings http://www.mdpi.com/2079-6412/2/2/64 Lead zirconate titanate (PZT) was plasma sprayed onto various substrates of different character. Additionally, a free-standing body made by plasma spraying was investigated. X-ray diffraction analyses of a decomposition of the as-sprayed coating products detected components of the PT-PZ system as well as binary oxides—PbO and ZrO2. Due to the comparatively complex phase character, the Curie temperature monitored by DTA, had a smeared appearance without pronounced maxima. The corresponding electrical properties are comparable with those typically observed for CaTiO3, but are worse than the normal values of bulk PZT due to defective stoichiometry. http://www.mdpi.com/2079-6412/2/2/64 Wed, 28 Mar 2012 00:00:00 CEST Coatings 2012-03-28 2 2 Article 64 75 2079-6412 Microstructure and Properties of Plasma Sprayed Lead Zirconate Titanate (PZT) Ceramics 2012-03-28 doi: 10.3390/coatings2020064 Pavel Ctibor Zdenek Pala Hanna Boldyryeva Josef Sedláček Viliam Kmetík http://www.mdpi.com/2079-6412/2/1/45 Polymer clay nanocomposites (NCs) show remarkable potential in the field of drug delivery due to their enhanced barrier properties. It is hypothesised that well dispersed clay particles within the polymer matrix create a tortuous pathway for diffusing therapeutic molecules, thereby resulting in more sustained release of the drug. As coatings for medical devices, these materials can simultaneously modulate drug release and improve the mechanical performance of an existing polymer system without introducing additional materials with new chemistries that can lead to regulatory concerns. In this study, polyurethane organosilicate nanocomposites (PUNCs) coated onto stainless steel wires were evaluated for their feasibility as blood compatible coatings and as drug delivery systems. Heparin was selected as the model drug to examine the impact of silicate loading and modifier chain length in modulating release. Findings revealed that better dispersion was achieved from samples with lower clay loadings and longer alkyl chains. The blood compatibility of PUNCs as assessed by thrombin generation assays showed that the addition of silicate particles did not significantly decrease the thrombin generation lag time (TGT, p = 0.659) or the peak thrombin (p = 0.999) of polyurethane (PU). PUNC coatings fabricated in this research were not cytotoxic as examined by the cell growth inhibition assay and were uniformly intact, but had slightly higher growth inhibition compared to PU possibly due to the presence of organic modifiers (OM). The addition of heparin into PUNCs prolonged the TGT, indicating that heparin was still active after the coating process. Cumulative heparin release profiles showed that the majority of heparin released was from loosely attached residues on the surface of coils. The addition of heparin further prolonged the TGT as compared to coatings without added heparin, but a slight decrease in heparin activity was observed in the NCs. This was thought to be from competitive interactions between clay-heparin that influenced the formation of the ternary complex between heparin, ATIII thrombin. In summary, the feasibility of using PUNC as drug delivery coatings was shown by the good uniformity in the coating, absence of by-products from the coating process, and the release of active molecules without significantly interfering with their activity. http://www.mdpi.com/2079-6412/2/1/45 Mon, 27 Feb 2012 00:00:00 CET Coatings 2012-02-27 2 1 Article 45 63 2079-6412 Polyurethane Organosilicate Nanocomposites as Blood Compatible Coatings 2012-02-27 doi: 10.3390/coatings2010045 Johnson H. Y. Chung Menno L. W. Knetsch Leo H. Koole Anne Simmons Laura A. Poole-Warren http://www.mdpi.com/2079-6412/2/1/8 A study has been made of permalloy (iron-nickel) contacts of reed switches before and after ion-induced surface modification using atomic force and optical microscopy, Auger electron and X-ray photoelectron spectroscopy. It has been found that the formation of surface nitride layers enhances corrosion and erosion resistance of contacts. We proposed to produce such layers directly into sealed reed switches by means of pulsing glow-discharge nitrogen plasma. http://www.mdpi.com/2079-6412/2/1/8 Fri, 24 Feb 2012 00:00:00 CET Coatings 2012-02-24 2 1 Article 8 44 2079-6412 Ion-Induced Surface Modification of Magnetically Operated Contacts 2012-02-24 doi: 10.3390/coatings2010008 Karen Arushanov Igor Zeltser Sergey Karabanov Rafail Maizels Evgeny Moos Alexander Tolstoguzov http://www.mdpi.com/2079-6412/2/1/1 Electroplated coatings for reed switches were developed and investigated. The optimal compositions of industrial electrolytes currently used in the mass production of reed switches were given. The pros and cons of the different electroplated coatings, including those containing precious metals and with barrier layers of base metal alloys, were discussed. http://www.mdpi.com/2079-6412/2/1/1 Fri, 23 Dec 2011 00:00:00 CET Coatings 2011-12-23 2 1 Article 1 7 2079-6412 Electroplated Coatings for Magnetically Operated Contacts (Reed Switches) 2011-12-23 doi: 10.3390/coatings2010001 Lyudmila Shishkina Olga Lokshtanova Sergey Karabanov http://www.mdpi.com/2079-6412/1/2/117 A fundamentally new family of thermal spray processes has emerged. These new processes, collectively known as very low pressure plasma spray or VLPPS, differ from traditional thermal spray processes in that coatings are deposited at unusually low chamber pressures, typically less than ~800 Pa (6 Torr). Depending upon the specific process, deposition may be in the form of very fine molten droplets, vapor phase deposition, or a mixture of vapor and droplet deposition. Resulting coatings are similar in quality to coatings produced by alternative coating technologies, such as physical vapor deposition (PVD) or chemical vapor deposition (CVD), but deposition rates can be roughly an order of magnitude higher with VLPPS. With these new process technologies modified low pressure plasma spray (LPPS) systems can now be used to produce dense, high quality coatings in the 1 to 100 micron thickness range with lamellar or columnar microstructures. A history of pioneering work in VLPPS technology is presented, deposition mechanisms are discussed, potential new applications are reviewed, and challenges for the future are outlined. http://www.mdpi.com/2079-6412/1/2/117 Tue, 20 Dec 2011 00:00:00 CET Coatings 2011-12-20 1 2 Review 117 132 2079-6412 Very Low Pressure Plasma Spray—A Review of an Emerging Technology in the Thermal Spray Community 2011-12-20 doi: 10.3390/coatings1020117 Mark F. Smith Aaron C. Hall James D. Fleetwood Philip Meyer http://www.mdpi.com/2079-6412/1/2/108 Porous light-absorbing and thermoregulating low-vacuum aluminum coatings (AC) precipitated by thermal evaporation were the object of this study. The small-angle X-ray scattering (SAXS), electron microscopy, precision hydrostatic weighing, and the dynamical technique for argon low-temperature desorption were used for our investigations. It was shown that AC pore formation in open space (OS) is conditioned by the reduction of molecular flow orienting impact and the increase of the diffusing-vacancy mechanism on coatings formation in zero-gravity conditions, which causes the formation of coarse and equiaxed pores with lowered polydispersity levels. http://www.mdpi.com/2079-6412/1/2/108 Tue, 13 Dec 2011 00:00:00 CET Coatings 2011-12-13 1 2 Communication 108 116 2079-6412 The Influence of Space Environment on Substructure of Light-Absorbing Thermoregulating Al Coatings 2011-12-13 doi: 10.3390/coatings1020108 Leonid Skatkov Petr Cheremskoy Valeriy Gomozov Boris Bayrachny Gennadiy Tulskiy Svetana Deribo http://www.mdpi.com/2079-6412/1/2/88 Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN) coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN) based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN) to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma) by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm) AlN coating with high hardness (approximately 1000 Hv). The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma spraying. Moreover, the fabricated coatings consist of hexagonal (h-AlN), c-AlN (rock-salt and zinc-blend phases) and certain oxides: aluminum oxynitride (Al5O6N), cubic sphalerite Al23O27N5 (ALON) and Al2O3. The zinc-blend c-AlN and ALON phases were attributed to the transformation of the h-AlN feedstock during the reactive plasma spraying. Thus, the zinc-blend c-AlN and ALON phases were not included in the feedstock and were not formed through nitriding of the Al. http://www.mdpi.com/2079-6412/1/2/88 Mon, 03 Oct 2011 00:00:00 CEST Coatings 2011-10-03 1 2 Abstract 88 107 2079-6412 In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder 2011-10-03 doi: 10.3390/coatings1020088 Mohammed Shahien Motohiro Yamada Toshiaki Yasui Masahiro Fukumoto http://www.mdpi.com/2079-6412/1/1/72 Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS) substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 mm. To evaluate the biocompatibility of the coatings three different in vitro tests, using human alveolar bone derived cells, were performed: cellular adhesion, proliferation and viability. Stainless steel substrates and tissue culture plastic were also studied, in order to give comparative information. No toxic response was observed for any of the surfaces, indicating that the Nb coatings act as a biocompatible, bioinert material. Cell morphology was also studied by immune-fluorescence and the results confirmed the healthy state of the cells on the Nb surface. X-ray diffraction analysis of the coating shows that the film is polycrystalline with a body centered cubic structure. The surface composition and corrosion resistance of both the substrate and the Nb coating were also studied by X-ray photoelectron spectroscopy and potentiodynamic tests. Water contact angle measurements showed that the Nb surface is more hydrophobic than the SS substrate. http://www.mdpi.com/2079-6412/1/1/72 Thu, 22 Sep 2011 00:00:00 CEST Coatings 2011-09-22 1 1 Article 72 87 2079-6412 Biocompatibility of Niobium Coatings 2011-09-22 doi: 10.3390/coatings1010072 René Olivares-Navarrete Jhon Jairo Olaya Claudia Ramírez Sandra Elizabeth Rodil http://www.mdpi.com/2079-6412/1/1/53 Hydroxyapatite (HA) coating of hard tissue implants is widely employed for its biocompatible and osteoconductive properties as well as its improved mechanical properties. Plasma technology is the principal deposition process for coating HA on bioactive metals for this application. However, thermal decomposition of HA can occur during the plasma deposition process, resulting in coating variability in terms of purity, uniformity and crystallinity, which can lead to implant failure caused by aseptic loosening. In this study, CoBlastTM, a novel blasting process has been used to successfully modify a titanium (V) substrate with a HA treatment using a dopant/abrasive regime. The impact of a series of apatitic abrasives under the trade name MCD, was investigated to determine the effect of abrasive particle size on the surface properties of both microblast (abrasive only) and CoBlast (HA/abrasive) treatments. The resultant HA treated substrates were compared to substrates treated with abrasive only (microblasted) and an untreated Ti. The HA powder, apatitic abrasives and the treated substrates were characterized for chemical composition, coating coverage, crystallinity and topography including surface roughness. The results show that the surface roughness of the HA blasted modification was affected by the particle size of the apatitic abrasives used. The CoBlast process did not alter the chemistry of the crystalline HA during deposition. Cell proliferation on the HA surface was also assessed, which demonstrated enhanced osteo-viability compared to the microblast and blank Ti. This study demonstrates the ability of the CoBlast process to deposit HA coatings with a range of surface properties onto Ti substrates. The ability of the CoBlast technology to offer diversity in modifying surface topography offers exciting new prospects in tailoring the properties of medical devices for applications ranging from dental to orthopedic settings. http://www.mdpi.com/2079-6412/1/1/53 Tue, 13 Sep 2011 00:00:00 CEST Coatings 2011-09-13 1 1 Article 53 71 2079-6412 A Modified Surface on Titanium Deposited by a Blasting Process 2011-09-13 doi: 10.3390/coatings1010053 Caroline O’Sullivan Peter O’Hare Greg Byrne Liam O’Neill Katie B. Ryan Abina M. Crean http://www.mdpi.com/2079-6412/1/1/17 In this work High Velocity Oxy-fuel (HVOF) thermal spray techniques, spraying process optimization, and characterization of coatings are reviewed. Different variants of the technology are described and the main differences in spray conditions in terms of particle kinetics and thermal energy are rationalized. Methods and tools for controlling the spray process are presented as well as their use in optimizing the coating process. It will be shown how the differences from the starting powder to the final coating formation affect the coating microstructure and performance. Typical properties of HVOF sprayed coatings and coating performance is described. Also development of testing methods used for the evaluation of coating properties and current status of standardization is presented. Short discussion of typical applications is done. http://www.mdpi.com/2079-6412/1/1/17 Fri, 02 Sep 2011 00:00:00 CEST Coatings 2011-09-02 1 1 Article 17 52 2079-6412 Optimization and Characterization of High Velocity Oxy-fuel Sprayed Coatings: Techniques, Materials, and Applications 2011-09-02 doi: 10.3390/coatings1010017 Maria Oksa Erja Turunen Tomi Suhonen Tommi Varis Simo-Pekka Hannula http://www.mdpi.com/2079-6412/1/1/3 CoNiCrAlY powders with similar granulometry and chemical composition, but different starting reactivity toward oxygen, were sprayed onto superalloy substrates by High Velocity Oxygen-Fuel producing coatings of similar thicknesses. After spraying, samples were maintained at 1,273 K in air for different test periods of up to 5,000 hours. Morphological, microstructural, compositional and electrochemical analyses were performed on the coated samples in order to assess the high temperature oxidation resistance provided by the two different powders. The powder with higher starting reactivity towards oxygen improves the oxidation resistance of the coated samples by producing thinner and more adherent thermally grown oxide layers. http://www.mdpi.com/2079-6412/1/1/3 Fri, 26 Nov 2010 00:00:00 CET Coatings 2010-11-26 1 1 Article 3 16 2079-6412 Improvement of the Oxidation Resistance of CoNiCrAlY Bond Coats Sprayed by High Velocity Oxygen-Fuel onto Nickel Superalloy Substrate 2010-11-26 doi: 10.3390/coatings1010003 Alessio Fossati Martina Di Ferdinando Alessandro Lavacchi Andrea Scrivani Carlo Giolli Ugo Bardi http://www.mdpi.com/2079-6412/1/1/1 The journal Coatings is starting its activity as a peer-reviewed, open access journal. As editors, we believe that it will fulfill an important role in the community of researchers and developers in the field of coatings. There already exists several high quality journals dedicated to coatings, but none of them has “free access”, a characteristic that we believe is very important in a field which is traditionally very close  to  industrial  activity  and  where  researchers  aim  not  only  at  academic  research  but  toward products  of  an  industrial  and  marketable  value.  For  these  researchers,  it  is  important  that  they  can publish their results in a journal that guarantees quality that comes from peer-review, but that at the same time breaks the traditional boundaries of academic journals which need a subscription or a pay-per-view option to access the published data. [...] http://www.mdpi.com/2079-6412/1/1/1 Wed, 22 Sep 2010 00:00:00 CEST Coatings 2010-09-22 1 1 Editorial 1 2 2079-6412 Welcome to Coatings: a New Open Access Journal 2010-09-22 doi: 10.3390/coatings1010001 Ugo Bardi Alessandro Lavacchi