HVM Plasma Ltd.

Prague, Czech Republic

HVM Plasma Ltd.

Prague, Czech Republic
SEARCH FILTERS
Time filter
Source Type

Prachar P.,Fm Mu And St Annes University Hospital Brno | Bartakova S.,Fm Mu And St Annes University Hospital Brno | Brezina V.,Fm Mu And St Annes University Hospital Brno | Cvrcek L.,HVM Plasma Ltd. | Vanek J.,Fm Mu And St Annes University Hospital Brno
Bratislava Medical Journal | Year: 2015

Introduction: The positive cell response to the implant material is reflected by the capacity of cells to divide, which leads to the tissue regeneration and osseointegration. Technically pure titanium and its alloys are mostly used for implant manufacturing. These alloys have the adequate mechanical, physical and biological properties; nevertheless, the superior biocompatibility of bioceramics has been proven. With the arrival of new coating techniques, surface modification of materials used for implants has become a widely investigated issue. Methods: The paper studied properties of titanium nitride (TiN) and zirconium nitride (ZrN) coatings deposited by PVD (Physical Vapour Deposition). Coatings were applied to substrates of pure titanium, Ti6Al4V, Ti35Nb6Ta titanium alloys and CoCrMo dental alloy. Different treatments of substrate surfaces were used: polishing, etching and grit blasting. Cytocompatibility tests assessed the cell colonization and their adherence to substrates. Results and conclusion: Results showed that TiN layers deposited by PVD are suitable for coating all substrates studied. The polished samples and those with TiN coating exhibited a higher cell colonization. This coating technique meets the requirements for the biocompatibility of the implanted materials; furthermore, their colour range solves the issue of red aesthetics in oral implantology as the colour of these coatings prevents titanium from showing through the gingiva. This is one the most important criteria for the aesthetic success of implant therapy (Tab. 5, Ref. 18). Text in PDF www.elis.sk.


Polasek J.,Charles University | Masek K.,Charles University | Marek A.,HVM Plasma Ltd. | Vyskocil J.,HVM Plasma Ltd.
Thin Solid Films | Year: 2015

In this work, we investigated the possibilities of tungsten and tungsten oxide nanoclusters generation by means of non-reactive and reactive magnetron sputtering with gas aggregation. It was found that in pure argon atmosphere, cluster aggregation proceeded in two regimes depending on argon pressure in the aggregation chamber. At the lower pressure, cluster generation was dominated by two-body collisions yielding larger clusters (about 5.5nm in diameter) at lower rate. At higher pressures, cluster generation was dominated by three-body collisions yielding smaller clusters (3-4nm in diameter) at higher rate. The small amount of oxygen admixture in the aggregation chamber had considerable influence on cluster aggregation process. At certain critical pressure, the presence of oxygen led to the raise of deposition rate and cluster size. Resulting clusters were composed mostly of tungsten trioxide. The oxygen pressure higher than critical led to the target poisoning and the decrease in the sputtering rate. Critical oxygen pressure decreased with increasing argon pressure, suggesting that cluster aggregation process was influenced by atomic oxygen species (namely, O- ion) generated by oxygen-argon collisions in the magnetron plasma. © 2015 Elsevier B.V.


Silvennoinen R.,University of Eastern Finland | Hason S.,Academy of Sciences of the Czech Republic | Vetterl V.,Academy of Sciences of the Czech Republic | Penttinen N.,University of Eastern Finland | And 6 more authors.
Applied Optics | Year: 2010

Adsorption of the elongated human plasma fibrinogen (HPF) and globular human serum albumin molecules on a titanium-based surface is monitored by analyzing permittivity and optical roughness of protein-modified surfaces by using a diffractive optical element (DOE)-based sensor and variable angle spectro-ellipsometry (VASE). Both DOE and VASE confirmed that fibrinogen forms a thicker and more packed surface adlayer compared to a more porous and weakly adsorbed albumin adlayer. A linear relation of the permittivity (ε′)and dielectric loss (ε″)was found for some of the dry titanium-doped hydrocarbon (TDHC) surfaces with excellent HPFadsorption ability.We discuss some aspects of TDHC's aging and its possible effects on fibrinogen adsorption. © 2010 Optical Society of America.


Silvennoinen R.,University of Eastern Finland | Vetterl V.,Academy of Sciences of the Czech Republic | Hason S.,Academy of Sciences of the Czech Republic | Silvennoinen M.,University of Eastern Finland | And 3 more authors.
Advances in Optical Technologies | Year: 2010

The adsorption/desorption of Human Plasma fibrinogen (HPF) molecules on biosurfaces was measured in spectroscopic cuvette by a diffractive optical element- (DOE-) based sensor. To characterize the surfaces, the basic parameters as surface tension was obtained by sensing of a contact angle of water droplet and dielectric constant was measured by ellipsometry in the absence of HPF molecules. It was observed a significant correlation between the adsorption ability of HPF molecules (sensed by DOE on the basis of the changes in optical roughness (R opt) of studied surface in the absence and presence of HPF molecules), and dielectric constant (measured by ellipsometry) of differently treated titanium surfaces, where the permittivity and dielectric loss have the known linear relation. These findings with carbon-treated biomaterial surfaces can help us to understand mechanisms behind attachment of HPF molecules on biomaterial surfaces to realize and extend variety of implants for hard tissue replacement. Copyright © 2010 Raimo Silvennoinen et al.


Polcar T.,Czech Technical University | Vitu T.,Czech Technical University | Cvrcek L.,Czech Technical University | Cvrcek L.,HVM Plasma Ltd. | And 2 more authors.
Tribology International | Year: 2010

Chromium nitride-based coatings are often used in application at high temperature. They possess high wear and oxidation resistance; however, the friction coefficient is typically very high. Therefore, we doped CrN coatings by carbon with the aim to improve tribological properties at elevated temperature, particularly to lower the friction. CrCN coatings were prepared by cathode arc evaporation technology using constant N2 flow and variable C2H2 flow. The coatings with a thickness of 3-4 μm were deposited on hardened steel substrates and high-temperature resistant alloy. The carbon content varied from 0 at.% (i.e. CrN) up to 31 at.%. The standard coating characterization included the nano-hardness, adhesion, chemical composition and structure (including hot X-ray diffraction). Wear testing was done using a high temperature tribometer (pin-on-disc); the maximum testing temperature was 700 °C. The coatings with carbon content 12-31 at.% showed almost identical tribological behaviour up to 700 °C. © 2009 Elsevier Ltd. All rights reserved.


Penttinen N.,University of Eastern Finland | Hason S.,Academy of Sciences of the Czech Republic | Joska L.,Institute of Chemical Technology Prague | Cvrcek L.,HVM Plasma Ltd. | Silvennoinen R.,University of Eastern Finland
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Chemical components and initial optical responses of Ti 35Nb 6Ta alloy are reported. Polished titanium and other titanium alloy Ti 6Al 4V served as reference surfaces. The chemical composition was determined with an X-ray photoelectron spectroscope (XPS) for the surfaces as well as for water, phosphate buffered saline (PBS) and for human plasma fibrinogen (HPF in PBS) exposed surfaces. The reflectance of the surfaces was modeled utilizing Bruggeman's model, to evaluate the optical changes that the chemical reaction of each liquid can produce. After the model, a diffractive optical element (DOE) based sensor was used to determine the temporal optical signal from the sample surfaces. The coherent and non-coherent signals gathered with DOE sensor were compared to the reflectance model. Exposing to the liquids showed surface oxidation, which could produce lowered reflectance of the surface. The model and the initial temporal responses showed similarities in non-coherent reflectance. © 2011 SPIE.


Fort T.,Academy of Sciences of the Czech Republic | Vitu T.,Czech Technical University | Novak R.,Czech Technical University | Grossman J.,Academy of Sciences of the Czech Republic | And 2 more authors.
Chemicke Listy | Year: 2011

W-C: H hard composite coatings were studied. The comparison of the wear rate of the coating/substrate system and the bare substrate obtained from dynamic impact test clearly demonstrated that the coating significantly extended the lifetime of the samples even for high loads and high number of loading cycles. The obtained results will support the research and development of new metal-doped a-C:H coatings, which exhibit promising properties for future engineering applications, especially in dynamically loaded contacts.


Sobota J.,Academy of Sciences of the Czech Republic | Grossman J.,Academy of Sciences of the Czech Republic | Vyskocil J.,HVM Plasma Ltd | Novak R.,Czech Technical University | And 3 more authors.
Chemicke Listy | Year: 2010

We evaluated the influence of humidity on tribological behaviour, impact resistance and tribological behaviour at elevated temperatures of carbon-based hard composite coatings deposited by PACVD with an interface metallic layer prepared by unbalanced magnetron sputtering. Impact tests were carried out at a relative humidity of 2.5% and 95% at an impact force of 600 N. Comparing measured values of crater volumes we can see, that the relative humidity substantially influences dynamic resistance of the coating - substrate system, in particular in the region of mechanical erosion of the coating. It is well known for years, that humidity can significantly influence the tribological behaviour of carbon-based coatings. However, unexpectedly, humidity also influences the impact resistance of this type of films. By increasing the relative humidity, the value of dynamic impact resistance significantly increases. Simultaneously the wear rate of the coated part increases by many orders of magnitude. By optimising components coated by carbon-based coatings exposed to dynamical load, we must take into account not only temperature and, roughness of surfaces, but also the influence of the relative humidity at which the coating - substrate system runs.


Franta L.,Czech Technical University | Fojt J.,Institute of Chemical Technology Prague | Joska L.,Institute of Chemical Technology Prague | Kronek J.,Czech Technical University | And 4 more authors.
Tribology International | Year: 2013

The primary goal was to compare model replacements with and without DLC layer. Components were made of the Ti6Al4V alloy and coated with a DLC layer, the sliding sleeve made of a PEEK polymer. Testing was done in the saline physiological solution (9 g/L NaCl). The measuring system was supplemented with the corrosion behavior monitoring. The results show that the applied DLC coating significantly increases the service life of the implant. Based on the results it is possible to state that an accurate mechanical load together with corrosion behavior monitoring shifts testing in the given field to a qualitatively higher level. © 2012 Elsevier Ltd. All rights reserved.


Feng F.,Texas A&M University | Zhou Y.,Texas A&M University | Yun H.,Texas A&M University | Rocha A.,Texas A&M University | And 4 more authors.
Journal of the American Ceramic Society | Year: 2012

A coating of Ti-C:H was investigated for potential applications as artificial joint materials. Herein, we conducted experimental study using fluid shear method and tribolgoical study to evaluate and analyze the adhesive strength of proteins on Ti-C:H coatings and Ti6Al4V. Sample surfaces were worn against a steel bearing (E52100) under the lubrication of egg white protein solution. The following wear track and debris analysis helped further understand their wear mechanism. Research results showed that Ti-C:H coatings on silicon substrate had a porous topography that enhanced its adhesion with the protein. The friction coefficient and wear rate for Ti-C:H was much lower than Ti6Al4V. This can be attributed to the chemical inertness and functional diamond-like features of Ti-C:H coatings enhancement in wear resistance, making it superior to Ti6Al4V. © 2011 The American Ceramic Society.

Loading HVM Plasma Ltd. collaborators
Loading HVM Plasma Ltd. collaborators