Lukáš Voleský

• Technical University of Liberec

In our research, the corrosion mechanism on the surface of anti-corrosion glass fibers of type AR and glass fibers of type E was studied. The monitoring was performed under the influence of an alkaline environment. The glass fibers were placed in a solution of calcium hydroxide Ca(OH)2 for a specified period of 2, 4, 6, 12, 24, 48 weeks. The change...

In this present research, a novel microwave hydrothermal method was applied to cotton fabrics to develop a superhydrophobic surface by rapid synthesis of aligned ZnO nanorods on the surface of the cotton fabric. A two-step approach was used to grow the ZnO nanorods. Firstly, the cotton fabric was coated by a seed layer of ZnO nanocrystals, synthesi...

In this work, geopolymer foam composites containing waste basalt fibre (10, 30, and 50%wt) were exposed to elevated temperatures of 200, 400, 600, 800 and 1000 ∘ C. With an increase in high temperature, the geopolymer foams material exhibits a decrease in compressive strength and bending strength. When heated above 600 ∘ C, geopolymer foams materia...

Geopolymer foam is classified as a lightweight material with high porous in its matrix which has great offer for applications requiring fire-resistant, thermal, and acoustic properties. However, the high sensitivity to humid environments can be a major barrier of geopolymer foam that limits the variety of applications of this material. Based on thi...

Basalt fiber is a novel type of inorganic fiber which is produced from the extrusion of natural vocalnic basalt rocks through their melting process at high temperature. So the quality and strength characteristics of basalt fiber depend mainly on both the quality of raw material and manufacturing processing. Basalt fabric-reinforced cementitious com...

This paper introduces a non-destructive method of analysis of the internal structure, occurrence and pore size in a specific volume of geopolymer composite material, with and without the addition of inorganic fibres in the form of meshes using computed tomography. A desktop micro-tomography device Skyscan 1272 was used for visualization and accurat...

The main aim of this experimental work is to find out possible improvement in thermal protective performance of firefighter protective clothing when subjected to different level of radiant heat flux density. Firefighter protective clothing normally consists of three layers: outer shell, moisture barrier and thermal liner. When thermal protective pe...

Reduced friction and wear of materials after the use of the carbon nanomaterials including nanodiamonds (NDs) have been confirmed by several studies in material engineering. Mechanical cleaning of the tooth surface by brush bristles should leave as little tissue roughened as possible. Higher surface roughness increases the tissue’s wear and encoura...

Geopolymers are modern, amorphous inorganic aluminosilicate polymers with specific composition and proper-ties. However, to use a geopolymer as an engineering material, its mechanical properties need to be improved. As part of this work, a composite material was obtained - the matrix is a geopolymer, and the reinforcement is basalt fibers. Research...

This research is engaged in monitoring changes in the tribological behaviour of CrCN thin films at room and elevated (300°C) temperatures. The monitored thin films are deposited by cathodic arc deposition of a pure Cr (99.99 %) cathode under an atmosphere of a mixture of CH4 and N2 gasses. Tribological measurements were performed at a load of 10N,...

Herein, the results of a study focused on graphene in activation and crosslinking reactions with hydrazine are reported. The method provides an approach to the preparation of graphene-based materials, in this case, with a pre-set distance between individual layer and a relatively low ratio between the Raman G and D bands - ID/IG, ca. 1.81 (for unmo...

This paper deals with experimental determination of toughness, hardness and impact properties of AISI H13 (DIN 1.2344) tool steel which was manufactured using Selective Laser Melting (SLM) technology. The H13 is a chromium-based tool steel which is primarily used for hot working applications such as pressure casting moulds for automotive industry....

Geopolymers are modern, amorphous inorganic aluminosilicate polymers with specific composition and properties. However, to use a geopolymer as an engineering material, its mechanical properties need to be improved. As part of this work, a composite material was obtained - the matrix is a geopolymer, and the reinforcement is basalt fibers. Research...

This research is engaged in monitoring changes in the tribological behaviour of CrCN thin films at room and elevated (300°C) temperatures. The monitored thin films are deposited by cathodic arc deposition of a pure Cr (99.99 %) cathode under an atmosphere of a mixture of CH4 and N2 gasses. Tribological measurements were performed at a load of 10N,...

Recently electrospinning has gained significant attention due to unique possibilities to produce novel natural nanofibers and fabrics with controllable pore structure. The present study focuses on the fabrication of electrospun fibres based on gum karaya (GK), a natural tree gum, with polyvinyl alcohol (PVA), and functionalization of the membrane w...

Polypyrrole-coated polyethylene terephthalate is very attractive for various applications as electrically conductive fiber. This paper investigates the importance of polyester pre-treatment on the quality of the polypyrrole coating and its conductivity efficiency. The results showed nucleophilic pre-treatments by Grignard reagents resulting in the...

Poly(ethylene terephthalate)—PET, is one of the most common polyesters, widely used in biomedical applications ranging from catheters to stents, vascular grafts, heart valves, sutures, and scaffolds. PET surface modification is necessary to impart desired properties for biomedical applications, making the polymer biocompatible, noncytotoxic and ant...

The Oliver–Pharr method has extensively been adopted for measuring hardness and Young’s modulus by indentation techniques. However, the method assumes that the contact periphery sinks in, which limits the applicability to the materials pile-up [1]. In this work, we characterize the pile-up (shape and height) in steel sheets with different mechanica...

EBSD is an analytical technique, which uses diffraction of backscattered electrons on the sample’s crystal lattice to determine the crystal structure and orientation. Point-by-point mapping of crystal orientation and misorientation, calculation of sub-grain boundaries angles and statistical processing of grain data allow identifying and displaying...

The results of investigating the plasma-immersion ion implantation of titanium into Zr–1Nb alloy from arc-discharge plasma are presented. The investigations are performed using 1.5-kV bias voltage applied to the sample by means of a coaxial plasma filter for 5, 15, and 30 min. Scanning electron and atomic-force microscopy data demonstrate that, aft...

Process fluids are important as they create the appropriate conditions for machine cutting by improving heat transfer, whereby extending the life of the cutting tool and increasing the surface quality of the product. The use of nanoadditives in the form of nanoparticles is highly efficient due to their high chemical and biological activity. Nanopar...

In order to study the effect of titanium ion implantation and deposition on hydrogenation behavior of Zr?1Nb alloy, the samples were subjected to plasma immersion implantation and deposition (PIII&D) of titanium ions at the bias voltage of 0.5?1.5 kV using a filtered metal vapor vacuum arc source. The crystalline structure, surface morphology and d...

This paper deals with finding the building parameters for manufacturing of fine structures with regard to their size precision and structural consistency. Practical use of these structures can be found in areas such as microelectronics, fine mechanics and automotive. Very fine structures with thickness lower than 0.3 mm are very hard to be manufact...

A series of titanium carbonitride (TiCN) films with differing C content were deposited by cathodic arc evaporation of pure Ti in a gas composite environment of N2 and C2H2. The increase of the C2H2 fraction in the gas environment leads to a continuous increase in the deposition rate of the TiCN thin films, as well as an increase in the adhesion of...

Titanium carbonitride (TiCN) thin films with differing C content were deposited by cathodic arc evaporation of pure Ti in a gas composite environment of N2 and C2H2. Scanning electron microscopy (SEM), scratch test, mechanical profilometer and “ball-on-disc” tribometer methods were used to characterize the surface, the coefficient of friction (CoF)...

The article describes the effect of the pressure in the chamber during the deposition of thin layers on the basic mechanical properties of thin layers based on carbon. Monitoring parameters are mainly nanohardness, coefficient of friction and adhesion between the layer and substrate. This parameters are observed using nanohardness tester and scratc...

This paper deals with establishing of building parameters for 1.2344 (H13) tool steel processed using Selective Laser Melting (SLM) technology with layer thickness of 50 µm. In the first part of the work, testing matrix of models in the form of a cube with chamfered edge were built under various building parameters such as laser scanning speed and...

Tribology deals with interaction of surfaces in relative motion depending on their design, friction, wear and lubrication. The proper use of process fluids or lubricants can bring a significant reduction in friction and the amount of wear, thereby leading to a reduction in power consumption. During different technological operations contamination o...

The occurrence of any cracks or defects in car body parts processed by deep drawing technology is not allowed by high quality standards. This kind of defect is considered as the most dangerous for the process quality and stability because it cannot be easily detected during the manufacturing in the steel plant and also in final inspection after pre...

Aluminium nitride films with a thickness of 2 μm are grown on high speed steel and Si (100) substrates by DC magnetron sputtering at 200°C in a gas mixture of argon and nitrogen, using a pure aluminium target. The influence of process parameters on the mechanical and tribological properties of deposited AlN films was studied. The surface topography...

In this study process fluids were tested after the addition of nanoparticles. Cooling and lubricating process fluids are used in machining to reduce wear on tools, to increase machine performance and to improve product quality. The use of process fluids leads to their pollution and contamination. Nanoparticles were added to the process fluids in or...

Nanosized TiO2t hin f ilms w ere d eposited b y c onventional v acuum thermal evaporation and triode-cathode sputtering of Ti on silicon and quartz substrates. To form TiO2a high temperature annealing of the Ti films was carried out in the range of 450÷800 ºC. The optical properties of TiO2were studied by measuring UV-VIS transmittance spectra and...

The Oliver–Pharr method has extensively been adopted for measuring hardness and elastic modulus by indentation techniques. However, the method assumes that the contact periphery sinks in, which limits the applicability to the materials pile-up [1]. This study proposes an improved methodology to calculate the real mechanical characteristics of indiv...

Productivity growth in the machining industry is associated with a reduction in the cost of cleaning and recycling contaminated process fluids. The proper use of process fluids or lubricants can bring a significant reduction in friction and the amount of wear, thereby leading to a reduction in power consumption. The use of nanolubricants in modern...

Radio frequency plasma enhanced chemical vapor deposition (RF PECVD) technique was applied for the purpose of deposition of iron doped titanium dioxide coatings from a gaseous mixture of oxygen with titanium (IV) chloride and iron (0) pentacarbonyl. Glass slides and silicon wafers were used as substrates. The coatings morphology was investigated us...

Iron doped titanium dioxide coatings were synthesized with the help of RF plasma enhanced CVD technique. As a source of titanium, titanium chloride (IV) TiCl4 was used while iron pentacarbonyl (0) Fe(CO)5 served as iron supply. The coatings were diagnosed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Their elemental an...

When using cooling and lubricating process fluids (PF), a contamination occurs, due to the technological process. These contaminations have a negative effect on decreasing the fluids lifespan and changes in their functional attributes. That can be strongly expressed not only by inappropriate actions of the fluid during the technological process, bu...

Tribology is an important method for evaluating the coefficient of friction and wear of friction pairs of technical materials. The most commonly used modes are "pin on disc", resp. "ball on disc". Tribology can simulate the stress of two objects (the friction between the objects) under the real conditions. The output of the tribological test is a s...

Using cutting fluids often enables an increase of cutting tool life. A large amount of cutting fluids produced in the European Union exists on the market of Czech Republic. It is quite difficult for purchasers of cutting fluids to acquire reliable test data about the performance of the fluids in industrial conditions and choose the best cutting flu...

Mechanical properties by depth sensing indentation are derived from the indentation load-displacement data used a micromechanical model developed by Oliver & Pharr (O&P). However, O&P analysis on the indentation unloading curve is developed from a purely elastic contact mechanics (sink-in). The applicability of O&P analysis is limited by the materi...

The search for new solutions to medical problems has led to a considerable development in the application of nanotechnologies to medicine. Silanization of substrates with hydroxyl (-OH), amino (-NH2) or carboxy (-COOH) functional groups on the surface of nanofibers is a process currently being used in the engineering of biocompatible nanomaterials...

Exceptional high-temperature oxidation resistance makes iron aluminides promising candidates to replace Ni-Cr-based stainless steels. On the other hand these alloys suffer from insufficient high-temperature strength. Addition of Zr leads to formation of hard intermetallic phases that increase the high-temperature strength. Correlative microscopy ha...