Marek Kostecki

Influence of Milling Media on Mechanically Exfoliated MoS2

Wet ball milling was used to exfoliate MoS2. The aim of the study was to examine how the surface energy of all the individual materials affected the formation of the nanosheets. Two types of milling balls were selected: one made of steel and one made of Al2O3. The liquids used were water (H2O), isopropyl alcohol (C3H8O) and kerosene. The obtained nanosheets were identified and characterized using transmission/scanning electron microscopy and electron diffraction. Following sedimentation, scattered light intensity was measured. Our experiments showed that the material of the milling balls played a significant role in the experiment and had an influence on the number of the nanosheets obtained. Irrespective of the liquid employed, the number of nanosheets in the suspension obtained by milling with Al2O3 balls was greater by 100% than those obtained via milling with steel balls.

Liquid exfoliation — new low-temperature method of nanotechnology

Two-dimensional nano-crystals, nanosheets, are a new special type of nanomaterials recently discovered. They have attracted interest due to their unique potential applications especially in electronics. In this mini review, we present the current status of liquid exfoliation of layered crystals — an original new method of production of nanosheets. This “top down” synthesis is a low-temperature physico-chemical process already used to graphene production.

Tribological Properties of Aluminium Alloy Composites Reinforced with Multi-Layer Graphene—The Influence of Spark Plasma Texturing Process

Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological properties, particularly in the higher load regime.

Zirconium – Based Ceramic Targets for Producing Nanocrystalline Coatings Resistant to Heat and Thermal Creep

Technology of thermal ceramic barriers (TBC) has been chiefly designed for materials with a single thermal barrier of the 7YSZ type. A high content of Y2O3 ensures a good phase stability of the YSZ material. In search for other alternative materials suitable for TBC, the material most often examined is modified zirconium oxide. The modification consists of stabilizing the ZrO2 powder with Y2O3 and doping it with La, Gd and Nd. This paper presents the results of studies on producing cathodic zirconium oxide-based ceramic targets intended for depositing refractory heat-resistant nano-crystalline TBC coatings. The targets are characterized by a high density (close to its theoretical value) and have a homogeneous phase and chemical structure.

Thermal Properties of Zirconium Oxide-Based Ceramic Targets Modified with Oxides of Rare Earth Elements

The paper is concerned with the thermal properties of cathodic ceramic targets built on the basis of zirconium oxide modified with rare earth metal oxides such as La2O3, Nd2O3, and Gd2O3. The experiments also included the production of the TZ-3Y, TZ-3Y+20mol% coatings (La2O3, Gd2O3) using the EB-PVD method, and characterization of these coatings. Within the temperature range examined (20 to 120oC), the targets that contained rare earth metal oxides appeared to have lower thermal conductivity λ (2.07-1.22 Wm-1K-1) than the TZ-3Y target (3.6-3.05 Wm-1K-1). The present study was a continuation of our earlier experiments devoted to the examinations of zirconium oxide ceramic targets intended for producing refractory, heat-resistant nanocrystalline coatings.

Closed Die Upsetting of Aluminum Matrix Composites Reinforced with Molybdenum Disulfide Nanocrystals and Multilayer Graphene, Implemented using the SPS Process—Microstructure Evolution

New methods for producing composite materials such as SPS (Spark Plasma Sintering) are becoming more and more popular due to the ease of implementation in industrial conditions and the versatility of the materials used for processing. In order to fully exploit the potential of this method, modifications were proposed which consisted in the deliberate induction of deformation during the sintering process. The influence of the manufacturing method on the microstructure of aluminum alloy matrix composites reinforced with layered crystals in the form of nanoflakes was investigated. Composites with the addition of 10 vol % of multilayer graphene and molybdenum disulfide were prepared and their density, hardness, and the influence of the deformation ratio on the changes occurring in the microstructure were examined. The potential of the method to shape the properties of the tested composites and the strong dependence of the obtained results on the morphology of the reinforcing phase was indicated. An interesting phenomenon observed for composites with the addition of MoS2 during the process was the reaction of the components leading to in situ formation of the Al12Mo intermetallic phase.

Measurements of Strain in Ceramic Components Using Magnetostrictive Delay Line

Paper presents a novel application of magnetostrictive delay lines, which give a possibility of real time monitoring of strain in ceramic components. Magnetostrictive delay line was based on highly magnetostrictive Fe-Si-B amorphous alloy ribbon, mounted outside of ceramic component, what is a new solution for increasing sensor’s sensitivity. Developed specially for this sensor, hybrid digital-analog signal processing unit covers the sample-and-hold integrated circuit. The achived sensitivity and repeatability of the sensor confirms, that such solution is suitable for ceramic machine tool monitoring.