Martin Fides

Surface analysis of polymeric substrates used for inkjet printing technology

Purpose – This paper aims to find an optimal surface treatment of commonly used polymeric substrates for achieve the high adhesion of printed structures. For this reason, the investigation of substrates surfaces from different perspectives is presented in this paper. Design/methodology/approach – The contact angle measurements as well as the roughness measurements were realised for the analysis of surface properties of investigated substrates. The impact of applied chemical agents for surface treatment onto the wettability is analysed for polyimide, polyethylene terephthalate and polyethylene naphthalene substrates. Findings – The results prove the correlation among wettability, surface energy and work of adhesion with respect to the theoretical background. The surface treatment of polymeric substrates by chemical agents, such as acetone, toluene, ethanol, isopropyl and fluor silane polymer, has a significant impact onto the wettability of substrates which affects the final deposition process of nanoinks....

Local Mechanical Properties of SiC - TiNbC Composite and its Constituents

SiC based composite with 50 % of additives (Ti and NbC with ratio of 9:16) has been prepared. The microstructure, porosity, and chemical composition were studied using SEM equipped with EDS analyser. Local mechanical properties such a hardness and elastic modulus of individual components of the composite were investigated by nanoindentation using Berkovich indenter tip. Hardness and fracture toughness of studied material as a whole was evaluated by means of classic Vickers macroindentation. Indentation cracks were observed and their propagation was analyzed. It was shown that the present phases were distributed uniformly. Moreover, final density was satisfactory with porosity lower than 1 %. The individual constituents shown similar elasticity modulus (550 - 590 GPa). Hardness (HIT) exhibited very pronounced load-size effect. At 10 mN load, hardness was 42.33 GPa ± 1.1 GPa for SiC and 35.73 GPa ± 0.9 GPa for TiNbC, while at 500 mN the composite hardness was 27.61 GPa ± 0.505 GPa. It is in good agreement with macrohardness values, when 27.6 GPa and 25 GPa has been measured for 1 and 10 kg loads, respectively. Indentation fracture toughness was 3.3 MPa.m1/2 ± 0.22 MPa.m1/2. Electrical conductivity was measured by four point probes method and its value was 8.8×104 ± 0.3×104 Sm-1.

Microstructure, Properties and Damage Mechanisms by Water Jet Cutting of TiB2-Ti Cermets Prepared by SPS

Process parameters of abrasive water jet (AWJ) machining of TiB2+Ti ceramic matrix composites with 10%, 15% and 20% of Ti reinforcement were investigated. The article focuses on microstructure damage processes and kerf geometry in AWJ machining of TiB2+Ti composites. Two different abrasive water jet cutting speeds and three sorts of composite materials, together with a reference monolithic one, are considered. Microstructure in machined samples was observed using scanning electron microscope. The characteristics of the cuts such as kerf top width, kerf angle and surface roughness were studied. The influence of cutting speed on abrasive process in composites with various amounts of Ti was investigated. It was found that roughness decreases and kerf taper ratio increases with increase in amount of Ti.

Microstructure and Crack Propagation of Electrically Conductive SiC Based Composites

The work deals with the observation of microstructure and crack propagation from macro-indentation in a set of newly developed materials. Complex composites based on SiC matrix with 30, 40 and 50 wt. % of additives (Ti and NbC) were hot pressed at 1960 oC in air atmosphere under 30 MPa pressure for 1.5 hour. The microstructure and chemical composition were studied by SEM equipped with EDX analyzer. Hardness of the composites was evaluated by means of classic Vickers macro-indentation and fracture toughness was determined by the Anstis method. Indentation cracks were observed and their propagation was analyzed. The electrical conductivity as function of volume fraction of additives was determined.

Wear and Mechanical Properties of Various Bone Cements – Influence of Saline Environment

Several bone cements were prepared in two ways of mixing (manual and vacuum bowl). Wear behavior, friction coefficient were studied by ball on disc method. Nano-hardness and Young`s modulus was studied by instrumented indentation. Obtained results were summarized by taking into account their way preparation, antibiotics content and testing conditions. There was found no significant time dependence of saline acting on Young`s modulus and nano-hardness values. Friction coefficient in saline was less than half in compare to dry sliding conditions