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Open access

M. Kawalec and E. Olejnik

Abrasive Wear Resistance of Cast Iron with Precipitates of Spheroidal VC Carbides

The paper presents the results of abrasive wear resistance tests carried out on high-vanadium cast iron with spheroidal VC carbides. The cast iron of eutectic composition was subjected to spheroidising treatment using magnesium master alloy. The tribological properties were examined for the base cast iron (W), for the cast iron subjected to spheroidising treatment (S) and for the abrasion-resistant steel (SH). Studies have shown that high-vanadium cast iron with both eutectic carbides and spheroidal carbides has the abrasion resistance twice as high as the abrasion-resistant cast steel. The spheroidisation of VC carbides did not change the abrasion resistance compared to the base high-vanadium grade.

Open access

B. Hutera, A. Kmita, E. Olejnik and T. Tokarski

The paper presents a method for obtaining nanoparticles of ZnO by thermal decomposition of the Zn-containing compounds. The experiment was based on the thermal decomposition of basic zinc carbonate to zinc oxide (with a content of 58-61 wt.%). Basic zinc carbonate was analysed by derivatography and then annealed at a selected temperature (about 600ºC) for about 1 h. Products of thermal decomposition of the compound were studied by XRD analysis and SEM scanning microscopy.

Open access

B. Stypuła, M. Starowicz, M. Hajos and E. Olejnik

Electrochemical Synthesis of ZnO Nanoparticles During Anodic Dissolution of Zinc in Alcohols Solvents

Studies of the effect of the kind of alcohol, electrolyte concentration and water on the anodic dissolution of zinc and the nature of dissolution products were performed. The dissolution products were analyzed by spectroscopic methods (SEM/EDS, XPS and UV-vis) and X-ray diffraction. These studies have shown that the process of anodic dissolution of zinc in alcohol electrolytes (methanol and ethanol) in the presence of water (1-5% vol.), is a simple way to obtain ZnO nanoparticles.

Open access

E. Olejnik, S. Sobula, T. Tokarski and G. Sikora

Abstract

Application of in-situ technique allows for fabrication of composite zone in the casting with a matrix of cast steel with low carbon content. The reinforcing phase in the composite zone is titanium carbide, produced by the synthesis of substrates introduced into the mould in the form of pressed compacts. Metallographic studies were performed in order to determine of homogeneity of composite zones and characteristic features existed in transition area between the composite zone and core of the casting. The transition areas of composites zone were blurred and there were no discontinuities caused by poor bonding between the composite zone and the core of the casting. To confirm the correct run of the TiC synthesis, phase analysis was performed of the base alloy as well as composite zone. The results of this examination indicated that there were two phases in composite zone, i.e. α Fe and TiC and only α Fe was observed in base alloy. Changes of mechanical properties in the composite zone were examined, measuring its hardness HV. The average hardness values of the base alloy and composite zone were 175 ±4 and 696 ±201 HV, respectively.

Open access

S. Sobula, E. Olejnik and T. Tokarski

Abstract

Wear resistance of TiC-cast steel metal matrix composite has been investigated. Composites were obtained with SHSB method known as SHS synthesis during casting. It has been shown the differences in wear between composite and base cast steel. The Miller slurry machine test were used to determine wear loss of the specimens. The slurry was composed of SiC and water. The worn surface of specimens after test, were studied by SEM. Experimental observation has shown that surface of composite zone is not homogenous and consist the matrix lakes. Microscopic observations revealed the long grooves with SiC particles indented in the base alloy area, and spalling pits in the composite area. Due to the presence of TiC carbides on composite layer, specimens with TiC reinforced cast steel exhibited higher abrasion resistance. The wear of TiC reinforced cast steel mechanism was initially by wearing of soft matrix and in second stage by polishing and spalling of TiC. Summary weight loss after 16hr test was 0,14÷0,23 g for composite specimens and 0,90 g for base steel.

Open access

E. Olejnik, Ł. Szymański, P. Kurtyka, T. Tokarski, B. Grabowska and P. Czapla

Abstract

In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.

Open access

S. Sobula, A. Kwiecień, E. Olejnik and P. Pałka

Abstract

In this study, low-carbon cast steel was reinforced with TiC by SHS-B method, also known as combustion synthesis during casting method. The composite zone was then subjected to surface remelting by Gas Tungsten Arc Welding (GTAW) method. The remelting operation was realized manually, at 150 A current magnitude. Microstructure, phase composition and hardness of remelted zone were investigated. XRD results reveal that the phases of the composite zone in initial state consist of TiC and Feα. Surface remelting resulted in formation of thick layers containing TiC carbides, Feα and Feγ. Microstructural examination has shown strong refinement of titanium carbides in remelted zone and complete dissolution of primary titanium carbides synthetized during casting. The average diameter of carbides was below 2 μm. The structural changes are induced by fast cooling which affects crystallization rate. The hardness (HV30) of the remelted layer was in the range between 250 HV and 425 HV, and was lower than hardness in initial state.

Open access

B. Grabowska, A. Bobrowski, E. Olejnik and K. Kaczmarska

Abstract

This publication describes research on the course of the process of cross-linking new BioCo polymer binders - in the form of water-based polymer compositions of poly(acrylic acid) or poly(sodium acrylate)/modified polysaccharide - using selected physical and chemical factors. It has been shown that the type of cross-linking factor used influences the strength parameters of the moulding sand. The crosslinking factors selected during basic research make it possible to obtain sand strengths similar to those of samples of sands bonded with commercial binders. Microwave radiation turned out to be the most effective cross-linking factor in a binder-matrix system. It was proven that adsorption in the microwave radiation field leads to the formation of polymer lattices with hydrogen bonds which play a major role in maintaining the formed cross-linked structures in the binder-matrix system. As a result, the process improves the strength parameters of the sand, whereas the hardening process in a microwave field significantly shortens the setting time.

Open access

E. Olejnik, M. Górny, T. Tokarski, B. Grabowska, A. Kmita and G. Sikora

The study discusses a method of producing composite zones at the edge of castings made of ferritic-pearlitic ductile iron. Composite zones were produced in castings made of ferritic-pearlitic ductile iron at the casting edge. The reinforcing phase for the composite zone was TiC carbide, obtained by in-situ synthesis of substrates introduced into the mould in the form of compacts. The composition of the substrates of the reaction of the TiC synthesis was next enriched with an Fe filler added in an amount of 10 and 50 wt. % to investigate the possibility of changing the hardness of the composite zone. The addition of filler changed the surface fraction and the average size of TiC precipitates. In the case of the 50 wt. % addition, a tenfold reduction in the dimensions of the carbides was obtained. This increased their surface fraction relative to the compact composition containing only 10 wt. % of the filler. Changes in mechanical properties were analysed within the zone area by the measurement of hardness HV. The study showed a gradual decrease of the zone hardness in function of the amount of the filler added. This trend was also true as regards the composite zone in castings, where a significant refinement and increased surface content of the TiC precipitates was observed.

Open access

M. Trepczyńska-Łent and E. Olejnik

Abstract

Directional solidification of the Fe - 4,3 wt % C alloy was performed with the pulling rate equal to v=83 μm/s. Sample was frozen during solidification to reveal the shape of the solid/liquid interface. Structures eutectic pyramid and spherolitic eutectic were observed. The solidification front of ledeburite eutectic was revealed. The leading phase was identified and defined.