The Microstructure and Mechanical Properties of Cylindrical Elements from Steel 38Mn6 after Continuous Induction Heating

The paper deals with the influence of induction surface hardening on the microstructure and mechanical properties of cylindrical elements made of steel 38Mn6. The first stage was based on computer simulation of the induction hardening process. The second stage - experiments were provided on laboratory stand for induction surface hardening located at the Silesian University of Technology. Microstructure tests were conducted on light and scanning microscopes. The hardness penetration pattern and thickness of hardened layer were marked. It was found that due to properly chosen parameters of the process, the appropriate properties and thickness of hardened layer were achieved

The Microstructure and Mechanical Properties of Cylindrical Elements from Steel 38Mn6 after Continuous Induction Heating

The paper deals with the influence of induction surface hardening on the microstructure and mechanical properties of cylindrical elements made of steel 38Mn6. The first stage was based on computer simulation of the induction hardening process. The second stage - experiments were provided on laboratory stand for induction surface hardening located at the Silesian University of Technology. Microstructure tests were conducted on light and scanning microscopes. The hardness penetration pattern and thickness of hardened layer were marked. It was found that due to properly chosen parameters of the process, the appropriate properties and thickness of hardened layer were achieved

Comparative Morphological Analysis of Graphene on Copper Substrate obtained by CVD from a Liquid Precursor

Graphene film has been produced on untreated Cu substrate by a chemical vapor deposition technique in ambient pressure with liquid ethanol serving as the carbon precursor. The obtained material has been subjected to morphological study, directly on Cu substrate, by means of optical microscopy, scanning electron microscopy, atomic force microscopy, and a detailed Raman analysis. As a benchmark material, graphene obtained on Cu by a conventional CVD from gaseous methane was used. This simple experimental setup has proved to enable obtaining large area graphene samples with nearly 100% substrate coverage and large domains of one carbon layer. As compared to graphene from gaseous precursor, the presented approach resulted in visibly more defects and impurities. These imperfections are due to more complex precursor molecular structure and lack of Cu pretreatment with hydrogen, the later cause being easy to eliminate in course of further optimization of the method. The described approach can be regarded as a viable, low-cost, and experimentally simple alternative for the existing techniques of producing large area graphene. By providing direct comparison with the conventional method, the paper's intention is to provide deeper insight and to fill gap in the understanding of mechanisms involved in graphene formation on copper

Synthesis and characterization of the thermally reduced graphene oxide in argon atmosphere, and its application to construct graphene paste electrode as a naptalam electrochemical sensor

New insight into the preparation of sensitive carbon–based electrochemical electrode is provided by examining the properties of thermally reduced graphene oxide (TRGO). In this paper, TRGO was prepared by thermal reduction of graphene oxide (GO) in argon atmosphere, and characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). Results showed that thermal reduction in argon was effective to remove oxygen-containing functional groups in GO, and graphene sheets were obtained. Furthermore, TRGO was used to prepare thermally reduced graphene oxide paste electrode (TRGOPE) which showed excellent conductivity and fast electron transfer kinetics confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrode was applied to determination of the pesticide naptalam (Nap) in square–wave voltammetric (SWV) mode. The corresponding current at approx. +1.0 V increased linearly with the Nap concentration within two linear dynamic ranges (LDR) of 0.1–1.0 μmol L−1 (LDR1) and 1.0–10.0 μmol L−1 (LDR2). The limits of detection (LOD) and quantification (LOQ) for Nap were calculated as 0.015 μmol L−1 and 0.051 μmol L−1, respectively. In comparison to the carbon paste electrode (CPE) the results showed that the TRGOPE possesses advantages in terms of linearity, sensitivity and detectability. © 2018 Elsevier B.V