Konrad Dybowski

Single and Multilayer Growth of Graphene from the Liquid Phase

The preparation of poly crystalline graphene from the liquid phase has been discussed.The mechanism of graphene growth from the liquid phaseon the Cu-Ni alloy and the type of atmosphere, used inthe graphene fabrication-acetylene, ethylene, hydrogen has been presented. Stages of nucleation and poly crystalline growth of graphene were identified. The paper presents theresults of a single-and multi-layered graphene growth phase.It is assumed the final result will mean the optimization of the industrial-scale production of low-cost poly crystalline graphene.

Properties of Surface Layers Processed by a New, High-Temperature Vacuum Carburizing Technology with Prenitriding - PreNitLPC®

The variety of vacuum carburizing with prenitriding (PreNitLPC® technology) consists in metering ammonia in the stage of charge heating for carburizing to reduce grain growth in the surface layer of carburized steel. This paper presents the effect of nitrogen interaction on the reduction of austenite grain growth during vacuum carburizing and on the mechanical properties (fatigue strength, impact resistance) of the layer treated in this way in relation to conventional carburizing methods.

The Precipitation and Dissolution of Alloy Iron Carbides in Vacuum Carburization Processes for Automotive and Aircraft Applications - Part II

The article is dedicated to the experiments and tests on the phenomena of precipitation and dissolution of alloy iron carbides in vacuum carburization processes. Special attention has been paid to the possibility of using artificial neural networks to predict the speed of the processes examined. In the section below, we are presenting the precipitation phenomena taking place in vacuum carburization processes and the experiments that were conducted. Moreover, a qualitative and metallographic analysis of carbide phenomena was described together with the method of numerical modelling and predicting the processes with the use of artificial neural networks.

DISTORTION OF 16MnCr5 STEEL PARTS DURING LOW-PRESSURE CARBURIZING

One of the many advantages of low pressure carburizing (LPC) is that it can be combined with high-pressure gas quenching. This makes it possible to achieve workpieces with pure metallic surfaces, less distortion hardening, and, above all, it allows a more reliable and repeatable treatment than conventional oil quenching. This article presents a study of the distortion rate of workpieces carburized at low pressure then quenched in nitrogen at 1.4 MPa. By comparing the distortion which takes place during the carburizing stage only and the carburizing combined with post-carburizing heat treatment it will be possible to assess the distortion rate and its causes at the different stages of the heat treatment process.

Resistance-temperature characteristics of CVD and high strength metallurgical graphene

Gas sorption conditions on the graphene surface, as well as their influence on graphene properties, play a significant role when applications are considered. The influence of temperature and pressure on electric properties of graphene were investigated and discussed within this work, which was conducted in order to determine the border values for the sorption and desorption process of hydrogen on the graphene surface. The temperature was changed within the range of 243-373 K. Two types of graphene were used for comparison: one of graphene synthesised by our own method using chemical vapour deposition (CVD) and one of high strength metallurgical graphene (HSMG) in both conducting (cHSMG) and semiconducting (scHSMG) varieties. The characteristics were determined under hydrogen atmosphere in a fitted apparatus under pressure. The overall target material relies on the hydrogen storage of a designed graphene-based composite.

EFFECT OF ALUMINIUM AND MAGNESIUM ON THE CORROSION RESISTANCE OF ZINC COATINGS

This article presents the research on corrosion resistance of Zn-Al-Mg coatings with varying aluminium and magnesium content. Aluminium and magnesium were added directly to the zinc bath at 10:1 rate. There was found more than sixfold increase in corrosion resistance of zinc coatings with aluminium content at the level of 4% of weight and magnesium content at the level of 0.4% of weight. In contrast to the amounts applied in the literature, such content of these alloy additives in the zinc bath limits to a significant extent the amount of intermetallic phases in zinc coatings obtained from such baths. This, in consequence, results in high resistance to corrosion with simultaneous retention of high plasticity of these coatings.

HYBRID LAYER TYPE Cr/LPC

Application of metal coatings and the carburized layer are widely known and readily used for various elements, depending on the application. Metal coatings based on chromium are used in order to increase resistance to wear, corrosion and erosion. The coatings applied by different methods have a significant drawback they are not well related with the substratum, so there is a risk of cracking or flaking. Any discrepancies and flaws disqualify such a way as to protect the surface. Carburizing processes will be carried out, primarily in order to increase the hardness of the surface layer while maintaining a ductile core of the object. It is likely that the combination of these treatments will provide to increase the hardness of the material. The behavior of the proper order to create hybrid layer ensures the continuity of the resulting layer and its good connection with the steel. The paper presents a hybrid layer consisting of the deposited chrome and PVD in the next stage of low pressure carburizing. Conducted process allows chromium diffusion into the material, the enrichment of the steel and to ensure the continuity of the layer.