Papers by Keyword: Roughness

Abstract: One of the possibilities of the dieless drawing is the production of ultrafine wire. In this case, it is possible for additionally stretch the wire, obtained in the conventional way. This may allow to obtain a wire of smaller diameter than the industry produces. However, the significant problem is the increase of the strain induced roughness of wire during dieless drawing. This problem has become important due to the fact that the resulting roughness can be comparable to the diameter of the wire and significantly reduce the workability. Thus, the solution of these problems requires plastometric studies of the material, physical and numerical modeling for prediction the roughness of the wire under conditions of dieless drawing. The experimental study shown, that the surface roughness of the copper wire after dieless drawing increases significantly at a deformation temperature above 300°C. The total roughness is associated both with the formation of oxides and the strain induced roughness.

Abstract: The aim of this study was to investigate and compare the relationship between corrosion resistance and roughness in the samples of carbon steel SAE 1020 and DOMEX^® 700 MC steel. Surfaces with different roughnesses were compared. The metal alloys were analyzed via electrochemical impedance spectroscopy (EIS), anodic potentiodynamic polarization (APP), roughness tester and scanning electron microscopy (SEM). It was observed that the samples exhibited different behavior with respect to corrosion resistance, according to the surface conditions and materials that were tested. The lowest roughness values represented the best results in the electrochemical tests. The samples of carbon steel with lower maximum depth of valleys (Rv) showed the best protection properties compared to other samples.

Abstract: Underwater laser machining process is a material removal technique that can minimize thermal damage and offer a higher machining rate than the laser ablation in ambient air. This study applied the underwater method associated with a nanosecond pulse laser for turning a commercially pure titanium rod. The effects of laser power, surface speed and number of laser passes on machined depth and surface roughness were investigated in this work. The results revealed that a deeper cut depth and smoother machined surface than those obtained from the laser ablation in ambient air were achievable when the underwater laser turning process was applied. The machined depth and surface roughness were found to significantly increase with the laser power and number of laser passes. The findings of this study can disclose the insight as well as potential of the underwater laser turning process for titanium and other similar metals.

Abstract: For precise investigation of distribution for impurity or composition at SiO₂/SiC interface, dual-beam Time-of-flight Secondary ion mass spectrometry (TOF-SIMS) with low energy sputtering beam was available. In addition to the experimental profiles, simulation using MRI model, in which Mixing, Roughness and Information depth were employed as parameters, enabled to acquire a more authentic distribution at the SiO₂/SiC interface. Slight discrepancy on depth profiles between samples with different surface roughness was duplicated on the convoluted profiles in the simulation. Moreover, reconstructed profile of nitrogen indicated a real distribution with less impact of mixing and roughness, although that may contain uncertainty due to incompletion in the simulation model or variation of the distribution owing to detection species in the experiment. From the result of carbon profiles of both experimental and convoluted profiles, the relative discrepancy on the carbon distribution between samples was clarified, which suggested the possibility that a carbon thin layer at the SiO₂/SiC interface would be found in the future.

Abstract: Conventionally, chromium is deposited from hexavalent chromium baths containing extremely toxic compounds of Cr (VI). Due to serious health and environmental concerns of Cr (VI), trivalent chromium bath is proposed as a counter approach towards greener and safer chromium plating. In the present work, chromium coatings were electrodeposited onto copper substrate using a modified trivalent chromium electroplating bath with addition of polyethylene glycol (PEG 1500). The effects of PEG on the Cr coating were investigated. The crystalline structure, composition and surface morphology of the deposits were studied by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The surface roughness of the coatings were characterized by atomic force microscopy (AFM). With addition of PEG, the surface roughness of Cr coating decreased by 44.5 % and the corrosion rate decreased by 23.3 % compared to that of without PEG. Meanwhile, the hardness increased by 22.7 %.

Abstract: The article considers issues related to the choice of abrasive material and technology of its use for the formation of necessary roughness on the base material and necessary heat resistance of the heat-protective coating during plasma spraying. The influence of the shape and size of the abrasive on final roughness of the treated surface was studied at various angles of contact between the sprayed abrasive and the surface (angle of attack). From the condition of maximum heat resistance, the composition of the heat-resistant composite coating of the spinel type was determined, which consists of 3 layers: the 1st layer (sublayer) material is a chromium-aluminum composite and the 2nd layer of a transitional spinel-based aluminum and chromium oxide + chromium-aluminum composite and the 3rd a layer of spinel based on aluminum and chromium oxides.

Abstract: The effect of electric-spark deposition (ESD) on carbon steel 35 by functional-gradient electrode materials based on tungsten carbide with additions of chromium and vanadium carbides is shown. These dopants increase the total weight gain of the cathode and the mass transfer coefficient at ESD. The change of anode material erosion resistance parameters and roughness of alloyed layers using R_a, R_z, R_p, R_q, T_n parameters were studied. It is shown that an increase in the roughness parameters is observed with a decrease in the duty cycle and with an increase in the duration of the pulses in the period of the electric-spark discharge, as well as with an increase in the total gain of the cathode and with mass transfer coefficient. For the studied anode materials, an averaged series of increasing erosion resistance was obtained for ESA: M1→ BK15→ BK8→ M2_10% → M2_8%. and a series of increasing roughness parameters R_a, R_z, R_p, R_q, T_n: BK8→ BK15→ M2_8%→ M2_10%→ M1. With a long-term ESD up to t = 20 min, the dependence of the roughness parameter growth on the increase of ΣΔ_к, К_ср and processing regimes and processing modes t_sк, t_р remains the same. It has been established that the addition of grain growth inhibitors 0.4Cr₃C₂ + 0.4VC and 0.4VC-0.4Cr₃C₂ + 0.4C to anodic W-Co materials significantly increases the total cathode weight ΣΔ_к, mass transfer coefficient K_p and the thickness of the alloyed layer in ESA steel 35, at the same time, the microhardness of the alloyed layer remains almost the same.

Abstract: The considered theoretical analysis of the roughness parameters formation of the rolling face of the pinch pass mills, when they are indented with shot, allows to obtain more adequate and convenient theoretical results for use in practice. The formation of a rough layer on the rolling working surface of the pinch pass mill is determined by the impact and penetration of the shots into its surface. When this occurs, the elastic and plastic deformation of the roll materials and shot with the dimple formation and the displacement of a portion of the deformed roll material on the edges of this dimple takes place. The obtained results allow using the mathematical dependencies to control purposefully the process of shot blasting and correct it when texturing the working rolling faces of the pinch pass mills.

Abstract: This work provides the results of research of the wear resistance of the surface of samples of low carbon structural of 18HN3MA-SH steel, subjected to electrolytic-plasma treatment by nitriding and carbonitriding. The effect of the structure on the surface wear resistance of steel is shown. Changes in abrasive wear and dry friction characteristics were studied depending on temperature and processing time. The results of studies of tribological tests show that after electrolytic-plasma nitriding, the wear resistance of steel 18HN3MA-SH increases by 1.5–2 times compared with the initial state. The observed effects can be explained by the flowing surface modification - the formation of a modified surface layer with the formation of hardening phases. The nature of changes in the surface roughness R_a of steel samples after cementation, carbonitriding and nitriding was studied.

Abstract: This paper analyzes the effect of SLM parameters on mechanical characteristics and surface roughness of a single-component copper powder. The study reports on appropriate SLM conditions for a single-component copper powder; to form a layer a technique within layer-by-layer selective laser melting is suggested and comprises roughing, semi-finishing and finishing modes. The work establishes a range to vary surface roughness, porosity and ultimate compressive strength of a single-component copper powder by means of laser processing conditions. Rz is variable 332 to 689 μm, porosity ranges approximately 13-39%, and ultimate compressive strength is 8 to 104 МPа.