Search Results (11)

Microbiologically influenced corrosion (MIC) has long been a critical issue due to its potential to cause severe damage to equipment and the associated risk of operational failures, leading to significant financial losses. This study investigates the resistance to MIC caused by sulfate-reducing bacteria (SRB) in four types of pipeline steel materials, which are soon to be introduced to the market. Two of these materials have been alloyed with copper during the metallurgical process. The uniform corrosion rates of the copper-alloyed materials were found to be 0.012 ± 0.002 mm/y, 0.060 ± 0.01 mm/y, and 0.010 ± 0.001 mm/y under test conditions of 25 °C, 40 °C, and 60 °C, respectively. In contrast, the unalloyed steels exhibited corrosion rates of 0.370 ± 0.033 mm/y, 0.060 ± 0.01 mm/y, and 0.378 ± 0.032 mm/y, respectively. The data indicate that the copper-alloyed materials demonstrate superior resistance to MIC, as confirmed by corrosion morphology, weight loss measurements, and electrochemical data. These findings suggest that copper alloying can significantly enhance the MIC resistance of steel materials, offering a promising direction for future material development. Full article

Cu–Al bronzes are interesting metallic materials, demonstrating higher hardness, higher wear resistance, higher corrosion resistance and a lower friction coefficient as compared with unalloyed copper. The powder metallurgy approach to the fabrication of these alloys presents opportunities to tailor their phase composition and grain size. In the present work, the structural characteristics, phase composition and properties of Cu-10 wt.% Al alloys obtained by spark plasma sintering (SPS) of powder blends and a powder obtained by mechanical alloying (based on Cu(Al) solid solution) are reported. Alloys with different interaction degrees between the metals were obtained by SPS. The blends demonstrated better sinterability than the mechanically alloyed powder: a nearly fully dense alloy was obtained by SPS of the blend at 480 °C, whereas a temperature of 800 °C was necessary to consolidate the mechanically alloyed powder. The hardness and electrical conductivity of the sintered alloys were comparatively analyzed. It was shown that the Cu-10 wt.% Al alloys obtained without the mechanical alloying stage possess hardness and electrical conductivity comparable to those of the alloys obtained from the mechanically milled powder. Full article

This work is devoted to the physical and mechanical properties of porous alloys based on TiNi alloyed with different amounts of Cu additive. We show that by doping a porous TiNi alloy with copper instead of nickel, it is possible to obtain characteristics acceptable for use in implantology and superior to those of known porous TiNi alloys. Cu addition in the range from 1 to 10 at.% is shown to optimize the properties of tested alloys. There is a decrease in the minimal martensitic transformation stress ${\tau }_{M_s}^{min}$ from 37 to 17 MPa when compared to initial unalloyed TiNi. Alloys with 3 and 6 at.% of Cu are found to be optimal for use in medical practice. Along with a wide temperature range of reversible deformations that cover the range of operating temperatures (273–313 K), such alloys demonstrate their martensitic transformation stress values below 28 MPs. This permits to model implantable structures of complex configuration from such materials under a certain temperature regime. Full article

This paper presents a new macroscopic method for identifying chop marks on archaeological faunal assemblages and highlights the major differences in the morphology of chop marks created by stone and metal axes. The method provides macroscopic criteria that aid in the identification of both complete and incomplete chop mark types as well as the raw material of the axe. Experiments with modern stone (chipped and ground) and metal (copper and bronze) axes found that the degree of fragmentation within a chop mark is related to both the width and sharpness of the axe and can be classed on a scale from 1–5 using a variety of criteria. The experiments demonstrate that sharp chipped stone axes are fragile (often break upon impact) and do not create clean and well-defined chop marks. Ground stone axes are more durable but tend to create very fragmented chop marks without a clean cut (sheared) surface. Unalloyed copper metal axes can create sheared chopped surfaces; however, the relatively soft metal creates more crushing at the point of entry than bronze axes. In contrast, bronze axes are durable and create chop marks with exceptionally low rates of fragmentation resulting in a clean-cut sheared surface that extends into the bone for more than 3 mm. The method is applied to the faunal assemblage from the Early Bronze Age site of Göltepe, Turkey to determine whether the chop marks on bones were made by stone or metal axes at this early metal processing settlement. The results suggest that many of the chop marks were made by metal implements (e.g., axes). Hence, this method provides another means to monitor the adoption rates of new raw materials at a time when both metal and stone axes coexisted. Full article

It is a well-known fact that to manufacture an automobile tire more than 200 different materials are used, including high-carbon steel wire. In order to withstand the affecting forces, the tire tread is reinforced with steel wire or other products such as ropes or strands. These ropes are called steel cord. Steel cord can be of different constructions. To ensure a good adhesive bond between the rubber of the tire and the steel cord, the cord is either brass-plated or bronzed. The reason brass or bronze is used is because copper, which is a part of these alloys, makes a high-strength chemical composition with sulfur in rubber. For steel cord, the high carbon steel is usually used at 0.70–0.95% C. This amount of carbon ensures the high strength of the steel cord. This kind of high-quality, unalloyed steel has a pearlitic structure which is designed for multi-pass drawing. To ensure the specified technical characteristics, modern metal reinforcing materials for automobile tires, metal cord and bead wire, must withstand, first of all, a high breaking load with a minimum running meter weight. At present, reinforcing materials of the strength range 2800–3200 MPa are increasingly used, the manufacture of which requires high-strength wire. The production of such wire requires the use of a workpiece with high carbon content, changing the drawing regimes, patenting, and other operations. At the same time, it is necessary to achieve a reduction in the cost of wire manufacturing. In this context, the development and implementation of competitive processes for the manufacture of high-quality, high-strength wire as a reinforcing material for automobile tires is an urgent task. Full article

Mechanical properties of powder bed fusion processed unalloyed copper are reported majorly in the as-fabricated condition, and the effect of post-processes, common to additive manufacturing, is not well documented. In this study, mechanical properties of unalloyed copper processed by electron beam powder bed fusion are characterized via room temperature quasi-static uniaxial tensile test and Vickers microhardness. Tensile samples were extracted both perpendicular and parallel to the build direction and assigned to three different conditions: as-fabricated, hot isostatic pressing (HIP), and vacuum annealing. In the as-fabricated condition, the highest UTS and lowest elongation were obtained in the samples oriented perpendicular to the build direction. These were observed to have clear trends between sample orientation caused primarily by the interdependencies between the epitaxial columnar grain morphology and dislocation movement during the tensile test. Texture was insignificant in the as-fabricated condition, and its effect on the mechanical properties was outweighed by the orientation anisotropy. The fractographs revealed a ductile mode of failure with varying dimple sizes where more shallow and finely spaced dimples were observed in the samples oriented perpendicular to the build direction. EDS maps reveal that grain boundary oxides coalesce and grow in HIP and vacuum-annealed specimens which are seen inside the ductile dimples and contribute to their increased ductility. Overall, for the post-process parameters chosen in this study, HIP was observed to slightly increase the sample’s density while vacuum annealing reduced the oxygen content in the specimens. Full article

The debate about the highly radiogenic lead in Chinese archaeology has never ceased. However, previous studies have mainly focused on high leaded bronzes and lead materials, and with little specific discussion on the unalloyed copper artifacts and the sources of copper materials in China. In this work, a trace of highly radiogenic lead was found in ten copper spearheads unearthed from Huili County, Sichuan Province, southwest China, which inspired our research on this issue. The pXRF results showed that their lead content is extremely low, so the lead isotope ratios can indicate the source of copper, and the data correspond to the local copper deposits. Combined with other relevant highly radiogenic lead isotope data of unalloyed copper artifacts, the results indicate that there were multiple sources of copper ores used in the Shang Dynasty, and copper mines were continuously used in Southwest China until the Eastern Zhou Dynasty. Full article

The aim of this in vitro study was to evaluate the alterations of a titanium surface after treatment with two different types of ultrasonic tips: conventional steel versus an innovative copper alloy silver-plated one. Twenty smooth-surface, grade IV unalloyed titanium discs were divided into two groups. The discs were ultrasonically instrumented and the scaler was connected with a loading machine. The surface morphology was examined using scanning electron microscopy (SEM) and fractal analysis of lacunarity was calculated to highlight the alteration of the surface using the two different tips. The SEM analysis showed different degrees of surface roughness between the two types of scaler tips. Moreover, these observations demonstrated that the new tip showed fewer irregularities on the disc’s surface than the conventional steel tip. The statistical and fractal analysis showed a statistically significant difference between the two groups. Surface alterations of titanium induced by the conventional ultrasonic tips were much greater than those made by copper alloy silver plated tips. The presented results suggest that the use of this new ultrasonic tip may reduce the alterations on the implant surface during its use in dental practice. Full article

In situ micro-TiB₂/Cu cermets with a different TiB₂ content (40, 50, and 60 vol %) were successfully fabricated by combustion synthesis (CS) and hot press consolidation in Cu-Ti-B systems. In addition, different contents of Cr and Zr were added to the Cu-Ti-B systems. The microstructure, mechanical properties, and abrasive wear properties of the TiB₂/Cu cermets were investigated. As the ceramic content increased, the yield strength and compressive strength of the cermets were found to increase, while the strain decreased. An increase in load and abrasive particle size caused the wear volume loss of the TiB₂/Cu cermets to increase. When the ceramic content was 60 vol %, the wear resistance of the TiB₂/Cu cermets was 3.3 times higher than that of pure copper. The addition of the alloying elements Zr and Cr had a significant effect on the mechanical properties of the cermets. When the Cr content was 5 wt %, the yield strength, ultimate compressive strength, and microhardness of the cermets reached a maximum of 997 MPa, 1183 MPa, and 491 Hv, respectively. Correspondingly, when the Zr content was 5 wt %, those three values reached 1764 MPa, 1967 MPa, and 655 Hv, respectively, which are 871 MPa, 919 MPa, and 223 Hv higher than those of the unalloyed cermets. The wear mechanism of the in-situ TiB₂/Cu cermets, and the mechanisms by which the strength and wear resistance were enhanced by the addition of Zr, were preliminarily revealed. Full article

The anodic oxidation process is an established means for the improvement of the wear and corrosion resistance of high-strength aluminum alloys. For high-strength aluminum-copper alloys of the 2000 series, both the current efficiency of the anodic oxidation process and the hardness of the oxide coatings are significantly reduced in comparison to unalloyed substrates. With regard to this challenge, recent investigations have indicated a beneficial effect of nitric acid addition to the commonly used sulphuric acid electrolytes both in terms of coating properties and process efficiency. The present work investigates the anodic oxidation of the AlCu4Mg1 alloy in a sulphuric acid electrolyte with additions of nitric acid as well as oxalic acid as a reference in a full-factorial design of experiments (DOE). The effect of the electrolyte composition on process efficiency, coating thickness and hardness is established by using response functions. A mechanism for the participation of the nitric acid additive during the oxide formation is proposed. The statistical significance of the results is assessed by an analysis of variance (ANOVA). Eventually, scratch testing is applied in order to evaluate the failure mechanisms and the abrasion resistance of the obtained conversion coatings. Full article

The effects of pH and chloride concentration on the electrochemical corrosion of copper in aqueous sodium chloride (NaCl) media were studied at the micro scale using a microcapillary droplet cell and at the macro scale using a conventional large scale cell. Using an experimental design strategy, electrochemical response surface models of copper versus pH and NaCl concentration were constructed with the minimum number of experiments required. Results show that the electrochemical behavior of copper under corrosive media shows significant differences between the micro and macro scale experiments. At the micro scale, the pit initiation of copper occurs at more negative potentials for high NaCl concentrations and alkaline pH values. Also, the micro scale potentiostatic measurements indicate higher stabilised passive currents at high NaCl concentrations and low (acidic) pH values. At the macro scale, the pH is shown to have a greater influence on the corrosion potential. The chloride concentration is the most significant factor in the passive current case while at the micro scale the effect of these two factors on the passive current was found to be the same. The surface morphology of the formed patina on the corroded copper in both micro and macro systems reveal a more significant role of the chloride concentration on the structure and the grain size of the patinas. Finally, micro and macro electrochemical impedance spectroscopy of copper at various NaCl concentrations and pH values demonstrates a different behavior of copper after several potentiodynamic polarization cycles. Full article