Papers by Keyword: Brass

Abstract: This study proposes the use of an innovative acidified metallic halide solution to address brass corrosion. The research identifies key parameters that contribute to corrosion and demonstrates that the new solution can effectively restore oxidized brass surfaces, serving as a simple and safer alternative corrosion inhibitor. The formulated solution consists of a metallic halide, an organic acid, and alumina as an abrasive. The metallic halide functions as an oxidation inhibitor, preventing the formation of copper (I) oxide (Cu₂O) and zinc oxide (ZnO). Analytical results confirmed the effectiveness of the treatment solution. FTIR spectroscopy showed reduced oxide formation, while EDX revealed a lower oxygen signal and the presence of iodine, indicating successful corrosion inhibition and surface modification. SEM images demonstrated significant surface improvement after treatment, with reduced pitting and oxidation compared to the corroded sample. Contact angle measurements confirmed that treated surfaces transitioned from hydrophilic to hydrophobic states, indicating successful restoration. This process offers a practical, efficient, and safer corrosion mitigation method for brass, addressing a critical need for metal manufacturers and suppliers.

Abstract: Dezincification is one of the specific types of corrosion attack on brass, very often on brass fittings in particular and is caused by the selective removal of zinc from brass, resulting in the formation of areas of spongy and brittle copper, and eventually leading to the total destruction of the component. The dezincification process is greatly facilitated by the presence of chlorine in the water and is also aided by poor aeration, low fluid circulation rates, higher temperatures and permeable deposits or coatings on the surface. This paper describes the analyses of two cases of dezincification of brass fittings, one appearing in hot water distribution pipeline and another in the nozzle of a lion's head shaped urban fountain. Although each of these components operated under different operating conditions, both were confirmed to have been damaged from this specific form of corrosion attack, often permeating the entire wall thickness.

Abstract: In this investigation, the resistance of brass material to stress corrosion cracking (SCC) in a chloride solution was assessed through adjustments in temperature (25°C, 35°C, and 45°C) and bending angles of the brass material (1.0 wt%, 2.0 wt%, and 3.5 wt%). The chosen solution closely resembles saltwater, making it suitable for testing, especially considering the widespread use of brass materials in various industrial sectors, particularly shipping. Stress corrosion cracking tends to impact brass materials under heavy loading. The primary objective of this study is to characterize the corrosion rate of brass materials. The method involved a bending test with angle variations of 180°, 90°, and 0°. Corrosion assessment utilized the Open Circuit Potential method, Anodic Polarization Tafel, and a digital microscope for the material's microstructure properties. According to the findings, brass material exhibits the lowest corrosion rate (10 x 10^-6 mmpy) at a temperature of 25°C distilled water and an angle variation of 0°. Conversely, the corrosion rate increases with variations in bending angle, temperature, and the concentration of NaCl solution, as evidenced by the corrosion rate of 28.035 x 10^-5 mmpy with an angle variation of 180°, to a corrosive solution of NaCl 3.5 wt% at a temperature of 45°C.

Abstract: Electropolishing has been widely used for surface finishing of metallic products in the industry, owing to its excellent capability of producing metallic components with a homogeneously smooth surfaces. However, this treatment is often constrained by the long duration required for the processing. Therefore, an improvement in this process is needed. The aim of this research is to introduce the use of electropolishing with circulated electrolytes for improving the surface finish of brass. In this work, electropolishing was carried out by using circulated H₂SO₄ electrolyte for 10 to 30 min in a customized electropolishing chamber. The effect of this treatment on surface morphology, surface roughness, and thickness reduction of the brass specimen was determined. The results showed a better capability of electropolishing with circulated electrolyte in decreasing the brass roughness, i.e., by 84%, than that without electrolyte circulation which only reached 45% during 30 min of the treatment.

Abstract: The paper deals with changes in the stoichiometry of nanopowders obtained under staged irradiation of a brass ingot placed in a graphite crucible. Composite core-shell CuO/ZnO nanoparticles, copper nanoparticles, and copper and zinc oxides were obtained. The use of a relativistic electron accelerator is necessary to produce nanopowders on an industrial scale. Transmission electron microscopy and energy-dispersive analysis of the obtained nanoparticles were carried out. Thermodynamic calculation of the temperature dependence of the equilibrium content of copper and zinc is presented for the condensed and gas phases. The formation mechanism of CuO/ZnO composite nanoparticles is discussed.

Abstract: Among other parts made of brass there are also the blades and the rotors of the hydraulic machines, respectively ship propellers, which during operation are degraded by cavitation erosion. As a result, most of the researches, including the most recent ones, are focused on the morphological analysis of structures eroded under the impact of micro-jets and shock waves, produced by cavitation hydrodynamics. The goal is to create new materials, but also to use new treatment technologies to increase cavitation resistance. As the literature is quite poor in studies related to the materials resistance to cavitation erosion, respectively treatments and technological procedures of it’s improvement, this paper presents the research results on the behavior of vibration cavitation erosion, carried out on three sets of CuZn39Pb3 brass samples, subjected to volumetric heat treatments of hardening for putting in solution at 800°C, followed by tempering at 250°C, 400°C and 600°C. The characterization of the behavior and the cavitation resistance of the structures resulting from the applied heat treatments is performed based on macroscopic images, taken at different representative periods, SEM images at the end of the test duration and values ​​of specific parameters recommended by ASTM G32-2016. The analysis highlights the differences caused by the change in structure by varying the temperature, but also the hardness of the surface exposed to the cavity. Thus, of the three treatments, it is found that the best resistance to cavitation is conferred by the structure resulting from hardening at 800°C, with tempering at 250°C.

Abstract: Cartridge case ammunition is made from brass alloy by deep drawing process with high degree of deformation. For this reason, the material with a good formability, strength, and hardness is required. The improvement of mechanical propeties of the brass alloy can be conducted by severe process such as addition of alloying element and also termomechanical process. The purpose of this study is to determine the effect thermomechanical processing by cold rolling process with 70% thickness reduction followed by annealing process with variation temperature of 400°C, 500°C and 600°C for 30 minutes to the microstructure and mechanical properties of Cu-28Zn-4Mn alloy. The samples of Cu-28Zn-4Mn alloy were produced by gravity die casting process by using the ingot of Cu, Zn as well as the Mn powder as the feeding materials. The investigation results show that thermomechanical prosess change the microstructures of Cu-28Zn-4Mn alloy. The cold rolling process with 70% thickness reduction will convert the equiaxial grain into an elongated structure (shear band). Furthermore, the heat treatment by annealing process will return the microstructure from elongated to equiaxial grain. Thermomechanical process also tends to change mechanical properties. The 70 % cold rolling process increases the hardness of the Cu-28Zn-4Mn alloy. The hardness of as homogenized and 70% cold rolled samples are 62.34 VHN and 103.96 VHN, respectively. Further, the annealing process tend to decrease the tensile strength and hardness of Cu-28Zn-4Mn alloy. Tensile strength of Cu-28Zn-4Mn after annealing process with variation of 400°C, 500°C, and 600°C are 355.13 MPa, 299.16 MPa, and 294.79 MPa, respectively. On the other hand, the hardness of Cu-28Zn-4Mn with the same treatment are 91.84 VHN, 71.76 VHN and 67.46 VHN, respectively. In contast, the annealing process tend to increase the elongation value. The samples elongation after the annealing process with variation of 400°C, 500°C, and 600°C are 25%, 28%, and 30%, respectively.

Abstract: This research was conducted to investigate the effect of thermomechanical process on microstructures and mechanical properties of Cu-28Zn-2Al alloys. Thermomechanical process was carried out by cold rolling process with 70% thickness reduction and followed by annealing process with variation temperature of 400°C, 500°C and 600°C. The result show that the β phase and shear bands are found in the samples. Further, cold rolling process can increase hardness of Cu-28Zn-2Al alloys from 100 to 172 VHN. The heat treatment with annealing process at 400°C tend to decrease the tensile strength of cold rolled samples from 695 to 472 MPa and more decreased until 422 MPa at 600°C. In contrast, annealing process at 400°C tend to increase the elongation from 10 to 28% and more increased up to 56% at 600°C. This phenomenon prove that the annealing process will increase ductility of cold rolled samples of Cu-28Zn-2Al alloys.

Abstract: The article describes the features of the process of casting copper alloys in the chill mold. The main properties of alloys depending on the content of various components in it are revealed. The main negative factors leading to a decrease in the casting properties of the process, as well as the quality of the castings obtained, are indicated. Based on the information and analytical review, possible options for improving the efficiency of the process are identified. These include: alloying, refining, modification, the use of various one-time coatings, the use of heat treatment of castings. The use of hard coatings applied by the method of physical vapor deposition in order to increase the efficiency of the entire casting process is proposed.

Abstract: We investigated the process of laser heat treatment of polished brass samples (36% zinc, containing a small amount of lead, which does not dissolve in the alloy and is in the form of inclusions, having micron and submicron size) by impacting to a series of 25 - 30 ultraviolet (UV) pulses of a Nd:YAG laser (third harmonic, wavelength λ = 355 nm, duration τ = 10 ns, pulse repetition rate f = 10 Hz, pulse energy density ~ 0.15 - 1.0 J/cm²) in the stationary spot mode. Copper and its alloys absorb up to 90% of the energy of this laser. It is found that the relaxation of the absorbed energy of laser radiation in the metal occurs nonuniformly. Defects in the metal structure such as grain boundaries and lead inclusions are visualized. Traces of crystallographic sliding appear inside some grains. With an increase in the number of impacting impulses, accumulation of damage is observed. A further increase in the radiation energy density leads to an aggravation of the observed phenomena.