Iron Samples Research Articles

Formation of Residual Stress Diagram after Quenching in a Magnetic Field

Introduction. After hardening, a product has residual stresses: structural and thermal. The magnitude of the total stresses in the finished part determines its crack resistance under the influence of operational loads. Quenching in a constant magnetic field affects the process of martensite nucleation, and the kinetics of martensite transformation, as well as the processes of martensite decomposition. However, there is currently no data available on how these changes in structure affect the stress diagram in a heat-treated product. The aim of this study was to investigate the influence of a constant magnetic field during hardening of iron-carbon alloys on the stress distribution across the cross-sectional area of parts.Materials and Methods. The studies were conducted on samples of technical iron, steel 45, and ferritic malleable cast iron. Cylindrical samples with a diameter of 16 mm and ring samples with an outer diameter of 20 and 55 mm were used. The samples were heated in an electric furnace or an induction heating lamp generator LZ-13, and quenched in water or mineral oil. A constant magnetic field with strength of 768 to 1600 kA/m during hardening was created in the bore of a FL-1 electromagnet. Residual stresses were determined using the original method developed by V.A. Blinovskii based on measuring bending deformations in hollow bodies of revolution.Results. The change in temperature on the surface, in the core, and the temperature difference across the cross-section of a cylindrical sample during cooling in water with and without a magnetic field was obtained. The distribution of stresses over the cross-section after quenching with and without a field for industrial iron in still water was studied. The stress distribution over the cross-section was studied after quenching in a field and without a field in calm water, as well as during spray cooling of steel 45 and ferritic ductile cast iron at different rates.Discussion and Conclusion. The obtained calculated and experimental data allowed us to evaluate possible changes in the residual stress diagrams under the influence of a magnetic field after quenching with volumetric and surface heating. A study of the kinetics of cooling in water under the influence of a magnetic field showed that the temperature difference across the cross-section remained practically unchanged, but there was a decrease in the cooling capacity of the water, which contributed to a reduction in the level of thermal stress. Hardening in a magnetic field led to a reduction of residual stresses in iron-carbon alloys. The change in the distribution of total residual stresses during magnetic tempering was due to a change in their structural component. The magnetic field influenced the distribution of structural, thermal and total residual stresses. The reason for the observed effects was the change in the structural state of steel and cast iron and the cooling ability of water-based quenching liquids under the influence of a magnetic field. The reduction of the level of residual stresses during heat treatment in a magnetic field reduced the likelihood of brittle fracture and cracking, led to a decrease in deformation and warping of hardened steels, and created favorable conditions for the operation of parts under conditions of alternating loads and abrasive friction.

Application of Pseudomonas cepacia CCT 6659 Biosurfactant as a Metal Corrosion Inhibitor in a Constructed Accelerated Corrosion Chamber (ACC)

Corrosion is the deterioration of metals due to environmental exposure. Commercial inhibitors used to control corrosion often contain heavy metal salts, which are highly toxic to both the environment and human health. A biosurfactant produced by the bacterium Pseudomonas cepacia CCT 6659 was tested as a corrosion inhibitor on carbon steel and galvanized iron surfaces. Matrices based on plant ingredients with different compositions were tested in a laboratory-constructed accelerated corrosion chamber (ACC) simulating a critical maritime atmosphere in conditions of 40 °C, 5% NaCl, and 100% humidity. The most stable matrix was selected for biosurfactant incorporation in different concentrations, expressed as critical micellar concentration (CMC), and was applied to metal surfaces to evaluate its ability to inhibit corrosion. Additionally, to evaluate the potential of the biosurfactant as a low-toxicity corrosion inhibitor additive in paint systems, iron and carbon steel samples were coated with three biosurfactant-containing commercial paints and subjected to critical atmospheric conditions for testing coating effectiveness. The formulation containing vegetable resin as a plasticizer, oleic acid, ethanol, and CaCO3 was chosen to incorporate the biosurfactant. The addition of the biosurfactant at twice its CMC led to a reduction in carbon steel sample mass loss from 123.6 to 82.2 g/m2, while in the galvanized iron plates, the mass loss decreased from 285.9 to 226.7 g/m2 at the same biosurfactant concentration. When supplemented with the biosurfactant, the alkyd resin-based paint (A) ensured less mass loss in samples (46.0 g/m2) compared to the control without biosurfactant (58.0 g/m2). Using the paint formulated with oil-based resin (B), the mass loss decreased from 53.0 to 24.1 g/m2, while with that based on petroleum derivatives (C), it decreased from 82.2 to 27.6 g/m2. These results confirm the feasibility of using biosurfactants in biodegradable coatings, reducing the need for commercial corrosion inhibitors.

Experimental and Numerical Analysis of Thermal Fatigue of Grey Cast Iron Ingot Mould

This article presents the results of experimental studies and numerical calculations that were conducted to analyse the phenomena that occur during the operation of an ingot mould that is designed for casting steel ingots. The studies were conducted on an experimental stand in a foundry on an ingot mould that was designed to make ingots that weigh up to six tons; they consisted of determining the temperature of the ingot mould and measuring the displacements of its walls during filling with steel and cooling. These studies were used to create and verify a numerical model that was used to determine the temperatures, displacements, deformations, and stresses in ingot mould walls during the operating cycle using the FEM method. Microstructure studies of ingot cast iron that was subjected to thermal fatigue were also conducted on a laboratory stand; the temperature changes and test times were the same as those used under the normal operating conditions of the ingot mould. Cast iron samples were subjected to heating and cooling cycles within a range of 0 to 60 cycles; then, tensile tests were performed to determine their stress–strain curves. As a result of the conducted tests, a great influence was found of the number of cycles on decreases in the values of the modulus of elasticity and tensile strength—especially within a range of 0 to 10 cycles. A relationship was also found between the changes in these values and the image of the cast iron microstructure. Based on images of the cast iron microstructure after being subjected to different numbers of thermal fatigue cycles, the mechanism of the crack initiation and propagation was determined. The influence of the changes in the strength of the cast iron and the stress state that was determined by the FEM method on the durability of the tested type of ingot mould was analysed. The obtained research results will be useful for introducing design changes that are aimed at increasing the fatigue durability of ingot moulds.

A tracer-free photographic method for the estimation of the velocity field in a liquid metal pool

Abstract Accurately measuring the velocity field (VF) of liquid metals is essential for optimizing and controlling high-temperature industrial processes, yet remains a challenging task despite the numerous existing velocimetry techniques. In this paper, a methodology for estimating the VF of a liquid metal pool is proposed. The experimental set-up used here to heat the metal sample up to the liquid state and collect data is presented. This set-up primarly intented to perform flash experimetns on liquid metals, allows contactless heating and data measurements by a high speed camera. The proposed methodology for estimating the VF consists then in implementing a Non-Rigid Registration between the different frames of the recorded temperature fields (TFs). This method is applied on TFs resulting from multiple experimental tests conducted on iron samples in the temperature range of 1 850 − 2 100 K. The consistency of the results is put to test via multiple validation tests. The influence of the main parameters is also evaluated. The results show that the proposed methodology allows a fine experimental quantification of liquid metal VFs with an estimated error of 8 % and confirm the feasibility of the proposed approach.

Significant enhancment of the accuracy of impurity determination in vacuums using classification one-point laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a highly promising technique for the in-situ, real-time diagnosis of impurity deposits on the inner walls of tokamak devices. The deposited impurity on plasma-facing materials (PFCs) pose a significant risk to the steady-state operation of the tokamak. Under vacuum conditions, an accurate quantitative analysis of the thin co-deposition layers is a technical challenge. In this study, 30 co-deposited layer samples of tungsten (10.0–92.3 a.t.%), molybdenum (2.0–77.8 a.t.%), iron (2.9–12.1 a.t.%) and copper (1.2–18.7 a.t.%) were prepared to simulate the co-deposition layers found on PFCs in Experimental Advanced Superconducting Tokamak (EAST). A variation of the CF-LIBS algorithm, the so-called One Point Calibrated LIBS (OPC-LIBS), was employed to analyze these co-deposited layer samples under conditions of 5 × 10−5 mbar. It was found that the matrix matching degree among the measured samples and the selection of standard samples play a decisive role in the quantitative analysis capability of OPC-LIBS. In actual situations, the composition of the co-deposited impurity layers at different locations in the Tokamak will be quite different. We addressed this challenge by developing the Classified OPC-LIBS (COPC-LIBS) model, an enhanced version of OPC-LIBS with pre-classification to offset matrix effects in LIBS analysis. For tungsten in the co-deposition layers, the root mean square (RMSE) calculated by the CF-LIBS method was 14.7, the OPC-LIBS method was 11.5, and the newly invented COPC-LIBS was reduced to only 5.1. The COPC-LIBS method is a highly efficient technique that can precisely measure the distribution of co-deposited layers on the surface of inner wall materials. The diagnostic data obtained from this method will provide valuable insights into the interaction between plasma and wall materials during the operation of fusion devices.

Effect of Cerium Addition on Microstructure and Mechanical Properties of the Ductile Iron

The effect of the cerium addition on the microstructure and properties of the ductile iron is investigated. The ferrocerium is added to obtain ductile iron samples with cerium contents of 10–750 ppm. In the ductile iron with a cerium content of 60 ppm, the amount and the spheroidization rate of graphites are the highest. The tensile strength of the ductile iron is 488 MPa and the elongation rate reaches 20.17%. For the ductile iron with a high toughness demand, it is necessary to add 60 ppm Ce in the ductile iron to increase the number density and spheroidization rate of graphites. The formation of CeS inclusions effectively promotes the heterogeneous nucleation of graphites, increasing the amount of graphites. The stronger carbon diffusion during the eutectic process increases the ferrite formation in the ductile iron, leading to a lower tensile strength and a higher elongation rate. When the cerium content exceeds 460 ppm, the precipitated Ce2C3 significantly reduces the performance of the ductile iron.

Experimental study of wear and rolling contact fatigue in railway wheel steels coupled with various brake block materials: Insights from innovative small-scale testing

This study presents a comprehensive analysis using an innovative testing method of two wheel steels paired with cast iron and organic composite brake block materials. By conducting tests under consistent conditions and varying in duration, the study examines temperature profiles, friction coefficients, surface characteristics, weight loss, and microstructural changes in wheel samples, emphasizing the distinct behaviour of these materials in braking applications and the damage evolution over time. The results demonstrate that organic composite brake samples outperform those in cast iron, showcasing smoother wheel sample surfaces and stable friction coefficients. Weight loss analysis reveals the environmental benefits of organic composite brakes, emitting fewer particulates than cast iron counterparts. Microstructural examinations uncover the formation of a Thermal White Etching Layer (T-WEL) on wheel samples tested with cast iron samples, leading to cracks and material detachment. Conversely, extended use of organic composite samples led to a "thermal fuse effect", impacting their efficiency and suggesting the need of careful temperature management in sustained braking scenarios. Despite significant differences in wheel steels, the study underscores the critical role of brake material in braking improvements. The findings not only enhance the scientific understanding of brake material behaviour but also introduce an innovative, cost-effective, and fast 4-contact machine testing method.

NEW METHODOLOGIES FOR ASSESSING CAVITATION LOAD AND RESISTANCE OF STRUCTURAL MATERIALS AND PROTECTIVE COATINGS IN NUCLEAR POWER INDUSTRY. PART I. MONOFRACTIONAL APPROACH

The paper presents a new method for assessing the cavitation load and durability of structural materials and protective coatings. To determine the cavitation load on a rotating disk or other test rig, a new method for extracting erosion loads based on tests of reference materials on a reference cavitation rig is proposed. Direct measurements of the cavitation load in a cavitation tunnel with a slot cavitator, performed using piezoelectric sensors, made it possible to obtain information on the spatial distribution of the impact load. As an analytical function for modeling cumulative erosion curves in the monofractional approach, the logarithmic formula of L. Sitnik is used, assuming that cavitation erosion is a stochastic process described using fatigue theory. Armco iron is chosen as a reference material, in view of the weak dependence of its erosion rate on cavitation qualitative features. Therefore the local load value could have been extracted from the eroded surface profile of the Armco iron sample. Using the example of TiN coating analysis on stainless steel and VT3-1 titanium alloy, the time dependencies and threshold characteristics of their resistance were determined depending on the parameter of the density of the supplied energy.

Characterization of the lattice preferred orientation of hcp iron transformed from the single-crystal bcc phase in situ at high pressures up to 80 GPa

Studying the anisotropic physical properties of hexagonal closed-packed (hcp) iron is essential for understanding the properties of the Earth’s inner core related to the preferred orientation of the inner core materials suggested by seismic observations. Investigating the anisotropic physical properties of hcp iron requires (1) the synthesis of hcp iron samples that exhibit several distinctive types of strong lattice preferred orientation (LPO) and (2) the quantitative LPO analysis of the samples. Here, we report the distinctive LPO of hcp iron produced from single-crystal body-centered cubic (bcc) iron compressed along three different crystallographic orientations ([100], [110], and [111]) in a diamond anvil cell based on synchrotron multiangle X-ray diffraction measurements up to 80 GPa and 300 K. The orientation relationships between hcp iron and bcc iron are consistent with the Burgers orientation relationship with variant selection. We show that the present method is a way to synthesize hcp iron with strong and characteristic LPO, which is beneficial for experimentally evaluating the anisotropic physical properties of hcp iron.

Integrating selective flocculation techniques for enhanced efficiency in manufacturing processes: A novel approach through artificial neural network modeling

The use of medium and low-grade iron ore is gradually becoming more important due to the depletion of high-grade iron ore reserves and stringent environmental acts/rules. Slimes from iron ore washing were discarded in tailing dams; however, there is currently consideration for recovering iron values from ultra-fines as well. There are enormous fine dumps that are still unutilised. Hence, this study attempt to delve the optimization of iron ore slimes an indeed requirement for manufacturing and design in industries. Leveraging a flocculation process, coupled with the implementation of an Artificial Neural Network (ANN) predictive model, the Kiriburu processing plant serves as the primary source for iron ore slime samples. Chemical analyses of the collected iron samples reveal a composition featuring 58.24 % iron content, 3.47 % Al2O3, 4.72 % SiO2, and 5.18 % LOI (Loss on Ignition). The investigation explores the performance of the flocculation technique under varying pH levels, different pulp densities, and diverse flocculant dosages. Furthermore, the varying parameters selected are pH from 6 to 11, pulp density from 1 % to 15 %, and flocculant dose from 0.03 to 0.27 mg/g. The study's findings showcase a substantial improvement in the Fe grade of iron ore, escalating from 58.24 % to 66.12 %, with an impressive recovery rate of 82.54 % achieved using a flocculant dosage of 0.09 mg/g at pH 10. Additionally, a performance assessment of the selective flocculation method for iron ore slimes is conducted using an ANN predictive model, with recovery as the pivotal parameter. The input parameters for this model encompass pH, pulp density, and flocculant dosages. Employing a three-layer ANN model with a 3–3–1 architecture and utilizing feed-forward back propagation, the study demonstrates a close alignment between predicted values and experimental data, confirming the model's effectiveness for practical manufacturing applications. Information regarding the potential applications of the model's iron ore slime beneficiation efficacy for the manufacturing sector should be considered. This could entail lower waste, more effectiveness, or cost savings. Emphasise any possible ramifications for sustainability or the environment that would make the study pertinent in a larger perspective.

Effect of Gentamicin Sulfate and Polymeric Polyethylene Glycol Coating on the Degradation and Cytotoxicity of Iron-Based Biomaterials.

The work is focused on the degradation, cytotoxicity, and antibacterial properties, of iron-based biomaterials with a bioactive coating layer. The foam and the compact iron samples were coated with a polyethylene glycol (PEG) polymer layer without and with gentamicin sulfate (PEG + Ge). The corrosion properties of coated and uncoated samples were studied using the degradation testing in Hanks' solution at 37 °C. The electrochemical and static immersion corrosion tests revealed that the PEG-coated samples corroded faster than samples with the bioactive PEG + Ge coating and uncoated samples. The foam samples corroded faster compared with the compact samples. To determine the cytotoxicity, cell viability was monitored in the presence of porous foam and compact iron samples. The antibacterial activity of the samples with PEG and PEG + Ge against Escherichia coli CCM 3954 and Staphylococcus aureus CCM 4223 strains was also tested. Tested PEG + Ge samples showed significant antibacterial activity against both bacterial strains. Therefore, the biodegradable iron-based materials with a bioactive coating could be a suitable successor to the metal materials studied thus far as well as the materials used in the field of medicine.

In-situ resistance mapping of surface corrosion of iron using contact-mode carbon fibre as potentiometric tip

Scanning Probe Microscopy (SPM) has recently gained significant attention from both scientists and engineers for its unique capability to investigate localized corrosion phenomena. This paper introduces a novel application of SPM that offers a unique in-situ means to quantitatively evaluate the resistance of a spontaneously formed oxide layer on the conductive surface of an uncoated iron sample. This approach involved rastering a thin carbon fibre on the iron sample immersed on a corrosive medium while maintaining direct contact between the tip of the carbon fibre and the studied surface. Depending on the resistance between the tip and the sample, the measured voltage proportionally varied between 0 and the potential of the potentiometric circuit formed by the iron sample, the electrolyte and the carbon fibre. Through the application of the voltage divider formula, the measured potential map was transformed into a resistance map. This process allowed us to render a visual representation of the resistance distribution across the surface of the iron sample, providing some insights into the properties of the oxide layer.

Development of a laser-driven shock compression platform for time-resolved XRD experiments at the ID09 beamline of the European Synchrotron Radiation Facility

ABSTRACT We present a newly developed laser-driven shock compression platform at the ID09 beamline of the European Synchrotron Radiation Facility (ESRF). This platform combines a custom high-power EKSPLA laser with ESRF's high-energy X-ray pulses to perform in situ, time-resolved X-ray diffraction (XRD) measurements in materials under well characterized, moderate pressure (up to 1 Mbar) and short-duration shock waves. Its purpose is to serve as a shock driver to study materials under dynamic pressure, focusing on phase transitions in condensed matter. We provide a detailed description of this platform's design and functionalities, along with preliminary experimental results obtained from iron and tin samples subjected to shock compression. These results not only demonstrate the platform's ability to acquire high-quality X-ray diffraction data but also highlight its potential for advancing research in material science and high-energy-density physics.

Experimental Simulation of Directional Crystallization of SiMo Cast Iron Alloyed with Al and Cr.

SiMo ductile cast iron combines ease of part fabrication with good mechanical properties, including a usable plasticity range. Its poor corrosion resistance inherited from grey cast iron could be alleviated through alloying with Al or Cr additions capable of forming a dense oxide scale protecting the substrate. However, the presence of Al and Cr in cast iron tends to make the material brittle, and their optimum alloying additions need to be studied further. The present work was aimed at investigating the effect of crystallization rates on microstructure changes during directional crystallization of SiMo-type alloys with up to 3.5% Al and 2.4% Cr. The experiment was performed using the Bridgman-Stockbarger method. The tubular crucible was transferred from the hot section to cold section at rates ranging from 5 mm/h to 30 mm/h with a 4/5 crucible length and then quenched. The introduced Al promoted graphitization up to a point, wherein, at the highest applied addition, the graphite precipitation preceded crystallization of the rest of the melt. A rising level of Cr in these alloys from 1% to 2.4% resulted in the formation of low and high contents of pearlite, respectively. The higher crystallization rates proved effective in increasing the ferrite content at the expense of pearlite. In the investigated cast iron samples with smaller applied alloying additions, Widmanstätten ferrite or ausferrite, i.e., fine acircular phase, were often found. The switch from directional crystallization to quenching caused a transition from a liquid to solid state, which started with nucleation of islands of fine austenite dendrites with chunky graphite eutectic separating them. As these islands expanded, they pushed alloying additions to their sides, promoting carbide or pearlite formation in these places and forming a super-cell-like structure. The performed experiments helped gather information concerning the sensitivity of the microstructure of SiMo cast iron modified with Al and Cr to crystallization rates prevailing in heavy cast structures.

Nanoindentation responses of Fe–Cr alloys from room temperature to 600 °C

In this work, the evolution of nanomechanical properties was studied systematically as a function of temperature, chemical, and microstructural complexity of different Fe-based alloys. Experiments were performed at different temperatures (room temperature, 200 °C, 400 °C, 600 °C) using the nanoindentation technique on low activation Fe9Cr–1WVTa (Eurofer97), model Fe–9Cr–NiSiP, Fe–9Cr alloys, and pure iron samples, followed by microstructural observations. The results show varying softening and hardening effects depending on the experimental temperature, demonstrating Portevin-Le-Chatelier effect, i.e., dynamic strain aging phenomenon in model alloys. Sources of the dynamic strain aging instabilities were traced back to the interaction between dislocations and alloying elements such as interstitial carbon and substitutional chromium. The materials undergo dynamic recovery and recrystallization below the regions of high-temperature indentation depending on the pre-indentation dislocation density and the alloy composition. Our findings help in the understanding of the structure and mechanical property relationship in complex Eurofer97 alloy at high-temperatures for potential nuclear applications as structural materials.

A HOMEMADE SEMIAUTOMATIC GRAPHITIZATION DEVICE FOR AMS 14C DATING AT NTUAMS LAB

ABSTRACT A low-cost and computer-controlled graphitization system connected to an elemental analyzer (EA) has been designed and built at the NTUAMS Lab. This semiautomatic system equips 6-unit reactors for the graphitization of CO2 with H2 on the iron catalyst. The entire procedure takes about 7 hours for iron conditioning, sample combustion and loading, and graphitization. The system can produce good-quality graphite for samples containing 0.5–1.6 mg carbon mass, with the pressure yield of graphitization ranging from 57.7% to 87.1%. The average values of OXI and OXII agree well with the consensus value, but the result of ANU sucrose was observed to be slightly higher than the reported one. The background samples of anthracite over ten months yielded an average of 0.38±0.10 pMC (n=21) corresponding to a 14C age of 45 kyr BP. Intercomparison samples L and M of FIRI exhibit that the measured 14C ages are almost identical to the consensus values and have a small spread in these values. The system has been carrying out graphitization for total organic carbon (TOC) of peat samples, and providing a more efficient and convenient way for AMS 14C dating.

Structural integrity and hybrid ANFIS-PSO modeling of the corrosion rate of ductile irons in different environments

Ductile iron (DI) samples were immersed in near-neutral, alkaline sodium hydroxide (NaOH), and sodium chloride (NaCl) environments for 180 days. The influence of microstructure on the corrosion resistance of three DI specimens was investigated. Microstructures, electrochemical measurements, and the characterization of the corroded surfaces were analyzed. The experimental results from this study were used to validate a model generated from hybrid adaptive neuro-fuzzy inferences system-particle swarm optimization (ANFIS-PSO) algorithms. The hybrid ANFIS-PSO modelling technique was improvised for a detailed evaluation of corrosion rate of ductile cast iron materials in different environments. The integrated hybrid ANFIS-PSO model revealed a sharp rise in localized corrosion caused by chloride-induced structural deterioration at the nanoscale for some of the grains. The performance results revealed that the fuzzy c-mean (FCM) clustering outperformed other clustering approach in the neuro-fuzzy model. Accuracy values of 92.9% and 93.7% were recorded for the training phase of ANFIS-FCM and ANFIS-PSO-FCM respectively for corrosion rates. The percentage error of the ANFIS-PSO predictions is significantly lower than the ANFIS-standalone prediction. This shows that the ANFIS-PSO with FCM approach is a better model for predicting corrosion rates. This will contribute to the body of knowledge for ductile iron, corrosion, and corrosion modelling using machine learning.

Spatial distribution of drinking, irrigation water quality, and health risk indices of high-altitude lakes

High-altitude lakes (HAL) play a key role in several ecological services of the environment by managing the water supply and flood control. The slow rate of inflowing contaminant circulation results in a buildup of higher levels of contamination level and makes these lakes more vulnerable. The present study focused on determining HAL's water quality parameters (WQP) in the Swat District, northern Pakistan. Water samples (n = 32) were collected and analyzed for basic parameters, anions, and potentially harmful elements (PHE). Results of examined parameters were noted under WHO threshold values, except for a few samples of iron (Fe) and arsenic (As). The concentrations of WQP in HAL were used to calculate drinking and irrigation water quality indices (WQI). Results revealed that the water of HAL was excellent and suitable for drinking and irrigation purposes. Gibbs plot and Piper model were used to identify water as a mixed type and source characterization of rock dominance. Water quality data were used for average daily dose (ADD) and hazard quotient (HQ) to find HAL water's potential health risks. The highest ADD value of 188 μg/kg-day was observed for nitrate (NO3), and the lowest of 0.31 μg/kg-day was noted for arsenic (As). However, maximum HQ values of 0.18 were reported for As and were observed to be less than the threshold of 1. Therefore, based on water quality, the HAL was recommended for use in drinking, domestic, and irrigation purposes.

Effect of corrosion rate on pipe material's chemical composition in water distribution network

This study investigated the effect of corrosion on the galvanized iron due to exposure to supply water in the water distribution network. A galvanized iron sample was installed in the distribution network pipeline for 315 days. Water samples were tested for their physicochemical characteristics. The corrosion rate of galvanized iron was also determined. XRD analysis of the by-products was carried out after exposure. The EDX analysis of the galvanized iron sample was carried out without and after exposure to supply water. As a result of the experiment, the sample material's composition changed from C 11.0 % to 7.7 %, O 14.0 % to 25.3 %, Fe 10.8 % to 65.8 %, and Zn 63.2 % to 0.6 % by weight. It was illustrated by the XRD graph that when Zn reacted with supply water, by-products of Zinc Sulphate Hydroxide, Zinc Oxide, Zinc Sulphate, or Zinc Chloride were produced. It was also noticed that Zn was reduced by 62.60 %. SEM analysis indicates that Zinc coating has disappeared from the top layer. So, it can be concluded that after exposure to supply water in the distribution network, Zn reduced almost to zero. It indicates due to corrosion Zn coating was disappears from the pipe.

Исследование влияния комбинированного модификатора из отходов кремниевого производства на свойства серых чугунов

Introduction. During the metallurgical production of silicon, waste is generated that accumulates in dumps, causing harm to the environment. Disposal and recycling of solid waste from silicon production is especially important because They contain important chemical compounds (silicon dioxide, silicon carbide, carbon nanotubes) that can be used in other industries, which will bring greater economic value. Considering the possibilities for extracting these useful components from silicon production waste, it is necessary to bring processing technologies to the stage of widespread practical application. Therefore, the development of a special waste processing technology to obtain a useful product in the form of a composition of silicon dioxide and silicon carbide remains an urgent problem. Purpose of the work: to study the formation of the morphological form of graphite with the introduction of nano-modifiers from silicon production waste. The work examined samples of gray cast iron after modification with a combined modifier obtained from silicon production waste. The research methods are mechanical tests for statistical tension, analysis of the chemical composition and metallographic studies. Results and discussion. It was revealed that the mechanical properties of gray cast iron increased by 30-50% after modification with a combined modifier, compared with witness samples. The morphology of graphite is an important parameter affecting the properties of cast iron. It has been established that during the modification process the morphology of graphite changes from lamellar to vermicular. Specimens of gray cast iron with vermicular form of graphite have high strength values compared to specimens of gray cast iron with lamellar form of graphite. The presented results confirm the promise of the developed approach aimed at obtaining new classes of modifiers and products made of gray cast iron with a high range of mechanical properties.