Iron Components Research Articles

LAM-DED Process for Repair and Maintenance of Cast Iron Components using Metallic Powder Alloys

Laser Additive Manufacturing Directed Energy Deposition (LAM-DED) technology is a promising process for the maintenance and repair of ductile cast iron components. LAM-DED can produce high quality results compared to conventional welding processes. This is due to a narrow and specific heat-affected zone (HAZ) and a strong interface between the base material and filler, caused by reduced heat input with the high energy density. This method also maintains the composition of the clad material in the repair zone and deposits small volumes of filler in specific areas.This paper presents a succinct review of metallic powder alloys as cladding materials for the repair and maintenance of cast iron components. It introduces commercial additive manufacturing (AM) powders used as filler materials for laser cladding of cast iron components, discussing the evolution in microstructure, phase transformation, mechanical properties, and processing issues. This paper summarizes LAM-DED of AM powders for cast iron components and will be a helpful reference for researchers and industry professionals. Key words: LAM-DED process, Laser cladding, Repair & maintenance, Cast iron, AM metal powder

Synthesis of Zeolite from Electrolytic Manganese Residue: Investigation on the Variation of the Propert of Zeolite during the Conversion Process

In this study, the cation exchange capacity (CEC); phosphate immobilization capacity (PIC); and chemical, mineralogical, and morphological characteristics of the synthesized electrolytic manganese residue (EMR) based zeolite (EMRZ) were systematically investigated during the synthesis process. By varying synthesis conditions, different zeolites with different purity were generated, and it was proven that a lower Si/Al ratio, relatively higher temperature, and relatively longer time favored the synthesis of zeolite. Besides, the decrease in Si/Al ratio and variation within a narrow range contributed to the forming of Al rich zeolite. Meanwhile, the discrepancy of CEC and PIC of EMRZ contributed to the case in which various elements in EMRZ do have an impact on CEC (Na2O element and type of zeolite) and PIC (calcium and iron components). Moreover, the synthesis conditions were optimized and evaluated in terms of their CEC, specific surface area (SSA), and crystallinity. According to the analyses using XRD, FE-SEM, and XRF and the SSA analysis, the EMRZ (mainly zeolite A, LTA) synthesized under the optimum conditions (initial Si/Al ratio of 1.5, at 100°C, for 1.5 h) was found to be mainly composed of highly ordered cubic zeolites A crystals with a Si/Al ratio of 1.02 and a CEC of 3.45 meq/g.

Quantitative µ-CT Analysis of Scale Topology Formed During Oxidation of High SiMo Cast Iron

High SiMo cast iron components in automotive exhaust systems are exposed to high-temperature oxidation over time. Quantitative analysis of formed oxide scale is therefore important for the assessment of a component durability. The brittle nature of multilayered scale and thermal stress limits capture of a true topology using traditional 2D destructive cut and polish methods. In this study, nondestructive high spatial-resolution 3D µCT analysis was performed on 2.90-mm-diameter oxidized specimens which permitted direct observation with 3.5 µm pixel resolution. The specimens were oxidized in three sequential time steps for a total 100 h at 700 °C and 800 °C in air and combustion gas atmospheres. A MATLAB-coded algorithm was used to quantify the topology, thickness variation in internal and external scale layers, and scale/metal interface unevenness. Scale topology was linked to oxidation temperature and gas atmosphere. A water vapor environment increases scale/metal interface unevenness and scale layer thickness irregularity which were related to an accelerated oxidation rate.

Simultaneous recording and marking of brain microstructures

The vast majority of techniques to study the physiology of the nervous system involve inserting probes into the brain for stimulation, recording, or sampling. Research is increasingly uncovering the fine microstructure of the brain, each of its regions with dedicated functions. Accurate knowledge of the placement of probes interrogating these regions is critical. We have developed a customizable concentric marking electrode (CME) consisting of an iron core within a 125 μm-stainless steel (SS) sheath for co-localization of targeted regions in the brain. We used a dielectric layer stack of SiO2, Al2O3, SiO2 to electrically encapsulate the iron core and minimize exposure area to avoid significant increases in inflammatory response triggered by the probes. The CME can record multi-neuronal extracellular firing patterns. Appropriate electrical polarity of the iron and SS components controls the deposition of iron microdeposits on brain tissue. We show that in vivo labels by this method can be as small as 100 μm, visible via noninvasive magnetic resonance imaging (MRI) as well as post-mortem histology, and illustrate how deposit size can be tuned by varying stimulus parameters. We targeted the CA3 area of the hippocampus in adult rats and demonstrate that iron microdeposits are remarkably stable and persist up to 10 months post-deposition. Using a single probe for recording and marking avoids inaccuracies with re-insertion of separate probes and utilizes iron microdeposits as valuable fiducial markers in vivo and ex vivo.

Characterization of Potential Micrometeorites by Synchrotron Analysis

Micrometeorites (MMs) are small particles that account for most of the extraterrestrial material deposited on Earth. Synchrotron X-ray fluorescence and diffraction allowed for chemical and mineral characterization to distinguish MM from atmospheric particulate. The relative components of iron, nickel, and other elements were considered in the identification of ferrous MM while high amounts of titanium were considered an indication that the particles were of atmospheric origin. Out of 100 samples collected by high school students and teachers, eight were taken to a synchrotron for analysis. Of those eight, three exhibited extraterrestrial compositions. X-ray absorption near-edge structure analysis revealed that the same three samples contained sulfide, the main sulfur form constituent in MM. X-ray microdiffraction analysis showed the presence of the minerals pentlandite and forsterite. Collectively, these results support the extraterrestrial nature of the three particles.

Altered iron metabolism in cystic fibrosis macrophages: the impact of CFTR modulators and implications for Pseudomonas aeruginosa survival

Cystic fibrosis (CF) is a genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in chronic bacterial lung infections and tissue damage. CF macrophages exhibit reduced bacterial killing and increased inflammatory signaling. Iron is elevated in the CF lung and is a critical nutrient for bacteria, including the common CF pathogen Pseudomonas aeruginosa (Pa). While macrophages are a key regulatory component of extracellular iron, iron metabolism has yet to be characterized in human CF macrophages. Secreted and total protein levels were analyzed in non-CF and F508del/F508del CF monocyte derived macrophages (MDMs) with and without clinically approved CFTR modulators ivacaftor/lumacaftor. CF macrophage transferrin receptor 1 (TfR1) was reduced with ivacaftor/lumacaftor treatment. When activated with LPS, CF macrophage expressed reduced ferroportin (Fpn). After the addition of exogenous iron, total iron was elevated in conditioned media from CF MDMs and reduced in conditioned media from ivacaftor/lumacaftor treated CF MDMs. Pa biofilm formation and viability were elevated in conditioned media from CF MDMs and biofilm formation was reduced in the presence of conditioned media from ivacaftor/lumacaftor treated CF MDMs. Defects in iron metabolism observed in this study may inform host–pathogen interactions between CF macrophages and Pa.

The Mechanical Properties of Ductile Iron at Intermediate Temperatures: The Effect of Silicon Content and Pearlite Fraction

The use of ductile irons in thermo-mechanically loaded components is increasing, necessitating more knowledge of material properties at intermediate temperatures. A study of the mechanical properties of ductile irons at intermediate temperatures was conducted, investigating the effect of different pearlite fractions along with silicon content tests in fully ferritic microstructures. The effect of the pearlite fraction and silicon content on tensile and yield strength was measured at different temperatures, from room temperature to 450 °C. Models of tensile and yield strengths were developed based on those measurements. These resulting regression models were tested with data from the literature. Such models can be applied in various design tools, such as FEM calculations and in the optimisation of thermally and cyclic loaded ductile iron components.

Effects of quench-tempering and laser hardening treatment on wear resistance of gray cast iron

The present research studied the combined effects of quench-tempering and laser surface hardening treatments on wear behavior of gray cast iron, and compared results with conventional austempered gray cast iron. Four tempering temperatures of 316 °C (600 °F), 399 °C (750 °F), 482 °C (900 °F) or 552 °C (1025 °F) with a constant holding time of 60 min and four austempering temperatures of 232 °C (450 °F), 288 °C (550 °F), 343 °C (650 °F) or 399 °C (750 °F) with a constant holding time of 120 min were utilized in the heat treatment design. The wear tests were carried out on a universal mechanical tribometer with a reciprocating ball-on-plate sliding configuration. Also, the microstructure, micro-hardness profiles and worn tracks were examined. Through this work, it was found that three zones existed under the laser hardened surface. Zone 1 was the laser hardened zone containing ledeburite with hardness of approximately 68HRC. Zone 2 was the heat affected zone containing the martensite with hardness of approximately 66HRC. Zone 3 was the substrate with hardness ranging from 42.1 to 24.8HRC. In the sliding wear tests, the quench-tempering treatment only resulted in higher wear resistance of gray cast iron when compared with untreated specimens, but lower wear resistance than that of austempered gray cast iron under similar macro-hardness. The wear performance of the quench-tempered gray cast iron was enhanced after receiving the laser surface hardening treatment. Finally, the laser hardened and quench-tempered gray cast iron with tempering temperature of 552 °C showed similar mass loss due to wear as austempered gray cast iron with an austempering temperature of 232 °C. By observing the worn surfaces, the laser hardened regions could effectively inhibit the formation and propagation of cracks developed within the substrate regions. In addition, the substrate with low hardness in laser hardened and quench-tempered gray cast iron may provide enhanced ductility and toughness for gray cast iron engineering components. The results obtained in this research have significant value in selecting the optimum heat treatment process for laser hardened gray cast iron components.

Contributions and mechanisms of components in modified biochar to adsorb cadmium in aqueous solution

Recently, researchers have carried out a large number of studies on the adsorption of heavy metals by modified biochar, but there have been fewer explorations of the contributions and mechanisms of components in biochar composites on heavy metals adsorption. In this paper, the biochar was modified by Fe2+/Fe3+ and NaOH, and a further analysis of the adsorption of cadmium on the new biochar was conducted. It was found that (1) the adsorption capacity for cadmium of the modified biochar (M85) was 406.46 mg/g, which was 16 times that of the original biochar (C800); (2) the increased adsorption of cadmium onto the modified biochar had little correlation with the specific surface area, and the pure iron component was not the decisive factor for the huge adsorption capacity; and (3) the modified biochar was a kind of composite material with special construction, where the C-O-Fe structure that formed on its surface was the main reason for the sharp increase in adsorption. Among the iron components, iron oxides (Fe3O4, γ-Fe2O3 and Fe-O-Fe), iron-containing functional groups (-Fe-R-COOH and Fe-R-OH, etc.) and the mineral crystal XiFeYjOk reacted with the cadmium ion in aqueous solution to exchange, form complexes and precipitate, achieving the purpose of fixing the heavy metal. In addition, the aromatic structure C=Cπ can also adsorb Cd2+ to generate C=Cπ-Cd.

The Effect of Yttrium on the Distributions of Elements in Different Phase Structures and Properties of Chromium White Cast Iron

The research results on the effect of small additions of yttrium 0-0.3 wt.% on the structure, hardness, microhardness and distribution of elements in various structural components of chromium white cast iron are presented. It has been established that small additions of yttrium contribute to the grain refinement of the carbide phase and the formation of trigonal chromium carbide (Fe,Cr)7C3 in the structure of chromium white cast iron.

Ciao1 interacts with Crumbs and Xpd to regulate organ growth in Drosophila

Ciao1 is a component of the cytosolic iron–sulfur cluster assembly (CIA) complex along with MMS19 and MIP18. Xeroderma pigmentosum group D (XPD), a DNA helicase involved in regulation of cell cycle and transcription, is a CIA target for iron–sulfur (Fe/S) modification. In vivo function of Ciao1 and Xpd in developing animals has been rarely studied. Here, we reveal that Ciao1 interacts with Crumbs (Crb), Galla, and Xpd to regulate organ growth in Drosophila. Abnormal growth of eye by overexpressing Crb intracellular domain (Crbintra) is suppressed by reducing the Ciao1 level. Loss of Ciao1 or Xpd causes similar impairment in organ growth. RNAi knockdown of both Ciao1 and Xpd show similar phenotypes as Ciao1 or Xpd RNAi alone, suggesting their function in a pathway. Growth defects caused by Ciao1 RNAi are suppressed by overexpression of Xpd. Ciao1 physically interacts with Crbintra, Galla, and Xpd, supporting their genetic interactions. Remarkably, Xpd RNAi defects can also be suppressed by Ciao1 overexpression, implying a mutual regulation between the two genes. Ciao1 mutant clones in imaginal discs show decreased levels of Cyclin E (CycE) and death-associated inhibitor of apoptosis 1 (Diap1). Xpd mutant clones share the similar reduction of CycE and Diap1. Consequently, knockdown of Ciao1 and Xpd by RNAi show increased apoptotic cell death. Further, CycE overexpression is sufficient to restore the growth defects from Ciao1 RNAi or Xpd RNAi. Interestingly, Diap1 overexpression in Ciao1 mutant clones induces CycE expression, suggesting that reduced CycE in Ciao1 mutant cells is secondary to loss of Diap1. Taken together, this study reveals new roles of Ciao1 and Xpd in cell survival and growth through regulating Diap1 level during organ development.

Procedure for the Precipitation of Iron, Chromium, Molybdenum, and Tungsten in the Determination of Arsenic and Antimony in Alloy Steels

A possibility of the separation of trace amounts of arsenic and antimony and macroquantities iron, chromium, molybdenum, and tungsten by the precipitation of the latter was investigated; regularities of the coprecipitation of arsenic and antimony are studied. The coprecipitation of arsenic and antimony in the precipitation of iron, chromium, molybdenum, and tungsten can be inhibited by introducing a certain amount of hydrofluoric acid. This decreases the specific surface and porosity of the precipitates and inhibits the coprecipitation process. A method is developed for the simultaneous determination of arsenic and antimony in alloy steels by inductively coupled plasma atomic emission spectrometry with preliminary separation of the main components of iron, chromium, molybdenum, and tungsten.

Features of the Anode Behavior of the Combined Iron–Titanium Electrode in Halide-Containing Electrolytes

The electrochemical behavior of a combined iron–titanium electrode in aqueous halide solutions has been studied. The distribution of the potential on the surface of metals of the combined anode under external polarization is shown. The possibility of changing the rate of anodic dissolution of titanium and iron component of the combined electrode with a change in the current density and ratio of the areas of electrodes is established.

Electro-mechanical modelling of the iron force distribution with superconducting magnets

This paper shows the influence of the local magnetic forces on the mechanical analysis of a superconducting dipole magnet employing Nb3Sn technology. On high field magnets, the iron yoke has several functions: (1) magnetically, it increases the magnetic field in the bore and it has a shielding function; (2) mechanically, iron helps on the coil pre-load, transferring the mechanical forces provided by the external support structure. In many Nb3Sn magnets for particle accelerators, the cable is wound around an iron piece. As a consequence, the magnetic force on the iron can play an important role on the coil stress. The magnetic forces on the iron components can be computed using several different methods and the goal of this paper is to compare three expressions for the Maxwell stress tensor to compute local magnetic forces on iron considering a B-H curve. The influence of these forces on the mechanical behavior of the magnets is then analyzed, taking into account the uncertainties in determining their correct distribution. To achieve this goal, a numerical tool to perform Finite Element Analysis (FEA) was developed using vector potential formulation with first order nodal elements. The solution obtained from the magneto-static problem was used to calculate and compare the magnetic force distribution. The contributions from the Lorentz forces on coils are also taken into account in the mechanical analysis and are compared to the ones computed by using the Maxwell stress tensor on coils.

An investigation on oxidation behaviour of high velocity oxy-fuel sprayed Inconel718-Al2O3 composite coatings

The grey cast iron (GCI) components such as exhaust manifolds, turbocharger housings, and furnace parts are subjected to high temperature oxidation. GCI alone cannot retain its mechanical strength at elevated temperatures due to this high temperature oxidation. The composite coatings can effectively be used to counter the high temperature oxidation induced degradation of the GCI components. In the present work, Inconel718-Al2O3 (INAL) based composite coatings were deposited on GCI substrate by using high velocity oxy-fuel (HVOF) spray process. The effects of varying Al2O3 contents (10, 20, and 30 wt%) on the microstructure, porosity, micro-hardness, and oxidation resistance of Inconel718 (IN718) coating were studied. High temperature cyclic oxidation testing was conducted on these coatings and bare GCI substrate in a laboratory tube furnace at 900 °C in air. The kinetics of oxidation were determined by using weight change measurements of the bare GCI and coated specimens at regular intervals for a duration of 50 h. The important phases present in the feedstock powders, deposited coatings, and the oxidised specimens were identified by using X-ray diffraction (XRD). The surface morphology and chemical compositions of the coated and tested specimens were determined by using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microhardness of IN718 coating was found to be improved with an increase in alumina contents and a maximum average hardness of about 801 ± 40 HV0.2 was observed in case of IN718-30 wt% Al2O3 composite coating. The increase in alumina contents resulted in an increase in porosity and proportion of un-melted feedstock powder particles in the IN718 coating. The coating with 30 wt% alumina contents showed the maximum resistance to oxidation with a minimum weight gain of 1.29 mg/cm2 as compared to the other coatings. The improved oxidation of composite coatings can be attributed to the formation of protective phases such as Al2O3, NiCr2O4 and Cr2O3 on its exposed surface during the hot corrosion condition.

The Environmentally Friendly Possibility of Using Recycled Plastic from Electrical Waste to Rainwater Detention

In view of the dynamic development of electrical and electronic equipment and the reduction of its lifetime, the share of electronic equipment that has become waste has risen. In proportion to this situation, there is a constant improvement in separating industrial methods aimed at removing hazardous components of electrical waste (PCBs containing condensers, mercury switches or asbestos insulation). Another commodity, and economically more interesting, is the obtaining of the utility component of the waste iron and non-ferrous metals. After the separation of the interesting components what remains is a heterogeneous mixture of plastic pulp, which is usually landfilled or incinerated in the waste incinerator. This leads to the loss of valuable material, which could be further exploited. The paper deals with the issue of the disposal of plastics from electrical waste and its subsequent use as plastic pulp, which can be used to fill the rainwater detention reservoir.

Microstructural Adjustment of the Degenerated Graphite Layer in Ductile Iron for Targeted Evaluation on the Fatigue Properties

Graphite degeneration is the most prominent microstructural defect in the casting skin of ductile iron. Induced by either sulfur or oxygen contained in the molding material, its occurrence can be observed in a large range of iron castings, having substantial negative influences on the mechanical properties, especially fatigue resistance. Previous investigations predominately focused on the influence of the degenerated graphite layer, while accompanying changes of the iron matrix were neglected. The superposition of these effects hinders the evaluation of casting skin defects in state-of-the-art design of ductile iron components. The presented solution utilizes an experimental procedure, which enables the production of specimens with specific, individual microstructural configurations in the casting skin. This approach is based on the application of a modified sand core coating. By adding sulfurizing additives to the coating and adjusting its binder content and viscosity, a predominately homogeneous degenerated layer of 0.5 mm thickness was obtained. Using specific heat treatment steps assured a fully ferritic or pearlitic iron matrix, isolating the degenerated layer as the main microstructural defect. Fatigue testing of these specimens will further enable the numerical evaluation of the fatigue resistance in dependence of the casting skin microstructure.

Photo-oxidation of particle phase iron species dominates the generation of reactive oxygen species in secondary aerosol

This study presents an experimental investigation on the photochemical transformation of iron species in aerosol including dissolution of insoluble iron species into soluble fraction, and soluble ferric oxidation to ferrous form. This process has significantly contributed to the aerosol oxidative potential in generation of reactive oxygen species (ROS). We conducted both laboratory experiment of UV irradiation and real world solar irradiation on large variation of aerosol samples for the characterization of iron speciation in insoluble and soluble fractions to investigate their transformation under photooxidation process. The results showed that the real world solar irradiation significantly increased the soluble Fe(II) fraction, and this is corroborated by laboratory simulation of UV irradiation showing increasing soluble Fe(II) fraction with elongating aging time. The results further exhibited that the dissolution of iron component into soluble fraction was a dominant process, followed by the conversion of soluble ferric to ferrous ions. Further, the study confirmed that the oxidative potential of particulate matter (PM) is attributed dominantly to the abundance of transition metals, i.e. Fe, and the incremental ROS generation after photochemical process is attributed largely to the transformation of solid phase iron species to soluble Fe(II). The results suggest that transition metals, for example by iron in this study, play an important role in secondary aerosol process.

Coating properties, energy consumption, and cost analysis of the induction cladding process

Induction cladding may provide an innovative approach for repairing or remanufacturing grey cast iron components. A complete analysis of the induction cladding technology is important for promoting practical applications. Three commonly used alloy powders were chosen for the research, and the induction cladding technology was thoroughly investigated from three aspects: the coating properties, energy consumption, and unit cost. The porosity, microhardness, and frictional performance were defined as the coating properties. An energy consumption measurement system was set up to quantitatively assess the energy consumption during the induction cladding process. Finally, the unit costs of alloy powders used for the induction cladding were assessed. The results suggest that the Ni-based coating possesses the best coating properties except for a porosity that is relatively high (but still lower than that of coatings fabricated using other surface coating technologies). The microhardness values of Ni-based and Fe-based coatings are higher than that of the Co-based coating, and the Ni-based coating has the lowest coefficient of friction and smallest wear volume. The energy consumptions per unit coating of the three alloy powders are similar, although that of the Fe-based coating is slightly lower. The unit cost of the Co-based alloy powder is approximately three times higher than that of Ni-based and Fe-based alloy powders. Therefore, based on comprehensive assessment, the Ni-based alloy coating shows the best performance.

Equations of state, phase relations, and oxygen fugacity of the Ru-RuO2 buffer at high pressures and temperatures

Abstract Experimental studies and measurements of inclusions in diamonds show that ferric iron components are increasingly stabilized with depth in the mantle. To determine the thermodynamic stability of such components, their concentration needs to be measured at known oxygen fugacities. The metal-oxide pair Ru and RuO2 are ideal as an internal oxygen fugacity buffer in high-pressure experiments. Both phases remain solid to high temperatures and react minimally with silicates, only exchanging oxygen. To calculate oxygen fugacities at high pressure and temperature, however, requires information on the phase relations and equation of state properties of the solid phases. We have made in situ synchrotron X-ray diffraction measurements in a multi-anvil press on mixtures of Ru and RuO2 to 19.4 GPa and 1473 K with which we have determined phase relations of the RuO2 phases and derived thermal equations of state (EoS) parameters for both Ru and RuO2. Rutile-structured RuO2 was found to undergo two phase transformations, first at ~7 GPa to an orthorhombic structure and then above 12 GPa to a cubic structure. The phase boundary of the cubic phase was constrained for the first time at high pressure and temperature. We have derived a continuous Gibbs free energy expression for the tetragonal and orthorhombic phases of RuO2 by fitting the second-order phase transition boundary and P-V-T data for both phases, using a model based on Landau theory. The transition between the orthorhombic and cubic phases was then used along with EoS terms derived for both phases to determine a Gibbs free energy expression for the cubic phase. We have used these data to calculate the oxygen fugacity of the Ru + O2 = RuO2 equilibrium, which we have parameterized as a single polynomial across the stability fields of all three phases of RuO2. The expression is log10fO2(Ru – RuO2) = (7.782 – 0.00996P + 0.001932P2 – 3.76 × 10–5P3) + (–13 763 + 592P – 3.955P2)/T + (–1.05 × 106 – 4622P)/T2, which should be valid from room pressure up to 25 GPa and 773–2500 K, with an estimated uncertainty of 0.2 log units. Our calculated fO2 is shown to be up to 1 log unit lower than estimates that use previous expressions or ignore EoS terms.