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By K. S. Raja, B. McNall, B. Pesic

"High-level radioactive wastes are stored in large underground storage tanks made of low-carbon steel. The wastes consist of concentrated solutions of sodium nitrate (NaNO3) and sodium hydroxide (NaOH), and the radionuclides 137Cs, 99Tc, and 90Sr. The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV), which in turn modifies the kinetics of corrosion of the storage tank. To understand the influence of technetate ions on the corrosion of steel, electrochemical polarization studies of A 537 steel samples were carried out in 1 M NaNO3 + 0 .05 M S r(NO3)2 + 0.1 M NaOH with and without addition of HReO4 at different temperatures (24 – 85 °C). The concentration of HReO4 was varied from 0.014 – 0.04 M.INTRODUCTIONAqueous processing of spent nuclear materials generates a large amount of high-level radioactive wastes. The wastes are primarily salt solutions of sodium hydroxide and sodium nitrate which also contain fission products such as 137Cs, 99Tc, and 90Sr. Among the high level radioactive fission products, Tc-99 is of great importance because of its high concentration, long half-life (2.1 x 105 years), high solubility in geologic waters as technetate, and rapid diffusivity through the geologic systems. The solubility of technetate ions varies depending on the oxidizing conditions prevailing in the storage containers. High level radioactive wastes are stored in single shell or double shell tanks made of low carbon steels such as ASTM type A15, A516-70 and A537. Most of the available literature on corrosion of steel in simulated radio active waste environments pertains to nitrate induced stress corrosion cracking (Subramanian & Mickalonis, 2005). The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV). Corrosion of steel and formation of Fe(II) and Fe(III) will affect adsorption and reduction of Tc species. The radioactive species can irreversibly be sorbed on the steel surface by oxidation of Fe(II) to more stable Fe(III) and fixed as less soluble Tc(IV)/Fe(III). The solubility of Tc species is also affected by other factors such as dissolved oxygen, local pH, temperature etc. How the corrosion behavior of steel will be affected in the presence of Tc species is not clearly understood.Cartledge (Cartledge, 1960) demonstrated that passivation of iron can be achieved in the presence of oxygen along with suitable inhibitor ions/molecules of the general formula XO4 n-, such as pertechnetate (TcO4 -). The pertechnetate ion is univalent. Since it is derived from a strong acid, no buffering action can be expected from this ion. The redox potential of the reaction (1) is 0.738 VSHE (Pourbaix, 1974)."

Jan 1, 2012

By C. O. Bounds

The performance of AB5-type alloys for hydrogen absorption including the electrochemical absorption as an electrode for rechargeable batteries has been demonstrated' to be a complex function of the composition, microstructure and surface condition. The compositional studies have focused primarily on substitutions for Ni on the B-site (e.g. Co, Al, Mn, etc.). This current study examines the effect of rare earth substitutions for La on the A-site and considers both other "light" rare earths (Ce, Nd, Pr) and "heavy" rare earths (Dy, Sm, etc.).

Jan 1, 1997

By Richard L. Stowe, Donnie L. Ainsworth

The static, rapid, and shock-loading response of rock is of interest to many in the field of rock mechanics. For example, the effects of loading rates on strength and stress-strain characteristics of rock are quite important in defining input loading for use in the design of underground protective installations. Response data on rock subjected to shock loading over a wide range of pressures are also vital in the field of underground nuclear testing. In addition, material response is needed in design of shock-absorbing liners. A number of investigators have reported that ultimate compressive strength of rock increases with increased rates of loading.1-6 Wuerker3 stated that modulus of elasticity, obtained from sonic determinations, increased in some rocks by a factor as high as 4.5. It appears that only a limited amount of work has been done on comparing static modulus and modulus obtained from impact testing.6 Phillips4 showed that with increased rates of loading the deformation decreased. More recent work by Atchley and Furr5 showed that when moderate-strength concrete is stressed with increased loading rates, the axial strain at failure increased. One would expect this to occur if we think in terms of purely elastic materials. For example, if E is constant and maximum strength [amax], increases, the axial strain would also increase. However, in rock testing thus far we have worked almost exclusively with nonhomogeneous and inelastic rocks. From this fact alone the increase in axial strain with increased load application is noteworthy.

Jan 1, 1972

By D. Malhotra

The effect of some of the reagents, namely hydrocarbon oil, Syntex (sulfated coconut oil surfactant), pine oil, sodium silicate, and lime, used at the Climax mill on the recovery and grade of molybdenite and gangue minerals has been investigated experimentally using factorially designed test approach in the laboratory. The results of the investigation are presented in two dimensional plots. The lower additions of lime (equivalent to a pH of 8 to 8.5) were desirable for maximizing recovery subject to constraints on grade. Higher additions of pine oil improved recovery, but only at the expense of grade. A mathematical model of the objectives of an operating plant was formulated and optimum reagent conditions obtained.

Jan 1, 1977

By L. Shang

In conventional continuous hot rolling processes, metals are usually reheated to a temperature such that the workpiece will maintain appropriate hot working characteristics as it proceeds through the rolling mill, assuming that the temperature is continually decreasing. Metallurgically, reheating will reduce micro-segregation in the as-cast material, may increase the as-cast grain size and will affect any second phase particles present in the as-cast structure. All these changes can affect the hot working characteristics, and the final as-hot rolled microstructure. In order to study the effect of reheating on AZ31 magnesium alloy, a plate sample was cast in a water cooled copper mould and a series of compression tests was performed at a temperature of 350 °C, strain rate 0.01 5-1, and strains from 0.2 to 1.0, after different reheating schedules. It was found that there is no significant difference in flow behavior between the as-cast sample and all but one of the reheated ones. The reheat treatment of the 'anomalous' sample was a two stage heat treatment; it was first reheated to 450 °C, cooled to room temperature, then reheated to 350 °C. The effect on the flow curve was to increase the flow stress. This result may be related to changes in second phase particle characteristics.

Jan 1, 2006

By K. J. Shoop

An analysis of an iron ore processing plant showed that its performance was affected by seasonal temperature variations, resulting in reduced grinding efficiency in the winter months. Laboratory and pilot plant studies were conducted to determine the cause of the observed loss of efficiency at lower temperatures. Experiments were divided into two groups: 1) Drop testing, which was performed to determine the effect of brittleness and frozen pore water on the breakage characteristics of the ore. 2) Wet grinding, which was further divided into laboratory tumble tests and pilot plant scale tests. Laboratory tumble tests were performed to determine the effect of temperature on the grinding of iron ore. This was done by varying the percentage of fines and percentage of metamorphic clay material added to the iron ore grinding charge. The pilot plant scale tests were conducted as a scale-up of the laboratory tumble tests and to determine the effect of temperature on slurry rheology, and how this changing rheology affected the grinding of iron ore. The combined results of drop testing and wet grinding were used to make some predictions of the performance of plant scale autogenous grinding. In drop tests the breakage characteristics of the iron ore had no noticeable change in size stabilities for dry and water saturated samples over the temperature range studied (-25°C to 25°C). The effect of frozen pore water was not observed due to the low apparent porosity of the iron ore. The addition of fines to the test charge caused a decrease in the amount of new fines produced for both the laboratory tumble tests and pilot plant scale tests. The production of fines further decreased when tests were performed at the colder temperature. The increased energy consumption at lower temperatures was dominated by rheology phenomena. The addition of metamorphic clay material to the iron ore test charge resulted in more fines being produced in the laboratory tumble tests. This was due to the metamorphic clay material grinding easier than the iron ore. This caused an increase in the amount of fines in the mill, which in turn, would prematurely slow down the grinding of iron ore because of an increase in the viscosity of the slurry.

Jan 1, 1995

By P. Fawell, C. Castillo, C. Ihle

"The need to reduce fresh water consumption has pushed many Chilean mining companies to utilize seawater obtained from distant locations. At the same time, increasing amounts of fine particles in copper tailings raise new operational challenges, in particular, the thickening and transport of tailings featuring significant fine fractions, which are predominantly clays. In the present paper, we study the role of salinity – using seawater and NaCl – on the flocculation efficiency of copper sulphide tailings to which kaolinite was added. To mimic the water recovery stage in thickeners, flocculation has been induced in jar tests and the corresponding aggregate size distribution has been estimated from chord length distribution data obtained using a focused beam reflectance measurement (FBRM) probe, at various mean turbulence intensities. Results show that for constant flocculant dosing, a measurable influence of the salt on the resulting aggregation exists. For each case, resulting optimal turbulence levels are also reported, a particularly interesting feature when comparing flocculation efficiency of the coarse and fine fraction. INTRODUCTION The concentration of copper minerals through comminution and flotation is intensive in the use of fresh water. The need to reduce the consumption of fresh water and the environmental standards associated with increasingly demanding mining operations have driven improvements in the techniques of recovering water from tailings. The challenges are even greater when required to treat minerals with high clay contents. In Chile, kaolinite is one of the most important clays to consider due to its abundance in the tailings from many operations. The most common and highest throughput unit operation in the mining industry for the recovery of water from tailings is gravity thickening, with sedimentation of fine particles assisted by flocculation. Flocculation is the process of forming aggregates by contacting the suspended particles with a flocculant. The flocculant is typically a water-soluble synthetic long-chain polymer, where copolymers of acrylamide and sodium acrylate are the most common types used in the Chilean mining industry. The aggregation mechanism includes the following key steps: (1) flocculant distribution through the suspended particles, (2) flocculant adsorption onto particle surfaces, and (3) collisions between particles leading to polymer bridging to form aggregates, but concurrently (4) breakage of aggregates becomes a factor under prolonged shear (Gregory, 1988)."

Jan 1, 2018

By B. Q. By

TiO2 is an ideal material for catalytic technology due to its unique properties. In this paper, Sm3+ doped TiO2 photo-catalyst was developed to improve the efficiency of TiO2 and to use the natural light as irradiation source, which was made from Titanium Tetrabutoxide and Samarium Oxide with the Sol-Gel process. The Sm3+-TiO2 photocatalyst was used to degrade reactive orange 4 (RO4) in Azo Dyes. The effects of solution pH, Sm3+ concentration and catalytic time on the degradation rate of RO4 were studied. The characteristics of the catalyst were analyzed with XRD and TEM. The experimental results show that the catalyst has high activity in the degradation of RO4. The Azo bonds of RO4 are active and easily broken by oxidation. The catalytic activity of the Sm3+ doped catalyst greatly depends on the pH of solution. The catalyst has high photo-catalytic activity at both neutral and alkaline conditions. The degradation mechanism of the Sm3+ doped TiO2 photo-catalyst was also discussed.

Jan 1, 2014

By Champoux. G., E. Ghali, W. Zhang, G. Monteith, A. -M. Lafront, G. Houlachi

The efficiency of the electrowinning process of zinc depends on the performance of oxygen evolution reaction, anode quality and corrosion resistance of lead anodes. Original surfaces of rolled commercial lead-silver anodes were examined using conventional polarisation methods in acid zinc sulfate electrolyte with manganese sulphate at 38 °C. The self-discharge method (potential decay) following 5 h polarisation at 50 mA cm-2 was considered to evaluate electrochemical activity, oxygen overpotential and anode stability. The influence of silver content is compared to that of the microstructure, the fabrication process and the composition of the corrosion products. Polished anode samples have also been examined for microstructural and corrosion performance studies. The experiments show that the duration of the plateau at 1600 mV versus SHE, the potential level (active corrosion state/stationary state) and the rate AEco/At during the decay could be a good indicator to compare the corrosion rates of the anodes in industrial zinc electrolytes.

Jan 1, 2008

By J H. Park, M J. Lee

Because the environmental problems are occurred by greenhouse gases such as CO2, the industries have tried to increase electric motor efficiency to reduce CO2 emissions. A core material of electric motor is high-silicon electrical steel. The ferrosilicon (FeSi) alloy, a raw material for the production of electrical steel, affects the electric properties of silicon steel. The main impurities such as Ca, Al and Ti make inclusions or precipitates that causes core loss. The slag treatment has been widely used to remove impurity elements. Thermodynamic principles for the refining of several impurities, specifically Ca and Al, have been investigated, whereas thermodynamic behaviour of Ti has not been fully understood yet. Therefore, in the present study, the titanium distribution ratio () between ferrosilicon and CaO-SiO2-Al2O3 slag system at 1773 K was investigated. The results show that is influenced by both the basicity and stability of titanium ion in the slag. Specifically, exhibits a minimum value at about C/S=0.7 indicating a shift in the titanate structure unit from [TiO5]-square pyramid to [TiO4]-tetrahedron because of lack of Ca2+ ions in a C/S<0.8 region, contributing to an increase in titanate capacity and .

Jun 19, 2024

Flotation of dolomite from apatite was investigated, using dodecylamine hydrochloride or sodium oleate as the collector, in the absence and presence of inorganic modifiers such as sodium chloride. Separation of dolomite from apatite was anticipated from the single mineral experiments under various pH and collector concentration conditions. Flotation selectivity in the mixtures, however, was found to be limited. Attempts to control the flotation response of these minerals by addition of salts such as NaCI and KCI indicated that selectivity is possible. The presence of sodium chloride was determined to depress apatite flotation using sodium oleate leaving dolomite flotation unaffected (Moudgil and Ince, 1989). In this paper, conditions for optimum separation and the effect of major parameters on the desired selectivity are discussed.

Jan 1, 1990

In the present work, the flotation behaviours of zircon, rutile and ilmenite using sodium oleate as collector in absence and presence of depressants were thoroughly investigated. The maximum in the flotation recovery of any of the above minerals falls within similar pH ranges. A range of inorganic and polymer depressants were examined in order to improve the separation of zircon from rutile and ilmenite. Optimum values of conditioning pH and depressant concentration to achieve maximum recovery and best selective floatability of zircon were obtained. Selective flotation of zircon from Ti-bearing minerals was anticipated from single mineral experiments under different pH values, depressant and collector conditions.

Jan 1, 2014

By A Van den Bulck, K Verbeken, O Vergote, I Bellemans

Viscosity is one of the most important physicochemical properties during pyrometallurgical operations. In the sub-liquidus regime, an important factor is the presence of suspended solid particles, yet its influence is not well-described in earlier literature, despite the significance of this factor. This project aims to determine the influence of spinel particles (Zn(Al,Fe)2O4) on the rheology of a multiphase synthetic PbO-SiO2-ZnO-Fe2O3-CaO-Al2O3 slag system. Three data sets with a wellcontrolled methodology and three different spinel sizes (small (13 μm), medium (34 μm) and large particles (76 μm)) were published previously, using a custom-built high-temperature rheometer. This study presents an additional data set of slag viscosity measurements, performed using a different apparatus, the Anton Paar FRS 1800, to verify the consistency of the earlier determined viscosity behaviour. Within this data set, no consistent trend could be found between the predicted wt per cent spinel and the relative viscosity. Therefore, additional quenching experiments were conducted to identify the morphology and experimentally determined volume fraction of the spinel particles in the slag. These measurements revealed a difference in spinel size across the samples and corresponding viscosity behaviour, emphasizing the importance of spinel particle size on slag viscosity. Once the spinel size was taken into account, consistent viscosity results (relative apparent viscosity and flow index) were observed across the two devices. This study confirms that, once all parameters affecting slag viscosity are considered, the viscosity behaviour of a heterogeneous slag can be uniquely determined. The resulting optimised slag viscosity models can be used to predict viscosity before processing, addressing relevant phenomena such as slag tapping, slag foaming and copper droplet settlement.

Aug 21, 2024

By Larry M. Southwick

Extraction of gold and other metals from ores suspended in liquid slurries often involves gases (such as oxygen) as a participant in the reaction. An important factor then in setting the rate of extraction can be mass transfer of the gas into the liquid and/or solids. A number of recent studies have indicated that as solids loadings increase, mass transfer rates of gas into solid-liquid mixtures decreases. This would seem to imply that lower solids loadings would be beneficial to increased reaction rates. However, since it is the solids which are being reacted, a most intriguing paradox is created. More solids should lead to more surface area to react, but it seemingly also provides less gas to react. So is the reaction faster or slower as solids loadings increases? The creation of this paradox is imbedded in how mass transfer and reaction data is collected and measured, how it is analyzed and correlated, and finally on the rate controlling steps in the reaction. An alternative analysis of these studies is presented which clarifies and eliminates the paradox. The analysis applies to water slurries as used in gold or other metal leaching processes or in bio-hydrometallurgy, as well as to molten metal/solid/gas mixtures such as might be encountered in submerged gas injection.

Jan 1, 1999

By Atsushi Sainoki

Blast vibration induced by mining activities, such as stope production blasts, could lead to the initiation of seismic events that inflict damage to mine openings. In this paper, the effect of stope production blasts on nearby fault is examined. First, validation of blast vibration attenuation is performed with a numerical model representing a single blast hole through comparison with that calculated from charge-weight scaling law derived from in-situ data. Subsequently, a mine-wide scale model with a fault parallel to a steeply dipping, tabular ore deposit that is mined out with sublevel stoping method is generated, and the stopes are extracted and backfilled with static analysis to simulate burst-prone conditions on the fault. Based on the stress states, dynamic analysis is performed, in which blast vibration is applied to grid points on a stope wall on the hanging wall side. This assumes 9 blast holes located close to the wall, and blast-induced particle velocities that consider the positional relationships between the assumed blast holes and the stope wall are applied. During the dynamic analysis, blast sequence is considered, and stress states and shear displacement on the faults are examined. It is found from results that, after a rise in normal stress on the fault due to compressive waves induced by the blasts, the normal stress decreases because of the reflection of the compressive waves on the fault. The reduction in the normal stress due to the reflected waves is found to be large enough to cause the fault to slip. The results also show that the level of normal stress eventually keeps decreasing with time as the blast sequence proceeds and that an increase in shear displacement on the fault is accompanied by a decrease in normal stress. This study clarifies the mechanism by which blast vibration causes the fault to slip. In addition, the simulation technique to apply blast vibration that takes into account blast sequence and the locations of blast holes to a stope wall is developed.

Aug 1, 2013

By Xiaodong Ma, Marek Pawlik

Introduction Guar gum is a natural nonionic polysaccharide. Guaran, the functional polysaccharide in guar gum is a chain of (1?4)-linked ß-D-mannopyranose units with a-D-galactopyranose units connected to the mannose backbone through (1?6) glycosidic linkages. The poly-mannose chain is randomly substituted with galactose units at a mannose-to-galactose ratio of 1.8-1.0 [1]. Cheng et al. reported that the molecular weight of natural guar gum is 1.935 • 106 [2]. Robinson et al. found that the molecular weights of five grades of commercial guar gums ranged from 4.4 • 105 to 16.5 • 105 [3]. Guar gum is frequently used as a depressant of naturally hydrophobic gangue minerals (e.g. talc) in the flotation of PGM-bearing ores, and according to Harris et al. a wide variety of modified guar gums are available for this application [4]. The Canadian potash industry utilizes natural guar gum as a blinder of water-insoluble slimes in the flotation of potash (sylvinite) ores, a process that is carried out in a saturated KCl/NaCl brine. The role of the polysaccharide is to prevent a primary amine collector from adsorbing onto these unwanted fine minerals. Hydrophobic interactions between basal cleavage planes and the polymer appear to be involved in guar gum adsorption on talc [5,6]. Liu and Laskowski stressed the importance of metal impurities on mineral surfaces that can serve as the active sites for polysaccharide adsorption [7]. This postulate was consistent with the later observation that, in addition to hydrogen bonding, the adsorption of guar gum onto talc was strongly dependent on the surface concentration of magnesium sites [8,9]. In this case the adsorption process was visualized as metal-polysaccharide complexation facilitated by the cis-configuration of the hydroxyl groups of mannose monomers. Hydrogen bonding and chemical interactions with metal sites were also suggested by Rath and Subramanian in their studies on guar gum adsorption on biotite mica [10]. In a recent study, Wang et al. demonstrated that hydrogen bonding is the main driving force behind guar gum adsorption onto talc [11]. Their data also show that the adsorption density of guar gum on alumina is about five times lower than the adsorption density on talc. Pawlik and Laskowski reported that the amount of guar gum adsorbed on illite was independent of ionic strength over a wide range of salt concentrations [12]. The adsorption density of the polysaccharide on illite did not measurably change with ionic strength from that of distilled water to about 50%-saturated KCl/NaCl potash brine (~3N KCl/NaCl). However, guar gum adsorption on dolomite dramatically decreased over the same range of ionic strengths, and no reliable explanation of that phenomenon was proposed [12]. The water structure-breaking or structure-making capabilities of background ions are usually ignored when discussing adsorption mechanisms of polymers. The concept of “structure breakers” and “structure makers” was first introduced by Gurney, and Frank and Wen who postulated that each ion is surrounded by three distinct regions of water structure [13,14]. In the first layer, water molecules are tightly bound to the ion. The second region extends farther away from the ion and is referred to as the region of structure breaking. Only at larger distances, where the ionic field is weak, water molecules form the “normal” ice-like structure. It is also now recognized that the first layer can be further divided into the primary and secondary hydration shells. Small, strongly hydrated ions reinforce the “normal” structure of water and the region of structure breaking disappears. In contrast, large less-hydrated ions disturb the ice-like structure and generate an extensive region of structure breaking. Experimentally, these two effects can readily be distinguished through viscosity measurements. Increasing concentrations of structure-breaking ions result in a decrease of the viscosity of aqueous solutions. On the other hand, increasing amounts of structure-makers significantly reduce the viscosity of water. Alkali metal cations form a sequence known as the Hofmeister series. The Hofmeister series - Cs+, K+, Na+, Li+ - orders the cations from the least hydrated to the most hydrated. Based on literature viscosity data for aqueous

Jan 1, 2005

By A. Ashrafi

The electrochemical deposition of polypyrrole coating on different pretreated aluminum-alloy 7075 substrates was carried out using cyclic voltammetry, The pretreatment of specimens consisted of mechanical polishing and/or electrochemical etching, In the latter case, an aqueous solution of phosphoric acid and ethanol was used, The electrodeposition solution was 0,25 M pyrrole and 0,1 M oxalic acid in double-distilled water, The cyclic voltammetry scan rate used was 700mv/s, Morphology of the coatings was examined using scanning electron microscope (SEM), Using the Tafel experiment, corrosion resistance of the coated substrates was investigated in 0.1 M NaC1 solutions, Results obtained revealed that electropolymerization of polypyrrole on 7075 aluminum alloy would increase the resistance against corrosion in 0,1M NaC1 solution, Also it was observed that, compared with mechanical polishing, electroetching pretreatment would be more effective.

Jan 1, 2005

By M. Mirnezami, J. A. Finch, M. S. Hashemi A.

This study examined the effects of pH and sulphate concentration on the surface charge and stability of alumina and pyrite dispersions. The relationship between these properties was investigated using measurements of electrophoretic mobility and settling velocity. The maximum aggregation for both minerals was observed near the iso-electric point (iep) where the force of repulsion is at a minimum. Aggregation decreased at pH values away from the iep, where an increased surface charge causes electrostatic repulsion between particles. Zeta potential data revealed that sulphate ions were adsorbed only on positively charged surfaces for both minerals. Adsorption of sulphates on the alumina surface increased aggregation by reducing the surface charge from >+25 mV to close to zero. These results indicate an electrostatic bonding of sulphate ions to alumina surface. Preliminary results on the interaction of pyrite and sulphate ions indicate a similar response.

Jan 1, 2004

By X. Zhang, E. Li, Y. Xiao, Z. Yu, H. Han, J. Xie, J. Tian, W. Sun, K. Hong

In a pulp environment, the surface properties of magnesite and dolomite tend to be similar, due to the re-adsorption of dissolved calcium species, which makes the flotation separation difficult. In this paper, the chelating reagent EDTA is introduced to eliminate the adverse influence of the calcium species and to restore the selectivity of magnesite-dolomite separation using sodium hexametaphosphate (SHMP) as a depressant. Flotation experiments confirm that the recovery of magnesite improves significantly in the presence of EDTA. Zeta potential experiments confirm that the negatively charged EDTA4+ and HEDTA3+ species can form soluble and stable chelates with positively charged Ca2+ and Ca(OH)+ species preventing their adsorption on the magnesite surface. Adsorption measurements prove the addition of EDTA can decrease the adsorption of depressant SHMP on the magnesite surface. X-ray photoelectron spectroscopy (XPS) measurements further confirm the transformation from the surface of magnesite to dolomite in the presence of calcium ions, and the possible adsorption mechanism of EDTA and SHMP on the magnesite and dolomite surface. Key words: Magnesite; Dolomite; Surface dissolution; Flotation separation

Jan 1, 2020

By M. Rafieazad, P. Fathi, X. Duan, M. Mohammadi, A. M. Nasiri

"Direct metal laser sintering (DMLS) is a metal additive manufacturing technology that creates highly complex components by fusing metal powder into a solid part. In this study, the impact of surface roughness on corrosion resistivity of AlSi10Mg_200C alloy manufactured through DMLS was investigated. The as-printed DMLS-AlSi10Mg _200C alloy was subjected to various surface finishing processes including grinding and sandblasting. The corrosion performance of the surfaces was then evaluated using potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution to mimic seawater environment. Surface characterization and corrosion morphology of the samples were assessed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) spectroscopy. The results of this study show that the surface finishing process and the resultant surface roughness has a significant impact on the corrosion resistivity of the DMLS-AlSi10Mg_200C alloy in the seawater environment.INTRODUCTION Direct Metal Laser Sintering (DMLS), also known as Selective Laser Melting (SLM) (Sames, List, Pannala, Dehoff, & Babu, 2016), Laser Beam Melting (LBM), or Laser Metal Fusion (LMF) (Herzog, Seyda, Wycisk, & Emmelmann, 2016), is an additive manufacturing process that utilizes a precise, high-power laser to micro-join powdered metals and alloys layer by layer to form almost fully dense and functional components in three dimensions from the 3D computer-aided design (CAD) data. Complex geometries not possible with conventional manufacturing processes can be readily manufactured with high accuracy using the DMLS process with no need to time-consuming tooling."

Jan 1, 2018