Russian Journal of Non-Ferrous Metals最新文献

{"title":"Study of the limiting parameters of deep drawing of sheet blanks made of heat-resistant copper alloys","authors":"E. Demyanenko, I. Popov, D. Nikonov","doi":"10.17073/0022-3438-2021-6-42-48","DOIUrl":"https://doi.org/10.17073/0022-3438-2021-6-42-48","url":null,"abstract":"This article studies the mechanism of thin-walled workpiece deep drawing in the mould with a conical die and determines the forming limit state that occurs at the time of the bottom detachment in the radius part of the punch when stresses in the meridional direction reach their maximum value. This condition is determined by a decrease in the workpiece edge size at the stage of slow material hardening and a decrease in the workpiece flange area that are main factors hindering the process. This condition makes it possible to establish a criterion used to determine the limiting drawing ratio (ratio of the diameter of the workpiece to the diameter of the part), namely: equality of meridional stresses in the punch radius rounding area and the material tensile strength. The paper establishes the effect of the workpiece material strength properties, friction and die taper on the limiting drawing ratio. A change in the plastic and strength properties of the BrKh08 heat-resistant copper alloy (tensile strength, yield strength) does not affect the material hardening constant values and practically does not affect the limiting drawing ratio. The paper uses a comprehensive research method including theoretical analysis and modeling in the ANSYS/LS-DYNA software with input data for the 1.35 mm thick workpiece 100 mm in diameter made of BrKh08. The article presents computer simulation stages indicating main process parameters such as the workpiece material model, mechanical properties, type of elements, kinematic loads, conditions of contact interaction between elements, etc. Process simulation results confirmed theoretical conclusions necessary for the process implementation without part defects.","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"69 3 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77451041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of heating VK and TK group hard alloys in various media on surface quality","authors":"S. I. Bogodukhov, E. Kozik, E. V. Svidenko","doi":"10.17073/0021-3438-2022-6-71-80","DOIUrl":"https://doi.org/10.17073/0021-3438-2022-6-71-80","url":null,"abstract":"The studies carried out to explore the modifying effect on the surface of a hard alloy, surface alloying and thermochemical treatment of metal, thermal diffusion saturation, vacuum ion-plasma deposition demonstrated changes in surface roughness and performance. This paper used roughness to evaluate the behavior of various hard alloy groups when heated in various media. The samples were 5× 5× 35 mm bars and 15.8 ×15.8 mm tetrahedral plates made of VK8 and T14K8 hard alloys. Surface roughness parameters were measured on the profilometer implementing the contact (probe) method. Roughness values obtained were analyzed in the Microsoft Excel system based on an integral percentage and histograms were constructed. The effect of the heating medium on the surface roughness was studied both on bars and plates (with and without holes) using the saturating element/buffer substance (50–100 % BaCl2) melt. K4(Fe(CN)6 potassium ferrocyanide and Na2B4O7 borax were used as a saturating element (25 %). Microhardness and cutting wear were determined directly on the products (after determining the heating media effect on roughness). The heating of VK8 and T14K8 hard alloys in various media increases roughness and reduces cutting wear up to 2 times. The structure of initial materials before and after heating in various melts was studied using the JCM-6000 scanning electron microscope (Jeol Ltd., Japan) at a magnification of 1000–3000×. Plates in their initial state and after heating in various melts were subjected to resistance tests on the 1A616 screw-cutting lathe by face turning of an axle billet made of OS steel (similar in structure and properties to St45) 210 ×1650 mm in size of continuously cast metal (GOST 4728-2010). X-ray diffraction analysis of the VK8 hard alloy after heating in various media demonstrated the absence of changes in the phase composition. Along with this, there was a slight change in the carbide phase fine structure parameters of the alloy, namely a slight increase in micro-stresses with a simultaneous decrease in mosaic blocks.","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"23 4 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83389661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of converting process for matte of oxidized nickel ores and sulfide copper ores joint smelting based on thermodynamic simulation","authors":"A. Klyushnikov, G. I. Maltsev","doi":"10.17073/0021-3438-2022-6-12-21","DOIUrl":"https://doi.org/10.17073/0021-3438-2022-6-12-21","url":null,"abstract":"The paper presents the results obtained in the thermodynamic modeling of converting copper-nickel matte (11.3 wt.% Ni + Cu + + Co, 61.5 wt.% Fe, 25.9 wt.% S) produced by joint smelting of oxidized nickel ore and sulfide copper ore. Calculations were made in the approximation of ideal molecular solutions using the HSC Chemistry software package (Outotec Research Oy, Finland). The possibility of low-iron matte, converter slag and gas phase separation was shown. Estimated conditional equilibrium constants of exchange reactions between low-iron matte and slag (KNi/Fe = 0.004÷0.005, KCo/Fe = 0.056÷0.099) are close to ideal values. Statistical data processing was carried out using the mathematical experiment planning method. The converting temperature (t = 1100÷1300 °C) and iron and sulfur oxidation completeness level (q = 0.9÷1.0) determining the air and flux (SiO2) consumption were chosen as the factors to study. Obtained mathematical models of the process were used for its optimization. It was shown that the best converting performance can be achieved at t = 1150 °С and q = 0.950 when the low-iron matte contains 70.7 wt.% Ni + Cu + Co. At a yield of 8.74 % of the charge mass, the nickel, copper and cobalt recovery rates are 67.9, 97.9 and 9.1 %, respectively. The supposed air consumption (145.1 m3 (under normal conditions) per 100 kg of matte) and SiO2 (34.4 kg per 100 kg of matte) as well as slag yield (89.1 % of the charge mass) are close to working regime parameters. The results of the study confirm the possibility of cost-effective processing of poor copper-nickel matte and after experimental verification they can be used to develop automation flowcharts for converter departments at existing and designed production facilities.","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"17 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82515863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrometallurgical processing of deactivated nickel catalysts on Al2O3 carrier","authors":"A. Demidov, A. Kalmykov, I. A. Matveev, V. K. Shevchuk","doi":"10.17073/0021-3438-2022-6-4-11","DOIUrl":"https://doi.org/10.17073/0021-3438-2022-6-4-11","url":null,"abstract":"The paper considers the use of deactivated nickel-containing catalysts based on Al2O3 as a significant raw material resource of one of the most important metals. The research highlights the features of this secondary nickel source that determine the acceptable methods of processing such raw materials. The effect of fluxing additives on the properties of the melt containing catalysts prepared beforehand has been studied subject to limitations as to their list (lime, fluorspar) in order to implement a pyrometallurgical method of metal extraction featuring by a relatively small amount of additives themselves. Due to induction heating used in combination with a graphite crucible, adding the total amount of fluorspar and marble additives close in mass made it possible to obtain the melt at a temperature slightly higher than the nickel melting temperature. In this case, the level of metal losses was about 2 %, which indicates the applicability of this method in laboratory conditions to ensure correct incoming analysis. It was proposed to use the pyrometallurgical method on an industrial scale using closed arc heating. To confirm this conclusion, experiments were conducted with a representative (more than 100 kg) amount of catalyst using a tailored arc furnace. Graphite chips were used as a reducing agent. The necessity of electrical matching of the load with the power source resulted in some adjustment of the fluxing additive ratio towards a reduction of calcium oxide content. As a result of a series of experiments, nickel with an up to 5 % iron admixture, similar in composition to the metal formed in the graphite crucible, was obtained. The presence of iron was caused by the fundamentally distinctive capability of the pyrometallurgical technology to reduce unstable compounds. Therefore it was suggested to use this metal for ferronickel production. The use of scarce fluorspar is justified by the fact that the resulting slag can be in demand in the production of fluxes for the electroslag remelting process.","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"173 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76190738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studies of the Structure and Properties of Weld Deposits of the Sv-AK5 Filler Wire in Robotized Deposit Welding","authors":"K. V. Nikitin,&nbsp;D. A. Dunaev,&nbsp;S. S. Zhatkin,&nbsp;V. I. Nikitin","doi":"10.3103/S1067821222050066","DOIUrl":"10.3103/S1067821222050066","url":null,"abstract":"<p>The effect of the welding arc current (47, 57, and 67 A) on the structure and properties of the deposited samples obtained by electric arc robotic deposition has been studied. Welding wire Sv-AK5 (ER4043) of the Al-Si system was used as a filler material. The weld deposition was carried out on a substrate in the form of a plate 6 mm thick made of AMg6 alloy (Al–Mg system). In the process of surfacing, a typical two-phase structure of a hypoeutectic composition is formed in the samples, which is characteristic of alloys of the Al‒Si system with a silicon content of 5%. A trend to the enlargement of the structure in the direction from the substrate is observed along height of the deposited layers, which is associated with the accumulation of heat in the layers deposited along the height. With an increase in the welding arc current, dendrites based on α-Al and eutectic Si crystals are refined, while their density increases and microhardness decreases. The increase in density is due to a decrease in the proportion and size of gas pores and the refinement of structural components. The decrease in microhardness is associated with an increase in the proportion of the soft phase (α-Al dendrites) and a decrease in the number hard eutectic silicon crystals. The average content of silicon in the samples deposited in three modes is in the range of 5.46–5.91%, which corresponds to the chemical composition of the welding wire Sv-AK5 (ER4043). An increase in the welding arc current facilitates a growth of tensile strength and a slight decrease in the conditional yield strength and relative elongation. The patterns of the change in the mechanical properties of the deposited samples are due to the specifics of the formation of the cast structure of the deposited layers under conditions of directional solidification in the direction away from the substrate.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"537 - 543"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4875268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Joining Cu30Zn (Brass) and AA6063 Alloys Using the Mechanical Locking Method","authors":"Hatice Varol Özkavak","doi":"10.3103/S1067821222050078","DOIUrl":"10.3103/S1067821222050078","url":null,"abstract":"<p>Different types of materials with unique performance are used together in the industry, and soluble and/or insoluble joining methods are applied to join these materials. However, the joining process is quite problematic due to the technological drawbacks that arise during the joining of materials with distinctive characteristics. For this reason, mechanical locking (frictional) joining method is recommended to reduce some of the problems emerging during the joining of different materials. Various material groups such as ferrous and non-ferrous metals could be able joined by the mechanical locking method (MLM). In this study, to the main aim is to determine the effect of rotation speed, which is one of the influential process parameters, on the process of joining CuZn30 (brass) and AA6063 aluminum alloy materials using MLM. The mechanical properties and microstructures of the specimens joined by applying different rotation speeds were examined. Consequentially CuZn30 and AA6063 materials were successfully joined using the MLM and the number of rotation speeds applied during joining had a significant effect on the joining process.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"560 - 572"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4875269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selective Hydrochloric Acid Leaching of Zinc, Lead and Silver from Mechanically Activated Zinc Plant Residue","authors":"M. Deniz Turan,&nbsp;Shoeleh Assemi,&nbsp;Rashid K. Nadirov,&nbsp;Galymzhan A. Karamyrzayev,&nbsp;Omirserik Baigenzhenov,&nbsp;Norman Toro","doi":"10.3103/S1067821222050108","DOIUrl":"10.3103/S1067821222050108","url":null,"abstract":"<p>A solid waste from zinc production, zinc plant residue (ZPR) is a valuable resource for the recovery of zinc (Zn), lead (Pb), and silver (Ag). However, the ferritic structure of ZPR makes it difficult to leach these metals. Here, in order to increase the reactivity of the ZPR, mechanical activation using a high-energy ball mill was used. The sample mechanically activated for 15 min was subjected to two-stage leaching with the hydrochloric acid (HCl) solution. At the 1st stage, 74% of Zn was recovered from mechanically activated ZPR sample into the solution under the following conditions: 1 M HCl, 120 min leaching duration, liquid-to-solid ratio (L : S) of 4, the temperature of 25°C, and a rotation speed of 600 rpm. At the 2nd stage, 56% of Pb and 53% of Ag were recovered from the leaching residue, under the following optimized conditions: 8 M HCl, 120 min leaching duration, liquid-to-solid ratio (L : S) of 20, the temperature of 25°C, and a rotation speed of 600 rpm. Сonceptual flow-diagram of the zinc, lead and silver selective recovery from ZPR is proposed herein.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"490 - 499"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4877434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Floatability and Calculated Reactivity of Gold and Sulfide Minerals","authors":"V. A. Ignatkina,&nbsp;A. A. Kayumov,&nbsp;N. D. Yergesheva","doi":"10.3103/S1067821222050054","DOIUrl":"10.3103/S1067821222050054","url":null,"abstract":"<p>This paper presents the results of theoretical calculations of the reactivity of gold, molybdenite, stibnite, galena, chalcopyrite, arsenopyrite, and pyrite in comparison with experimental data on the floatability of monomineral fractions with butyl xanthate, measured contact angles, and variation in the kinetics of the potential of mineral electrodes. The calculation method establishes the following series of the reactivity and oxidation ability: Au &lt; Sb₂S₃ &lt; MoS₂ &lt; PbS &lt; CuFeS₂ &lt; FeAsS &lt; FeS₂. During flotation in the Hallimond tube, natural gold grains demonstrate the highest recovery (70%) in the range of pH 5–7 as compared to all the sulfides; molybdenite and stibnite are recovered under the same conditions at the level of 50%. With an increase in pH in an alkaline environment to pH 12, the floatability of all the sulfides decreases with the exception of chalcopyrite. It is found that the duration of conditioning with the collector required for the highest recovery is inverse to the reactivity value. The measured contact angle of a drop of water on an untreated surface is the highest for a gold plate (78°) and the lowest for pyrite (67°), but the greatest increase in the contact angle (by 15°) for pyrite is noted after treatment with butyl xanthate at a concentration of 10^–4 mol/L and pH 6; for molybdenite, treatment with butyl xanthate has almost no effect on the measured value of the contact angle. According to the value of the electrode potential in the region of pH 2.0–5.6, the following series is determined: Sb₂S₃ &lt; PbS &lt; CuFeS₂ &lt; FeAsS &lt; FeS₂. Theoretical calculations and experimental data of the study of monofractions of sulfides and gold establish that the conditions of the experiment (pH, duration of conditioning, concentration of the collector) significantly affect the floatability. The calculated data on the reactivity of chemical sulfide compounds and gold in comparison with experimental results show the importance of maintaining certain flotation conditions to create contrast in the floatability of minerals.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"473 - 481"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4881097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Ti, Sr, and B Addition on the Fluidity of A356.2 Grade Aluminum Alloy","authors":"V. E. Bazhenov,&nbsp;I. I. Baranov,&nbsp;A. Yu. Titov,&nbsp;A. V. Sannikov,&nbsp;D. Yu. Ozherelkov,&nbsp;A. A. Lyskovich,&nbsp;A. V. Koltygin,&nbsp;V. D. Belov","doi":"10.3103/S1067821222050029","DOIUrl":"10.3103/S1067821222050029","url":null,"abstract":"<p>At the present time, aluminum alloys with silicon are the most widespread construction materials. In order to increase the mechanical properties of aluminum alloys, modifying with Sr, Ti, and B is used. However, in the foundries, when using scrap and secondary aluminum alloys, the modifying elements are accumulated in alloys in the form of intermetallic particles, which can lead to a decrease in the level of castability. This is connected with the fact that the used modifiers exert a short-term effect and cannot be activated upon remelting. Hence it is necessary to add the modifiers without taking into account the intermetallic particles already contained in the melt. This paper is devoted to studies on the effect of additions of Sr, Ti, and B on the fluidity of an A356.2 grade aluminum alloy determined by means of vacuum fluidity testing. It is shown that, when AlSr10 and AlTi5B1 commercial master alloys are used (containing up to 0.3 wt % Sr and 0.5 wt % Ti), no decrease in fluidity is observed. However, adding the same amount of Ti with the use of a homemade AlTi4 master alloy leads to a considerable decrease in the fluidity. With the help of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the microstructure and phase composition of master alloys and of an A356.2 grade alloy after adding the mentioned master alloys have been investigated. Additionally, the Thermo-Calc software package has been used to evaluate the effect of modifier addition exerted on the phase composition and phase transition temperature of the alloy. It has been established that the effect of the modifier addition on the fluidity of the A356.2 grade alloy is connected with the shape and size of crystals containing the modifying elements in the master alloy structure. When there are coarse crystals formed by such phases, it is quite possible that the crystals are dissolved incompletely, which could hinder the free flow of melt.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"526 - 536"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4875267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the Heat Treatment Process on the Properties of SiCp/AL Composites","authors":"Bo Yin,&nbsp;Fankun Meng,&nbsp;Lei Wang,&nbsp;Wei Ding,&nbsp;Qiu Zhaozhong,&nbsp;Gang Liang,&nbsp;Jianyong Wang","doi":"10.3103/S1067821222050121","DOIUrl":"10.3103/S1067821222050121","url":null,"abstract":"<p>In this study, the effects of different treatments (annealing, solid solution and Solution + aging) on the bending and thermal conductivity of SiC_p/Al composites fabricated by the pressure infiltration method were investigated. The fracture form of the composites was indicated to be characteristic brittle fracture with local ductile fracture. The bending strength of the composites was 674 MPa with Solution + aging, which is 57% higher than that in the as-cast condition. The microhardnesses of the composites increased after heat treatment, resulting in the maximum microhardness 276 HV with Solution + aging. By calculating the thermal conductivity of the composites, the order was determined to be cast &lt; annealed &lt; solid solution &lt; solution + aging, and the thermal conductivity with solution + aging treatment reached 182 m^–1 K^–1, which is higher than 153 m^–1 K^–1 in the as-cast condition.</p>","PeriodicalId":765,"journal":{"name":"Russian Journal of Non-Ferrous Metals","volume":"63 5","pages":"551 - 559"},"PeriodicalIF":0.8,"publicationDate":"2022-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4876698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}