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Roller tables, rollers, and pinch rolls are widely used in different industries ranging from rolling mills, sheet metal works, ceramic and tile production industries, etc. Their harsh working conditions, like heating furnaces with high temperatures, oxide debris, and ceramic materials, have been a matter of concern. High wear-resistant cast iron has always been a common material for making these tools. In the present study, motivated to use in the rollers of the rolling line, the production of cast iron-based matrix surface composite reinforced with tungsten carbide (WC), as a surface metal matrix composite (SMMC), using a centrifugal casting process was evaluated in detail. The microstructure of samples was characterized using optical microscopy (OM) and scanning electron microscopy equipped with energy dispersive X-Ray spectroscopy (SEM-EDX). The results indicated that a 3 mm thick composite layer was formed on the sample surface. The findings reveal that the formation of a composite structure on the surface can dramatically improve the wear resistance of cast iron; as a result, the weight loss of composite samples was decreased by 61% after a 1000 m sliding distance at 25 °C when compared with non-composite samples. Results suggest that the production of cast iron-based matrix surface composite reinforced with WC using centrifugal casting, as a feasible and acceptable process, can be a promising and cost-effective way to improve the performance of rollers of rolling lines and even hot rolling mill rolls.

To evaluate the effect of magnesium content on the microstructure and hardness of the Al-Si-Mg composites in the centrifugal casting method, three cylinders with the chemical composition of Al-20Si-XMg (X = 6, 9, 12) (as weight percent) were cast. Then the microstructure and hardness of the different radial sections were studied by optical microscope, SEM equipped with a micro-analysis system (EDS), and standard brinell hardness testing method, respectively. The phase diagram of Al-20Si-XMg system was plotted as a function of Mg% using Thermo-Calc software. Also JMat Pro software was employed to plot the variation of the mass fraction and density of the in situ formed phases during the solidification of the alloys. The results show clearly that while the coarse Mg2Si particles are formed in high Mg content alloys; however, these particles along with the primary Si particles, both, due to the low density, based on Stokes' law in fluid mechanics, are centripetally segregated towards the inner layers of the cylinders. In addition, by increasing the Mg content of the alloys from 6% to 9% then 12% the volume fraction and average size of the Mg2Si particles in inner layer of the cylinders, both, increase respectively from less than 7% to about 28% and from less than 54 microns to about 166 microns. But, since Mg2Si particles are softer than Si particles, by increasing the volume fraction of the Mg2Si particles, the hardness of the inner layers of the cylinders reduces from 86 to 81 and then 78 brinell.

In this study, centrifugal casting method was used to produce a hyper-eutectic composite Al-Mg2Si ‎with hybrid microstructure and graded hardness. For this purpose, two cylinders with a chemical ‎composition of Al-20Si and Al-20Si-9Mg (weight percent) were cast using a vertical centrifugal ‎casting machine. Then the microstructure and hardness of the cast cylinders were studied along the ‎radial direction by optical and scanning electron microscopes and brinell method, respectively. The ‎results show that in Al-20Si cast cylinder; in contrary to the outer layer which shows only a binary ‎eutectic Al-Si microstructure, the inner layer contains a high volume fraction of in situ segregated ‎primary silicon particles inside the eutectic matrix. By addition of 9% Mg to Al-20Si alloy, the inner ‎layer of the cast cylinder form a hybrid microstructure containing of both Si and Mg2Si particles ‎inside the eutectic matrix, while the outer layer shows only a ternary eutectic Al-Si-Mg2Si ‎microstructure. As a result of these microstructure changes along the radial direction of the ‎cylinders, not only the hardness of both cylinders are smoothly increased from the outer towards the ‎inner layers, but also all radial sections of the Al-20Si-9Mg cylinder in compared with the other one, ‎indicate higher hardness (about 18 brinell).

Application of composites of two or more metals has been increased, aiming to increase productivity, in various sectors of industry in recent years. In this work an Al/Cu bimetallic composite was prepared by casting Al melt into a Cu bush with 40 mm height and 79 and 84 inner and outer diameters, rotating at 1480 revolutions per minute (rpm), and 100, 150, 200, 300, and 400°C preheating temperature, respectively in a vertical centrifugal casting machine. Cooling rate increment, due to lower preheating temperature, not only lead to interface thinning but also it can modify microstructure. The results of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis showed that four discrete layers have been formed from the Cu side, including AlCu2, AlCu, Al2Cu continuous layers, Al2Cu precipitates scattering in anomalous eutectic structures and finally α-Al/Al3Cu anomalous eutectic structure near the Al side. Micro hardness measurements showed that hardness of various presented phases decreases from outward to the inward.

In this study, the effect of silicon content on the graded microstructure of Al-Si alloys fabricated by centrifugal casting method was investigated. For this purpose, two cylinders with a chemical composition of Al-11.9wt.% Si (hypoeutectic alloy) and Al-20wt.% Si (hypereutectic alloy) were cast through vertical centrifugal casting method. Then the microstructure and hardness of radial sections of the cast cylinders were studied using optical/scanning electron microscopes and standard Brinell test method, respectively. According to the results, two hypo and hypereutectic Al-Si cylinders illustrate two different patterns of functionally graded microstructure thus hardness along the radial direction. In hypoeutectic cylinder, due to the segregation of the heavy and soft α-Al phase in centrifugal force direction, the outer and inner layers show hypoeutectic and eutectic microstructures, respectively. While in the hypereutectic cylinder due to the segregation of the light and hard primary Si particles in the centripetal direction, the outer and inner layers contain eutectic and hypereutectic microstructures, respectively. As a result of these continuous and gradual microstructural changes in radial direction of the cylinders; firstly: the hardness of all radial sections in hypereutectic cylinder is about 10 Brinell more than the hypoeutectic one; secondly: the inner layer of hypoeutectic and outer layer of hypereutectic cylinders both with full eutectic microstructure show similar hardness; thirdly: the hardness of both cylinders moderately increase from outer periphery towards the inner periphery of the cylinders.

Composites made of dissimilar metals are designed and used in components subjected to various condition such as serious mechanical force, heat and erosion. Fabrication of Al- brass hollow cylinder, as a composite bimetallic part, is an example. In this work, Al-brass bimetallic hollow cylinders were produced using vertical centrifugal casting device and effective variables were studied. To achieve this, Al melt at 1.5 and 2.5 melt-to-solid volume ratio was cast into 100-400°C preheated cylindrical brass bush rotating at 800 and 1600 revolutions per minute (rpm) respectively and the interface characteristics were investigated. The results of scanning electron microscope (SEM) showed that the achieved interface consisted of four discrete layers from the brass side, including Al2Cu5Zn4, Al3Cu3Zn, Al2Cu precipitates scattering in aluminum matrix and finally α-Al/Al2Cu anomalous eutectic structure near the aluminum side. Micro hardness measurements showed that the hardness of various presented phases decreases from the brass side to the aluminum side.

The aim of this research is to investigate interface evolution during centrifugal casting of Al-Cu bimetal composite. In this work, 100 grams aluminum melt was cast into a 150°C preheated Cu cylindrical bush rotating at 700, 900, 1500, and 3000 rotation per minute (rpm) inserted in a vertical centrifugal casting (VCC) machine. Obtained samples were studied using optical microscope (OM) and scanning electron microscopy (SEM) equipped with EDS system and also microhardness test on various available phases. Centrifugal force, due to the rotational speed, leads to increase in the cooling rate. Cooling rate increment not only causes thinning the interface but also with increasing nucleation sites leads to modify the resulted microstructure. EDS results showed that the achieved interface consisted of four discrete layers from the Cu side, including Cu2Al, AlCu, Al2Cu continuous layers, Al2Cu precipitates scattering in anomalous eutectic structures and finally α-Al/Al3Cu anomalous eutectic structure near the Al side. Micro hardness measurements showed that hardness of various presented phases decreases in both Al and Cu side but have a maximum pick, more than 500 Vickers, near to Cu bush as a result of intermetallic compound formation.

In this research interface of aluminum-brass bimetal composite, fabricated by a vertical centrifugal casting machine, were investigated. At first, brass bushes were preheated at 100-300 °C temperature range and then aluminum melt with 1.5 melt-to-solid volume ratio was cast into cylindrical bush rotating at 800, 1600, and 2000 (rpm), respectively. Obtained samples were studied using optical microscope (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Image J software. Results show that metallurgical joint in this work is probably due to particular dissolving condition, provided by multiple mechanical forces involved and also possible solid diffusion at the end of solidification process. Study of the EDS results show that layers formed at the achieved interface consisted of four discrete layers from the brass side, including Al3Cu5Zn4, Al3Cu3Zn, Al3Cu precipitates scattering in aluminum matrix and finally α-Al/Al3Cu anomalous eutectic structure near the aluminum side.

Functionally graded aluminum matrix composites to the advantage of lightness as same as high hardness and good wear resistance can have many applications in the aerospace and automotive industry, which with more investigations can be reached to the optimum condition by centrifugal cast method. A390 hypereutectic alloy was cast cylindrically as the base alloy with rotational speed of , 1200, 1400, 1600 & 2000rpm by vertical centrifugal cast method. The Microstructures of samples were investigated by optical microscope. Also the volume fraction of reinforcement particles and their hardness from inner wall through outer wall were investigated. It was found because of smaller density of primary Si particles than molten Al, These particles were moved to the inner wall of the samples due to centrifugal force and were distributed from inner layer through middle layer as gradient. The rotational speed of 1400 rpm was chosen as optimum speed and therefore the centrifugal sample with rotational speed of 1400 rpm was chosen as optimum sample.

In this study, centrifugal casting process was used for producing Al/Mg bimetal. Molten Mg was poured at 700 oC, with 1.5 and 3 melt-to-solid volume ratio (Vm/Vs) into the 450 oC preheated solid Al rotating at 800, 1200, 1600 and 2000 rpm. Castings were kept inside the centrifuged casting machine and cooled down to 150 oC. Investigating the effect of melt-to-solid volume ratio showed that increasing volume ratio from 1.5 to 3 results in diminishing metallurgical bonding in Al/Mg interface, because the force of contraction overcomes the resultant force acted on the interface. The results of study by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) showed that bimetal compounds of Al3Mg2, Al12Mg17 and δɝ瘲ൻ eutectic structure (δ is the solid solution of Mg in Al) are formed in the interface. Atomic force microscopy (AFM) image of Al surface showed that the surface was rough in atomic dimentions, which can result in the formation of gas pores in the interface.

Centrifugal casting is one of the methods which is used for producing bimetallic composite parts. This method runs both horizontal and vertical mode. Vertical mode, used in this work, is currently taken to produce casting parts with height to diameter ratio less than unity. In this study, aluminum melt with 1.5 and 2.5 melt-to-solid volume ratio was cast into 100°C preheated brass bush rotating at 800, 1600, and 2000 (rpm), respectively. In order to characterize the cast samples, possible phases and casting defects various equipment such as optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) have been used. Flowing of Al melt, at centrifugal field, is possibly associated with surface oxide film rupture so that metallurgical bonding is attained. On the other hand, these oxide films flowing at the melt surface and inherent turbulence of this process may cause defects in the casting. It was noted that bimetal composites produced at 2000 rpm are subjected to more defects than the other. This article categorizes various defects seen and analyzes different effective parameters.

Most popular semi-solid casting processes involve two stages. The first stage includes producing a semi-solid slurry which is formed in a high strength metallic die in the second stage of the process. Because of high pressures applied on the semi-solid slurry during the second stage, the die should be made of expensive alloy steels. In the present research, the possibility of single stage semi-solid casting of a high melting point alloys, i.e. a hypereutectic gray cast iron, in a sand mold was investigated. For this purpose, a specially designed runner chilled sand mold rigged to a vertical centrifugal casting machine was used. The hypereutectic gray cast iron was poured in the sand mold at 1275 and 1285 ºC and at rotation speed of 400 rpm. The microstructures and hardness of the specimens were then characterized. The results showed that the average length of the eutectic flake graphite and the thickness of the Kish graphite in semi-solid centrifuged castings were smaller and their hardness was higher than those in the castings prepared by conventional gravity or centrifugal casting methods.

Production of Mg-Al bimetal composite, for weight reduction of industrial components and decrease in fuel consumption, has taken attentions in the transport industry during recent years. In this research Mg melt was poured at 700 Celsius into Al hollow cylinder, with 1.5 melt to solid volume ratio (Vm/Vs), preheated at various temperature including; 320, 400 and 450 Celsius, respectively, while they were rotating at 1600 rpm in a vertical centrifugal casting machine. Effect of the cooling process after pouring, and also contraction behavior of magnesium-aluminum bimetal during solidification, under centrifugal force, was studied. Preheating temperature from 350 to 450 Celsius led to the increasing of reaction layer and phase changes. Study of microstructure using scanning electron microscope (SEM) equipped with x-ray spectroscopy showed Al3Mg2 and Al12Mg17 intermetallic compounds, eutectic structure and Mg solid solution are formed in the interface. Keep the casting in the casting machine, while rotating and cooling to the range of 150 Celsius, prevented creation of contraction cracks and separation of two layers composite alloy.

Al/Mg composite have new applications in various industries such as car manufacturing and aerospace. In this work characteristic of metallurgical interface and the behavior of melt-solid-gas during production of Al/Mg composite via vertical centrifugal casting process was investigated Aluminium melt, at 700 oC and volume ratio of nearly one, was poured into a solid Mg rings preheated up to 30, 100, 150 and 200 oC, respectively while rotating at 1200 rpm, in a vertical centrifugal casting machine. After casting samples were cut and interfacial microstructure was studied by optical and scanning electron microscopes. Results show that the heat content of Al melt lead to dissolving preference prominent locations and creating local Mg rich regions. Study of the Al/Mg interface also showed that intermetallic compounds, Al3Mg2, Al12Mg17 are formed. Furthermore, gas pores may form, on notches present on the rough surface of the solid Mg ring, possibly as a result of melt/gas reaction. Possible states and conditions of the formation of bubble and gas porosity are discussed.

To evaluate the effect of inoculant addition on functionally graded microstructure of centrifugally cast Al-Mg2Si composites، two cylinders of Al-13. 8 wt. % Mg2Si with and without the addition of 1 wt. % Al-5Ti-B inoculant were cast in a vertical centrifugal casting machine. The chemical composition، microstructures and microstructural phases of the different radial sections of the cast cylinders were studied using induction coupled plasma (ICP) method، optical/scanning electron microscopes، and X-ray diffractometry، respectively. The results showed that in the inoculant content cylinder، owing to the prevailing thermal regime as well as the specific mode of eutectic solidification in this composite، the titanium and boron compounds were segregated towards the middle layer of the cylinder and caused the formation of primary Mg2Si particles and non-eutectic Al () in this layer. In addition، due to the effect of centrifugal force during solidification، a higher volume fraction of the light primary Mg2Si particles، according to Stocks law، was segregated towards the inner layer of the cast cylinders.

The modification of microstructural grading of the cast hollow cylinders of eutectic composite Al-13.8 wt.% Mg2Si was studied via 0.5 wt.% Al-75Fe addition to the melt during centrifugal casting. The chemical composition, microstructure and hardness of different radial sections of the cast cylinders were studied using energy dispersive spectroscopy (EDX), optical microscope, scanning electron microscope, X-ray diffractometry and hardness testing, respectively. The results show that due to specific thermal regime, prevailed in centrifugal casting, the rod-shape fine eutectic microstructure in external periphery of the cast hollow cylinder changes to a coarse lamellar-shape eutectic microstructure in its internal periphery of cylinder. Also owing to segregation of FeAl3/Al8Fe2Si brittle particles with needle morphology towards the inner periphery of cylinder, thus their effective role in heterogeneous formation of Mg2Si and developing the α-Al in matrix phase, the inner periphery of the iron-contained cylinder showed the lower hardness in compared with the outer periphery of cylinder.

Centrifugal casting as a high capable technique has been frequently used for production of high performance castings. In two decades its capabilities has been progressed towards the production of cast components with functionally graded microstructures. A controlled attribution of the centrifugal force in this technique can cause a desirable grading of the microstructures hence properties in different sections of the castings. In this research, functionally graded Al-wt.%MgSi hypoeutectic alloy with graded distribution of α-Al phase was cast as a cylindrical specimen using the centrifugal casting. During the solidification, the initially formed α-Al grains due to the higher density in compared with the remained melt, were segregated in the centrifugal force direction. The microstructural observations reveal two distinguished layers in radial direction of the cast cylinder: the outer layer with a higher volume fraction of α-Al grains and the inner one with the eutectic structure. To modify the cast structure hence mechanical properties, the cast sample was subjected under solution and ageing heat treatments. The microstructural observations of the heat treated sample shows no noticeable change in the cast graded microstructure; however the eutectic structure was distorted from laminar to a fine dot-like structure. This minor microstructural evolution is accompanied with an increase in hardness of different sections of the sample.