Papers by Keyword: Centrifugal Casting

Abstract: Spent Bleaching Earth (SBE) is a solid waste produced from the palm cooking oil refining industry. The commercial ceramic membranes are quite pricey, therefore SBE solid waste is possible to be an alternative for reduction of membrane material cost due to high silica content. This work demonstrates the fabrication of ceramic tubular support membrane with varied SBE addition and investigates the functionalization group of its membranes. The ceramic support membrane was prepared from regeneration SBE with varied loading composition 15 and 35 wt%. The regeneration SBE using n-Hexane as solvent. Membranes were casted into tubular configuration using centrifugal casting technique at 3000 rpm. The tubular ceramic SBE membranes were dried and followed by calcined at 900°C with heating rate 2°C/min using programable furnace for 2 h. Both of raw SBE material and membranes were analyzed using Fourier transform infrared (FTIR). The SBE material after regenerated exhibits has high Si-OH and Si-O-Si peaks over raw material. Interestingly, the fabrication ceramic support membrane with tubular configuration is successfully preparation by centrifugal casting. Ceramic SBE membrane exhibits functionalization and deconvolution the present of siloxane, Al-OH-Al, Ti-O-Ti, and Al-O bands for both of 15 and 35wt% SBE loading. It concluded this tubular ceramic support membrane from SBE has appropriated chemical functionalize properties to applicates as membrane separation.

Abstract: In this work, functionally graded materials were synthesized by centrifugal technique at different volume fractions (0, 0.5, 1, 1.5, and 2% Vf) with different rotational speed of (0, 600, 800, 1000 and 1200) r.p.m and different rotational time (0, 1, 2, 3 and 4) min. The hardness and tribological properties were characterized to study the graded and non-graded nanocomposites and the pure epoxy material. Using a pin-on-disc machine, sliding wear tests are conducted with the following parameters: rotation speed (400 rpm), normal load (30 N), filler content (0–2% Vf), and sliding distance (0.15 km). The hardness and wear parameters of graded composites were investigated and compared to those of epoxy composites with homogeneous filling. This work demonstrates that incorporating Al2O3 nanoparticles improves graded composites' hardness and sliding wear resistance. Epoxy–Al2O3 epoxy composites with a volume fraction of 2 had the lowest specific wear rate of all samples. The FGMs had superior sliding wear performance compared to homogenous composites. The maximum difference in hardness and coefficient of friction occurred at (FGM), which is loaded from the rich side of the nanoalumina at (Vf = 2%, N = 1200 r.p.m and T = 6 min), where the maximum value was 168% and 78 % as compared with neat epoxy, respectively. The wear rate of the functionally graded samples was enhanced by (87.7%) compared with neat epoxy if loaded from the alumina-rich side.

Abstract: Creating a gradient of properties in a single material is challenging for scientists and engineers. For this purpose, such methods are used as: welding of steels of different chemical compositions, joint rolling of steel sheets, sealing and surfacing of various kinds. All of these methods have a big disadvantage: under load, the material is destroyed in the weakest place - the place where the layers join. In this article, the authors proposed to obtain a gradient of properties in steel castings due to the introduction of dispersed particles of tungsten carbide into the crystallizing melt during centrifugal casting. The particles introduced serve as crystallization centers, accelerate the crystallization process and increase certain types of mechanical properties (hardness, microhardness, tensile strength). In addition, the particles of tungsten carbide have high hardness; therefore, in the structure of the workpieces they serve as reinforcing elements that strengthen the structure. The uneven distribution of particles in the preform being formed is possible for two reasons: tungsten carbide has a density greater than the melt, and besides, centrifugal force acts on them. The article describes the experiment and its results on the production of metal preforms with a gradient of properties. The introduced particles significantly influenced the macro-structure of the prepared castings. The article also presents the results of a study of the effect of particles on the hardness and micro-hardness of the resulting blanks.

Abstract: In this article, we present our developed and manufactured centrifugal casting machine. We present the results of mechanical testing of samples from polymer composites made on it. At the beginning we give an overview of the main trends in the market of polymer composites. We consider the main factors affecting the mechanical characteristics of polymer composites, and determine the main limitations of using centrifugal casting technology for polymer composites. In conclusion, we give directions for further research. Many industries use polymer composite materials (PMC) to meet production needs. The main advantage of PMC is the possibility of obtaining high strength with relatively low weight, as well as the possibility of obtaining additional necessary properties, such as dielectric, magnetic, etc. The PMC market continues to grow, and now PMC is widely used in aircraft manufacturing, automotive, medicine, etc. [1]. Despite the positive aspects of using PMC, this method has some drawbacks. Firstly, low automation of the process of casting parts from PMC. Many technologies are quite difficult to automate due to their process complexity and constant monitoring. Development in this direction is already underway, and there are practical solutions, such as automatic tape placement (ATL) / automatic fiber placement (AFP) [2]. On the other hand, the cost of these solutions is quite high. Secondly, the high cost of the equipment and tooling manufacturing. Such technologies as pressing, pressing and autoclave molding using prepregs are attached to certain technological equipment and need to organize pressure, maintain temperature, etc. This increases the range of equipment used and overall process complexity. In some technologies using high pressure and heat-cooling such as pressure casting (RTM) [3], it is necessary to use high-strength steels for molds, the processing of which takes a long time and wears the tool. Thirdly, increased knowledge-intensive work and high requirements for staff qualifications [4]. Manufacturing products from PMC requires careful monitoring by the technologist, since the influence of such parameters as: temperature, pressure will affect on the product structure and, accordingly, its characteristics. Fourthly, loss of strength after cutting operations (such as drilling, milling, taping and so on) and further stratification of PMC [5]. This leads us to the fact that used technology should maximally ensure the product geometry with minimization of subsequent post-processing.

Abstract: Horizontal centrifugal casting machine was adopted to fabricate tubes of functionally graded materials (FGM) made of commercially pure aluminum reinforced with different weight fractions of SiC particles. Tubes with 2.5, 5 and 10%wt. SiC_p were produced in the speed range 800 to 1100 rpm. Wear experiments involving dry sliding under different loading conditions were conducted on samples taken from three consecutive layers across the wall of the FGM tubes. Analysis of variance (ANOVA) was used to determine the significant FGM production parameters and wear test parameters (normal load and test duration) affecting the wear resistance of the samples. Obtained wear test results have been used to build a regression model to predict the expected weight loss across the wall thickness of the tube depending on the production parameters and the loading conditions.

Abstract: The centrifugal casting process was adopted to fabricate Al-30Si-8Mg composites tubes reinforced with in-situ particles, which was used to produce the cylinders used in 149cc engine by high pressure die casting. The relations between the microstructures along the radial direction and the hardness and wear resistance of the casting were researched. The internal surface of the cylinder was treated and a bench test for the engine was carried out. The results show that, 1) a large number of primary Si/Mg₂Si particles are segregated and enriched in the inner layer of the Al-30Si-8Mg casting, while no particle is in the outer layer, and the maximum particle volume fraction is up to 31.9 vol. %; 2) the region which has more primary particles, the hardness value is higher, and the wear resistance is better as well in the casting; 3) the cylinder assembled on the air-cooled engine successfully passes through the endurance test for 200 hours, and the maximum output power and torque reach 8.18 KW and 10.77 N·m, respectively, while a slight scuffing occurs on the internal surface of the cylinder in the later phase of the test.

Abstract: This paper is focused on multi-scale modeling of solidification and alloy microstructure evolution through computer-aided simulation of the technological processes. Microstructure characterization of cast alloy after centrifugal casting including grain size, dendrite cell size and porosity is of interest in this paper. The centrifugal technological process was simulated using special LVMFlow program for computer-aided analysis of casting technologies to predict shrinkage porosity in axi-symmetric part blanks. The cast blanks were made of Fe-Ni-Co alloy with low thermal expansion and after turning could be used as bearing parts in contact with glass or ceramics. A method of combined simulation of technological processes and operating regimes of cast components was developed. The proposed method of simulating the complicated model allows separating the component from casting geometry in CAE postprocessor and the plot distribution of calculated parameters over the component. Also, this method allows varying diameters of hollow cylindrical casting and choosing the best location of components relative to the predicted porosity in the blank for high quality turning. The distribution of temperature and porosity could be used for more precise calculation of internal stresses in cast component under loading conditions with respect to the structural factors. The structural parameter was stated on a base of the calculated temperature fields to associate grain structure of cast alloy with solidification conditions. The austenitic microstructure of Fe-Ni-Co super-invar alloy was studied on the samples, which were cut from the axi-symmetric part after turning the blank. The calculated structural parameter was assigned with the types of grain structure.

Abstract: This paper discusses the main Functionally Graded Materials (FGMs) and their bulk fabrication techniques, their development, principles and applications. The fabrication processes considered include powder metallurgy (PM), sintering, squeeze casting, infiltration process, compocasting, centrifugal casting, stir casting, material prototyping. The paper provides an overview of the FGM processing parameters including reinforcement particles size and volume %, temperature, pressure (for PM), and stirrer and mould rotational speeds (for stir and centrifugal casting processes respectively). The paper notes that the FGMs are widely used in the following sectors: automotive, medical, aerospace, aviation, nuclear energy, renewable energy, chemical, engineering, optics electronics etc.

Abstract: The study investigates the application of centrifugal casting process in the production of a complex shape component, Pelton turbine bucket. The bucket materials examined were functionally graded aluminium A356 alloy and A356-10%SiC_p composite. A permanent mould for the casting of the bucket was designed with a Solidworks software and fabricated by the combination of CNC machining and welding. Oil hardening non-shrinking die steel (OHNS) was chosen for the mould material. The OHNS was heat treated and a hardness of 432 BHN was obtained. The mould was put into use, the buckets of A356 Alloy and A356-10%SiCp composite were cast, cut and machined into specimens. Some of the specimens were given T6 heat treatment and the specimens were prepared according to the designed investigations. The micrographs of A356-10%SiC_p composite shows more concentration of SiC_p particles at the inner periphery of the bucket. The maximum hardness of As-Cast A356 and A356-10%SiC_p composite were 60 BRN and 95BRN respectively, recorded at the inner periphery of the bucket. And these values appreciated to 98BRN and 122BRN for A356 alloy and A356-10%SiC_p composite respectively after heat treatment. The prediction curves of the ultimate tensile stress and yield tensile stress show the same trend as the hardness curves.

Abstract: In the present research, the possibility of single stage semi-solid casting of a hypereutectic gray cast iron in a sand mold was investigated. For this purpose, a specially designed chilled sprue sand mold rigged to a vertical centrifugal casting machine was used. The molten cast iron was poured in the chilled sprue sand mold at 1275 oC at a rotation speed of 400 rpm. Two control samples were also poured at 1275 oC under gravity and centrifugal casting conditions in the same mold without sprue chilling. Microstructures and mechanical properties of the specimens were then characterized. The results showed that the average length and thickness of the primary solid phase, i.e. the Kish graphite, and those of the eutectic flake graphite were smaller in semi-solid centrifuged castings and their hardness were higher than those of the control samples. The results are discussed in terms of the shearing and chilling effects of the designed sprue during the initial stages of pouring.