This study investigates the fabrication and properties of Al2O3-Ni composites produced by centrifugal slip casting under a constant external magnetic field, aiming to optimize particle alignment and distribution for enhanced material performance. The research compares two series of samples made with nickel powders from Sigma Aldrich and Alfa Aesar. Series I exhibited non-uniform nickel particle distribution, while Series II demonstrated a more uniform dispersion and consistent particle size, likely due to improved alignment under the magnetic field. The optimal results from compression tests revealed that Series II achieved a compressive strength of 410 MPa, roughly twenty times greater than Series I, highlighting the effectiveness of the magnetic field in enhancing the microstructure and mechanical properties. These findings suggest that centrifugal slip casting with a constant magnetic field holds significant potential for applications in aerospace and electronics, where robust material performance under extreme conditions is required.
This paper investigates the stress and strain state as well as formation processes of structure and features of aluminum alloys during the hot extrusion. It has been shown that during the hot extrusion the ring layers of an extruded element experience not only longitudinal and transverse deformations, but also a slip. The slip increases from inner layers to the surface layer. The tensile principal stresses and the sum of slip deformations also increase. It has been also demonstrated that at the exit of the pressing part the tensile principal stresses have different directions, forming an angle with extruder axis, which also increases towards the surface. In conclusion, it has been stated that the main radial and circumferential deformations act as restraining deformations.
The production and characterization of UNS C65620 (CuZn3Fe2Si3) and UNS C87800 (CuZn15Si4) coded alloys were investigated. The alloys poured into the gravity die casting method were hot forged with a ram, followed by stress relief annealing heat treatment. While the formation of Cu4Si, Cu0.83Si0.17 and Cu5Zn8 phases were detected in the structure of the UNS C65620 coded alloy, Cu12.75SiZn2.92 and Cu3Zn intermetallics with the phases given above were observed in the structure of the alloy containing more Zn and Si. The formation of phases containing more Si and Zn resulted in an increase in both the hardness and strength of the UNS C87800 coded alloy, while the decrease in the % reduction of area and the observation of dynamic deformation aging caused the increase in both the wear rate and deformation hardening rate, which led to embrittlement of the alloy. The deterioration of the corrosion resistance of the UNS C87800 coded alloy can be attributed to the formation of Zn-rich corrosion products on the surface during corrosion.
The work done in this study is a preliminary investigation into the possibility of modelling the filling and solidification process of castings in molds made with the additive method. The work originated from an experiment to produce a bronze casting with a high tin content in an additive mold. The mold filling and solidification simulation was carried out in the MAGMASOFT program, and the lambda thermal conductivity coefficient used in the program’s material database was corrected based on the actual temperature values of the printed form. The results were compared with the modeling results for the physical properties of furan molds based on the program database. The microstructure of the castings obtained in the compared forms was assessed.
Assessing the level of metallurgical and foundry technology in prehistoric times requires the examination of raw material finds, including elongated ingots, which served as semi-finished products ready for further processing. It is rare to find such raw material directly at production settlements, but Wicina in western Poland is an exception. During the Hallstatt period (800-450 BC), this area, situated along the middle Oder River, benefited from its favorable location in the heart of the Central European Urnfield cultures and developed networks for raw material exchange and bronze foundry production. Numerous remnants of casting activities, such as clay casting molds, casting systems, and raw materials, have been discovered at the Wicina settlement. This article aims to provide an archaeometallurgical interpretation of raw material management and utilization by prehistoric communities during the Early Iron Age. To achieve this, a collection of 31 ingots from the defensive settlement in Wicina, along with two contemporary deposits from Bieszków and Kumiałtowice, both found within a 20 km radius of the stronghold, were studied. Investigations were conducted using a range of methods, including optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence spectroscopy (ED-XRF), powder X-ray diffraction (PXRD), AAS and ICP-OES spectrometer. The significance of ingots is examined in the context of increasing social complexity and the rising popularity of bronze products, which necessitated diversified production and a demand for raw materials with different properties and, consequently, different chemical compositions.
This study deals with the effect of magnesium content in Al-Mg-B alloy (with a boron content of about 5 wt. %) on the formation of intermetallic phases and elimination of inclusions in the form of boron powder particles in the final structure. At first look, the high melting temperature difference between pure aluminium (660 °C) and boron (2 076 °C) appears to be a potential problem. Moreover, boron has a minimal solubility in aluminium (0.055 wt.%) and the liquidus temperature increases very rapidly with increasing boron content (liquidus temperature approx. 1 160 °C at 5 wt.% for Al-B binary alloy). Alloying with magnesium results in the transformation of the intermetallic phases AlB12 and AlB2 to the (Al, Mg)B2 phase and has a significant beneficial effect on the formation of intermetallic boron phases in the aluminium alloy without residual boron powder particles.
The article presents the results of studies of the process of accelerated drying performed by means of microwave radiation of ceramic moulds deposited on patterns made of foamed plastics used in the Ceramic Shell technology. The studies aimed at determining the microwave radiation parameters (power, downtime, and uninterrupted operation time) in order to obtain the maximally short drying times which do not cause pattern destruction. The analysis of results confirmed that an increase of the microwave radiation power shortens the drying time of the particular layers of the ceramic mould, however, at the same time, it excessively raises the temperature of the mould. With the microwave power over 1200 W, we can obtain the drying time of one layer at the level of about 30 min, and the temperature of the mould reaches the value of 70oC, which does not cause deformation or partial melting of the polystyrene pattern. From the point of view of production effectiveness, as a result of the application of microwave drying, the time of production of ceramic moulds was shortened from 7 days to 1 working day.
Accurate kinetic parameters are vital for quantifying the effect of binder decomposition on the complex phenomena occurring during the casting process. Commercial casting simulation tools often use simplified kinetic parameters that do not comprise the complex multiple reactions and their effect on gas generation in the sand core. The present work uses experimental thermal analysis techniques such as Thermogravimetry (TG) and Differential thermal analysis (DTA) to determine the kinetic parameters via approximating the entire reaction during the decomposition by multiple first-order apparent reactions. The TG and DTA results reveal a multi-stage and exothermic decomposition process in the binder degradation. The pressure build-up in cores/molds when using the obtained multi-reaction kinetic model is compared with the earlier approach of using an average model. The results indicate that pressure in the mold/core with the multi-reaction approach is estimated to be significantly higher. These results underscore the importance of precise kinetic parameters for simulating binder decomposition in casting processes.
This paper presents and describes the research capabilities of a prototype experimental bench for realising the composite processing of liquid aluminium alloys by involving gas refining by rotary degassing technology and refining with salts (fluxes) in powder form. The constructed unit was installed in the Experimental Foundry of the Faculty of Foundry Engineering at AGH in the Department of Moulding Processes, Mould Technology, and Non-Ferrous Metals Foundry; it is an integral part of a thyristor-based medium-frequency induction furnace with a melting capacity of up to 60 kg for aluminium alloys. The new experimental bench performs barbotage refining using a rotating head with the possibility of alternating the introduction of refiners/modifiers in powder form. This method can be used in casting lines: continuous in reactors, or batch in ladles. The innovation of the design of the stand and the treatment of the liquid metal with powdered additives consists of dosing the refiner fluid deep into the metal bath through a channel that was made in the rotor axis and the head; this differs from conventional methods in the small amounts of introduced salts and, at the same time, in the very good metal-inert gas-salt homogeneity of the treated metal bath. This method of dosing the refining salts increases the efficiency of their use, reduces any losses, and limits the formation of post-refining slag (thus, minimising the negative environmental effect). The feedstock that was used for the test smelts consisted of recycled materials: aluminium 99.7 (in the form of wires of various cross-sections that were used in electrical engineering – so-called ‘SECTOR’), and the sub-eutectic AlSi7Mg0.3 alloy (in ingot form). The scope of the tests included verifying the technical solutions that were adopted for the dosing of the bulk materials in the form of a fluid, selecting the melting temperature, and dispersing (distributing) the materials in the bath via the rotor head. The results of the trials were reviewed in terms of the changes in the hydrogen content of the performed process and information on such powder-flux-introduction parameters as the type of the rotor head and the melting temperature of the powder flux. Preliminary trials showed that the performed complex refining (rotary degassing + refining with salts being blown as a fluid into the lower parts of the liquid metal) allowed us to reduce the hydrogen content to a level that could not be achieved by gas refining alone.
RTV 10A silicone rubber composites have many applications in forming many medical products and one of the recent applications is for orthotic insoles. This is because the RTV silicon rubber has excellent flexibility, elasticity, and resistance against splitting. However, these mechanical properties still need improvement when applied in certain medical applications. One way to improve mechanical properties is by adding talc. The process of mixing silicon rubber with talc requires special techniques to prevent the formation of porosity that may lead to unexpected mechanical properties. This porosity occurs due to trapped air during the mixing process or pouring into molds. Efforts to eliminate this porosity include Vacuum Die Casting (VDC) techniques. This study presents the mechanical properties improvement of RTV 10A silicon rubber composite with the addition of using 30% talc. The objective is to achieve a more convenient orthotic insole to reduce the pain in human foot joints during walking due to planar stress. This study aims to reduce the porosity and minimize the trapped air by adding 30% talc into RTV 10A silicone rubber composite using VDC. In the experiment, the pressure variation was determined at -0.04 MPa, -0.06 MPa, -0.08 MPa, and -0.1 MPa through a mold size of 45 mm in diameter and thickness of 7 mm. Fluidity, density, porosity, and hardness were tested during the experiment. The results show that by decreasing vacuum pressure, the density and the hardness increase. This is because the size and distribution of porosity are decreased and more homogeny. Furthermore, it also produces higher fluidity. However, the porosity of the specimen after vacuum casting is not partially filled.
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W publikacji przedstawiono charakterystykę staliwa stopowego wysokomanganowego, potocznie określanego mianem staliwa Hadfielda. Staliwa z tej grupy w warunkach wzrostu ciśnienia lub obciążenia, np. w wyniku uderzenia, wykazują dużą skłonność do tzw. umocnienia zgniotem, objawiającego się zwiększeniem powierzchniowej twardości i odporności na zużycie przy zachowaniu ciągliwości rdzenia.
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The paper presents the characteristics of a high-manganese alloy cast steel, commonly referred to as Hadfield cast steel. Cast steels of this group demonstrate a high tendency to the so-called strain hardening under the conditions of pressure or load increase, e.g. as a result of an impact, which is manifested by an increase in surface hardness and wear resistance while maintaining the ductility of the core. This is decisive for the applicability of a high-manganese cast steel for the castings of hammers and liners for coal mills and other mills, crusher cones, working elements of construction machines as well as cast elements of turnouts. In particular, the paper presents the chemical composition and usable properties of a high- -manganese cast steel intended for use in railway infrastructure as well as the characteristics of its microstructure finally shaped by heat treatment.
This work focused on how self-compacting concrete (SCC) performs in situ in hot weather conditions at an ambient temperature of about 35°C. Tests for the rheological properties and compressive and splitting tensile strength aspects were carried out. The results of SCC mix ingredients on the rheological and hardened features of SCC mix were studied. Variations in the amount of portland cement content (CC), water to cement ratio (w/c), coarse to fine aggregate ratio (C : F), chemical admixture ratio, and pozzolanic admixture ratio were considered. Optimum values were obtained for these ingredients, which satisfied the SCC rheological characteristics and gave a 28-day compressive strength of 42 MPa, and 52 MPa after 28 days and 56 days, respectively. These optimum constituent values were 450 kg·m–3 of cement, 0.45 water cementitious ratio, and a coarse to fine material ratio of 1 : 0.8, a high range superplasticizer of 2%, and a mineral admixture of either 5% silica fume or 25% fly ash as a substitute for a similar amount cement.
Purpose: The current paper aims to present a new casting approach in dentistry by eliminating some conventional preliminary procedures and digitalising the process as much as possible. Design/methodology/approach: The experiment uses six digital crown patterns. They are aligned with each other and to the wall of a virtual casting ring. Then a digital sprue system is created. The object alignment and sizes are revised, and the optimal correlation is set. Finally, a single virtual object is created and is 3D printed of light curing acrylic resin suitable for casting, invested, and cast. Findings: The castings that are achieved have good quality and no defects. At the same time, the virtual designing and aligning of the patterns and all the components of the sprue system and casting ring save much time and allows better precision to be achieved. All these facts allow better control of the casting process results, making the process faster, more predictable, and more accurate. Research limitations/implications: The limitations of this study concerns pattern selection. It is well-known that the acrylic resin sublimates and expands massively during a temperature rise, which may cause mould fracture. This obstacle is very representative as solid objects with higher volumes are examined. This may enforce alignment revision or even temperature rate modification. Practical implications: Suggested approach will be very useful for daily dental laboratory practice by optimizing the working time of the dental technician, making the denture production process faster, more predictable, and more accurate. As a result, the process optimizes the working process in dental offices, by allowing shortening the time of each visit and treatment plan terms. Originality/value: Presented approach reveals some new opportunities for dental technicians to substitute the conventional raw stages of sprue system fabrication with digital planning and designing. This allows dental technicians to take advantage of the full potential of digital technologies.
This paper presents the results of a study to determine the influence of casting parameters (cooling rate in the casting mould, casting temperature) on the primary structure of Mg-4%Li-1%Ca alloy ingots. The macro- and microstructure analysis of the Mg-4%Li-1%Ca alloy was performed using light and electron microscopy techniques. Microhardness measurements were made for the Mg-4%Li-1%Ca alloy and phase identification in the Mg-4%Li-1%Ca alloy was made using X-ray phase analysis.
Air entrainment defect is a common type of defect in the casting process, which will seriously affect the quality of the casting. Numerical simulation technology can predict the occurrence of casting defects according to the evolution law of liquid metal in the process of filling and solidification. The simulation of air entrainment process is a hot and difficult issue in the field of numerical simulation. The evolution law of air entrainment and the tracking of induced bubbles in the process of metal filling are still lacking. So is the quantitative prediction of trained gas. In this paper, based on the numerical simulation software of Inte CAST, this paper proposes an algorithm for air entrainment search and tracking, which is used to develop a quantitative prediction system for air entrainment. The feasibility of the system is verified through the simulation calculation of the typical test pieces of the air entrainment and the prediction of air entrainment defects of the casting in the process of filling is obtained through the simulation calculation of the actual casting, which can provide a certain guiding role for the optimization of the process in the production practice.
Modified LCD-based method was used to print three-dimensional (3D) elements. This innovative method combines printing the external shell and filling, thus obtaining mould by casting resin. In order to compare the properties of prints obtained with this method with the ones fabricated in a standard procedure, we conducted bending tests of vertically/horizontally printed and shell-printed cast specimens. The shell-cast samples showed higher flexural strength and larger values of apparent Young’s modulus. The presented results also concern the kinetics of curing samples obtained with different fabrication routes.
The demand for castings with superior properties has compelled the development and optimization of manufacturing technologies. By further developing already known techniques, we are able to contribute to the introduction of new research possibilities. The article presents the methodology of conducting simulation tests of the gravity casting process into sand moulds with the use of ablation. The ablation technique consists in spraying water through evenly spaced nozzles onto a mould into which the liquid casting alloy has been poured. The conducted research focuses on an alloy from the group of Al-Si alloys. In order to compare the effects of different techniques, additional tests were carried out for gravity casting into sand and metal die moulds. At the same time, virtual experiments were conducted to develop a simulation methodology for ablation casting technology, taking into account mould degradation. Additionally, the possibility of predicting the final mechanical properties of various manufacturing technologies was tested. Destructive tests were carried out to determine the mechanical properties in the cast samples, as well as microstructure tests and secondary dendrite spacing. The results of the mechanical tests are compared with the predicted simulation properties.
One of the most interesting categories of artifacts for archaeometallurgical research includes deposits of bronze items, so-called “metallurgists hoards”. They contain, aside of final products, many fragments of raw material and, moreover, metallurgical tools. An important source for the studies on the history of metallurgical technology is hoard from Przybysław, Greater Poland district. Thus, the aim of the work is the identification and interpretation of bronze-working practices and strategies adopted by prehistoric communities of the Late Bronze Age and the Early Iron Age (ca. 600 BC). The examined objects are characterized in terms of their design, structure, and chemical composition. The methods chosen for the studies of artifacts include: metallographic macro- and microscopic observations using optical microscopy (OM) and scanning electron microscopy (SEM), the analysis of chemical composition with the methods of energy dispersive X-ray spectroscopy (EDS), and X-ray fluorescence (ED-XRF). The thermodynamic analysis of the alloys was performed on the basis of the CALPHAD method. The experimental melts allowed to verify the theoretical considerations and to determine the characteristic temperatures of changes. The old casting technology can be analyzed basing on computer modeling and computer simulation methods. Simulations in the MAGMASOFT® software are a good example to illustrate how to fill a mould cavity with a molten bronze for a hoop ornament. It is also an appropriate tool to determine temperature distribution in a mould. The simulations also show the possible disadvantages with this old technology.
The study investigated the primary structure of the new generation of superalloys based on Co-10Al-5Mo-2Nb and Co-20Ni-10Al-5Mo-2Nb cobalt. Research on a group of cobalt-based materials was initiated in 2006 by J. Sato [1]. These materials may replace nickel-based superalloys in the future due to their excellent properties at elevated temperatures relative to nickel-based superalloys. The primary microstructure characterisation of the Co-10Al-5Mo-2Nb and Co-20Ni-10Al-5Mo-2Nb alloy are the basic subject of this article. The Co-10Al-5Mo-2Nb and Co-20Ni-10Al-5Mo-2Nb alloy are tungsten free alloys of a new type with the final microstructure based on the Co-based solid solution L12 phase of the Co3(Al,Mo,Nb) type as a strengthened structural element. The analysed alloys were investigated in an as-cast state after a vacuum casting process applied on graphite moulds. The primary microstructure of the alloys and the chemical constituent of dendritic and interdendritic areas were analysed using light, scanning electron and transmission microscopy. Currently, nickel-strengthened γ’ phase steels are still unrivalled in aerospace applications, however, cobalt based superalloys are a response to their existing limitations, which do not allow maintaining the current rate of development of aircraft engines.
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Aluminum and its alloys are one of the most favored metal-based materials for engineering applications that require lightweight materials. On the other hand, composites are getting more preferable for different kinds of applications recently. Boron nitride nanotubes (BNNTs) are one of the excellent reinforcement materials for aluminum and its alloys. To enhance mechanical properties of aluminum, BNNTs can be added with different processes. BNNT reinforced aluminum matrix composites also demonstrate extraordinary radiation shielding properties. This study consists of BNNT reinforced aluminum matrix composite production performed by casting method. Since wetting of BNNT in liquid aluminum is an obstacle for casting, various casting techniques were performed to distribute homogeneously in liquid aluminum. Different methods were investigated in an aim to incorporate BNNT into liquid method as reinforcement. It was found that UTS was increased by 20% and elongation at fracture was increased by 170% when BNNT was preheated at 800°C for 30 minutes.
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