Pressure Casting Research Articles

INTERDIFFUSION ZONE CHARACTERISTICS OF INTERFACE BIMETAL ALUMINUM-COPPER PRODUCED BY SQUEEZE CASTING

Bimetals are metallurgical bonds formed by the mixing of two materials. One method of producing bimetal is through squeeze casting. However, there is currently no established optimal pressure reference for the pressing during bimetal production. This research aims to determine the optimal pressure in the form of bushings to achieve an optimal interdiffusion bond at the interface. The study uses copper and aluminum alloys. The melting temperature of the aluminum is set at 770°C, while the copper is 1150°C. The molten metals are alternately poured into a mold. In the first stage, aluminum is poured into the mold, followed by copper in the second stage, gradually forming an aluminum-copper bimetal bushing. In the third stage, pressure is applied. The squeeze pressure variations used are 30, 40, 50, and 60 MPa. The results show that increasing the squeeze casting pressure leads to an increase in the thickness of the interdiffusion layer. The highest hardness is observed in the interface because of the formation of AlCu compounds. The increase in hardness also enhances wear resistance in the interface. Therefore, squeeze casting with a pressure of 60 MPa is recommended for producing Al-Cu bimetal to achieve optimal interdiffusion at the interface.

Evaluation of novel 3D printed foam patterns for rapid investment casting based on fused filament fabrication

Purpose This study aims to evaluate the effectiveness of three-dimensional (3D) printed foam polylactic acid (PLA) patterns in reducing ceramic shell stresses and cracking during burnout in the rapid investment casting (RIC) process to improve casting yield and dimensional tolerances. Design/methodology/approach Cylindrical and step-wedge patterns were 3D printed using foam PLA feedstock and compared with patterns from plain PLA and Polyvinyl Butyral (PVB). The patterns were shelled using ceramic slurry and investment cast in A356.1 aluminum alloy. Shell cracking and dimensional tolerances of resulting castings were assessed. Additionally, a complex component was 3D printed, laser-scanned, then cast and rescanned to evaluate dimensional accuracy. Finite Element Analysis (FEA) was conducted on cylindrical geometries to analyze internal mold pressure because of thermal stresses during burnout. Findings The foam PLA for all patterns produced no shell cracking during both ramp and flash burnouts. Castings made from foam PLA patterns showed improved dimensional tolerances and a narrower error distribution in GD&T analysis compared to those made from PLA and PVB. FEA results indicated that the thermomechanical properties of foam PLA reduce internal mold pressure by over 90%, which decreased internal shell stresses. Originality/value This research introduces a novel application of 3D printed foam PLA feedstock in the RIC process as a pattern material. This study demonstrates that foam PLA patterns effectively eliminate shell cracking during burnout and enhance dimensional accuracy. The findings of this study offer a new approach for improving dimensional tolerances and casting yield in RIC, which has not been previously explored.

Effect of Cu addition on microstructure, wear, and corrosion resistance of AlCoCrFeNiSi0.5Cux (x = 0.01, 0.05, 0.1) high-entropy alloys

The influence of copper addition on the structure and selected properties of AlCoCrFeNiSi0.5Cux high-entropy alloys is described. Slowly cooled ingots were prepared by induction melting, and the samples in the form of plates were obtained by pressure casting. The conducted structural studies confirmed the presence of BCC/B2 phase. Microsegregation in the ingots was associated with the formation of intermetallic Cr3Si and Fe5Si3 phases. An increase in the cooling rate stopped segregation by reducing the mobility of Cr and Si. The hyperfine magnetic field distributions indicated the formation of the BCC Fe(Co,Ni,Si,Cr) solid solution for alloys in the form of plates. The lowest corrosion-current density (0.04 μA/cm2) in 3.5%-NaCl solution was obtained for the plate with the lowest copper content. The dominated aluminum surface states for the post-corrosive plates highlighted the binding energies of Al2O3. A tendency of reduced coercivity with increased copper content was observed. The positive effect of copper addition on wear resistance was confirmed for the AlCoCrFeNiSi0.5Cu0.1 alloy.

Effect of modified investment and casting system on the recasting properties of high-gold alloy

Background/purposeHigh gold (Au) alloys have many advantages, such as good mechanical properties and stable chemical properties for dental restoration. The purpose of this investigation was to investigate the effect of zirconia (ZrO2)-magnesia (MgO)-based investment combined with an argon arc vacuum pressure (Ar-arc VP) casting process on the recasting of high Au alloys. Materials and methodsThe recasting Au alloys were compared between the control group of conventional SiO2-based investment/horizontal centrifugal (HC) casting and the experimental group of ZrO2–MgO-based investment/Ar-arc VP die casting. The first-generation castings were defined as being made from purchased Au alloys and the second-generation castings were made from 50 wt% of the original Au alloys before casting, plus the balance of the remaining 50 wt% from the previous castings. The third-generation was made from all old surplus from the previous castings. The ingots were measured for the marginal gap, surface roughness, interface oxidation, hardness, and phase identification. ResultsThe results showed that the recasting success rate reached 100%. The ZrO2–MgO-based investment/Ar-arc VP group had better edge precision, smaller oxide layer thickness, and lower hardness than the SiO2-based investment/HC group. However, surface roughness analysis indicated little difference between the two groups. Phase analysis showed that the recasting alloys of the second and third-generation groups contained higher Au contents than those of the first-generation. ConclusionOverall, the Au alloy can be better recasted and retain good mechanical properties under the clinically used 5 wt% ZrO2–MgO-based investment/Ar-arc VP casting method.

Study on Protective Properties of Metal Confined Ceramic Hollow Ball Composites

Abstract Metal confined ceramic hollow ball composite was prepared by low pressure casting impregnation molding process. Because the ceramic hollow ball is fully constrained by metal in the circumference and radial direction, and takes into account high hardness of ceramic and strength and toughness of metal, it has a strong back strength and energy absorption effect and excellent impact resistance when it is penetrated by projectiles. The protection test of metal confined ceramic hollow ball composite material was carried out by using 14.5mm ballistic gun and firing 14.5mm perforating projectile. The test results show that the average protection coefficient of metal confined ceramic hollow ball composite structure is 1.53, and the damage area of metal confined ceramic hollow ball composite is small, and it has great advantages in resistance to multiple bullets.

INVESTIGATION OF DEFECTS IN METALLIC AND PLASTIC THREADED CONNECTIONS OF OILFIELD EQUIPMENT

The article is devoted to the study of the quality of parts made of metallic and plastic materials used in oil equipment. The precision and strength of details made of plastic materials in oil equipment have been studied. Operational qualities and indicators have been investigated. The manufacturing technologies of metallic and plastic parts were studied, pressure casting and pressing methods were applied, and ways of eliminating the defects that appeared in them were considered. Keywords: threaded joints, corrosion, equipment, polymer, lubricant, vibration.

Experimental assessment of freeze-thaw deterioration in compression-cast fiber-reinforced concrete

An increasing number of critical infrastructures are built in cold and perma-frost regions, resulting in higher susceptibility to damage due to freeze-thaw (F-T) cycles. This paper assesses the mechanical properties and F-T damage evolution of compression-cast fiber-reinforced concrete (CCFRC) through rapid F-T cycling tests. Nine types of fiber-reinforced concrete (FRC) are experimentally investigated through 144 cubic and 39 prismatic specimens. The main parameters considered in the tests include the casting pressure applied during the compression casting procedure (between 0 and 15 MPa), type of the internal added fibers (polypropylene, end-hooked steel, or their combination), fiber content, and number of F-T cycles. The effects of these parameters on the failure modes, strength degradation rates, deterioration evolution, frost resistance durability, microscopic behavior, and F-T resistance of FRC specimens, are examined in detail. The microscopic performance of different specimens is further investigated using the X-ray computed tomography (X-CT), scanning electron microscopy (SEM), and backscattered scanning electron (BSE) tests. Based on the test results, it is shown that: (i) compared with the mass loss rate, the relative dynamic elastic modulus can be a more suitable index to assess the F-T resistance of FRC; (ii) compression casting and addition of fibers can effectively enhance the F-T denudation resistance of CCFRC; (iii) compression casting reduces the compressive and flexural strength degradation rates of CCFRC, but at the expense of more brittle behavior; and (iv) compression casting and use of the mixed polypropylene and end-hooked steel fibers can effectively delay the F-T cycling induced damage, reduce porosity and internal defects, and enhance the micro-structural behavior and F-T resistance of CCFRC. F-T deterioration prediction models are also proposed and shown to provide accurate and effective representation of the behavior of CCFRC materials.

Local stress/strain field analysis of die-casting Al alloys via 3D model simulation with realistic defect distribution and RVE modelling

The deformation and fracture behavior of die-casting aluminium (Al) alloys is very complex. Due to local variations in properties, the microstructure and mechanical behavior of materials are highly anisotropic. In this paper, an attempt has been made to quantitatively study the defect characteristics of high pressure cast Al alloy parts using experimental and finite element calculation methods, and to analysis the effect of local porosity and pore size on plasticity. Three-dimensional solids with real defect distribution are obtained by using 3D X-ray computed tomography, and used as an input for building a finite element model. The damage initiation of cast Al alloys under complex stress states is analyzed from micro to macro scales. Crack propagation occurs through two modes of microporous agglomeration: aggregated pores produce cracks from internal necking and stress concentration. Then, they expand in the same direction, agglomerate in a specific direction and eventually fracture. Subsequently, the effect of porosity on non-homogeneity was elucidated by obtaining local stress/strain behavior through digital image correlation measurements. Additionally, a theoretical framework of elasto-plastic deformation of microstructures and a 3D representative volume element model are developed to simulate the deformation and damage processes under cyclic boundary conditions of materials. The simulation results show that the local stress/strain around the pores evolves gradually with deformation. During the die casting process, the method demonstrates the ability to predict the mechanical behavior of Al alloys.

Evaluation of fatigue behavior of a casting aluminum knuckle considering influences of inhomogeneous microstructure

Until now the fatigue behavior of casting aluminum components is usually evaluated in the safety analysis without considering the inhomogeneity of local properties. It can result in an underestimation of damage risk or an oversizing of the components. The purpose of the work is to quantify and to predict the influence of the inhomogeneity of microstructure and the corresponding local properties on the overall behavior of the selected casting aluminum knuckle under cyclic loading. Since no shrinkage pores are observed in the knuckle produced by the counter pressure casting process, influences of porosity on fatigue property are not taken into account in this study. Tensile specimens are extracted from different positions in the knuckle and tested under quasistatic and cyclic loading. The dependences of the flow stress, the fracture strain, and the S-N curve on position for specimen extraction are evaluated. Metallographic investigations are performed to reveal the relations between microstructure and the mentioned properties. A relationship between the S-N curves and the secondary dendrite arm spacing (SDAS) is derived from the experimental results. The corresponding parameters of the new fatigue damage model are determined and used to simulate the specimens and component tests. The distribution of SDAS in the component is determined by casting simulations and transferred to the FE-model for the fatigue analysis. The standard fatigue tests on knuckles are performed and the damage behavior is analyzed in view of the influence of microstructure. The simulations of the knuckle fatigue tests are performed with SDAS-dependent material parameters. The prediction of the fatigue behavior of the knuckles agrees with the experimental results well.

Diketopyrrolopyrrole‐Activated Dynamic Condensation Approach to Narrow‐Band Gap Vinylene‐Linked Covalent Organic Frameworks

Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well‐known π‐bridge used in the synthesis of high‐performance semiconducting materials. Two‐dimensional (2D) vinylene‐linked covalent organic frameworks (COFs) represent a promising class of π‐conjugated structures, however, the range of available monomers for the reversible formation of carbon‐carbon double bonds remains limited. In this study, a new class of 2D vinylene‐linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM‐DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L‐proline and 4‐dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP‐linking mode enhanced donor‐π‐acceptor conjugation and promoted π‐stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light‐harvesting capability across the visible to near‐infrared I (NIR‐I) regions. Furthermore, the COFs could be converted into free‐standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

Diketopyrrolopyrrole-Activated Dynamic Condensation Approach to Narrow-Band Gap Vinylene-Linked Covalent Organic Frameworks.

Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well-known π-bridge used in the synthesis of high-performance semiconducting materials. Two-dimensional (2D) vinylene-linked covalent organic frameworks (COFs) represent a promising class of π-conjugated structures, however, the range of available monomers for the reversible formation of carbon-carbon double bonds remains limited. In this study, a new class of 2D vinylene-linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM-DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L-proline and 4-dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP-linking mode enhanced donor-π-acceptor conjugation and promoted π-stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light-harvesting capability across the visible to near-infrared I (NIR-I) regions. Furthermore, the COFs could be converted into free-standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

A study on influence of sintering temperature, diameter and volume fraction of metal hollow spheres on the mechanical properties of metal hollow spheres composites

The structural parameters (the sintering temperature, diameter, and volume fraction of the hollow spheres) have a considerable influence on the mechanical properties of metal hollow sphere composites (MHSCs). Hence, the influence laws of the structural parameters on the mechanical properties of MHSCs possess certain research significance. To obtain these laws, MHSCs with different structural parameters were fabricated using a pressure casting method. Subsequently, the density of the MHSCs was determined through the direct measurement method. Meanwhile, X-ray diffraction and scanning electron microscopy were employed to conduct in-depth analyses of the phase composition and microstructure of the MHSCs. Additionally, the compression performance of the MHSCs was measured with the assistance of a universal mechanical testing machine. The analysis of the microstructure and phase composition results revealed that MHSCs consisted of γ-Fe, Al, Si, Fe₂Al₇Si, Fe₂Al₄Si, and Al₈Si₆Mg₃Fe phases, with the transition layer composed of the Fe₂Al₇Si phase. The results of the compression performance indicated that the compression performance of MHSCs increased with the rise of the sintering temperature and decreased with the increase of the volume fraction. However, as the diameter of MHS increased, the yield strength of MHSCs declined while the deformation strength of MHSCs increased. When the diameter of the MHSs was 2.55 mm and the volume fraction was 40 %, the compression performance of the MHSCs reached its optimum. At that point, the yield strength was 113.65±3.37 Mpa, and the average deformation strength was 81.26±5.45 Mpa.

Plastic Injection Molding Process Analysis: Data Integration and Modeling for Improved Production Efficiency

This paper presents a comprehensive analysis of the plastic injection molding process through the integration of data acquisition technologies and classification models. In collaboration with a company specializing in plastic injection, data were extracted directly from the machine during a specific period at the beginning of a shift change. These data were subjected to exploratory analysis to identify correlations between important variables, such as injection time, cycle time, and mold pressures. Additionally, classification models, including Random Forest and Logistic Regression, were constructed to predict and classify the process state based on these variables. The model results demonstrated high predictive performance, with 99.5% accuracy for Random Forest and 97% for Logistic Regression. These results provide a strong foundation for the early identification of potential problems and informed decision making to improve the efficiency of the plastic injection molding process. This study contributes to the advancement of the integration of intelligent technologies in industrial process optimization, aligned with the principles of Industry 4.0.

Effect of the refining process on porosity and selected mechanical properties of AlSi7Mg alloy pressure castings

Effect of the refining process on porosity and selected mechanical properties of AlSi7Mg alloy pressure castings

The Effect of Process Parameters on the Pore Structure of Lotus-Type Porous Copper Fabricated via Continuous Casting

The pores in lotus-type porous copper are formed due to the difference in hydrogen solubility between the liquid and solid phases of copper. In a pressurized hydrogen atmosphere, hydrogen gas is released at the gas release and crystallization temperature, which is the melting point of copper. This study systematically analyzes the effects of process parameters, including hydrogen ratio, total pressure, and continuous casting speed, on the pore structure of lotus-type porous copper, with the aim of identifying the most critical process parameters for controlling pore diameter and density. Within the hydrogen ratio up to 50%, it was observed that as the hydrogen ratio increases, the pores tend to increase in porosity, and the pore diameter increases. As the hydrogen ratio increased from 25% to 50%, the pore diameter increased from 300 μm to 400 μm, while the pore density decreased from 3.3 N·mm−2 to 2.8 N·mm−2. As the total pressure increased, the pore diameter tended to decrease, and the pore density increased. Specifically, when the total pressure increased from 0.2 MPa to 0.4 MPa, the pore diameter decreased from 1100 μm to 400 μm, while the pore density increased significantly from 0.5 N·mm−2 to 2.8 N·mm−2. In addition, as the continuous casting speed increased, 30 to 90 mm·min−1, the pore diameter decreased from 850 μm to 400 μm, and the pore density increased from 0.7 N·mm−2 to 2.8. N·mm−2. Specifically, the increase in total pressure led to a decrease in Gibbs free energy and a reduction in the critical pore nucleation radius, which promoted pore formation and resulted in the creation of more, smaller pores. These results suggest that total pressure is the primary factor influencing both pore diameter and density in lotus-type porous copper.

Tribological properties and related effects of compressed, thermally modified and wax-impregnated wood

This paper develops a process for the preparation of modified wood with low friction and low wear for tribological applications such as self-lubricating bearings. Two types of wood, beech (Fagus sylvatica) and robinia (Robinia pseudoacacia), have been studied and the results compared with naturally lubricated native lignum vitae. The process developed consists of plasticisation followed by compression in a mould, thermal modification and subsequent wax impregnation. Plasticisation was carried out by conditioning the samples to a low equilibrium moisture content of 10%, followed by heating to a sample core temperature of 80 °C. This process protects the internal wood structure from mechanical damage during densification. After plasticisation, the wood was compressed in a press mould. A low springback effect (SBE), resulting in compression of up to 40%, was achieved by unloading the mould without opening it. This step optimises compressive strength and hardness. Subsequent heat treatment reduces thickness swelling by up to 85%. Finally, a wax impregnation was applied to reduce friction. Sliding wear tests on modified beech wood have shown that the lowest wear occurs in the cross-sectional orientation (load perpendicular to the fibre ends; rxt orientation). Sliding friction studies using a steel ball on a ball-on-disc tribometer showed that compressed and thermally modified samples impregnated with rapeseed wax or beeswax exhibited coefficients of friction in a range of 0.08 to 0.09. These values are almost four times lower than those of plain compressed wood and even lower than those of lignum vitae, which was used for plain bearings decades ago. This study clearly demonstrates the high potential of compressed, thermally modified and wax-impregnated wood.

Moulding Test and Process Parameter Optimization of Biomass Seedling Pots for Cow Dung and Corn Stover

In order to determine the optimal moulding process parameters of biomass seedling pots prepared from fermented cow dung mixed with corn stover, the moulding pressure, baking time, and baking temperature of biomass seedling pots were taken as the influencing factors, and the expansion rate, durability rate, wet swelling rate (48 h), and resistance to damage were taken as the evaluation indexes, and the Box–Behnken design of the response surface method was used to analyze the significance of interactions among the different influencing factors in the moulding process of biomass seedling pots and to optimize the moulding process. The experiment was conducted in the Biomass Laboratory of Heilongjiang Bayi Agricultural University. The response surface method Box–Behnken design was used to analyze the significance of the interaction between different influencing factors in the biomass seedling pots moulding process and optimize the moulding process. The results showed that the optimum moulding process conditions obtained using the Box–Behnken design were the following: a moulding pressure of 520.393 kN, baking temperature of 202.870 °C, and baking time of 8.573 min. The model was validated by testing and a response value of 10.522% was obtained for expansion, 99.598% for durability rate, 11.145% for wet swelling (48 h), and 4503.545 N for resistance to damage. The experimental verification showed that the deviation of the actual value obtained under this condition from the predicted value is less than 5%, indicating that the model reproduces well and meets the experimental requirements. Based on the optimal moulding process conditions determined in this experiment, the total porosity, EC, and pH of the Biomass seedling pots were determined to be 67.32%, 1.63 mS/cm, and 6.7, respectively, which met the seedling requirements.

Reduction of Pressure Distribution Variation in Press Mold Based on Variable Lattice Optimization

Reduction of Pressure Distribution Variation in Press Mold Based on Variable Lattice Optimization

Microstructure and mechanical properties of freeze-casted in-situ ABOw@Al2O3/AZ91 composites

In this work, the A18B4O33w (ABOw) was in-situ generated on the surface of Al2O3 through the reaction of B2O3 and Al2O3, resulting in the thorn structure. Then, the ABOw@Al2O3/AZ91 composites were fabricated through a combination of freeze casting and pressure casting. The influence of the initial content of B2O3 on the microstructure and mechanical properties of ABOw@Al2O3/AZ91 composites was investigated. The results show that the lamellar structure of ABOw@Al2O3/AZ91 composites were weakened, which gradually changed to dendritic structure with the increasing B2O3 content. The in-situ formation of ABOw on the surface of Al2O3 was favorable to improve the compressive strength of both ABOw@Al2O3 ceramic scaffold and ABOw@Al2O3/AZ91 composites, while also reducing the anisotropy of the composites. Furthermore, the in-situ generated ABOw within the ceramic layer could effectively relieve stress concentration and delay crack initiation and propagation, which led to the enhancement of the load-bearing capacity of ABOw@Al2O3/AZ91 composites. The ABOw@Al2O3/AZ91 composite exhibited the outstanding mechanical properties with the compressive strength of ∼685 MPa, when the B2O3's content is 5 wt%.

Multiscale insights on compression cast sea sand and seawater concrete

Reinforced concrete (RC) structures in coastal and marine regions face two primary challenges, the shortage of raw materials and severe service environments. Concrete made from sea sand and seawater (SS-SW) can address the shortage of natural sand by utilizing locally available resources. Meanwhile, the newly developed compression cast technology (CCT) significantly improves the micro and macro properties of concrete, enhancing its durability in harsh environments. Therefore, the combination of SS-SW concrete and CCT to form a new compression-cast SS-SW concrete can simultaneously solve the problems of materials shortage and durability issues for coastal RC structures. However, till now, research on this type of concrete is still an open issue. This paper aims to carry out multilevel investigations on the macro and micro performance of compressed SS-SW concrete. First, 69 concrete columns were tested to understand the stress-strain behavior and associated mechanical indices. The compressive strength of compressed concrete was found to be up to 1.86 times greater than that of uncompressed concrete. Meanwhile, the porosities in both mortar and the interfacial transition zone (ITZ) of concrete under a casting pressure of 15 MPa were approximately 50 % of those in uncompressed counterpart. Existing models are inadequate for predicting the behavior of compressed SS-SW concrete, leading to the development of new and accurate models to predict its compressive strength, elastic modulus, peak strain and stress-strain curve. These findings pave the way for the design and application of this kind of concrete.