Centrifugal Slip Casting Research Articles

Gradient composites Al2O3-Ni obtained via the CSC technique in a magnetic field - microstructure and mechanical properties

This article presents the formation of composite microstructures by combining two established concepts: centrifugal slip casting and the utilization of a magnetic field to control the distribution of magnetic particles. The integration of these methodologies offers the potential to create zones within the composite with distinct hardness values. The study introduces a novel method for fabricating ceramic-metal composites, with a key focus on determining the feasibility of manipulating the location of the metallic phase using a magnetic field. Through this innovative approach, the research aims to produce composite hollow cylinders with a gradient distribution of metallic particles. The relative density of the composites was 97 %. The hardness values for the samples range from 970 HV to 2700 HV, displaying variability based on the metallic phase content within the material. The compressive strength for Al2O3-Ni samples was equal to 128.92 MPa. The Al2O3 grains in zone III after the sintering process have an average size of 1.27 ± 0.68 µm. The Al2O3-Ni composites indicate a smaller heat capacity of the material compared to pure Al2O3 samples.

The Structural and Mechanical Properties of Al2O3-Ni Composites Obtained by Magnetic Field-Assisted Centrifugal Slip Casting.

This study investigates the influence of a magnetic field on the microstructure and properties of Al2O3-Ni composites fabricated via centrifugal slip casting at 1500 rpm. Al2O3 and Ni powders were combined with water and deflocculants, homogenized, and then cast into a porous plaster mold surrounded by Nd-Fe-B magnets. The resulting composites, sintered in a reducing atmosphere, exhibited a three-zone structure with varying Ni content due to the combined effects of the magnetic field and centrifugal force. SEM, EDX, and XRD analyses confirmed the distribution and composition of the phases. Hardness tests revealed the highest values at the outermost zone, with a gradual decrease toward the inner zones. Compression tests employing digital image correlation revealed high internal stresses and a significant improvement in compressive strength compared to non-magnetic field methods. This study confirms that magnetic field-assisted centrifugal slip casting significantly enhances the structural, hardness, and compressive strength properties of Al2O3-Ni composites, indicating promising potential for advanced applications.

DISPERSION OF AQUEOUS Y2O3 NANO-SUSPENSION AND FABRICATION OF TRANSPARENT CERAMICS BY COLLOIDAL PROCESSING

In the present study, transparent Y2O3 ceramics were successfully fabricated via colloidal processing, employing polyethylenimine (PEI) as an effective dispersant. The effect of PEI on nanosized Y2O3 suspensions was characterized by zeta-potential, adsorption behavior, rheological properties, and sedimentation test. The addition of PEI shifted the IEP of the Y2O3 powder towards a more alkaline pH range, and the adsorption of PEI on the Y2O3 surfaces gradually increased with the amount of PEI until reaching the saturation adsorption at 1.5 w/%. The PEI amount of 1.5 w/% was superior for the preparation of Y2O3 suspension as a result of a lower viscosity or sedimentation behavior. The viscosity of the suspension depended on the solids loading, increasing with the amount of powder. The optimal rheological behavior was achieved with 29 /% Y2O3 in the suspension, enabling the centrifugal slip casting of complex-shaped green bodies with a packing density of 43 %. Including an additional CIP treatment boosted the packing density of the green compacts, achieving above 50 %. Vacuum sintering the compacts at 1700 °C for 5 h yielded high-density ceramics exhibiting an in-line transmittance of approximately 73 % at a wavelength of 1100 nm.

Ceramic-metal pipes with NiAl2O4 and TiAl2O5 spinel phases with different metallic phase content - Analysis of properties, and microstructure, taking into account LCA

The article describes the formation of samples into pipes with NiAl2O4 and TiAl2O5 spinel phases with different metallic phase content. The centrifugal slip casting method was used to form the composites. All suspensions used were shear thinning and were characterized by slight thixotropy. The analysis of the phase composition and chemical composition showed the presence of Al2O3, TiAl2O5 and NiAl2O4 in the produced samples. The produced materials were characterized by brittle fracture behaviour. The obtained life cycle assessment results clearly showed that as the content of the metallic phase increases, the environmental footprint of sinters in the A1 phase increases, which is a direct consequence of the increased use of raw materials.

The influence of Ti/Ni metallic phase content on the microstructure and environmental interactions of gradient Al2O3-based composites

Al2O3/Ti/Ni composites, enhanced with the inclusion of NiAl2O4 and TiAl2O5 phases, represent a novel class of advanced materials with multifaceted properties suitable for diverse engineering applications. Centrifugal slip casting method was used for preparation of two series of gradient Al2O3/Ti/Ni composite samples with different content of the metallic Ti and Ni phases. Series I containing 0.5 vol.% of Ni and 0.5 vol.% of Ti and Series II containing 2.5 vol.% of Ni and 2.5 vol.% of Ti. Each series contained 55 vol.% of a solid phase. Rheological properties of the suspensions as well as microstructure of the obtained composites were studied, with special attention paid to the analysis of the formed spinel phases. Both series in the green form were characterized by 3-zone structure with different metallic phase content. The widths of individual zones for the Series I and Series II, after sintering at 1450?C, were 0.53mm (zone I), 3.26mm (zone II), 0.8mm (zone III) and 1.27mm (zone I), 1.47mm (zone II), 1.87mm (zone III), respectively. The results showed that after sintering two spinel phases were formed. The NiAl2O4 spinel phase consists only of small grains with a size of approximately 1.3- 1.8 ?m, which form larger clusters with or without a void inside. The TiAl2O5 phase consists of grains with an average size of 4.3 to 4.5 ?m. The Life Cycle Assessment analysis revealed that the values of the global warming potential indicator in phase A1 are 0.16 kg and 0.20 kg equivalent of CO2 per sintered sample for the Series I and Series II, respectively.

The Influence of Formation Speed in Centrifugal Slip-Casting Method on the Microstructure of Al2O3-Cu-Cr Gradient Composites.

This work focuses on the production of gradient composite materials with an alumina matrix containing copper and chromium and examines the effect of the reinforcement and casting speed on the obtained microstructure. Al2O3-Cu-Cr composites with a microstructure gradient were produced via centrifugal slip casting. The research reveals that adding chromium to the Al2O3-Cu system improves the connection between the ceramic and metal particles, probably by reducing the contact angle at the interface between the ceramic and metallic phases during sintering. Additionally, it was found that higher casting speed was conducive to obtaining a better connection at the interface of ceramics and metal.

Comprehensive analysis of the microstructure, properties and environmental performance of Al2O3-ZrO2 composites obtained via centrifugal slip casting

This research investigates the possibility of preparing Al2O3-ZrO2 composites with different proportions of the Al2O3 and ZrO2 phases by centrifugal slip casting (CSC) method and the effect of the solid phase content (50 vol%, 45 vol%, 40 vol%) on the microstructure and selected properties of the produced materials. The hardness results showed that all the series produced were characterised by high hardness, in the range of 16–19 GPa. The results of the static compression test demonstrated that increasing the solid phase content of the slip in the samples promotes the formation of fewer cracks during the monotonic compression loading of the composites. The LCA results demonstrated that as the content of ZrO2 in the composites increase, their environmental footprint increases.

Properties of Al2O3/Ti/Ni composites fabricated via centrifugal slip casting under environmentally assessed conditions as a step toward climate-neutral society

The paper concerns functionally graded composites obtained by centrifugal slip casting method. Al2O3, Ni, Ti, differed is size and morphology, were used as starting powders. The influence of metallic phase content (2 vol% and 20 vol%) and homogenisation process (planetary-ball milling) on suspension viscosity as well as density, phase composition, microstructure and mechanical properties of sintered bodies was investigated. Planetary-ball milling decrease the viscosity of suspensions of lower metallic content due to increase of their homogeneity. Slurries of higher metallic content, after homogenisation process, exhibit higher viscosity due to refinement of large metallic particles which leads to more intense surface interactions. CSC was applied to shape samples in form of thick-wall tubes with gradient microstructure across the wall thickness. Relative densities, after sintering, were about 10% higher for the samples containing 2 vol% of metallic phase (99.40% and 98.42%) compared to specimens of higher metallic content (90.57% and 86.86%), regardless of homogenisation process. Planetary ball milling had a positive effect on microstructure of obtained graded composites, leading to more homogeneous microstructure with well defined zones and lower number of defects, in both types of sample (2 vol% and 20 vol% of metallic content). Higher content of Ti and Ni caused that metal-rich zone was thicker, but microstructure was more defected. Hardness was higher for samples of more homogeneous microstructure. XRD confirmed the presence of Al2O3 and Ni, Ti phases but also evinced occurrence additional intermetallic phases form Ni–Ti system. The environmental impact accompanying fabrication of composites was evaluated using the LCA method. It was done in order to determine burdens caused at the early beginning of the research and development stage, creating a reliable basis for further development of an environmentally friendly industrial process, simultaneously being a step toward transition to a climate-neutral society which is one of the main objectives of European Green Deal.

Sustainable ZTA composites produced by an advanced centrifugal slip casting method

The centrifugal slip casting method presented in the paper is used to form ceramic sleeves with a good shape representation, eliminating material losses in machining or other forms of mechanical treatment that could be necessary when other moulding methods with a poorer shape representation are used. Sleeves developed this way can be used as system components to transport aggressive substances under elevated pressure and temperature conditions. To confirm the functionality of the sleeves prepared with the method, Al2O3, ZrO2, and composite components of ZTA were characterised for acid-base behavior, phase composition, microstructure, and mechanical strength. The tests confirmed the formation of expected gradient structures for ZTA composites. It results in the generation of components with improved flexural and torsional strength compared to non-gradient ZTA composites with the same Al2O3 to ZrO2 ratio. Applying a smaller quantity of ZrO2 should bring a positive economic effect, considering its high price. The analysis of accompanying environmental impacts was carried out for developed materials along with the lifecycle analysis. The paper describes a reduced waste generation method for making components for aggressive substance transportation systems. The present paper presents characteristics of materials for their resistance to factors under working conditions, demonstrating their durability and potential to reduce waste related to the operation of such system types.

The Potential of Al2O3\u2013ZrO2-Based Composites, Formed via CSC Method, in Linear Infrastructure Applications Based on Their Mechanical, Thermal and Environmental performance

Ceramic-ceramic composites have been prepared using the centrifugal slip casting method (CSC). The method has so far been mainly utilized in making ceramic-metal composites. Al2O3–ZrO2 composites have been obtained with different shares of ZrO2, i.e., 15, 50 and 75 vol pct, respectively. Prior to sintering the composite samples, the rheological properties of the casting slips were investigated and thermogravimetric tests were performed. Upon sintering, all three series of the ceramic composites showed a density close to 100 pct and no microcracks or delamination. Phase, microstructural and mechanical investigations were carried out to determine what effect the share of ceramics has on the composites produced. An increase in the share of ZrO2 in the Al2O3–ZrO2 composite leads to a reduction in the growth of Al2O3 grains and a decrease in the average hardness. Cross-sectional hardness testing of the composites showed no evident gradient in any of the samples. Life cycle analysis (LCA) results indicate that the further optimization of the composite formation process, including up-scaling, allows to obtain Al2O3–ZrO2-based pipes possessing more favorable environmental characteristics compared with materials conventionally used for linear infrastructure, which is important in light of the global transformation toward sustainable construction and the circular economy.Graphical abstract

ZTA Pipes with a Gradient Structure-Effect of the Rheological the Behavior of Ceramic Suspensions on the Gradient Structure and Characterized of the Obtained Products.

This paper focuses on the verifying the possibility of producing Al2O3-ZrO2 composite pipes with a gradient structure using centrifugal slip casting method. The aim of the research is to define the correlation between the rheological properties of aqueous suspensions of ceramic powders with different solid loading and obtaining the ZrO2 phase gradient in the Al2O3 matrix. Such products, due to their unique properties, can be utilized in the transport of aggressive substances, even in extreme temperature or corrosive conditions. The suspensions and the sintered samples were characterized by: broad rheological analysis, scanning electron microscopy, X-ray diffraction, stereological analysis and Vickers hardness tests. The study reports on a series of samples produced of ceramic suspensions (70 vol.% Al2O3–30 vol.% ZrO2) differing in the total solid loading in the range of 30–55 vol.%. The results clearly indicate that obtaining the gradient structure of ceramic-ceramic composite pipes is closely related to the rheological properties of the suspensions from which the samples are cast. The phase gradient is obtainable from suspensions 30–40 vol.%, in which the possibility of moving ZrO2 particles relative to the Al2O3 is quite high—these suspensions are characterized by low viscosity and the dominance of viscous over elastic properties (G′ > G″).

Novel Functionally Gradient Composites Al2O3-Cu-Mo Obtained via Centrifugal Slip Casting

The investigations applied the original concept of the formation of materials as hybrid gradient composites. Two innovative technologies were used: formation by centrifugal slip casting and sintering with varying proportions of the liquid phase. This allowed us to create a gradient microstructure. This article presents the study of Al2O3-Cu-Mo gradient composites. This work aimed to determine the effect of the metallic phase content on the composite’s microstructure and basic properties. The most critical element of the study will be determining the ability to control the location and flow of the liquid phase during the sintering process. The research demonstrated that adding a third component in the form of Mo reduces the liquid Cu flow onto the surface of the composites during the sintering process. In this research, we achieve results with high cognitive value.Graphic

Al2O3/ZrO2 Materials as an Environmentally Friendly Solution for Linear Infrastructure Applications.

The present work deals with the evaluation of the effect of ZrO2 on the structure and selected properties of shapes obtained using the centrifugal slip casting method. The samples were made of alumina and zirconia. The applied technology made it possible to produce tubes with a high density reaching 99–100% after sintering. Very good bonding was obtained at the Al2O3/ZrO2 interphase boundaries with no discernible delamination or cracks, which was confirmed by STEM observations. In the case of Al2O3/ZrO2 composites containing 5 vol.% and 10 vol.% ZrO2, the presence of equiaxial ZrO2 grains with an average size of 0.25 µm was observed, which are distributed along the grain boundaries of Al2O3. At the same time, the composites exhibited a very high hardness of 22–23 GPa. Moreover, the environmental influences accompanying the sintering process were quantified. The impacts were determined using the life cycle analysis method, in the phase related to the extraction and processing of raw materials and the process of producing Al2O3/ZrO2 composites. The results obtained show that the production of 1 kg of sintered composite results in greenhouse gas emissions of 2.24–2.9 kg CO2 eq. which is comparable to the amount of emissions accompanying the production of 1 kg of Polyvinyl Chloride (PVC), Polypropylene (PP), or hot-rolled steel products.

Environmental footprint as a criterion in the ZTA composites forming process via centrifugal slip casting

The main goal of this study was to optimize the technological process of forming and sintering Zirconia Toughened Alumina (ZTA) composites in terms of reducing energy demand. Based on the results of Life Cycle Assessment carried out according to ISO 14044 and EN 15805 standards, the elimination of preliminary homogenization of ceramic suspension in the planetary mill, allowed to reduce energy consumption by over 25%. The method of forming ZTA materials by CSC method, allowed to obtain finished tube-shaped products, which did not require any mechanical treatment after sintering. Such an approach may be an alternative solution for production of ZTA pipes that can be used in transport of aggressive substances, even in extreme corrosive or temperatures conditions.

Influence of Magnetic Field on the Distribution of the Ferromagnetic Component in Centrifugally Cast Ceramic-Metal Gradient Composites

The main aim of the investigation was to determine the impact of the content of nickel and the content of slurry on the nature of the microstructure and physical properties of the final products. In the study, six types of slurries were examined and prepared, differing in both the amounts of content of Ni metallic phase particles (5 vol.%, 10 vol.%, and 20 vol.%) and the amount of content of solid content in the prepared slurries (35 vol.%, and, 50 vol.%). The centrifugal slip casting (CSC) method in a magnetic field was used to fabricate the composites. This technique allowed the production of high-density ZrO2-Ni composites after sintering. Composites containing 50 vol.% of the solid content were characterized by a relative density equal to 99%. Applying the magnetic field allows controlling the distribution of the ferromagnetic phase (Ni) in the ceramic matrix (ZrO2). Based on the results obtained, it was found that the nature of the composites obtained is influenced by the rheological properties of the slurries, depending on their composition. The applicability of the CSC in the magnetic field technique for the production of the composite is characterized by a gradient in the distribution of components on the longitudinal section and has been proved. Based on the obtained results, a model for shaping the microstructure of composites with a longitudinal section was proposed. This work enabled a better understanding of creating microstructures in materials fabricated by centrifugal slip casting in a magnetic field.

Zirconia-Alumina Composites Obtained by Centrifugal Slip Casting as Attractive Sustainable Material for Application in Construction.

This paper focuses on the possibility of adapting the centrifugal slip casting method to obtain zirconia–alumina composite materials in the form of finished tube-shaped products. These types of products, due to their unique properties, can be utilised, for example, in the transport of aggressive substances, even in extreme temperatures or corrosive conditions. The study reports on the two series of zirconia–alumina composites differing in the content of ZrO2—2.5 and 25 vol%. The fabricated and sintered materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and stereological analysis. Moreover, a life cycle assessment (LCA) was provided in accordance with the requirements of the ISO 14044 and EN 15805 standards. The obtained data clearly show that the centrifugal slip casting method allows obtaining samples with high density and extremely uniform distribution of the ZrO2 phase in the alumina matrix. The stereological analysis results proved also that the addition of ZrO2 is effective in reducing the growth of Al2O3 grains during the sintering process. The phase analysis carried out by means of XRD showed that during the sintering process, in the case of composites with a lower ZrO2 content (2.5 vol%), the monoclinic to tetragonal transformation of ZrO2 was total, while for samples containing 25 vol% ZrO2, the monoclinic phase remained in a small amount in the final product.

New Al2O3–Cu–Ni functionally graded composites manufactured using the centrifugal slip casting

AbstractThe aim of this paper was to establish the general suitability of the centrifugal slip casting technique for fabrication of graded material from the Al2O3–Cu–Ni system. The present investigation is a preliminary one and the obtained results may be regarded as a point for acquiring the new knowledge in the ternary ceramic metal system fabricated using centrifugal slip casting. The rheological study provided the evidence that the suspension used to fabricate composites is a non‐Newtonian slurry. Moreover, the results demonstrated that the prepared slurry is stable over time. The obtained composites has a hollow cylindrical shape with relative density of > 95%. The XRD study results revealed three phases: Al2O3, Ni, and CuNi. The microscopic investigations revealed a nonhomogeneous distribution of the metallic phase in the composite. It has been shown that the content of the metallic phase decreased with the increased distance from the outside to the inner edge of the ceramic‐metal composite. The study results allow to conclude that the interface between the phases is more continuous when sintering was carried out in a solid phase. However, it was found that when sintering was carried out in a liquid phase separated metal particles with spherical phase are formed.

Development of lotus-type porous material for heat pipe application using centrifugal slip casting process

Heat pipe is a heat conductor which has a large conduction capacity using a special fluid-filled pipe as a conductor of heat from the hot end (evaporator) to the cold end (condenser) used for thermal management. In the heat pipe, there is a sintered wick which transfers refrigerant fluid from condenser to evaporator. The objective of this research is to improve capillary performance by making a straight pore called as lotus-type porous material (LTP) using centrifugal slip casting technique. Copper powder is used as wick materials due to its high thermal conductivity. A starch solution is used as binder material to make the copper slurry. Nylon wire is applied as straight pore mold. Freeze drying is applied to curing and demolding. Vacuum sintering is conducted to increase metallurgical bonding between the particle. The results show that centrifugal casting machine is capable to make a wick with LTP structure. On the performance department, capillary pumping is affected by rotation speed, powder size, and powder loading. The optimum parameters were copper powder with 260.54 μm powder size, 50% Powder Loading with 688 rpm rotation speed. The LTP wick is proved to have a higher capillary pumping capacity compared to the conventional wick. Further work is necessary to verify the performance of LTP wick in the heat pipe.

Al2O3/Ni functionally graded materials (FGM) obtained by centrifugal-slip casting method

The fabrication and the characterization of Al2O3/Ni composites with a gradient distribution of the Ni particles are reported. The composites have been obtained by centrifugal-slip casting and subsequent sintering and had the shape of a hollow cylinder. TG/DTA analysis was done for the nickel powder with the addition of the dispersant used in centrifugal-slip casting as well as for the composite green body. The measurements were performed in two atmospheres: argon and the mixture of argon and hydrogen (1:1). Additionally, coupling the thermobalance with the mass spectrometer allowed to determine type of gases released from the samples during thermal treatment. The morphology and chemical composition of the produced composites were analyzed using a scanning electron microscope equipped with an EDS detector. Interface between alumina and nickel was described. Moreover, the X-ray diffraction was made. The stereological analysis confirmed that the nickel particles are distributed in the composite in a gradient way.

Processing and characterization of ceramic–metal composites obtained by centrifugal slip casting

Processing and characterization of ceramic–metal composites obtained by centrifugal slip casting