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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 μm, 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 μm. 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 aim of the work was to determine the influence of metallic phase content on the obtained properties of hybrid composites from the ceramics-metal system. Six series of samples from three systems (Al2O3-Cu, Al2O3- Cu-Ni and Al2O3-Cu-Cr) with two different contents of metallic phase (2.5 and 10 vol.%) were prepared by uniaxial pressing and pressure-less sintering. The research carried out in this work used the classic idea of material engineering, assuming the optimization of the material’s functional properties by shaping the microstructure in a suitably modified technological process. The possibility of producing composite samples with density exceeding 95%TD was confirmed. There was no significant effect of the composition and the share of the metallic phase on the obtained values. The microstructure observations showed that the addition of the second metallic component had a positive effect on the size of the metallic particles, limiting the formation of metal clusters of significant size visible in the case of Al2O3-Cu samples. Compressive strength tests have shown that the addition of the second component to the metallic phase has a positive effect on the compressive strength of the material.

Paper-related production of composite materials from Al2O3-pre-composite powder (NiAl–10 wt pct Al2O3). PPS allowed for forming ceramic–intermetallic composites. MA produced the pre-composite powder. Six series of composites were made, differing in temperature (1200 °C, 1300 °C, 1400 °C) and content of pre-composite powder (2.5 and 5 wt pct with respect to the amount of Al2O3). Highest hardness was obtained for composite series sintered at 1300 °C. Both series, with various pre-composite powder content, had a value of 20.8 to 20.9 GPa. Samples containing 2.5 wt pct pre-composite powder sintered at 1200 °C were highest KIC value of 4.72 ± 0.34 MPa·m0.5. Interestingly, the same value was obtained in composites containing 5 wt pct pre-composite powder sintered at 1300 °C. For both series with different pre-composite powder content, sintering at 1400 °C obtained the highest strength. For composites containing 2.5 wt pct pre-composite powder, splitting tensile strength value was 255.98 MPa, while for samples with 5 wt pct, pre-composite powder was 264.01 MPa [ABSTRACT FROM AUTHOR]

The study explores the microstructural design of hybrid Al2O3–Cu–Me composites formed by centrifugal slip casting into porous molds. Obtained composites are characterized by zones with different contents of metal phases. It was determined that there are two mechanisms driving thickening of slurries: capillary forces influencing smaller particles and centrifugal forces affecting larger particles. To enhance composite's cracking toughness, a gradient distribution of metallic phase with highest metal concentration near surface is essential. This is achieved by optimizing ceramic powder size, limiting processing time, and using gel centrifugal casting to eliminate undesired zones. Zone II's width is influenced by metallic phase proportion, mold rotation speed, and compaction rate, with heavier particles and greater metal content near outer surface. Zone III expands with lower rotational speeds and lighter metallic particles. The mutual reactivity and solubility of selected metallic elements also play a crucial role in the final microstructure. The findings highlight the potential for precise control over composite microstructures through careful selection of metallic elements, powder sizes, and casting parameters, offering valuable insights for model research and simulations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper aims to compare two ceramic materials available for additive manufacturing (AM) processes—vat photopolymerization (VPP) and material extrusion (MEX)—that result in fully ceramic parts after proper heat treatment. The analysis points out the most significant differences between the structural and mechanical properties and the potential application of each AM technology. The research revealed different behaviors for the specimens obtained via the two mentioned technologies. In the case of MEX, the specimens exhibited similar microstructures before and after heat treatment. The sintering process did not affect the shape of the grains, only their size. For the VPP specimens, directly after the manufacturing process, irregular grain shapes were registered, but after the sintering process, the grains fused, forming a solid structure that made it impossible to outline individual grains and measure their size. The highest compression strength was 168 MPa for the MEX specimens and 81 MPa for the VPP specimens. While the VPP specimens had half the compression strength, the results for the VPP specimens were significantly more repeatable. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The scientific goal of this paper is to study and explain the relationship between the microstructure of a ceramic–intermetallic composite fabricated by consolidating a mixture of Al2O3 and NiAl-Al2O3 using the PPS technique and its basic mechanical properties. Six series of composites were manufactured. The obtained samples differed in the sintering temperature and content of compo-powder. The base powders, compo-powder, and composites were investigated using SEM equipped with an EDS and XRD. Hardness tests and KIC measurements were applied to estimate the mechanical properties of the fabricated composites. The wear resistance was evaluated using a "ball-on-disc" method. The results demonstrate that the density of the obtained composites increases with the increased temperature of the sintering. The content of NiAl + 20 wt.% Al2O3 did not have a determining effect on the hardness of the manufactured composites. The highest hardness, contacting 20.9 ± 0.8 GPa, was found for the composite series sintered at 1300 °C and 2.5 vol.% of compo-powder. The highest KIC value from all the studied series equaled 8.13 ± 0.55 MPa·m0.5 and was also achieved for the series manufactured at 1300 °C (2.5 vol.% of compo-powder). The average friction coefficient during the ball-friction test with the Si3N4 ceramic counter-sample was between 0.8 and 0.95. [ABSTRACT FROM AUTHOR]

This paper aims to study the Al2O3/Ti ceramic-metal composite obtained by the slip casting method. Samples containing 50% volume of the solid phase, including 10% volume of the metallic phase, were investigated. The rheological properties were analyzed. Thermogravimetric analysis was performed. The properties of the obtained composite determined the phase composition using and SEM/EDS microstructural analysis and the XRD method. The size of the titanium particles equals 20.6 ± 10.1 mm, which corresponds to 27.5% of the initial size and indicates significant fragmentation of the titanium powder during the manufacturing of the composite. The relative density of the fabricated composites was equal to 99%. The slip casting method allows to obtain the proposed composite additionally enhanced by the presence of TiO2 and Al2TiO5 (thialite). Research results revealed a non-Newtonian character of the composite suspension flow with clear thinning under the influence of increasing shear forces. The obtained composites are characterized by the lack of visible defects (cracks, microcracks and delamination) on the surface. [ABSTRACT FROM AUTHOR]

This work analyzed ceramic-metal composites from the Al2O3/Ti/Ni system produced by the slip casting method. As starting powders, nanometric Al2O3, Ni and Ti of submicron size were used. Three series of composites were obtained and tested with the same solid phase content (50% vol.) and different metallic phase content: 5, 10 and 15% vol. The influence of the metallic phase content on the basic properties of the proposed composites was examined by determining the phase composition of the produced samples using the XRD method, rheological measurements, and microstructural analysis (SEM/EDS). Additionally, before the sintering process, the slip stability was analyzed. A study of the fractography of samples after the sintering process was also carried out. It was shown that the appropriate manufacturing process allowed to obtain NiTi intermetallic phases in the structure of composites. [ABSTRACT FROM AUTHOR]