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.

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″).

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.

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.