SiC-TiB₂-TiC composites with matrices consisting of semiconductor material (SiC), conductive materials (TiB₂-TiC), or their combination were fabricated by spark plasma sintering (SPS) at 2000 °C in a vacuum under a pressure of 80 MPa for 3 min. The composition and microstructure of the obtained composites were studied by X-ray diffraction and a scanning electron microscope equipped with an energy-dispersive detector. The flexural strength, Vickers hardness, and fracture toughness of SPSed samples were determined. Based on the observations in this work, three variations of the sintering process were proposed with different matrix compositions. The dense (99.7%) 60SiC-25TiB₂-15TiC vol.% sintered ceramic composites exhibited the highest strength and hardness values of the studied composites, as well as a fracture toughness of 6.2 MPa·m^1/2.

Spray drying is a widely used method of converting liquid material (aqueous or organic solutions, emulsions and suspensions) into a dry powder. Good flowability, narrow size distribution, and controllable morphology are inherent in powders produced by spray drying. This review considers the granulation factors that influence the final properties of the silicon nitride dried powders. The first group includes the types of atomizers, manifolds, and drying chamber configurations. The process parameters fall into the second group and include the following: inlet temperature, atomizing air flow, feed flow rate, drying gas flow rate, outlet temperature, and drying time. Finally, the last group, feedstock parameters, includes many factors such as feed surface tension, feed viscosity, solvent type, solid particle concentration, and additives. Given the large number of factors affecting morphology, particle size and moisture, optimizing the spray drying process is usually achieved by the “trial and error” approach. Nevertheless, some factors such as the effect of a solvent, dispersant, binder, and sintering additives considered in the literature that affect the Si₃N₄ granulation process were reviewed in the work. By summarizing the data available on silicon nitride powder production, the authors attempt to tackle the problem of its emerging demand in science and industry.

Machining is an indispensable manufacturing process for a wide range of engineering materials, such as metals, ceramics, and composite materials, in which the tool wear is a serious problem, which affects not only the costs and productivity but also the quality of the machined components. Thus, the modification of the cutting tool surface by application of textures on their surfaces is proposed as a very promising method for improving tool life. Surface texturing is a relatively new surface engineering technology, where microscale or nanoscale surface textures are generated on the cutting tool through a variety of techniques in order to improve tribological properties of cutting tool surfaces by reducing the coefficient of friction and increasing wear resistance. In this paper, the studies carried out to date on the texturing of ceramic and superhard cutting tools have been reviewed. Furthermore, the most common methods for creating textures on the surfaces of different materials have been summarized. Moreover, the parameters that are generally used in surface texturing, which should be indicated in all future studies of textured cutting tools in order to have a better understanding of its effects in the cutting process, are described. In addition, this paper proposes a way in which to classify the texture surfaces used in the cutting tools according to their geometric parameters. This paper highlights the effect of ceramic and superhard textured cutting tools in improving the machining performance of difficult-to-cut materials, such as coefficient of friction, tool wear, cutting forces, cutting temperature, and machined workpiece roughness. Finally, a conclusion of the analyzed papers is given.

The influence of WEDM parameters (Spark gap voltage, Pulse-on time, Spark frequency, and Wire speed) on the recast layer thickness and surface roughness of Spark Plasma Sintered SiC-TiB₂-TiC ceramic composite was investigated. For this, an orthogonal L9 Taguchi design was used, and grey relational analysis was carried out for multi-response WEDM parameter optimization in order to determine the minimum RLT and SR. It was noticed that for RLT, the Pulse-on time was observed as the most significant process parameter, followed by Spark gap voltage. On the other hand, Spark frequency and Wire speed had no significance for RLT. Moreover, Spark frequency was observed as the most significant process parameter, followed by Pulse-on time and Spark gap voltage, while Wire speed had a negligible effect on SR. It was found that at optimal process parameters (U = 48V; Ton = 1.0 µs; f = 10 kHz; q = 8 m/min), we obtained an RLT of 3.16 µm and an SR of Ra = 0.847 µm. The confirmation test showed a decrease in RLT and SR by 43.67% and 7.12%, respectively, in comparison to the initial machining conditions.

The main goal of the present work was to synthesize a composite consisting of h-BN particles coated with a γ-Al₂O₃ nanolayer. A method was proposed for applying nanocrystalline γ-Al₂O₃ to h-BN particles using a sol–gel technique, which ensures the chemical homogeneity of the composite at the nano level. It has been determined that during crystallization on the h-BN surface, the proportion of spinel in alumina decreases from 40 wt.% in pure γ-Al₂O₃ to 30 wt.% as a result of the involvement of the B³⁺ ions from the surface nitride monolayers into the transition complex. For comparison, nano-alumina was synthesized from the same sol under the same conditions as the composite. The characterization of the obtained nanostructured powders was carried out using TEM and XRD. A mechanism is proposed for the formation of a nanostructured γ-Al₂O₃@h-BN composite during the interaction of Al-containing sol and h-BN suspension in aqueous organic media. The resulting composite is a promising model of powdered raw materials for the development of fine-grained ceramic materials for a wide range of applications.

Using spark plasma sintering technology, SiC-TiB₂-TiC ceramic composites with various graphene oxide content (0.15, 0.25, 0.5 vol.%) were manufactured, and their microstructure as well as physico-mechanical and tribological properties were studied. Ceramic composite with 0.25 vol.% of graphene oxide showed a relative density of 99.9%, fracture toughness of 6.3 MPa·m^1/2, flexural strength of 583 MPa and Vickers hardness of 22.2 GPa. Moreover, this composite showed a coefficient of friction and wear rate of 0.53 and 1.92 × 10⁻⁶ mm³/N·m, respectively, under a load of 10 N. Similarly, under a load of 30 N, this composite showed a coefficient of friction and wear rate of 0.6 and 4.05 × 10⁻⁵ mm³/N·m, respectively. This research demonstrated that the addition of 0.25 vol.% of graphene oxide improved the physical–mechanical and tribological properties of ceramic composites based in the SiC-TiB₂-TiC ternary system, which in turn makes this composite more promising for use, for example, as a cutting tool material.