Papers by Keyword: Ceramic Materials

Abstract: A modification cutting tool is a type of cutting tool that can be altered or adjusted to change its cutting properties. This can include changing the angle or shape of the cutting edge, adjusting the depth of cut, or modifying the material or coating used on the tool. These modifications allow for greater precision and efficiency in cutting operations, particularly in industries for manufacturing and construction different products. Ceramic materials can be used in coatings to provide a variety of benefits, such as corrosion, wear resistance , and thermal insulation. They also offer high hardness, low friction, and chemical stability. Ceramic coatings can be applied to various substrates including metals and ceramic. Modification of cutting tools using nanomaterial deposition is a promising approach to enhance their performance and durability. The process involves depositing one or more layer of nanosized particles onto the surface of the cutting tool, which can improve its mechanical, thermal, and tribological properties. Keywords: Ceramic materials ; coating ;cutting tools; coating process.

Abstract: In view of the low performance of porous ceramics on the wall, the heavy task of saving clay resources, and the major problems of dredging the Yangtze River, this thesis uses low-grade quartz sand along the Yangtze River as the main raw material and kaolin as the plasticizer. Drying, sintering and other processes prepare high-performance porous quartz ceramics, and improve the performance of porous quartz ceramics by studying the control conditions and the control mechanism related to the performance of the sintered body. Quartz porous ceramic bodies were sintered at 1100 °C and 1200 °C, and no obvious gradient structure was found. However, the quartz porous ceramic bodies had obvious gradient structures after sintering at 1300°C. The quartz porous ceramic bodies were sintered. When the temperature is 1400 °C, the green body is not found to have a pore gradient structure. When the water-to-material ratio is 1.2 and 1.3, the quartz porous ceramic body has no obvious gradient structure; when the water-to-material ratio is 1.4, 1.5, the sample has an obvious gradient structure. Combining the cost performance between material performance and energy consumption, in order to obtain a better bonding point, porous silica ceramics should be prepared with a water-to-material ratio of 1.4 and a sintering temperature of 1300 °C to prepare porous silica ceramics with a better pore gradient structure. Its porosity is 32.45%, and its compressive strength is 5.23 MPa.

Abstract: In this article, the influence of the addition of the bottom ash to clay on the selected physical and mechanical properties of ceramic composite are discussed. The biomass (80% wood with the addition of 20% coconut shells) was combustion in the fluidised-bed boiler. The tests were carried out on the samples, in which the contents of bottom ash in relation to clay ranged from 5 to 15%. The absorbability, open porosity, apparent density, compression strength and freeze resistance have been determined. The obtained test results indicate that the increase of this bottom ash in clay-ash composite causes the increase of open porosity, absorbability and compression strength, but a reduction in resistance against frost attract.

Abstract: Ti-12Mo/ZrO₂ nanocomposites are fabricated using the powder metallurgy technique for the potential of aerospace applications. Titanium-12 wt. % molybdenum metal matrix composite containing various percentages of ZrO₂ (5, 10, and 15 wt. %) are prepared. The phase composition and microstructure of Ti-12Mo/ZrO₂ powder, as well as the consolidated composites), are investigated by both X-ray diffraction and scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) respectively. All the consolidated composites are characterized by measuring the density, Vickers hardness, and wear rate. XRD refers to no new phase are formed between Ti, Mo, and ZrO₂ during the sintering process. Also, a good microstructure is achieved. Results indicated that the density of the sintered composites is increased with increasing ZrO₂ percent up to 5 wt. %. On the other hand, the highest hardness and highest wear resistance are achieved for 5 wt. % ZrO₂ sample. The present work demonstrated that Ti-12Mo/ZrO₂ composites have a high potential for aerospace applications.

Abstract: The paper deals with the modeling of the technological texture of the pressed ceramic materials in the radial and axial direction, which consists in the graphical representation and subsequent analysis of the distribution of the electrostatic field potential differences on the surface of the dielectric sample with the diameter d and the thickness h located between the electrodes. In occasion of observing radial texture the electrodes have the cylindrical configuration and in occasion of observing the axial texture in the sample the electrodes have the axial configuration. The theoretical relationship in the paper is derived for the calculation of the voltage values measured at any position between the center electrode and the peripheral electrode, at a constant voltage U applied to the outer and inner electrodes of the dielectric sample of thickness h of the raw ceramic sample material (radial texture). Measurements have demonstrated the suitability of identifying the technological texture by measuring the potential differences on the sample surface which is located between the electrodes in the relation to the technology preparation and to the quality of the fired ceramic production.

Abstract: There are given technological factors of pressing of products from ceramic powders. The pressing process is represented as a functional dependence with a set of variables. Four stages of ceramic powders pressing have been found. The method on determination of the pressing parameters of ceramic products using the mounting for curves readout has been shown. Sediment of press powders from clay raw material is determined at different humidity and pressing pressure. The dependence of the physical and mechanical properties of ceramic samples on the humidity content of clay powder and the pressure of raw pressing is established. Compacting pressure values have been found by compression curve when plastic deformation ends and elastic deformations of powder grains start, which corresponds to a translation from the second to the third stage of the pressing process. Areas of rapid deceleration of sagging are in line with the point of the tangent to this curve in the translation from the third to the fourth compression stage have been found. The optimal values of semidry pressing of a ceramic brick have been defined.

Abstract: High emissive Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic materials were prepared by flame spraying and controlled crystallization method. The phase composition, microstructure, infrared optical properties of Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic powders were investigated. The physical mechanism for the significantly enhanced infrared emissivity of LaAlO₃ by doping with Ca²⁺ and Fe³⁺ was analysized. This high emissive Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic materials shows promising applications in high temperature thermal process field to enhance the radiative heat transfer and improve its thermal efficiency.

Abstract: A new method for dielectric materials milling has been developed. Instead of well-known ion milling used for metals the dielectrics were processed by broad beams of fast argon atoms. The fast atoms were produced due to charge exchange collisions of accelerated ions. Plasma emitter of the ions was generated in hollow cathode glow discharge. Emissive grid of a circular cross-section beam source consisted of six segments. Energy of the fast atoms ranged from 1 to 3 keV. The beam source was used for production of contoured grooves on flat surfaces of hard ceramic materials. On the surface of movable seal ring made of α-corundum were produced grooves with depth of 20±0.5 μm and roughness of R_a ≈ 0.4 µm. The rate of α-corundum etching amounted to 3 μm/h.

Abstract: In the jet engine the temperature of exhaust gases should be as high as possible, from the point of view of its efficiency. The value of this temperature is limited by toughness of the turbine blades material. Superalloy Inconel 625, which is commonly used in aerospace industry, indicates 13% less yield point in 800^OC than in 25^OC. The temperature of exhaust gases can reach 1500^OC. The blade material has to be protected due to this fact. The one possibility of turbine blade protection is using of thermal barriers coatings (TBC). The coating has a very low thermal conductivity and therefore it protects against the thermal shock failure of the substrate material. The TBC can be manufactured as: 1) monocrystalline, 2) layered structures (e.g. [1-3]) or 3) as a functionally graded material (e.g. [4-7]). The differences between the properties of blade material and TBC can lead to significant increase of the high shear stresses in the substrate-TBC interface.In this paper numerical analyses of cooled turbine blade with various kinds of functionally graded thermal coatings were performed. The main aim was to find the optimal material properties distribution of the functionally graded TBC to avoid damage initiation and growth between TBC and substrate. In the calculations the effect of temperature on material properties both mechanical and thermal was taken into consideration.

Abstract: Interface reactions and wettability between melt superalloys and ceramic mould materials were investigated by using a sessile drop experiment. The wetting angle of the melt alloy on the ceramic material was calculated and the microstructure of the alloy interface was investigated by metalloscope as well as SEM. It was found that active element C in the alloy is an important factor that influences the interface reactions and the wettability. Alloys with C content lower than 0.07wt.% were almost stable on the ceramic material and no interface reaction products were found. However, alloys with C content higher than 0.16wt.% reacted with the ceramic materials. Purple reaction products were found on the alloy surface and sand adhesions were observed at the alloy-ceramic interface. In the non-reactive system, the wetting angle is in the range of 135^o-150^o. In the reactive system, the wetting angle is lower than 120^o.