Influence of Sintering Conditions and Nanosilicon Carbide Concentration on the Mechanical and Thermal Properties of Si3N4-Based Materials

In the work, silicon nitride ceramics (Si3N4) and silicon nitride reinforced by nano silicon carbide particles (Si3N4-nSiC) in amounts of 1–10 wt.% were investigated. The materials were obtained using two sintering regimes: under conditions of ambient and high isostatic pressure. The influence of the sintering conditions and the concentration of nanosilicon carbide particles on the thermal and mechanical properties was studied. The presence of highly conductive silicon carbide particles caused an increase in thermal conductivity only in the case of the composites containing 1 wt.% of the carbide phase (15.6 W·m−1·K−1) in comparison with silicon nitride ceramics (11.4 W·m−1·K−1) obtained under the same conditions. With the increase in the carbide phase, a decrease in the densification efficiency during sintering was observed, which caused a decrease in thermal and mechanical performance. The sintering performed using a hot isostatic press (HIP) proved to be beneficial in terms of mechanical properties. The one-step high-pressure assisted sintering process in the HIP minimizes the formation of defects at the sample surface

Sintering Behavior, Thermal Expansion, and Environmental Impacts Accompanying Materials of the Al2O3/ZrO2 System Fabricated via Slip Casting

This work focuses on research on obtaining and characterizing Al2O3/ZrO2 materials formed via slip casting method. The main emphasis in the research was placed on environmental aspects and those related to the practical use of ceramic materials. The goal was to analyze the environmental loads associated with the manufacturing of Al2O3/ZrO2 composites, as well as to determine the coefficient of thermal expansion of the obtained materials, classified as technical ceramics. This parameter is crucial in terms of their practical applications in high-temperature working conditions, e.g., as parts of industrial machines. The study reports on the four series of Al2O3/ZrO2 materials differing in the volume content of ZrO2. The sintering process was preceded by thermogravimetric measurements. The fabricated and sintered materials were characterized by dilatometric study, scanning electron microscopy, X-ray diffraction, and stereological analysis. Further, life cycle assessment was supplied. Based on dilatometric tests, it was observed that Al2O3/ZrO2 composites show a higher coefficient of thermal expansion than that resulting from the content of individual phases. The results of the life cycle analysis showed that the environmental loads (carbon footprint) resulting from the acquisition and processing of raw materials necessary for the production of sinters from Al2O3 and ZrO2 are comparable to those associated with the production of plastic products such as polypropylene or polyvinyl chloride

The development of ceramic silicon carbide heat exchanger

Odzysk tzw. ciepła niskotemperaturowego wymaga specjalnych rozwiązań konstrukcji wymienników. W ramach działalności statutowej ICIMB podjęto prace nad opracowaniem ceramicznego wymiennika ciepła, którego powierzchnie robocze będą odporne na agresywne działania par i skroplin, a wskaźniki jakościowe procesu wymiany ciepła zapewnią wysoką efektywność procesu. W artykule przedstawiono wyniki badań właściwości materiału ceramicznego, założenia projektowe konstrukcji oraz pierwsze doświadczenia z realizacji modelu fizycznego wymiennika, a zwłaszcza formowania, spiekania i łączenia powierzchni wykonanych z węglika krzemu (SiC).The recovery of the low-temperature heat requires special solutions of heat exchangers. As part of the statutory activities of ICIMB works have been carried out to develop a ceramic heat exchanger, which working surfaces will be resistant to aggressive vapor and condensates. The quality parameters of the heat exchange process should ensure high efficiency of the process. The paper presents the results of research on the properties of the ceramic material, the design assumptions and the first experiments on the implementation of the physical model of the heat exchanger, in particular forming, sintering and joining surfaces made of silicon carbide (SiC)