Effect of CuO, NiO, MnO2 and sintering temperature on the formation of cordierite-spinel composites processed by direct coagulation casting

• Published in: Journal of materials science. Materials in electronics 2023-05, Vol.34 (15), p.1196, Article 1196
• Main Authors: Sadek, H. E. H., Zawrah, M. F., Khattab, R. M., Abo-Almaged, H. H.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coagulation; Composite materials; Copper oxides; Cordierite; Densification; Diamond pyramid hardness tests; Electrical properties; Electrical resistivity; Granite; Hardness; Manganese dioxide; Materials Science; Metal oxides; Nickel oxides; Optical and Electronic Materials; Parameters; Phase composition; Physical properties; Sinterability; Sintering; Sludge; Spinel; Talc; Transition metal oxides; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-023-10594-5

This study focuses on recycling of granite sludge for production of cordierite-spinel composites prepared by direct coagulation method. Furthermore, the effect of transition metal oxides (CuO, NiO, and MnO 2 ) on their in-situ formation, sinterability and properties (mechanical and electrical) was studied. The granite sludge, talc, and calcined alumina were utilized to prepare cordierite-spinel composites. Firstly, talc and alumina were mixed and fired at 1350 °C, then mixed with granite sludge and transition metal oxides to be ready for casting by direct coagulation method after adjusting the appropriate conditions. The casted specimens were firstly dried then sintered at 1200 and 1250 °C. The phase composition and physical properties of sintered composites were investigated by x-ray diffraction technique (XRD) and Archimedes method, respectively. The microstructure was investigated by scanning electron microscope while the hardness was tested by Vickers indentation method. The electrical properties of sintered bodies were also evaluated. All XRD patterns showed formation of cordierite and spinel phases after addition of metal oxides and sintering at 1200 or 1250 °C. Also, the results indicated enhancement of densification parameters for CuO- and MnO 2 -containing composites after sintering at 1250 °C while for NiO-containing composites, they enhanced after sintering at 1200 °C. Furthermore, the densification parameters were improved with increasing metal oxides contents. The highest hardness value (8.3 GPa) was obtained for 6% NiO-containing composite. The composites that contained 6 wt.% CuO or MnO 2 exhibited hardness values of 6.4 and 6.16 GPa, respectively. The trend of electrical conductivity values for sintered composites was as follows: CuO-containing composite > NiO-containing composite > MnO 2 -containing composites.