| This study chooses the feldspathic powder provided by Tangshan ore-processing factory (TY I) and the feldspathic powder provided by Shijiazhuang ore-processing factory (TY II) as the main raw materials. After the raw materials were rubbed, molded and sintered at 1260 C for five hours, K2O-Na2O-Al2O3-SiO2 quaternary system feldspathic ceramics, which are composed of the leucite crystals and K2O-Na2O-Al2O3-SiO2 glass phase, were produced successfully.X-ray diffractometry (XRD), scanning electron microscopy (SEM), and mechanical tests were used in this study. By changing the content of Potassium and adjusting sintering condition, microstructure, the content of leucite crystals and fracture toughness of machinable feldspathic ceramics is investigated. The results of this study show that:1. In the most appropriate range of sintering temperature for feldspathic ceramics, sintering time should be prolonged appropriately (5 hours) to increase the content of leucite crystals.2. As one of the main raw materials, the content of K2O or orthoclase (K2O-Al2O3-6SiO2) is the key factor in the formation of leucite.3. The content of leucite crystals will influence the fracture toughness of K2O-Al2O3-SiO2 system feldspathic ceramics greatly. With the increase of the content of leucite crystals, the fracture toughness of feldspathic ceramics will increase accordingly.4. With the decrease size of powder, not only will the sintering temperature range fall, but also there is no air pores in the ceramics.5. After adjusting content of raw materials and optimizing the fabrication process, feldspathic ceramics have been produced. Its fracture toughness reaches 1.19 Mpa-m1/2, which is equal to the one of Vita Mark II (1.21 Mpa-m1/2). |
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