Cattell M J, Chadwick T C, Knowles J C, Clarke R L, Lynch E
Department of Conservative Dentistry, St. Bartholomew's and The Royal London School of Medicine and Dentistry, QMW, Turner Street, London E1 2AD, UK.
Dent Mater. 2001 Jan;17(1):21-33. doi: 10.1016/s0109-5641(00)00046-4.
The aims of the study were to process a ceramic material with a fine leucite particle size using hot pressing techniques, to increase the flexural strength, reliability and ease of use.
A starting glass composition of wt%; 64.2% SiO(2), 16.1% Al(2)O(3), 10.9% K(2)O, 4.3% Na(2)O, 1.7% CaO, 0.5% LiO and 0.4% TiO(2) was used to produce a leucite reinforced ceramic material. Twenty-one porcelain discs were produced by sintering the ceramic frit (group 1) and sixty-three discs by heat pressing the frit (groups 2, 3 and 4). Twenty-one Empress 1 ceramic discs were also heat pressed (group 5). Disc specimens were tested using the biaxial flexure test at a crosshead speed of 0.15mm/min and the data analysed using the Scheffé F multiple comparison test and Weibull statistics. Specimens were characterised using X-ray diffraction (XRD), secondary electron imaging and energy dispersive X-ray analysis where applicable.
The heat pressed groups (2, 3 and 4) had higher mean biaxial flexural strengths and characteristic strength values than groups 1 and 5 (p<0.05). XRD revealed the presence of tetragonal leucite in all test groups. Fine leucite crystals, tabular platelets and minimal matrix microcracking were found in the microstructure of test groups (1-4) with a more uniform leucite distribution in the heat pressed specimen groups (2, 3 and 4), which were associated with a significant increase in the biaxial flexural strength and reliability.
Optimisation of the microstructure by producing a fine microstructure and controlling the distribution via the correct pressing parameters may be extremely advantageous in these systems.
本研究的目的是采用热压技术处理具有细小白榴石粒径的陶瓷材料，以提高其抗弯强度、可靠性和易用性。
使用质量分数为64.2% SiO₂、16.1% Al₂O₃、10.9% K₂O、4.3% Na₂O、1.7% CaO、0.5% LiO和0.4% TiO₂的起始玻璃组合物来制备白榴石增强陶瓷材料。通过烧结陶瓷熔块制备了21个瓷盘（第1组），通过对熔块进行热压制备了63个瓷盘（第2、3和4组）。还对21个Empress 1陶瓷盘进行了热压（第5组）。使用双轴弯曲试验以0.15mm/min的十字头速度对盘状试样进行测试，并使用Scheffé F多重比较检验和威布尔统计分析数据。在适用的情况下，使用X射线衍射（XRD）、二次电子成像和能量色散X射线分析对试样进行表征。
热压组（第2、3和4组）的平均双轴抗弯强度和特征强度值高于第1组和第5组（p<0.05）。XRD显示所有测试组中均存在四方白榴石。在测试组（1-4）的微观结构中发现了细小的白榴石晶体、板状薄片和最小的基体微裂纹，热压试样组（第2、3和4组）中的白榴石分布更均匀，这与双轴抗弯强度和可靠性的显著提高相关。
通过产生精细的微观结构并通过正确的压制参数控制分布来优化微观结构在这些系统中可能极其有利。
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