摘要
目的:利用弯曲强度和Weibull分析方法对可被CAD/CAM技术加工的渗透陶瓷的结构可靠性进行分析,为临床选择应用该陶瓷材料提供依据。方法:采用硫酸铝铵两步煅烧法制备的超细氧化铝粉体,经工业预烧结形成可渗透的机加工陶瓷块,经过镧铝硅酸盐玻璃渗透形成渗透陶瓷复合体。测试30个样本的三点弯曲强度,并计算Weibull模数(m)及破坏概率为1%和5%时的弯曲强度。采用X线衍射分析(XRD)并结合扫描电子显微镜(SEM),分别对材料的物相组成和微观形貌进行分析。结果:渗透陶瓷复合体的强度为(375.5±66.88)MPa,Weibull模数(m)为6.2,1%破坏概率时的弯曲强度为191.79MPa,5%破坏概率时的弯曲强度为249.83MPa。扫描电镜可见氧化铝预烧结体为连续多孔立体网状结构,开孔结构分布均匀;渗透复合体为致密的陶瓷复合体。XRD表明主晶相为α-alumina。结论:与单纯测试材料的弯曲强度相比,采用弯曲强度测试法并结合Weibull分析方法,能加深对口腔陶瓷修复失败机制的理解,更加有效地利用材料的平均强度值指导口腔陶瓷修复设计。
PURPOSE: To explore the structural reliability of machined infiltrated ceramic made from ultrafine alumina powder for dental CAD/CAM by means of flexural strength together with Weibull analysis. METHODS: Ultrafine grain-sized alumina powder made from ammonium aluminum sulfate was sintered into one kind of porous machined ceramic block. After being infiltrated by lanthanum glass powder, a glass infiltrated alumina composite was produced. Thirty bar specimens were prepared. The flexural strength was measured with the three-point bending test. The fracture stress values were analyzed by Weibull analysis to determine the Weibull modulus values(m). The strength values at failure probabilities of 1% and 5% failure were also calculated. X ray diffraction analysis (XRD) and scanning electron microscopy(SEM) analysis were conducted. RESULTS: The mean flexural strength and standard deviation were(375.5±66.88)MPa coupled with Weibull modulus of 6.2. Strength values at failure probability of 1% and 5% were 191.79MPa and 249.83MPa,respectively. The micrograph under SEM indicated the prefabricated sintered alumina block retained a structure of continuous three-dimentional open pores, whereas the composite characterized itself as a pore-free structure after glass infiltration. XRD indicated the major crystal phase was α-alumina. CONCLUSIONS: The average fracture strength can not be used reliably as a design parameter for brittle all-ceramic crown materials.Compared with the average fracture strength alone,the use of flexure strength test combined with the Weibull analysis as a method of predicting survival rates from the strength data could be favorable in identifying the failure mechanisms involved in ceramic crown fracture, which would result in an improved validation of the strength data.
出处
《上海口腔医学》
CAS
CSCD
2004年第6期549-552,共4页
Shanghai Journal of Stomatology
基金
辽宁省自然科学基金(002040)
