Kon M, O'Brien W J, Rasmussen S T, Asaoka K
Department of Dental Engineering, School of Dentistry, Tokushima University, Japan.
J Dent Res. 2001 Aug;80(8):1758-63. doi: 10.1177/00220345010800081501.
Low- and non-leucite-containing commercial porcelains with low firing temperatures have become popular. However, improving the strength of glass porcelains is difficult. The purpose of this study was to determine if dispersed glass particles could be used as a reinforcing agent for an all-glass porcelain. We produced 3 feldspathic glasses (high-fusing, medium-fusing, low-fusing) by melting powders consisting of potassium-feldspar and 0, 5, or 20 mass% Na2O, respectively. For high-fusing, medium-fusing, and low-fusing feldspathic glasses, the deformation temperatures were 945 degrees C, 647 degrees C, and 518 degrees C, and the thermal expansion coefficient values were 8.6 x 10(-6)/degrees C, 10.3 x 10(-6)/degrees C, and 13.4 x 10(-6)/degrees C between 25 degrees C and the glass-transition temperature, respectively. The high-fusing-glass (or medium-fusing-glass) powders were mixed with low-fusing-glass powders before being fired into test specimens. The mean flexural strength and fracture toughness (K1C) of 3 single-glass porcelains ranged from 57 to 63 MPa and from 0.68 to 0.73 MPa m(1/2), respectively, presenting no significant differences in one-way ANOVA. However, the flexural strength of 50% high-fusing-glass + 50% low-fusing-glass porcelain was 114 MPa (p < 0.05) and K1C was 1.2 MPa m(1/2) (p < 0.05). Microcracks were observed with a back-scattered scanning electron microscope and were associated with the high- (or medium-) fusing glass particles, suggesting residual stress in the low-fusing-glass matrix due to a coefficient of thermal expansion mismatch between the dispersed glass particles and the matrix glass. The dispersing glass particles appeared to act as a reinforcing agent for strengthening a glassy porcelain.
含少量或不含白榴石且烧成温度较低的商用瓷器已受到欢迎。然而，提高玻璃瓷器的强度却很困难。本研究的目的是确定分散的玻璃颗粒是否可用作全玻璃瓷器的增强剂。我们通过分别熔化由钾长石和0、5或20质量%的Na2O组成的粉末来制备3种长石玻璃（高熔、中熔、低熔）。对于高熔、中熔和低熔长石玻璃，其变形温度分别为945℃、647℃和518℃，在25℃至玻璃转变温度之间的热膨胀系数值分别为8.6×10(-6)/℃、10.3×10(-6)/℃和13.4×10(-6)/℃。将高熔玻璃（或中熔玻璃）粉末与低熔玻璃粉末混合后烧成测试试样。3种单一玻璃瓷器的平均抗弯强度和断裂韧性（K1C）分别在57至63MPa和0.68至0.73MPa m(1/2)范围内，在单因素方差分析中无显著差异。然而，50%高熔玻璃 + 50%低熔玻璃瓷器的抗弯强度为114MPa（p < 0.05），K1C为1.2MPa m(1/2)（p < 0.05）。用背散射扫描电子显微镜观察到微裂纹，且与高（或中）熔玻璃颗粒有关，这表明由于分散的玻璃颗粒与基体玻璃之间的热膨胀系数不匹配，低熔玻璃基体中存在残余应力。分散的玻璃颗粒似乎起到了增强玻璃质瓷器强度的增强剂作用。
