State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Changle Xi Road 145, Xi'an, Shaanxi, China.
Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China.
J Mech Behav Biomed Mater. 2018 May;81:52-60. doi: 10.1016/j.jmbbm.2018.02.023. Epub 2018 Feb 20.
The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes.
After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment. In the meantime, heat-pressed lithium disilicate glass-ceramics (GC-P) and original ingots (GC-O) were used as control groups. Glass-ceramics were characterized using X-ray diffraction (XRD) and were tested using flexural strength test, nanoindentation test and toughness measurements. The plate specimens were dynamically loaded in a chewing simulator with 350 N up to 2.4 × 10 loading cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 300,000 wear cycles. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pairwise comparisons of means were performed by Tukey's post-hoc test.
Materials with different crystal sizes (p < 0.05) exhibited different properties. Specifically, G3 with medium-sized crystals presented the highest flexural strength, hardness, elastic modulus and fracture toughness. G1 and G2 with small-sized crystals showed lower flexural strength, whereas G4, GC-P, and GC-O with large-sized crystals exhibited lower hardness and elastic modulus. The wear behaviors of all six groups showed running-in wear stage and steady wear stage. G3 showed the best wear resistance while GC-P and GC-O exhibited the highest wear volume loss.
After crystal refining, lithium disilicate glass-ceramic with medium-sized crystals showed the highest wear resistance and mechanical properties.
本研究旨在通过细化晶体尺寸来提高锂硅玻璃陶瓷的耐磨性和力学性能。
将锂硅玻璃陶瓷（LD）熔融制成预烧玻璃块后，制备棒（N=40，n=10）和板（N=32，n=8）试件。根据预烧玻璃的差示扫描量热法（DSC），设计了 G1-G4 组，采用两步热处理法形成不同晶体尺寸的锂硅玻璃陶瓷。同时，将热压锂硅玻璃陶瓷（GC-P）和原铸锭（GC-O）作为对照组。采用 X 射线衍射（XRD）对玻璃陶瓷进行表征，并采用弯曲强度试验、纳米压痕试验和韧性测量对其进行测试。将板试件在 350 N 的咀嚼模拟器中进行动态加载，直至 2.4×10 次加载循环。在每 30 万次磨损循环后，使用 3D 轮廓仪对玻璃陶瓷的磨损情况进行分析。使用扫描电子显微镜（SEM）对玻璃陶瓷的磨损形貌和微观结构进行分析。采用单因素方差分析（ANOVA）对数据进行分析。采用 Tukey 事后检验对均值进行多重两两比较。
具有不同晶体尺寸的材料（p<0.05）表现出不同的性能。具体而言，具有中等尺寸晶体的 G3 表现出最高的弯曲强度、硬度、弹性模量和断裂韧性。具有小尺寸晶体的 G1 和 G2 表现出较低的弯曲强度，而具有大尺寸晶体的 G4、GC-P 和 GC-O 则表现出较低的硬度和弹性模量。6 组材料的磨损行为均表现出跑合磨损阶段和稳定磨损阶段。G3 表现出最佳的耐磨性，而 GC-P 和 GC-O 则表现出最高的磨损体积损失。
细化晶体后，具有中等尺寸晶体的锂硅玻璃陶瓷表现出最高的耐磨性和力学性能。
