Temperature-dependent mechanical and long crack behavior of zirconium diboride–silicon carbide composite
Temperature-dependent mechanical and long crack behavior of zirconium diboride–silicon carbide composite
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DOI：
10.1016/j.jeurceramsoc.2012.03.029
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发表时间：
2012-09
影响因子：
5.7
通讯作者：
Marc W. Bird;Robert P. Aune;A. Thomas;P. Becher;K. White
中科院分区：
文献类型：
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作者：
Marc W. Bird;Robert P. Aune;A. Thomas;P. Becher;K. White
热压ZrB 2 - 20 vol.%制备了SiC超高温陶瓷复合材料，并对其强度和断裂进行了研究。采用热压工艺制备了两种含（ZS）B4 C和含（B4 B）B4 C烧结助剂的复合材料，并对其进行了室温抗折强度（莫尔）和单边缺口弯曲（SENB）断裂韧性实验。两种复合材料的结构性能关系进行了研究。还研究了高达1500°C的莫尔和刚度温度依赖性。在1400°C温度下，使用带有半人字形切口起始区的双悬臂梁几何结构进行了长裂纹扩展研究。残余的富硼碳化物的最大颗粒尺寸被发现是强度限制在C40 B坯料，而SiC控制强度在ZS坯料。挠曲强度随温度从1000 °C至1500°C线性降低，在断裂之前没有可见的塑性变形。在1100-1200°C的转变温度范围内观察到类似的刚度降低。长裂纹研究产生的R-曲线显示在室温下没有显著的增韧行为，在较高温度下出现一些适度上升的R-曲线行为。这些研究还表明，平台韧性随温度升高而增加，直至1200°C。这是由所观察到的过渡，从主要穿晶断裂在室温下，主要沿晶断裂在高温下。尾流区增韧在高达1000°C时是明显的，KR从0.1到0.5 MPa·m。超过1000°C，断裂机制转变为包括裂纹尖端前的蠕变区发展，尾流区增韧消失。
Hot pressed ZrB2–20vol.% SiC ultra-high temperature ceramic composites have been prepared for strength and fracture investigations. Two composites fabricated under differing hot pressing temperatures with (ZSB) and without (ZS) B4C sintering aids were selected for room temperature modulus of rupture (MOR) strength and single-edge-notch bend (SENB) fracture toughness experiments. Structure property relationships were examined for both composites. MOR and stiffness temperature dependence was also investigated up to 1500°C. Long crack propagation studies were conducted up to 1400°C using the double cantilevered beam geometry with half-chevron-notch initiation zones. Residual Boron-rich carbide maximum particle sizes were found to be strength limiting in ZSB billets while SiC controlled strength in ZS billets. Flexure strength decreased linearly with temperature from 1000 to 1500°C with no visible plastic deformation prior to fracture. Similar stiffness decreases were observed with a transition temperature range of 1100–1200°C. Long crack studies produced R-curves that show no significant toughening behavior at room temperature with some modest rising R-curve behavior appearing at higher temperatures. These studies also show the plateau toughness increases with temperature up to 1200°C. This is supported by an observed transition from primarily transgranular fracture at room temperature to primarily intergranular fracture at high temperatures. Wake zone toughening is evident up to 1000°C with KRrise from 0.1 to 0.5 MPa√m. Beyond 1000°C fracture mechanism transitions to include creep zone development ahead of crack tip with wake zone toughening vanishing.