Experimental study of ultra-high temperature interlaminar tensile strengths of 3D-needled C/C composites using the V-shaped notched specimen compression method

In this work, interlaminar tensile (ILT) strengths and microscopic failure mechanisms of 3D needled C/C composites were studied at ultra-high temperatures (up to 2800 °C). Experiments were conducted using the V-shaped notched specimen compression method. The measured ILT strengths compared favorably to results obtained via flatwise tension and diametral compression tests. In addition, the high-temperature transverse displacement field was measured using digital image correlation and the temperature field was measured using an infrared thermal imager. The transverse displacement and temperature fields were uniform in the gage section. The results confirm the effectiveness of this method for measurements of 3D needled C/C composites. The ILT strengths of the 3D needled C/C composites were measured at 1200 °C, 1600 °C, 1800 °C, 2000 °C, 2400 °C, and 2800 °C. The ILT strengths increased with the temperature up to 1600 °C, and then decreased in the 1600–2800 °C range. The failure mechanisms were investigated via optical microscopy. The needling fibers were pulled out, which indicates that the ILT strengths were primarily dependent on interfacial strength. It is intended that these results will provide some practical guidelines for ultra-high temperature engineering applications.