Z‐pin effect on interlaminar mechanical and ablation performance of quartz‐phenolic composites

Abstract

When a spacecraft flies at a high speed through a high‐heat flow, the ablative composites suffer from severe delamination and bulging due to their weak interlaminar performance. This will interfere normal operations of spacecraft. To improve the interlaminar performance of ablative composites is of great significance to the ablative structures. This study investigated Z‐pin reinforced quartz‐phenolic composites and reinforcement mechanism. First, a thermogravimetry (TG) test was used to analyze the thermal decomposition process of the phenolic. Second, a series of tests, including a single Z‐pin pull‐out, a single‐lap joint tensile and an oxyacetylene ablation test, were conducted to investigate composites' ablation performance. We also deployed a 3D morphometer and an infrared thermography to reveal the function of Z‐pins. The results demonstrated that Z‐pins can improve composites' ablation performance in both structure and function. In the structure, Z‐pins suppress the interlaminar delamination of composites by enhancing the interlaminar strength. As the ablation time increases, interface bridging between the Z‐pin and laminates contributes increasingly to the interlaminar shear strength of laminates. After 60 s of ablation in a flame of 920°C, the interlaminar shear strength of Z‐pin specimens is 84.66% stronger than that of the normal composites. In the function, the Z‐pins suppress large areas of bulges by providing escape channels for pyrolysis gas, and reduce bulging areas by 60%. Z‐pin technology can effectively suppress mechanical erosion of the ablative surface due to the delamination and bulging. It is an important way to improve ablation performance of ablative structures.

Experimental research on the high‐temperature compression mechanical properties of carbon/phenolic composites in rapid carbonization conditions

“…Due to the high porosity of the carbonized matrix, when the test temperatures being used were 1400°C and 1600°C, compression strengthening occurred during the compression process, so the curve fluctuated in the linear elastic stage. [ 26 ] The average high‐temperature strength of specimens after rapid carbonization at different test temperatures is shown in Table 3.…”

“…[24] The components of polymer matrix composites change dynamically at high temperatures, which also causes changes in their mechanical properties. [25,26] Considering the influence of dynamic changes (for various parameters) on the properties of composites during pyrolysis, the stress-strain relationship can be obtained by averaging different phase parameters. However, the strength predicted by this method may deviate by up to 30%.…”

Research on low-velocity impact characteristics of Z-pin reinforced quartz/phenolic laminates

“…The impactor is modeled using isotropic 3D solid elements and is constrained as a rigid body, with a predefined downward velocity assigned to the constrained point. The parameters involved in the simulation are obtained from [8][9][10] and experiments [11].…”

Co-Optimizing Insulative and Mechanical Properties of Quartz Fabric Reinforced Phenolic Composites by a Compromising Porous Structure for Thermal Insulation

“…The increase of porosity postpones the densification process of phenolic nanoparticles. In general, NPCs have stronger mechanical strength and even lighter density compared to carbon/ phenolic, 19,20 quartz/phenolic, 21,22 PICA, 23 and phenolic aerogel composites, 24 as shown in Figure 3f.…”