In order to meet the requirement of the more extreme and severe aerothermodynamic environment faced by the future spacecrafts for high-speed Earth return missions, novel ablation resistant/heat insulation/lightweight integrated resin matrix composites are designed for the heatshields for these vehicles. Proposing the concept of security zone and heat insulation zone into the novel designs, not only the ablation resistant and heat insulation abilities can be improved, but also the weight of the entire material can be effectively reduced.Simultaneously, a computer modeling is established to evaluate the comprehensive performance of integrated high temperature materials. A variety of material process design parameters is introduced into the model while taking the respective properties of fiber weave and matrix into consideration. Computer codes are written for solving the model based on the numerical method for solving nonlinear equations. Under two typical extreme aerothermodynamic environments faced by future aircrafts, the effects of material process design parameters on the comprehensive performance are analyzed, which includes ablation resistant ability, heat insulation capacity, and lightweight level. Finally, the optimal design scheme of the new integrated resin matrix composite under the specific environment is determined. This work helps to the on-demand design of new thermal protection materials for extreme entry or reentry environments.

Multi-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.

The thermal protection materials of hypersonic aircrafts in near space are subjected to extremely serious aerothermodynamic environment under long heating time, higher enthalpy, larger heat accumulation, and so forth. Proposing new concepts of materials and accurate evaluation of their performance take the dominant roles in developing high-efficiency thermal protection materials under this severe environment. By introducing the concepts of gradient and fiber hybridization, this study proposes a multifunctional integrated ablative material scheme to replace heritage ones in order to improve the heat insulation, ablation resistant, and weight reduction capacities. Meanwhile, a thermal-fluid-ablative coupling mathematical model taking the manufacturing processing parameters reflecting the gradient and fiber hybridization into consideration is established. Furthermore, the sensitivity analysis for the manufacturing processing parameters is carried out. A simulation tool is developed based on writing FORTRAN codes to solve the multi-field coupling model numerically. The results that the model and code are effective in analyzing the material's performance and the key manufacturing processing parameters influencing on the thermal protection performance of multifunctional integrated ablative material are pointed out. This work helps to design new thermal protection materials for hypersonic vehicles under extreme aerothermodynamic environments. Highlights • New scheme of multifunctional integrated ablative material is proposed. • Developed multi-field coupling thermal protection model for new material is established. • A bridge between material responses and manufacture processing parameters is built. • Key factors influencing on material performance are pointed out by sensitivity analysis.

Abstract-Wireless Underground Sensor Networks (WUSN) using Electro-Magnetic (EM) wave communication has to address the challenges posed by the underground environment. An alternative to EM wave communication for WUSN is Magnetic Induction (MI). This research aims to study the possibility of using MI communication for WUSN designed for irrigation control in horticulture. As a case study, a typical Pecan farm in Australia has been considered. The case study would focus on the application of accurate soil moisture reporting and regulation for the farm, under all climatic conditions. This application addresses the issue of water-shortage confronting irrigation in Australia.

In this paper, T-700™ carbon fiber-reinforced silicon carbide (C/SiC) minicomposites with pyrocarbon (PyC) interphase with different textural microstructure and thickness were fabricated using the chemical vapor infiltration method. The interface properties (i.e., textural microstructure, thickness, hardness, and modulus) were obtained through multiple testing methods (i.e., Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and nanoindentation tests). Relationships between the deposition temperature and residence time with the texture type (i.e., low, medium, and high texture) were established. Uniaxial tensile experiments were conducted for C/SiC minicomposites with different PyC interphases to characterize the composite's internal damage evolution and fracture. Relationships between the composite's tensile nonlinear damage evolution, fracture strength and strain, PyC interphase texture, and thickness were established. The composite's tensile strength and fracture strain were the highest for the C/SiC minicomposite with medium-high texture PyC interphase.For the C/SiC minicomposite with the same texture interphase, the composite's tensile strength and fracture strain were affected by the coating thickness. The higher the thickness of the coating, the lower the composite's tensile strength and fracture strain.