To investigate the changes in hydrogen embrittlement (HE) resistance of China Low Activation Martensitic (CLAM) steel during thermal aging, CLAM steels were aged at 550 °C and 600 °C up to 5000h. The evolution of microstructure, including the evolution of subgrains, the growth of M23C6 carbides and MX carbonitrides, as well as the formation of Laves phase, were carefully characterized. The observed trend revealed an initial increase followed by a subsequent decrease in HE resistance upon prolonged aging durations. The mechanisms for changes in HE resistance were analyzed based on the orientation relationship between precipitates and matrix.

The influences of polymer network structures on the properties of natural rubber (NR) based products were investigated in this work through blending NR with trans-1,4-poly(butadiene-co-isoprene) (TBIR) copolymers with varied crystallinity. Series of TBIR copolymers with varied chain sequence structure and crystallinity were synthesized. Blending 10 phr TBIR-1 (crystallinity 9.4%) with NR, the vulcanized NR/TBIR-1 composite pre-sented the highest fatigue resistance, reduced rolling resistance and abrasion, reduced tear strength when compared with NR composite. While NR/TBIR-3 (crystallinity 4.1%) vulcanizate presented satisfied dynamic properties, like much lower rolling resistance and abrasion, excellent fatigue resistance and tear strength. The chain sequence structures of TBIR had significant effects on the dynamic properties of NR composites by con-structing polymer ternary-network structures. This work is dedicated to understand the key parameters deter-mining the dynamic properties of rubber composites and proposed the ideal polymer network structure for high performance rubber composites.

A new organic silicone composite coating modified by Al, ZrO2, quartz and PbO-SiO2-Al2O3 glass powders was developed to protect Ti-6Al-4V alloy. During oxidation at 600 degrees C in dry air, the coating was oxidized and formed an inorganic composite coating composed of amorphous silica framework and fillers which greatly decreased oxidation rate of substrate. Al2SiO5 formed in coating due to reaction of Al with glass. Glass powders with softening point of 385 degrees C may play important roles in improving coating protectiveness because they can flow to fill the cavities formed by oxidation of organic components in coating at 600 degrees C.

As a classic in-situ reaction, the Al-TiO 2 reaction is expected to prepare aluminum matrix composites with high thermal stability. In this study, it was found that the preparation method of ensuring sufficient reaction using higher temperatures in previous studies was not conducive to acquiring optimized high-temperature strength. With the increase of hot-pressing temperature and the extension of holding time, the in-situ reaction became more thorough, but the strength of the composites first increased and then decreased. Coarsening of the microstructure at high temperatures would lead to degradation of strength and controlling the in-situ reaction process by the hot-pressing parameters could optimize the mechanical properties of the composites. Strengthening mechanisms at room and high temperatures were studied, and it was found that the load-transfer and Orowan strengthening mechanisms are the main strengthening effects at room temperature, while the pinning effect of fine particles became more crucial at elevated temperatures. As a result, the coarsening of the reinforcing phases was more detrimental to the high-temperature strength. Therefore, an insufficient in-situ reaction led to more excellent mechanical properties, and the composite hot-pressed at 605°C and held for 2 h exhibited the highest strength, which was 367 MPa at room temperature and 170 MPa at 350°C.

Cold spray has emerged as a viable technique for polymer surface metallization, featuring a low process temperature and high deposition rate. In literature, it is generally believed that the formation of metallurgical/chemical bonding is impossible to realize during cold spray metallization of thermoplastics. However, there is no clear evidence to support this argument, hence the exact nature of bonding mechanism is still unclear and debatable. In this study, for the first time, the adhesive feature of cold sprayed Al coating on polyetheretherketone (PEEK) substrate was studied in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), confirming the presence of chemical bonding at the Al/PEEK interface. The TEM images showed that the combination of Al coating and PEEK substrate is strongly related to the presence of continuous oxide film at the interface. Moreover, the FTIR and XPS results revealed that the metal-polymer complex was formed at the PEEK/amorphous oxide interface, which resulted in chemical bonding at Al/PEEK interface.

The uniformly dispersed carbon nanotubes (CNTs) reinforced 6061Al composites (CNT/6061Al) with different CNT concentrations were fabricated by powder metallurgy technology. It was found that the friction coefficient as well as wear rate decreased first and then increased as the CNT concentration increasing under 15 N as well as 30 N, and the minimum wear rate was achieved at the CNT concentration of 2 wt%. Adhesive wear and abrasive wear were the dominated wear mechanisms for the 1–2 wt% CNT/6061Al composites under 15 N and 30 N, while the delamination occurred on the wear surface at 3 wt% CNT. As the applied load increased to 60 N, the wear rate of composites increased dramatically. The wear mechanism transformed from abrasive wear to severe delamination wear, accompanied by the generation of wear debris with sharp edge due to the weaker anti-shearing strain capacity of CNT/6061Al composites.

Amorphous Al 2 O 3 -reinforced Al composite (am-Al 2 O 3 /Al) compacted from ultrafine Al powders for high-temperature usages confronts with drawbacks because crystallization of am-Al 2 O 3 at high temperatures will result in serious strength loss. Aiming at this unsolved problem, in this study, high-temperature Al materials with enhanced thermal stability were developed through introducing more thermally stable nano-sized particles via high-temperature pre-treatment of ultrafine Al powders. It was found that the pre-treatment at ≤ 550 °C could introduce a few Al 2 O 3 in the Al matrix and increase the strength of the composites, but the strength was still below that of am-Al 2 O 3 /Al because without being pinned firmly, grain boundaries (GBs) were softened at high temperature and intergranular fracture happened. When the pre-treatment was carried out at 600 °C, nitridation and oxidation processes happened simultaneously, producing large numbers of intergranular (AlN + γ -Al 2 O 3 ) particles. GB sliding and intergranular fracture were suppressed; therefore, higher strength than that of am-Al 2 O 3 /Al was realized. Furthermore, the (AlN + γ -Al 2 O 3 )/Al exhibited more superior thermal stability compared to am-Al 2 O 3 /Al for annealing treatment at 580 °C for 8 h. Therefore, an effective way to fabricate high-temperature Al composite with enhanced thermal stability was developed in this study.