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The blends with higher damping performance was prepared based on nitrile butadiene rubber(NBR) with addition of graphene oxide(GO) and modified graphene oxide(MGO) prepared by improved Hammer method. Meanwhile, the damping property and the anti-aging property of the blends were investigated by DMA, AFM, SEM and so forth. The results show that after the addition of the GO and MGO, the tangent of loss angle(tanδ) increases and also the anti-aging property is improved. When adding less amount of GO in the matrix, the anti-aging property is better; when adding MGO in the matrix, the amount of addition is not obviously related with the anti-aging property of the blends. The dispersion of GO and MGO has positive correlation with its anti-aging property. By microscopic analysis, the main reason for the decrease of anti-aging property of the blends is the agglomeration of the GO. The interface effect formed by the addition of MGO and GO is the main reason for its high damping property and anti-aging property.

Abstract 304 stainless steel (SS) was exposed to 325 °C water condition to simulate the operation condition of nuclear power reactor. The microstructural characteristics and corrosion behaviors of exposed 304 SS was investigated. Result shows that the exposed 304 SS surface form an oxide film, which consist of outer film and inner film. The outer film is composed of μm-size hematite and nm-size spinel oxide particles formed on top of the original metal surface. The continuous inner film contains Nano-crystalline spinel. Potentiodynamic polarization test results indicate that the corrosion behavior of 304 SS decrease with exposure time increasing. Because the quantity of pores on oxide film increase with exposure time increasing, and the corrosion behavior decrease. The oxide film gradually grows with exposure time. Finally, the formation and evolution mechanism of oxide film was proposed and the determining factors was discussed. Highlights • 304 stainless steel was exposed to 325 °C water condition to simulate the operation condition of nuclear power reactor. • The characterization and corrosion behaviors of the oxide film formed on 304 stainless steel surface was investigated. • The formation mechanism of the oxide film formed on 304 stainless steel surface was discussed. [ABSTRACT FROM AUTHOR]

F6NM martensitic stainless steel was exposed to 350 °C water condition for 500, 1500, and 2500 h to simulate pressurized water reactor (PWR) condition. The characterization and corrosion behavior of the oxide film were investigated. Results indicate that the exposed steel surface formed a double-layer oxide film. The outer oxide film is Fe-rich and contains two type oxide particles. However, the inner oxide film is Cr-rich, and two oxide films, whose thicknesses increase with increasing exposure time. The oxide film reduces the corrosion behavior because the outer oxide film has many crack and pores. Finally, the mechanism and factors affecting the formation of the oxide film were investigated. [ABSTRACT FROM AUTHOR]

The fretting corrosion behavior of zirconium (Zr) alloy under different pH conditions was investigated. The morphology, microstructure, and wear mechanism of Zr alloy under different pH condition was analyzed. The results indicate that the wear scar Zr alloy in acid condition presents a typical feature of wear debris, furrow, and delamination, indicating that the wear mechanism is oxidation wear and abrasive wear. The microstructure beneath the wear scar is composed of a thick wear debris layer (WDL), deformation layer (DL), and thin tribologically transformed structure (TTS). The WDL is a nano-sized grainy structure and the micro-crack is mainly formed on the interface of WDL and TTS. The largest wear volume belongs to the wear scar in pH of 1 condition. Because the corrosion and corrosion induced by wear would destroy the surface protective film and form a thick WDL, which is easy to separate to increase the material loss volume. The Zr alloy in pH of 1 condition shows the largest volume ratio of wear induced by corrosion and corrosion induced by wear. • The material loss volume by tribocorrosion is lowest at intermediate pH and highest at low pH. • The thick WDL at low pH is generated by the quick oxidation of TTS/DL and the accumulation of oxide particles. • The wear mechanism of Zr alloy at intermediate pH is abrasive wear and at low pH is oxidation wear and abrasive wear. [ABSTRACT FROM AUTHOR]

The high‐temperature fretting fatigue damage characteristics of dovetail specimens strengthened by nanosecond laser (NL) and nanosecond combined femtosecond laser (F‐NL) were investigated. The results show that the fretting fatigue life of the NL strengthened sample (NL sample) is improved by 211.2% compared to the base metal samples (BM sample). The lifetime of the nanosecond combined femtosecond strengthened sample (F‐NL sample) was increased by 319.6%. It was attributed to the strengthening introducing hardened layers, residual compressive stress field, and high density of dislocations. The combined strengthening process reduces the surface roughness of the NL strengthened surfaces, while the strengthening influence layer is further increased. The fracture morphology shows that the crack source of the strengthened specimen has changed from multi‐source sprouting to single‐source sprouting, and the crack source sprouted on the subsurface. The fatigue strip morphology similarly confirms that a reduction in the crack propagation rate occurs. [ABSTRACT FROM AUTHOR]

• Annealing at different temperatures was used on cold rolling fe-13cr-4al-2mo thin-walled tubes. • The microstructure and axial tensile properties of the samples before and after annealing were measured. • The annealed samples were embrittled by aging, and the enhanced particles and hardness were characterized. • The strengthening mechanism of FeCrAl alloy at room temperature and failure mechanism at high temperature were investigated. FeCrAl alloy has great application potential to replace traditional zirconium alloy as an accident-tolerant fuel (ATF) candidate material. In this study, Fe-13Cr-4Al-2Mo-0.65Nb-0.4Ta alloy was prepared into a thin-walled tube with a diameter of 9.5 mm and a wall thickness of 0.35 mm by cold rolling. The effects of different annealing temperatures on the microstructure morphology, texture growth direction, and mechanical properties of FeCrAl alloy were studied., alloy underwent recovery and recrystallization with increasing annealing temperature, and the grain size increased. The theoretical calculation showed that the pinning action of Fe2Mo4C and Fe2Nb increased the dislocation density, and the interaction with the dislocation increased the room temperature strength. The addition of Ta led to the formation of more second-phase precipitates at the grain boundary, which hindered the growth and refined grains. The high-temperature stable second phase provided sufficient temperature strength for the alloy. [ABSTRACT FROM AUTHOR]

• Microstructure and fretting wear properties of Zr alloys treated by LSP were studied. • The plastic deformation was caused by grain refinement and dislocation entanglement. • Zr alloys treated by LSP exhibit abrasive wear and oxidation wear. In this study, the microstructure and fretting wear properties of zirconium (Zr) alloy treated by laser shock peening (LSP) were studied. The Zr alloy treated by LSP presents grain refinement and dislocation entanglement, resulting in the increase of hardness. The friction coefficient, wear area, wear loss, and wear depth of Zr alloy treated by LSP are significantly reduced, indicating that LSP treatment can enhance the wear resistance. The primary wear mechanism of substrate is adhesive wear, and Zr alloy treated by LSP exhibits abrasive wear and oxidation wear. [ABSTRACT FROM AUTHOR]

Ultrasonic surface rolling processing (USRP) was carried out at zirconium (Zr) alloy with different rolling speeds to prepare gradient nanostructured layers, and the corrosion behavior of USRP treated Zr alloy was studied under 360 °C/18.6 MPa water condition. The surface morphology, microstructure, phase composition, and element distribution of USRP treated Zr alloy after corrosion was investigated. Results show that the oxide layer on Zr alloy comprises of t-ZrO 2 , m-ZrO 2 , and metal Zr. The thickness of oxide layer Zr alloy is reduced after USRP treatment, indicating that the gradient nanostructure can effectively improve corrosion resistance. This process is attributed to that the gradient nanostructure layer is helpful for the nucleation of equiaxed t-ZrO 2 at the oxide/metal (O/M) interface with small grain size. The high compressive stress induced by USRP treatment is beneficial for the maintenance of t-ZrO 2 phase and inhabiting the phase transformation from t-ZrO 2 to m-ZrO 2 , which reduces the micro-cracks and defects due to volume expansion. The oxide layer on USRP treated Zr alloy with high content of t-ZrO 2 phase presents a dense structure and prevents oxygen anions from diffusing to Zr alloy. • The characterization of oxide layer on USRP treated Zr alloy is investigated. • The gradient nanostructured layer is beneficial for improving the corrosion behavior of Zr alloy. • The corrosion mechanism of USRP treated Zr alloy is analyzed. [ABSTRACT FROM AUTHOR]

Low energy laser shock peening (LE-LSP) with different energies was carried out at zirconium (Zr) alloy. Characterization and electrochemical corrosion behavior of Zr alloy after LE-LSP treatment were investigated. Results show that the surface profile of Zr alloy after LE-LSP treatment is rough due to the regular undulations on the surfaces. The hardness of Zr alloy increases after LE-LSP treatment because the grain size of Zr alloy is refined, and the plastic deformation generated on the surface induces the working hardening. A melting layer, plastic deformation layer, and transition layer are formed on Zr alloy after LE-LSP treatment. The dislocation entanglement is observed at the plastic deformation layer, which indicates that the dislocation slip is the main deformation mechanism of Zr alloy. The electrochemical corrosion resistance of Zr alloy after LE-LSP treatment is improved because of an increase in the grain boundary, which improves the activity of Zr alloy and is beneficial for forming passive films. • A melting layer, plastic deformation layer, and transition layer were formed on Zr alloy after LE-LSP treatment. • The dislocation slip is the main deformation mechanism of Zr alloy during LE-LSP process. • The increase in the grain boundary of Zr alloy after LE-LSP treatment is beneficial for forming passive films. [ABSTRACT FROM AUTHOR]

The plasma electrolytic oxidation (PEO) coating on Zirconium (Zr) alloy was employed and immersed under 400 °C/10.3 MPa steam conditions. The surface morphology, phase composition, microstructure, and element distribution of the PEO coating after corrosion were analyzed. The results indicate that the PEO coating presents lower corrosion weight gain because the compact oxide layer on the PEO coating presents few cracks and prevents the corrosion media from entering the substrate. The compact oxide layer is caused by the high compressive stress in PEO coating, which is helpful for the nucleation of t-ZrO 2 grain and restricting the phase transformation from t-ZrO 2 to m-ZrO 2 , thus reducing the volume expansion and defects. Based on the XRD, SEM, XPS, Raman mapping, and TEM results, the corrosion mechanism and phase transformation processes of the PEO coating under 400 °C/10.3 MPa conditions were summarized. • The microstructure and corrosion mechanism of PEO coating under 400 °C/10.3 MPa condition are investigated. • The phase transformation process of zirconia under 400 °C/10.3 MPa condition is studied. • The corrosion weight gain of PEO coating are reduced by the compact inner layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • The friction performance of 2.25Cr-1Mo steel in liquid sodium were improved by salt bath nitriding. • The microstructure and corrosion behavior of the nitrided samples were characterized and discussed. • The fretting wear mechanism of matrix and nitrided samples in liquid sodium at different temperatures was revealed. In this study, nuclear grade 2.25Cr–1Mo steel was surface strengthened by quench–polish–quench (QPQ) at two salt bath nitriding temperatures (550 °C and 590 °C). At 250 °C and 450 °C liquid sodium, the fretting wear test was carried out, and the possible effects of salt bath temperature on friction performance and microstructure of different samples were investigated. The results show that the surface of 2.25Cr-1Mo steel after QPQ treatment forms a multilayer structure with a hardness 3.7–5.8 times higher than that of the substrate, while the excessively high nitriding temperature also causes premature failure of the nitride layer of QPQ 590. Compared to the substrate, QPQ 550 and QPQ 590 experienced 40% and 16% reductions in the material loss at 450 °C, and 86% and 57% at 250 °C, respectively. The substrate showed different wear mechanisms in liquid sodium at varying temperatures. At 250 °C, the abrasive wear is dominant, while at 450 °C, the adhesive wear is dominant, accompanied by abrasive wear. The nitrided samples are dominated by abrasive wear in liquid sodium at varying temperatures, accompanied by the corrosion effect of the liquid sodium. [ABSTRACT FROM AUTHOR]