Long-term Thermal Cycling Research Articles

Bio-based eutectic composite phase change materials with enhanced thermal conductivity and excellent shape stabilization for battery thermal management

Organic phase change materials (PCMs) are commonly used for battery thermal management. Organic petroleum-based PCMs such as paraffin have an adverse effect on environment. Fatty acids as environmentally friendly bio-based PCMs, have enormous potential in sustainable development strategies. Nevertheless, the application of fatty acids in battery thermal management (BTMS) is restricted by the leakage of liquid PCM, poor thermal performance and the improper phase change temperature. We proposed a novel bio-based eutectic composite phase change materials (CPCM) with enhanced thermal conductivity and excellent shape-stabilization, composed of ethylene-vinyl acetate (EVA), Aluminum nitride (AlN), and the eutectic PCM of Lauric acid (LA) and Stearic acid (SA). Significantly, the screened eutectic PCM of LA-SA possesses a suitable phase change temperature(37.03 °C) corresponding to the battery operating temperature, and long-term thermal cycling stability of up to 100 cycles. And the cross-linked structure of EVA effectively encapsulated the eutectic PCM, whose mass only lost below 4% after being heated at 80 °C for 24 h. Simultaneously, the introduction of AlN can greatly improve their heat transfer ability and mechanical properties. LA-SA/EVA/AlN composites with 5 wt% AlN has adequate latent heat of 107.94 J.g−1 and high thermal conductivity of 0.726 W.(m·K)−1 as well as with low flexural strength of 1.72 MPa. Additionally, the proposed CPCM with 5 wt% AlN achieved the maximum temperature of battery below 45 °C during 4C discharging test. It suggested that the CPCM incorporated with AlN is capable effective cooling battery and dissipate energy inside PCM rapidly.

Quantitative study on the microstructural evolution and dimensional stability mechanism of 2024 Al alloy during long-term thermal cycling

During the start-stop process of high-precision instruments in service, the critical materials of instruments undergo thermal cycling, resulting in changes in microstructure and dimension. In this paper, the evolution and coupling effects of dislocations and precipitates within 2024 Al alloy during 500 cycles were investigated, and their influence on the dimensional change was quantitatively characterized and decoupling analyzed. Transmission Electron Microscopy (TEM)/aberration-corrected scanning TEM (CS-TEM), X-ray diffraction (XRD), and Three-Dimensional Atom Probe Tomography (3D-APT) were used for microstructural evolution analysis and quantitative statistics. The dislocation density increased from 3.32 × 1014 m−2 to 5.75 × 1014 m−2 after 500 cycles, which accelerated elemental diffusion and provided nucleation sites of precipitates, contributing to an increase in the number density of the S'/S phase from 1.04 × 1024 m−3 to 1.41 × 1024 m−3. Based on the quantitative statistics of precipitate types and corresponding volume fractions, the dimensional change induced by precipitate evolution was −1.25 × 10−4. The dimensional change caused by the free volume introduced by dislocation density was 3.32 × 10−6. Comparing these values with the experimental value of −1.94 × 10−4, it is clear that the precipitate evolution is the main factor that triggers the dimensional change.

Preparation and Thermal Properties of Propyl Palmitate-Based Phase Change Composites with Enhanced Thermal Conductivity for Thermal Energy Storage.

Phase change materials (PCMs), which can absorb and release large amounts of latent heat during phase change, have been extensively studied for heat storage and thermal management. However, technical bottlenecks regarding low thermal conductivity and leakage have hindered practical applications of PCMs. In this paper, a simple, economical, and scalable absorption polymerization technique is proposed to prepare the polymethyl methacrylate/propyl palmitate/expanded graphite (MPCM/EG) phase change composites by constructing the microencapsulated phase change materials (polymethyl methacrylate/propyl palmitate, MPCM) with core-shell structures in the three-dimensional (3D) EG networks, taking propyl palmitate as the PCM core, polymethyl methacrylate (PMMA) as the shell, and long-chain "worm-like" EG as the thermally conductive networks. This technique proved to be a more appropriate combinatorial pathway than direct absorption of MPCM via EG. The MPCM/EG composites with high thermal conductivity, high enthalpy, excellent thermal stability, low leakage, and good thermal cycle reliability were prepared. The results showed that the MPCM-80/EG-10 composite demonstrated a high thermal conductivity of 3.38 W/(m·K), a phase change enthalpy up to 152.0 J/g, an encapsulation ratio of 90.3%, outstanding thermal stability performance, and long-term thermal cycle reliability when the EG loading is 10% and propyl palmitate is 80%. This research offers an easy and efficient approach for designing and fabricating phase change composites with promising applications in diverse energy-saving fields, such as renewable energy collection, building energy conservation, and microelectronic devices thermal protection.

A thermal network model considering thermal coupling effect and TIM degradation in IGBT modules

Thermal interface materials (TIMs), as important materials for heat dissipation of insulated gate bipolar transistor (IGBT) modules, degrade under long-term thermal cycling, resulting in elevated junction temperatures and threatening the safe operation of IGBT modules. In consideration of the thermal coupling effect in IGBT modules, this paper proposes a three-dimensional thermal network model characterizing the TIM degradation. An IGBT module with the TIM is adopted to establish the finite element method (FEM) model, in which the TIM layer is divided into regular areas. The thermal network is established by simulating the heat transfer paths. The thermal impedance in each path is extracted according to the heat flow through its area considering the TIM degradation. Thereby, the impact of thermal coupling and TIM degradation on junction temperature of IGBT modules could be characterized. Furthermore, the proposed thermal network is verified by simulation from calculation accuracy of junction temperature and TIM temperature.

Enhancement of La0.8Sr0.2MnO3-based amperometric total NOX sensor via modification with Pt nanoparticles

Pt nanoparticle (PtNP)-modified La0.8Sr0.2MnO3 (LSM)-sensing electrodes (SE) were developed successfully by the impregnation method for amperometric total NOX (NO and NO2) sensors. The structure, morphology, and surface valence state of SE were characterized by thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that all SEs of the sensors were uniformly modified with PtNPs; interestingly, the size of the PtNPs increased with an increase in the modified content. Compared with pure LSM, the sensor based on 0.50 vol% Pt/LSM exhibited enhanced gas-sensing properties toward total NOX. The sensitivity improved from − 9.04 to − 18.7 μA/decade in the NOX, ranging from 50 ppm to 800 ppm. Moreover, the sensor maintained a 94% response signal after a long-term stability test, showing a stable response during the long-term thermal cycling test towards total NOX. Meanwhile, the sensor exhibited markable selectivity and consistency. The catalytic effect of Pt nanoparticles was believed to be the main reason for the enhancement of gas-sensing characteristics.

Comparative Study of Heat-Discharging Kinetics of Fe-Substituted Mn2O3/Mn3O4 Being Subjected to Long-Term Cycling for Thermochemical Energy Storage

The heat-discharging kinetics of an iron-substituted Mn2O3/Mn3O4 redox pair subjected to long-term thermal cycling tests using a temperature swing process at high temperatures was investigated for next-generation concentrated solar power plants equipped with thermochemical energy storage. The heat-discharge mode kinetics for long-term thermal-cycled samples have never been reported. Additionally, comparisons of the heat-discharge mode kinetics for both long-term thermal-cycled and as-prepared samples have never been discussed. In terms of the reproducibility and sustainability of thermochemical energy storage, kinetic evaluations of samples with thermally stable morphologies subjected to long-term thermal cycling at high temperatures are important for next-generation solar thermal power plants. For the long-term thermal-cycled sample, the A2 model based on the Avrami–Erofeev reaction describes the discharging mode behavior in a fractional conversion range of 0–0.24, the contracting area (R2) model best fits in a fractional conversion range of 0.24–0.50, and the third-order (F3) model matches in a fractional conversion range of 0.50–0.70. For the as-prepared sample, the power-law (P2) model describes the behavior of the first part of the discharging mode, whereas the Avrami–Erofeev (A4) model best fits the last half of the discharging mode. The predicted theoretical models for both samples were compared with previous kinetic data.

Characterization of the Internal Stress Evolution of an EB-PVD Thermal Barrier Coating during a Long-Term Thermal Cycling

Electron beam physical vapour deposition (EB-PVD) technology is a standard industrial method for the preparation of a thermal barrier coating (TBC) deposition on aeroengines. The internal stress of EB-PVD TBCs, including stress inside the top coating (TC) and thermal oxidation stress during long-term service is one of the key reasons for thermal barrier failures. However, research on the synergistic characterization of the internal stress of EB-PVD TBCs is still lacking. In this work, the stress inside the TC layer and the thermal oxidation stress of EB-PVD TBC during long-term thermal cycles were synergistically detected, combining Cr3+-PLPS and THz-TDS technologies. Based on a self-built THz-TDS system, stress-THz coefficients c1 and c2 of the EB-PVD TBC, which are the core parameters for stress characterization, were calibrated for the first time. According to experimental results, the evolution law of the internal stress of the TC layer was similar to that of the TGO stress, which were interrelated and influenced by each other. In addition, the internal stress of the TC layer was less than that of the TGO stress due to the columnar crystal microstructure of EB-PVD TBCs.

The effect of Fe2O3 sintering aid on Gd0.1Ce0.9O1.95 diffusion barrier layer and solid oxide fuel cell performance

Solid oxide fuel cells (SOFCs) with the Gd0.1Ce0.9O1.95 (GDC) diffusion barrier layer require the densification of GDC to improve the performance of the cells. In this work, the addition of 0.5 mol% Fe2O3 in GDC diffusion barrier layer as sintering aid is studied. The symmetrical cell and the fuel cell are fabricated by hot-pressing, co-sintering and screen-printing technologies. It is found that the addition of Fe2O3 can make GDC barrier layer denser at a reduced sintering temperature of 1250 °C and prevent diffusion of Sr to form ionic insulating interface between YSZ (Y2O3 stabilized ZrO2) and La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF). The fuel cell based on the GDC-Fe2O3 barrier layer achieves better maximum power density of 0.89 W cm−2 at 800 °C than that of 0.68 W cm−2 without Fe2O3 addition. No obvious degradation was observed on fuel cell based on the GDC-Fe2O3 diffusion barrier layer after a stability test at 750 °C for 100 h under 0.75 V and the thermal cycling between 750 and 400 °C. The results indicate that the addition of Fe2O3 sintering aid in GDC diffusion barrier layer can promote the densification of GDC and exhibit good long-term stability and thermal cycle stability.

Influence of long-term thermal cycling in a corrosive environment on the change in properties and microstructure of SCh20 cast iron

The article considers the study of a metal sample of the wall of the working chamber of the compressor cylinder of the model 5G-100-7 made of SCh20 cast iron, which has been in operation since 1992 and is intended for pyrogas compression at a temperature of 110 °C, decommissioned due to the end of its service life. Mechanical tests were carried out as a result of which the mechanical characteristics of the metal were determined, such as tensile strength and Brinell hardness. The chemical composition of the metal was determined and an excess of sulfur content was established, which is explained by metal contamination due to the presence of sulfur compounds in the compressible medium. Pollution of the compressible medium is caused by the imperfection of the technology for cleaning pyrolysis gas from various impurities. The microstructure of the center of the wall and the edge of the sample, which are in direct contact with the compressible medium, has been studied. It has been established that the microstructure of the sample center is typical for gray cast iron. Along the edges of the wall, rounded corrosion pits and corrosion pits are observed. As a result of the analysis of the microstructure of the surface of the wall of the working chamber, it was found that there is a layer on the surface with dissolved graphite inclusions and the formation of pearlite grains with cementite along the boundaries. Under the surface layer, ferrite grains were found, as a result of the decomposition of perlite, and the transition of carbon to graphite with a morphology different from the base metal and cementite along the periphery of graphite inclusions and ferrite grains.

Oxygen permeation properties of Bi-doped La0.8Sr0.2FeO3−δ planar ceramic membranes at intermediate temperature

Ceramic oxygen permeable membranes (COPMs) have attracted attention as a “next generation” technology for oxygen separation. However, developing new oxygen permeable membrane materials with high oxygen permeability at an intermediate operating temperature is still challengeable. In this work, a series of perovskite La0.8-xBixSr0.2FeO3-δ (LBSF, x = 0.0, 0.2, 0.3 and 0.4) oxides were synthesized and used as the oxygen permeation membrane materials. The phase structure, electrical conductivity, chemical compatibility with 3 mol% yttria-stabilized zirconia (3YSZ), O2 temperature programmed desorption (O2-TPD) have been evaluated. An asymmetric three-layer structure with “porous-transition-dense” was developed by tape casting, hot-pressing and co-sintering technology. The membrane consists of a porous 3YSZ support layer, a 3YSZ-LBSF transition layer and a dense LBSF functional layer. The oxygen permeability was tested by a new designed electrochemical device based on the limit current method. The best oxygen permeability was found in the composition of La0.4Bi0.4Sr0.2FeO3-δ measured at an intermediate temperature of 800 °C with 20% oxygen partial pressure, which could reach 1.13 mL min−1 cm−2. No obvious degradation was observed on the three-layers La0.4Bi0.4Sr0.2FeO3-δ membrane after a stability test at 800 °C for 150 h under 1.6 V and subsequent 11 times thermal cycling between 700 °C and 800 °C. The membrane exhibited excellent long-term stability and thermal cycling stability.

Long-Term Thermal Cycling Test and Heat-Charging Kinetics of Fe-Substituted Mn2O3 for Next-Generation Concentrated Solar Power Using Thermochemical Energy Storage at High Temperatures

We studied the performance in terms of the long-term cyclic thermal storage and heat-charging kinetics of Fe-substituted manganese oxide for use in thermochemical energy storage at temperatures exceeding 550 °C in a next-generation concentrated solar power system in which a gas stream containing oxygen is used for reversible thermochemical processes. The Fe-substituted Mn2O3 was evaluated from the viewpoint of its microstructural characteristics, thermodynamic phase transitions, and long-term cycling stability. A kinetic analysis of the heat-charging mode was performed at different heating rates to formulate the kinetic equation and describe the reaction mechanism by determining the appropriate reaction model. Finally, the kinetics data for the sample obtained after the long-term cycling test were compared and evaluated with those of the as-prepared sample and kinetic literature data tested under different conditions. For the long-term cycled sample, the Avrami–Erofeev reaction model (An) with n = 2 describes the behavior of the first part of the charging mode, whereas the contracting area (R2) reaction model best fits the last half of the charging mode. For the as-prepared sample, except for the early stage of the charging mode (fractional conversion < 0.2), the contracting volume (R3) reaction model fits the charging mode over a fractional conversion range of 0.2–1.0 and the first-order (F1) reaction model fits in the fractional conversion range of 0.4–1.0. The predicted kinetic equations for both the samples were in good agreement with the experimental kinetic data.

Infrared thermographic analysis of thermal property variations in composites subjected to impact damage, thermal cycling and moisture saturation

The new results on the relationships between impact damage energy and thermal property variations in carbon and glass fiber reinforced plastics have been obtained on “dry” composite samples, as well as on the samples subjected to thermal cycling and moisture saturation. The estimates of impact damage detection limit are presented, and the impact energy ranges where variations of effusivity and diffusivity linearly depend on energy are obtained. The experiments on the samples subjected to long-term moisture saturation and thermal cycling revealed no significant influence of these impacts on thermal property. It is concluded that thermal nondestructive testing may serve as a reliable tool for estimating severity of impact damage in aircraft composite structures.

Stability of the microstructure and elevated-temperature mechanical properties of additively manufactured Inconel 718 superalloy subjected to long-term in-service thermal cycling

The present study investigates the thermal stability of the additively manufactured Inconel 718 (IN718) under a long-term thermal cycling exposure, similar to what is encountered in aircraft turbine engines, up to 3000 h. Before thermal cycling, the IN718 parts were heat-treated using two conditions designated, respectively, 2.5H and 4H. The results show that, after the simulated in-service thermal cycling conditions, the 2.5H and 4H treated samples exhibited initially a slight increase in their tensile (TS) and yield strengths (YS) at 650 °C to reach their maximum values after 500 and 1000 h, respectively, and then gradually decreased with further thermal cycling time to reach their lowest values after 3000 h. The microstructural analysis and the X-ray diffraction (XRD) results revealed that a slight initial strength increase is mainly due to a larger precipitation of γ′′ and inter-granular δ-phase during a relatively short-term thermal cycling exposure, whereas the prolonged thermal cycling time resulted in an undesired phase transformation of the metastable γ′′ to intra-granular δ-phase which adversely affected the mechanical properties. However, comparing the tensile results of both treated conditions revealed that the 4H treatment effectively delayed the deteriorations of the material strength until after 2000h as compared to the 2.5H condition for which the strength deterioration occurred after 1000 h due to a slower phase transformation of γ′′ into δ-phase in the former condition. Considering the thermal stability during in-service exposure, it was found that the 4H treated samples demonstrate a higher strength stability than their 2.5H treated equivalents, since after a thermal cycling exposure for 3000 h, the TS and YS values of the former decreased by only 3.3 and 1.3% of the initial state, respectively, as compared to 5.3 and 3.8%, for the latter.

Revealing the dimensional stability mechanisms of SiC/Al composite under long-term thermal cycling

Long-term thermal cycling causes irreversible dimensional changes of the material, which in turn affects the reliability of precision instruments. In this paper, dimensional stability mechanisms of SiC/Al composites during thermal cycling were revealed using high-precision thermal dilatometer, XRD and spherical aberration correction transmission electron microscope (Cs-TEM). First, how the factors including dislocations, internal stress and precipitates affect the dimensional change of SiC/Al composites were separately introduced. Then, the integrated effect of these factors affecting the dimensional stability of SiC/Al composites was further discussed. Among them, the integrated effect of dislocation-internal stress in SiC/pure Al composites leads to an increase in dislocation density and average lattice constant, which leads to an increase in dimensional change. The integrated effect of dislocation-internal stress-precipitates in SiC/2024Al composites leads to a decrease in the average lattice constant and some changes in the precipitation behavior (including the type, density and lattice constant of the precipitates), which ultimately leads to a decrease in dimensional change. The dimensional change of the two types of composites was semi-quantitatively estimated. Finally, the reasons for the significantly higher dimensional stability of the SiC/2024Al composites were given.

Structural and dynamical properties of H2O molecules confined within albite-quartz system under cyclic thermal loading: insights from molecular dynamic simulation

The motivation behind this work was to make a first attempt at gaining molecular-level insights into the structural and dynamical properties of H2O molecules confined within albite-quartz system under cyclic thermal loading, where CLAYFF force field was introduced into Forcite module. Derived from the distance variations of the tetrahedral atoms surrounding the Na position and RDF, the movement tendency of Na atom to be near Al atom and a stronger interaction between albite and H2O molecules can be observed. Accepting H-bonds from the H2O molecules near-surface are important for the development of continuous H-bond networks across the interfacial region. The discrepancy of the orientation order of H2O molecules and the H-bond configurations resulted from long-term thermal cycling are largely responsible for the structure and dynamics of near-surface H2O molecules.

Shape-Stable Hydrated Salts/Polyacrylamide Phase-Change Organohydrogels for Smart Temperature Management.

Flexible and environmentally friendly phase-change materials (PCMs) with appropriate phase transition temperatures display great potential in the regulation of environmental temperature. Here, we synthesized a series of room-temperature-use phase-change organohydrogels (PCOHs) comprising phase-change hydrated salts (disodium phosphate dodecahydrate, DPDH) and polyacrylamide (PAM) glycerol hydrogels through a facile photoinitiated one-step in situ polymerization procedure. Incorporating the environmentally friendly cost-effective DPDH hydrated salts PCMs into antidrying three-dimensional (3D) networks of the PAM organohydrogel can overcome the solid rigidity and melting leakage to achieve flexibility for wearable temperature management devices. The microstructures and physical interactions among the components of the PCOHs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD), which demonstrate that the DPDH were uniformly loaded in the networks of the PAM. Phase-change storage and thermal properties of the PCOHs were characterized by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), and the PCOHs show high energy transition efficiency and shape stability during the long-term storage and thermal cycling. Dynamic rheology and compression tests demonstrate that PCOHs can withstand a certain stress and display flexibility performance even above the melting temperature of DPDH. We also described the smart temperature management capability and the potential application of the PCOHs. This investigation offers a facile method to construct a skin-friendly flexible phase-change glycerol hydrogel and provides an alternative to the traditional melt impregnation or microencapsulation method to prepare phase-change energy storage composites.

Form‐stable phase‐change materials supported by 1‐octadecylamine‐modified montmorillonite for latent heat storage

Form-stable phase-change materials (FSPCMs) are of great significance for relieving the contradiction of energy supply and demand. Unfortunately, the practical application of FSPCMs is severely compromised by their intrinsic drawbacks including lower latent heat storage (LHS) capacities, inferior interfacial compatibility, and cycling durability. Herein, we have provided a group of novel FSPCMs with higher LHS capacities, using paraffin as the LHS materials, which tightly intertwines with the 1-octadecylamine-modified montmorillonite (C18-MMT) under the capillary action as well as induced dipole force due to its n-alkyl chains compatibility. The obtained composite FSPCMs not only exhibit high melting enthalpies (137.56 J/g) but also demonstrate enhanced shape stability and thermal stability. In addition, the composites also render an impressive long-term thermal cycling capability and structure stability even after 100 thermal cycling durability tests, which are believed to have great potential for application in the thermal management of green energy-saving buildings.

Conductivity and Oxidation Behavior of Fe-16Cr Alloy as Solid Oxide Fuel Cell Interconnect Under Long-Stability and Thermal Cycles

Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750 °C and thermal cycles from room temperature to 750 °C. The results showed that the area specific resistance (ASR) of Fe-16Cr alloy increased over time and reached about 56.29 mΩ cm2 after 40,000 h of long-term stability operation at 750 °C by theoretical calculation. The ASR of Fe-16Cr remained about 11 mΩ cm2 after 52 thermal cycles from room temperature to 750 °C. The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr2O3 and FeCr2O4 spinel phase under long-term stability operation at 750 °C. While the Cr2O3 phase was mainly observed on the surface of Fe-16Cr alloy after 52 thermal cycles, the oxidation rates of Fe-16Cr alloy were 0.0142 μm h−1 and 0.06 μm cycle−1 under long-term stability operation and under thermal cycle, respectively. The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell (SOFC) stacks. The Cr element all diffused onto oxidation surface, indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs. Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and thermal cycle condition.

The effect of generating reactive stresses in the spring elements of titanium nickelide

The article is devoted to the study of the effect of generation of reactive stresses in tension springs. The studies of the kinetics of generation and relaxation of these stresses in the TiNi alloy are presented. Regularities of the change in reactive stresses during long-term thermal cycling in the range of complete and incomplete MPs are considered. It was established that the level of reactive stresses depends on several factors, such as the degree of pre-deformation, the type of stress state, the stiffness of the opposing system, the strength properties of the alloy.

Effect of thermal cycling on the degradation of adhesively bonded CFRP/aluminum alloy joints for automobiles

Thermal cycling is one of the representative service environments of automobiles. As epoxy adhesive and resin matrix of CFRP (Carbon Fiber Reinforced Plastics) composites are polymer materials, their properties may change during long-term thermal cycling and thus affect the joint strength of adhesively bonded composites joints. To investigate the degradation mechanism of adhesively bonded CFRP/aluminum alloy joints subjected to thermal cycling, firstly, the chemical transformations of adhesive and CFRP were analyzed by FTIR (Fourier Transform Infrared Spectroscopy), DSC (Differential Scanning Calorimetry) and TG/DTG (Thermal Gravimetric/Differential Thermal Gravimetric), and changes in mechanical properties of adhesive and CFRP were also tested by quasi-static tests. Then the variations of failure strength and failure modes of adhesively bonded CFRP/aluminum alloy shear joints and butt joints after different aging time were investigated. Results show that the Tg (glass transition temperature), thermal stability, failure strength and Young's modulus of adhesive improved after thermal cycling because of post-curing. The Tg and thermal stability of the CFRP decreased due to surface oxidation, resulting in the decline of surface adhesiveness of CFRP and the appearance of interface failure. Besides, the mechanical performance of the fiber/matrix interface also declined after thermal cycling, which was verified by SEM (Scanning Electron Microscope). The failure strength of shear and butt joints dropped by more than 40% after thermal cycling for 30 days. The degradation of shear joints was mainly caused by the combined effect of thermal stress and post-curing of adhesive as well as interface failure, while the butt joints were also affected by the fiber tear of CFRP.