Difference In Thermal Expansion Coefficients Research Articles

Corrosion of cast iron sections of gas-collecting bells of EcoSoderberg electrolyser

The article presents results of the research of high-temperature gas corrosion of sections of EcoSoderberg electrolyzers’ gas-collecting bells (GSB) made of high-strength VCh50 cast iron with spherical graphite. The gravimetric method was used to study the specific mass losses of the sections due to corrosion. The microstructure of cast iron, structure, chemical and phase composition of corrosion products were studied using optical, electron microscopy and electron microprobe analysis. It was established that the specific weight loss of the sections during operation reaches 0.36 – 0.46 g/(cm2·month). Corrosion of cast iron sections of EcoSoderberg electrolyzers’ GSB is characterized by high unevenness by area. There are cases of decommissioning sections due to local through “burnouts” with a weight loss of 19 – 24 kg. With relatively uniform corrosion, the maximum allowable weight loss of the sections is 25 – 30 kg. To make predictive estimates based on experimental data, dependence of the sections’ mass loss on the operating time was obtained. It was found that the corrosion products of the sections consist of iron oxides and alloying elements of cast iron. Most samples are characterized by increased content of C, S, F, K, Al, and Na. Corrosion products have a pronounced layered structure and contain a large number of defects in the form of pores and cracks. The layers differ in chemical, phase composition, and macrostructure. All the studied samples are characterized by cyclic alternation of relatively dense layers of iron oxides Fe2O3 and Fe3O4 and more porous layers between them. The layers are characterized by increased content of C and F. Sulfur is evenly distributed over the thickness of corrosion products. The studied samples of corrosion products have high defectiveness, friability, large number of pores, cracks, discontinuities, and low adhesion to the surface of cast iron. This is due to the presence of phases and compounds with different coefficients of thermal expansion. The mechanism of corrosion products layers formation was established and scientifically proved.

Influence of Bonding Temperature on Interfacial Microstructure and Properties of Hypereutectic Al-Si Joints with Cu Interlayer

Hypereutectic Al-27Si and Al-50Si alloys have been bonded and the influence of the bonding temperature on the microstructure and properties of the joints investigated. The results showed that Al-27Si/Al-50Si joints were bonded metallurgically with wide soldering seams containing α-Al, β-Si, and θ-Al2Cu eutectic phases. The amount of θ-Al2Cu eutectic phase gradually decreased and the bonding interface became nonplanar with increasing temperature. Many cracks formed in the Si phases on the Al-50Si side because of the shrinkage mismatch between the Al and Si phases and the different coefficients of thermal expansion of the Al-27Si and Al-50Si alloys. Some Si phases on the Al-27Si side transformed from granular to needle-like shape at higher temperatures. The shear strength of the joints first increased then decreased with increasing temperature, reaching a maximum of 82.3 MPa at 540°C.

Synergistic passivation of MAPbI3 perovskite solar cells by compositional engineering using acetamidinium bromide additives

For the global commercialization of highly efficient and stable perovskite solar cells (PSCs), it is necessary to effectively suppress the formation of various defects acting as nonradiative recombination sources in perovskite light-harvesting materials. Interfacial defects between the charge-selective layer and the perovskite are easily formed in the solution process used to fabricate perovskite films. In addition, owing to the difference in thermal expansion coefficients between the substrate and the perovskite film, internal residual tensile stress inevitably occurs, resulting in increased nonradiative recombination. Herein, a simple compositional engineering scheme for realizing efficient and stable PSCs, which incorporates acetamidinium bromide (AABr) as an additive into the MAPbI3 lattice, is proposed. As an additive, AABr has been found to provide synergistic multiple passivation for both internal and interfacial defects. AABr was found to effectively release the tensile strain of the MAPbI3 film by forming a structure stabilized by NH–I hydrogen bonds, as evidenced by calculations based on density functional theory (DFT). Furthermore, the incorporated AABr additives created a charge carrier recombination barrier to enhance charge collection capability by reducing interfacial defects. Accordingly, a power conversion efficiency (PCE) of 20.18% was achieved using a planar device employing AABr-incorporated MAPbI3. This was substantially higher than the 18.32% PCE of a pristine MAPbI3-based device. Notably, unencapsulated PSCs using AABr-incorporated MAPbI3 absorbers exhibited excellent long-term stability, maintaining >95% of initial PCE up to 1200 hours in ambient air.

Raman Spectroscopy of GaN Epitaxial Layers Synthesized on Si(111) by Molecular Beam Epitaxy with Nitridation

Investigation of GaN epitaxial layers on silicon substrates is driven by high potential for fabrication of high efficiency and relatively low-cost electronic devises. Growth process of GaN layers on Si by molecular-beam epitaxy is complicated by mutual diffusion of Si and Ga and differences in thermal expansion coefficients and lattice parameters causing large number of defects. To improve the quality of GaN layers high temperature nitridation of silicon substrates was applied leading to stress relaxation and decrease of diffusion.

Effects of microstructures on the mechanical properties of lithium disilicate glass-ceramics for the SiO2–Li2O–P2O5–K2O–ZnO system

The effects of microstructures on the mechanical properties of lithium disilicate (Li 2 Si 2 O 5 :LS2) glass-ceramics (GCs) were carefully investigated for the SiO 2 –Li 2 O–P 2 O 5 –K 2 O–ZnO system. The microstructures of GC samples, having three different compositions but the same total 6 mol% of additives (P 2 O 5 , ZnO, K 2 O), could be controlled by varying heat treatment conditions of glass samples. In addition to major LS2 crystalline phase, two other minor crystalline phases of Li 3 PO 4 (LP) and cristobalite were detectable. Average crystal sizes of GC samples were in the region of 0.3–10 μm, and the volume fractions of crystalline phases were in the region of 0.70–0.73. The biaxial flexural strength was improved with decreasing the average crystal size from ~10 to ~1 μm by following the Hall-Petch relation, and the maximum flexural strength of 445.8 ± 7.2 MPa was obtainable from the GC samples with the additive compositions of 1.5 mol% P 2 O 5 , 2.75 mol% K 2 O and 2 mol% of ZnO which were nucleated at 540 °C for 1 h and grown at 850 °C for 4 h. When 8.4 vol% cristobalite was incorporated into the sample, however, there was a severe scattering in flexural strength data due to the formation of microcracks induced by the beta-to-alpha transition of cristobalite and also due to a micro tensile stress in the residual glassy phase induced by a large difference in thermal expansion coefficients between crystal and residual glassy phases. Meanwhile, the Vickers hardness was increased with decreasing the average crystal size down to ~0.3 μm, indicating that the factors for the deterioration of flexural strength have a negligible effect on hardness.

Numerical analysis of the reliability of photovoltaic modules based on the fatigue life of the copper interconnects

A typical photovoltaic (PV) module is composed of different layers bonded together, each with a different material and thus, a different coefficient of thermal expansion (CTE). While under operation, it is subjected to thermal loads due to continuous temperature variations. The CTE mismatch induces thermo-mechanical stresses, whose cyclic nature causes fatigue failure. Due to their relative small size, the copper interconnects are one of the most vulnerable constituents.In this work, the finite element (FE) analysis has been used to calculate these thermal stress/strain variations. To make the simulations more reliable, well-known material models have been adopted from the literature and used for each constituent of the PV module. Furthermore, to reduce computational time and complexity, a simplified modeling approach has been proposed in this work. In this approach, a 2-D FE global model was first used to identify the region that undergoes maximum strain. Then a 3-D FE local model was used for that particular region only. This approach helps calculate the maximum stress/strain variations. Thus, using the proposed modeling approach coupled with a fatigue criterion, one can calculate the fatigue life of the PV module, while significantly reducing the computational time. The initial conditions, in terms of residual stresses, due to the lamination process for the fabrications of the PV module are also accounted for in our approach. We applied our approach to silicon-based PV module under desert weather conditions of Doha (Qatar) and the results show a reduced life compared to the one provided by the manufacturer.

In-situ synchrotron X-ray micro-diffraction investigation of ultra-low-strain deformation microstructure in laminated Ti-Al composites

An ultra-low-strain deformation microstructure was revealed for the first time non-destructively in the bulk interior of an annealed laminated Ti-Al composite—in the “fully recrystallized” Al layer—by a synchrotron-based micro-diffraction technique, namely differential aperture X-ray microscopy (DAXM), through real space mapping with a very high angular resolution (0.01°). This ultra-low-strain deformation microstructure was found to result from the thermal stress, induced during cooling after annealing, due to the different coefficients of thermal expansion for the Ti and Al layers. The annealed sample was further tensile deformed to a strain of 1.66% and followed by in situ DAXM and analyzed by various misorientation mapping methods. The results pointed to the important effects of the initial microstructure and the interface constraint, as well as the grain size and crystal orientation, on the plastic deformation. A gradient in dislocation density from the layer interface to the center was found in the Al layer of the annealed sample, and this gradient increased slightly during tensile deformation. The variation of the dislocation density was further discussed based on the activation and interaction of dislocations in grains of different sizes and orientations during plastic deformation. The findings of this study provided valuable insights in understanding the constraint effect of the laminated metal composite and the design of novel composite materials.

Carbon fiber reinforced polymer metallization via a conductive silver nanowires polyurethane coating for electromagnetic shielding

AbstractFor electromagnetic shielding in space environment, the metallization of carbon fiber reinforced polymer (CFRP) is required. A specific attention is paid due to the thermal expansion coefficient difference between substrate and metal coating. A surface metallization of a CFRP has been elaborated by electrodeposition. This study presents an original process based on an electrically conductive polymer coating elaborated from a polyurethane matrix filled with a low content of silver nanowires (<10%vol). A continuous and adherent deposit is obtained by an optimization of the electroplating parameters. A minimal volume fraction was determined at 3%vol associated with an applied current density estimated near 0.1 A/dm2. The growth speed is 7 μm/h at 0.1 A/dm2. The adhesion was checked in severe environmental conditions (−196 to 165°C). The effectiveness shielding obtained with this solution reaches an attenuation value higher than 90 dB between 1 and 26 GHz necessary for space communication applications.

Epitaxial GaN layers synthesized on Si (111)

Realization of epitaxial synthesis of high quality gallium nitride layers on silicon substrates is driven by the high potential of GaN-on-silicon technology for fabrication of high efficiency and relatively low-cost electronic devises. Growth process of GaN layers on Si substrates by molecular-beam epitaxy is complicated by differences in thermal expansion coefficients and lattice parameters causing large number of defects and dislocations. Another issue is mutual diffusion of Si and Ga. To improve the quality of GaN layers high temperature nitridation of silicon substrates was applied. We used Raman spectroscopy and Hall measurements to study the effect of nitridation. The shift of E2 H phonon mode allowed to calculate biaxial stress and this indicated stress relaxation in GaN epitaxial layers. P-type conductivity was observed in GaN/Si(111) structures and nitridation was proven to reduce carrier concentration. Thus, high temperature nitridation of Si substrate led to stress relaxation and decrease of Ga diffusion into substrate.

Impact of Conformal Coating Material on the Long-Term Reliability of Ball Grid Array Solder Joints

A conformal coating is a protective chemical material that can be applied as a thin layer on printed circuit board assemblies (PCBAs). The purpose of conformal coating is to prevent the interaction between external environmental factors and the electrical assembly. However, since conformal coating materials have different mechanical properties than electronic components, their use may induce additional mechanical stresses on the board. This study focuses on the effect of having a different coefficient of thermal expansion (CTE) for the conformal coating material from the solder joints of ball grid array (BGA) packages on printed circuit boards (PCBs). Typical lead-free solders have a CTE of less than 25 ppm/°C, while coating materials have a much higher CTE. For example, polyurethane has a CTE around 193 ppm/°C. This CTE mismatch generates stresses in different directions on the solder joints, especially when the assembly is subjected to temperature cycling during its service. In this effort, four samples of PCB assemblies that have BGAs were used in temperature cycling tests. The sample size is nine modules, with each module having at least 272 exposed BGA joints. Three of the samples were coated by a layer of polyurethane and one baseline sample was not coated. Coating thickness was selected to be the experimental design factor. Thus, these three samples, which had different thicknesses (30, 80, and $130~\mu \text{m}$ ), were evaluated and compared against each other and against the noncoated sample. By comparing the four samples, it was found that a thick coating material significantly reduced the lifetime for BGA solder balls by initiating early solder cracks, which propagated and caused complete separation in the solder joint.

Study on a novel energy-saving cryogenic pre-treatment equipment for walnut kernel peeling

Walnut kernel peeling is a value-adding process which reduces the tannin content and improves the taste of the walnut product. However, current methods for walnut kernel peeling are limited by either high energy consumption or low peeling efficiency. In this paper, we introduce cryogenic pre-treatment as an effective method for walnut kernel peeling. We first show that the difference of thermal expansion coefficient between the seed and seed coat of walnut kernels leads to the separation of the two when being deeply cooled directly using liquid nitrogen (LN2, temperature −196 °C). An energy-saving cryogenic walnut kernel peeling process is then designed to reduce LN2 consumption, based on our Computational Fluid Dynamics (CFD) simulations. A large-scale experiment system is further constructed and tested. The results show that the optimized method, which saves the LN2 consumption up to 92.81%, is still able to achieve comparable peeling efficiency to that of direct LN2 immersion.

Epitaxial Ge-on-Nothing Virtual Substrates for 3D Device Stacking Technologies

Future monolithic heterogeneous integration of Ge and IIIV materials in electronic, optoelectronic and photonic devices requires advanced layer transfer and 3D device stacking technologies, which starts with the fabrication of suitable (virtual) substrates. A layer transfer process based on the reorganization of macro-porous Si at high temperature was developed by imec [1]. The developed fabrication scheme to fabricate macropores is based on standard UV lithography and dry etching techniques rather than electrochemical etching. This enables an easy transfer to full Si wafers (up to 300 mm). During a high-temperature step, the top part of the macro-porous Si reflows. By using proper anneal conditions, the layer detaches from the mother substrate, being anchored by a few attachment points only, forming a ‘Si on nothing’ (SoN) stack (Fig. 1a). The suspended Si layer can then easily be transferred to another substrate.In this contribution, we assess the suitability of macro-porous Si and SoN as starting material for Ge virtual substrates. The goal is to provide a fabrication scheme that allows an easy detachment of the virtual substrate after wafer to wafer bonding. Macro-porous Si was only fabricated in the inner 10x10 cm2 area of 200 mm wafers using imec’s qualified fabrication scheme. Ge layers were simultaneously grown on the inner macro-porous Si (or SoN) and the outer bulk Si. This allows to compare the material properties without the risk of wafer to wafer variations due to non-reproducibility issues. Our approach for making macro-porous Si and SoN provides mono-crystalline, nearly defect-free, and extremely smooth Si starting surfaces. A standard low temperature epitaxial Ge growth process in an ASM-Epsilon® 2000 system was used to deposit the Ge layers [2].As an example, Fig. 1b shows a 1.25 mm thick mono-crystalline epitaxial Ge layer grown on a macro-porous Si layer. The Ge growth proceeds in a 2-dimensional mono-crystalline growth mode. The surface morphology of the grown Ge is not affected by the starting surface (Fig. 1c,d). The Full Width at Half Maximum (FWHM) as extracted from w-2q High Resolution X-ray Diffraction scans acquired around the Ge (004) Bragg peak is strongly reduced after a post Ge deposition anneal, which was also reported for Ge on bulk Si [2]. Threading dislocations annihilate during the post-epi anneal. FWHM values as low as 160 arc sec have been measured for 1.25 mm thick Ge layers independent of the underlying layer. This reflects the high material quality of the grown Ge. The difference in thermal expansion coefficient between Si and Ge results in some tensile stress in the annealed Ge layer, which explains the well-known shift in XRD peak position. The improvement in material quality by using a post-epi anneal is also reflected in the carrier lifetime as extracted from room-temperature photoluminescence measurements. The carrier lifetime increases from <0.2 ns (as-grown layers) to 3.3 ns and 3.6 ns for Ge on porous Si and bulk Si, respectively. The TDD, as extracted from ECCI measurements, was identical for both parts of the Si wafer (2-4e7 cm-2) and close to the values expected from literature. The material properties listed above are not affected by the thickness of the closed Si layer in-between the Ge and the porous Si.In conclusion, we developed a fabrication scheme for strain-relaxed Ge grown on SoN (or on macroporous Si) starting from conventional Si substrates. The material properties of the virtual Ge substrate are identical to those obtained for Ge grown on bulk Si. The virtual substrate serves as starting material for layer transfer and 3D device stacking technologies. The fabrication scheme can be extended to (defect free) bulk Ge for which the fabrication of Ge on nothing followed by layer transfer has been demonstrated [3].

Determination and Validation of Residual Stresses in CFRP/Metal Hybrid Components Using the Incremental Hole Drilling Method

Lightweight materials contribute to an efficient decrease in fuel consumption in the automotive and aircraft industries. Hybrid components made of metal and carbon fiber-reinforced plastics (CFRP) have a high potential in lightweight applications due to their high strength-to-weight ratio. For cost-effective processing of hybrid materials, advanced manufacturing processes such as the prepreg-press-technology have been developed, in which the bonding between a metallic component and a fiber compound is exclusively realized in the forming process. However, upon processing of these hybrid components at elevated temperature, the difference in thermal expansion coefficients of the two materials leads to the formation of tensile residual stresses upon cooling. It is well known that these tensile residual stresses can be detrimentally effective with respect to the durability of a hybrid component. The objective of this work is to accurately measure and analyze residual stresses in hybrid components made of unidirectional CFRP and steel through the incremental hole drilling method. Within this study, the evaluation formalism for orthotropic materials is employed for measuring non-uniform residual stresses in hybrid materials. In order to improve the measurement accuracy, a customized strain gauge with eight grids is employed and a drilling increment size of only 20 µm is utilized. The influence of the angle between the strain gauge rosette and the fiber direction on the evaluation of the residual stresses is investigated. In order to evaluate the reliability of the results determined, a bending test applying a well-defined load is carried out. By direct comparison of the experimentally determined stresses and stress values calculated by the finite element method, the applicability of the hole drilling method for robust determination of residual stresses in CFRP/metal hybrid components is finally validated.

Formation of ordered L10-FePt phase in FePt–Ag thin films

In this work, the influence of an Ag layer, which is located at different positions of the layer stack (top, intermediate, bottom), on the structural and magnetic properties of ordered L10 phase in Fe50Pt50 films was investigated. It was found that the position of an additional Ag layer affects the stress state of the as-deposited FePt films. Mechanical stress is induced during deposition and post-annealing process due to the difference in thermal expansion coefficients and lattice mismatch of FePt, Ag, and substrate. The initial stress state affects the ordering process during subsequent heat treatment. The higher level of initial compressive stress (− 7.8 GPa) in FePt/Ag/FePt films results in L10 phase formation at a temperature of 700 °C which is about 100 °C lower than in films with Ag bottom (− 3.6 GPa) and top (+ 0.86 GPa) layers. A more pronounced (001) oriented growth of the L10 phase was observed in stacks with Ag top layer as compared to Ag bottom and intermediate layers. The highest values of coercivity were obtained for films with Ag intermediate and bottom layers, which is due to the distribution of Ag along FePt grain boundaries that result in strong exchange decoupling of FePt grains. Furthermore, the formation of the ordered L10 phase at comparatively low temperatures of about 370 °C was observed in a free-standing FePt/Ag (30 nm)/FePt film.

Residually Stressed Bimaterial Beam Specimen for Measuring Environmentally Assisted Crack Growth

Subcritical crack growth can occur in a brittle material when the stress intensity factor is smaller than the fracture toughness if an oxidizing agent (such as water) is present at the crack tip. We present a novel bi-material beam specimen which can measure environmentally assisted crack growth rates. The specimen is “self-loaded” by residual stress and requires no external loading. Two materials with different coefficient of thermal expansion are diffusion bonded at high temperature. After cooling to room temperature a subcritical crack is driven by thermal residual stresses. A finite element model is used to design the specimen geometry in terms of material properties in order to achieve the desired crack tip driving force. The specimen is designed so that the crack driving force decreases as the crack extends, thus enabling the measurement of the crack velocity versus driving force relationship with a single test. The method is demonstrated by measuring slow crack growth data in soda lime silicate glass and validated by comparison to previously published data. The self-loaded nature of the specimen makes it ideal for measuring the very low crack velocities needed to predict brittle failure at long lifetimes.

Study on the growth and wear behavior of the TiAlN-based composite coating deposited on TiCN-based cermets with different binder phase

The TiAlN-based composite coating was coated on TiCN-based cermets with different binder phase by arc ion plating. The effects of binder phase within cermets substrates on the microstructure, mechanical properties and wear behavior of the composite coating were investigated. The results show that the growth of the composite coating is affected by binder phase in the cermets substrates. With a higher content of Co binder in the cermets, the composite coating grows faster. Ni as a binder phase in the cermets is more favorable for the growth rate of the surface coating. The grain size of the coating on 10%Co-TiCN-based cermets is the finest and the hardness is the highest. The variation of binder phase in the cermets substrates leads to different adhesion strength of the composite coating. The adhesion strength of the composite coating on the 10%Co-TiCN-based cermets is the highest, which is because of the smallest differences in hardness and thermal expansion coefficient for this coating/substrate couple. The wear behavior of composite coating on 10%Co-TiCN-based substrate is dominated by abrasive wear while that on the other cermets with Ni binder or higher content of Co binder is a mixture form of diffusion wear, oxidation wear and abrasive wear.

A novel approach to mitigate stress induced defects at metal-dielectric interface in Redistribution layers for 3D IC stacking

Abstract The reliability of a redistribution layers in 3D IC is dependent on how well the different shape and size of metal connection with varying density are connected at the different metallization levels. The widely different coefficient of thermal expansion of metal (Cu ~16.5 × 10−6 m/mK) and dielectric (SiO2 ~ 3 × 10−6 m/mK) often leads to defects, such as cracking at the metal-dielectric interface. In this work, we present a manufacturing level friendly process modification to the conventional approach to present an almost crack free metal-dielectric interface for subsequent processing in the RDL fabrication. After the copper electroplating and chemical mechanical planarization (CMP), we use a cap layer to protect the top layer and anneal the metal. Finally, we repeat the CMP to remove the cap layer before sending the wafers for subsequent processing.

Impact of manufacture-induced blade shape distortion on turbine loads and energy yield

A blade shape distortion develops during the manufacturing process. The distortion is defined as the difference between the target blade shape as per the design and the shape under operational temperatures. This initial distortion varies under operational temperatures due to the different thermal coefficients of expansion of the various blade materials. The resulting manufacture-induced distortion and operational temperatures affect the twist angle, the cross-sectional shape, and the sweep of the blade. Young’s modulus of the blade’s raw materials, i.e., the matrix of the fiber-reinforced polymers and the adhesive material, changes during the manufacturing process, complicating the determination of the distortion. This work calculates the shape distortion for a reference temperature on the basis of a thermal stress analysis using a full 3D finite element blade model. It performs an aero-elastic load simulation for two models: one with the target blade shape and one with the distorted shape. The simulation reveals that the turbine with the distorted shape has an energy yield which is 0.5% lower and a lifetime extension of additional 4. 4 years.

Study on microstructure and oxidation behavior of Fe–xMn–14Al–8Ni–C alloy prepared by vacuum arc melting

In this study, Fe–xMn–14Al–8Ni–C alloy (x = 10, 15, 20, 25 wt.%) was prepared by vacuum arc melting method. The microstructure of this series of alloys and the oxidation behavior at 600 °C were studied. The conclusions are as follows: Fe–xMn–14Al–8Ni–C alloy mainly contains austenite phase, NiAl intermetallic compound phase and k-carbide phase. As the content of Mn increases, the amount of austenite increases while the amount of NiAl compound decreases. At the same time, the content of k-carbide phase precipitated at the interface between austenite and NiAl compound and inside austenite increases. The oxidation resistance results show that as the Mn content increases, the oxidation resistance of the alloy is improved. After oxidation, due to the difference in thermal stress and thermal expansion coefficient, the oxide film is mainly divided into two layers (when the Mn content is 10% and 15%, respectively), the outer oxides are Fe2O3 and a small amount of Mn2O3, the inner oxides are mainly the mixture of Al2O3, Mn2O3 and NiO. When the Mn content increases to 20%, the oxide film is a three-layer, and a uniform dense oxide film mainly composed of Al2O3 appears at the junction with the substrate, which better prevents the further diffusion of oxygen in the air to the inside and protects the substrate. The surface oxide film is dense and stable, so it can prevent further oxidation. Therefore, the alloy with 25% Mn content exhibits the most excellent oxidation resistance.

Simplified stiffness analysis for degraded single lap joints in the space sector – Comparative analytical and finite element analysis

Considering the aerospace sector, the use of adhesively bonded joints is constantly increasing over the last decades. Due to its lightweight and capability of joining various materials with different coefficient of thermal expansion, this joining technique offers many benefits over conventional methods like rivets, screws and welding. On the other hand, structural adhesives consists of polymer chains that can be severely affected by the environment. An example of such an environmental effect is the interaction of the polymer chains of the adhesive with ionizing radiation in space. Nevertheless in the literature, the influence of ionizing radiation on the mechanical properties of epoxides is covered but not well understood. The present work describes a method of determining the stiffness of an adhesively bonded single lap joint (SLJ) using closed form solution equations. This analytical approach is compared with a numerical model. The mechanical properties of the adhesive in both models is degraded due to irradiation, based on experiments conducted by the European Organization for Nuclear Research (CERN). The results show that the degradation of the mechanical properties of the adhesive layer has a significant influence on the joint stiffness. This effect increases with growing adhesive layer thickness. Comparing the results with a finite element model, it is shown that the developed calculation scheme overestimates the stiffness of the SLJ. This is caused by the neglection of bending stresses within the adherends.