Compact X-ray sources for spatially fractionated and ultra-high-dose-rate radiotherapy are limited by the extreme thermal and mechanical loads imposed on conventional rotary anodes. Here we investigate a hybrid rotary-anode architecture that separates X-ray generation from structural load bearing by bonding a tungsten–rhenium/titanium–zirconium–molybdenum (TZM) alloy target module to a lightweight titanium carrier. The diffusion-bonded interface was characterized by metallography and temperature-dependent tensile and shear testing up to 1000 ∘C. These experimentally determined strength limits were combined with three-dimensional thermomechanical finite-element simulations of a 600 mm high-speed anode exposed to transient absorbed heat loads up to 1 MW. The simulations show that the highest temperatures remain confined to the focal track and adjacent refractory target region, whereas the titanium–TZM interface remains below the experimentally identified temperature range of pronounced strength reduction. The segmented, lightweight architecture reduces centrifugal loading while providing a large transient thermal capacity. The revised analysis further discusses heat rejection, duty-cycle limitations, bearing concepts and the separated validation strategy required before full source integration.

In this work, the thermal stability of a BaO-CaO-SiO2-B2O3 glass sealant, named "H", was investigated by differential scanning calorimetry (DSC). The crystallization behavior of glass H as the sealant matrix was investigated by a combination of experimental X-ray diffraction (XRD) analysis and thermodynamic simulation with the FactSage package. A good agreement was found between the Rietveld refinement of XRD experiments and the FactSage simulation. Particular attention was also given to the influence of the Sr2SiO4 filler added to the glass matrix "H" on the thermal expansion and microstructures of glass-Sr2SiO4 composites by means of dilatometry and scanning electron microscopy (SEM). The reinforced 20 wt% Sr2SiO4 composite (HS2S20) showed excellent properties and, thus, its joining performance was investigated using SrTi0.75Fe0.25O3-delta (STF25) and Aluchrom as promising oxygen transport membrane (OTM) and counterpart, respectively. The joining behaviors were investigated by comparing different joining temperatures. 920 degrees C is the best joining temperature for HS2S20 sealant.

Three new BaO–SrO–SiO2–B2O3(BS) glasses with different SrO contents (6–25 mol%) are developed for oxygen transport membrane (OTM) joining application. The content of strontium is investigated first in terms of its effect on the glass‐forming tendency, thermal expansion coefficient, crystallization, shrinkage behavior, and viscous flow properties. Differential scanning calorimetry (DSC) is carried out. Dilatometric tests are performed to obtain coefficients of thermal expansion (CTEs) of BS glasses. The crystallization behavior of the BS glasses is investigated by X‐ray powder diffraction (XRD). Sinking dilatometric measurements simulate the joining procedure and observe the shrinkage behavior of the BS glasses. The viscous flow behavior of the BS glasses is examined via hot stage microscopy. The glass with 15 mol% SrO (BS15) glass shows the best glass‐forming tendency, most matching CTE (11.9 × 10−6 K−1), densest microstructure, highest shrinkage rate (24%), and good viscous behavior at high joining temperatures compared with other BS glasses. BS15 glass is chosen for helium leak test and assembly test joining with Aluchrom and SrTi0.75Fe0.25O3−δmembrane (STF25). The sandwiched sample with two Aluchrom plates sealed by BS15 glass at 1075 °C for 5 min achieves good gas‐tightness with low helium leakage rate <10−9 mbar·l s−1.

In this study, seven different filler materials in different proportions were added to a Ba-Ca-Si glass matrix "H" to investigate new sealant with higher thermal expansion coefficient (CTE) value and good sealing performance for application in oxygen transport membrane (OTM). SrTi0.75Fe0.25O3-delta (STF25) was used as an OTM, and the sealing partners were ferritic steel Aluchrom and pre-oxidized Aluchrom. Compatibility tests were carried out to investigate the feasibility of the composites. Higher CTE values were found in dilatometer tests on composite samples by adding 40 wt% Ag (HAg40) and 30 wt% Ni-Cr (HNC30). Gas-tightness measurements of sandwiched samples produced appropriate helium leakage rates in the range of 10(-6) mbar.l.s(-1). Sealing behaviour of sealants HAg40 and HNC30 were investigated by joining STF25 and as-delivered/pre-oxidized Aluchrom together. Scanning electron microscopy (SEM) on cross-sections of the joints revealed a homogeneous microstructure and good adherence of the glass sealants to support metals and STF25.

To improve the mechanical strength of sealants for solid oxide fuel cell (SOFC) stacks, several fillers were proposed in this work as reinforcement for a glass-ceramic sealant based on the system BaO-CaO-SiO2. The chosen reinforcement additives were metallic particles including nickel, a nickel-chromium alloy and silver, as well as ceramics such as gadolinium-doped ceria particles and yttrium-stabilized zirconia particles or fibers. The glass-ceramic sealant, with and without reinforcements, was used to join two parts made of stainless steel (Crofer22APU). A torsion test was used to measure the shear strength of the joined samples. The shear strength measurement by torsion gave reliable and reproducible results for all the joined samples. The lowest shear strength was found for the glass-ceramic sealant without any reinforcement. The composite prepared of a combination of glass matrix and 20 wt.-% Ni powder seems to be the best candidate sealant, able to fulfill all the requirements of a SOFC sealant. The samples made with this composite sealant presented the highest shear strength values as prepared and also after aging the sample in air atmosphere for 500 hours at 800 degrees C.

Fracture mechanics experiments are carried out to characterize the fracture energy of the joints before and during thermal cycling. Mechanical testing is accompanied by microstructural examination in optical and SEM resolution (with electron backscatter diffraction (EBSD) analysis). Decisive deformation and damage mechanisms governing the thermal cycling resistance of conventional RAB-brazes (AgCuO system) and an advanced “tailored microstructure” RAB-braze (Ag0.5Al) are uncovered. Discussion focuses on stress build up and the changes in the braze matrix crystal structures during thermal cycling.

A copper-doped ferrite with the chemical composition La0.7Sr0.3Cu0.2Fe0.8O3−δ (LaSrCuFe) was prepared using the classical ceramics method starting from the oxides. The linear thermal expansion coefficient in air was measured in the temperature range between 550 and 1,250 K to be between 10 × 10−6 and 15 × 10−6 K−1. The electrical conductivity in air was found to be higher than 100 S cm−1 for temperatures lower than 1,100 K. A change of oxygen stoichiometry was found above 650 K in an atmosphere of 20 vol% oxygen with argon. This change can be correlated with the electrical conductivity.

Glass-ceramics of the BaO–CaO–Al2O3–SiO2 system are frequently used in planar solid oxide fuel cells (SOFC) stacks to seal the fuel and air compartments and to join non-conductively the individual components. Due to the thermal mismatch of the ceramic and metallic materials in the stack, the seals experience predominantly shear stresses. A symmetric shear test has been developed to characterize the critical shear stress of the glass-ceramic at SOFC operation temperature. Specimens representative for the seal situation in an SOFC stack were prepared, using the glass-ceramic to join a center piece of a NiO-YSZ anode covered by yttria-stabilized zirconia (YSZ) electrolyte layers on both surfaces between two Crofer22APU interconnect steel blocks. Shear stress and based on a rheological model, shear modulus and viscosity of the sealant were determined. The investigations showed that the sealant exhibits viscous shear deformation at 800 °C, a temperature typical for SOFC operation. The influence of increasing crystallization on the shear deformation is demonstrated.

When assembling planar solid oxide fuel cell (SOFC) stacks, an electrically insulating and gas-tight sealing material is required. Glass-ceramic sealants have been shown to be an appropriate material for this application in the past. In the present study, the investigations are focused on a composite material consisting of zirconia in a glass matrix based on the system of BaO-CaO-SiO2 (BCS). The joining behavior with ferritic stainless steel is macroscopically observed by so-called ‘sandwiched’ samples made out of two steel plates (size 50 × 50 mm2) with the glass sealant in-between. Dilatometric measurements are carried out, and the coefficient of thermal expansion is taken for varying amounts of zirconia in the composite material. The crystallization behavior of the sealant is investigated by differential thermal analysis. The microstructure of joined samples, submitted to different scenarios of thermal treatment, is characterized by optical and scanning electron microscopy. The joining properties strongly depend on the amount of filler material. Additions of 20 wt% zirconia in the glass matrix prove to be the optimal composition. The glass matrix tends to crystallize very slowly, giving the prospect of an elastic seal during the initial operation of a stack.