@article{LaquaiGouraudMuelleretal.2019,
  author    = {Laquai, Rene and Gouraud, Fanny and M{\"u}ller, Bernd Randolf and Huger, Marc and Chotard, Thierry and Antou, Guy and Bruno, Giovanni},
  title     = {Evolution of Thermal Microcracking in Refractory ZrO2-SiO2 after Application of External Loads at High Temperatures},
  series = {Materials},
  volume    = {12},
  journal   = {Materials},
  number    = {7},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1996-1944},
  doi       = {10.3390/ma12071017},
  pages     = {15},
  year      = {2019},
  abstract  = {Zirconia-based cast refractories are widely used for glass furnace applications. Since they have to withstand harsh chemical as well as thermo-mechanical environments, internal stresses and microcracking are often present in such materials under operating conditions (sometimes in excess of 1700 °C). We studied the evolution of thermal (CTE) and mechanical (Young's modulus) properties as a function of temperature in a fused-cast refractory containing 94 wt.\% of monoclinic ZrO2 and 6 wt.\% of a silicate glassy phase. With the aid of X-ray refraction techniques (yielding the internal specific surface in materials), we also monitored the evolution of microcracking as a function of thermal cycles (crossing the martensitic phase transformation around 1000 °C) under externally applied stress. We found that external compressive stress leads to a strong decrease of the internal surface per unit volume, but a tensile load has a similar (though not so strong) effect. In agreement with existing literature on β-eucryptite microcracked ceramics, we could explain these phenomena by microcrack closure in the load direction in the compression case, and by microcrack propagation (rather than microcrack nucleation) under tensile conditions.},
  language  = {en}
}
@article{ErdmannKupschMuelleretal.2019,
  author    = {Erdmann, Maren and Kupsch, Andreas and M{\"u}ller, Bernd Randolf and Hentschel, Manfred P. and Niebergall, Ute and B{\"o}hning, Martin and Bruno, Giovanni},
  title     = {Diesel-induced transparency of plastically deformed high-density polyethylene},
  series = {Journal of materials science},
  volume    = {54},
  journal   = {Journal of materials science},
  number    = {17},
  publisher = {Springer},
  address   = {New York},
  issn      = {0022-2461},
  doi       = {10.1007/s10853-019-03700-8},
  pages     = {11739 -- 11755},
  year      = {2019},
  abstract  = {High-density polyethylene becomes optically transparent during tensile drawing when previously saturated with diesel fuel. This unusual phenomenon is investigated as it might allow conclusions with respect to the material behavior. Microscopy, differential scanning calorimetry, density measurements are applied together with two scanning X-ray scattering techniques: wide angle X-ray scattering (WAXS) and X-ray refraction, able to extract the spatially resolved crystal orientation and internal surface, respectively. The sorbed diesel softens the material and significantly alters the yielding characteristics. Although the crystallinity among stretched regions is similar, a virgin reference sample exhibits strain whitening during stretching, while the diesel-saturated sample becomes transparent. The WAXS results reveal a pronounced fiber texture in the tensile direction in the stretched region and an isotropic orientation in the unstretched region. This texture implies the formation of fibrils in the stretched region, while spherulites remain intact in the unstretched parts of the specimens. X-ray refraction reveals a preferred orientation of internal surfaces along the tensile direction in the stretched region of virgin samples, while the sample stretched in the diesel-saturated state shows no internal surfaces at all. Besides from stretching saturated samples, optical transparency is also obtained from sorbing samples in diesel after stretching.},
  language  = {en}
}
@article{ChenMuellerLebedevetal.2019,
  author    = {Chen, Cong and M{\"u}ller, Bernd Randolf and Lebedev, Oleg I. and Giovannelli, Fabien and Bruno, Giovanni and Delorme, Fabian},
  title     = {Effects of impurities on the stability of the low thermal conductivity in Fe2TiO5 ceramics},
  series = {Materials characterization},
  volume    = {149},
  journal   = {Materials characterization},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {1044-5803},
  doi       = {10.1016/j.matchar.2019.01.021},
  pages     = {111 -- 117},
  year      = {2019},
  abstract  = {The stability of the low thermal conductivity in Fe2TiO5 pseudobrookite ceramics has been studied. An increase in thermal diffusivity is observed after only three cycles of measurement. X-ray refraction shows an increase in the mean value of specific surface after the thermal diffusivity measurements. By using scanning electron microscopy and high-angle annular dark-field scanning transmission electron microscope equipped with energy dispersive Xray spectroscopy, we observe a segregation of Ca- and F-rich nanocrystals at grain boundaries after three cycles of thermal diffusivity measurement. Therefore, impurities seem to be more efficient to scatter phonons as point defects in the pseudobrookite lattice rather than as nanocrystals at pseudobrookite grain boundaries. This emphasizes the importance of precursor purity and the influence of redistribution of impurities on thermoelectric properties: stability of micro-/nano-structures is a key point, and repeated thermoelectric measurements may allow detecting such metastable micro-/nano-structures and producing stable and reliable data.},
  language  = {en}
}