High Temperature Thermo-Mechanical Properties of Praseodymium Doped Ceria Thin Films Measured Two Ways

The temperature dependence of a Mixed Ionic Electronic Conducting (MIEC) material’s thermo-chemical expansion coefficient, biaxial modulus, and/or Young’s modulus are crucial in determining the internal stress, strain, and/or mechanical stability...

The dual function of impurity on protein crystallization

It is widely believed that high purity protein is critical to crystallization, and crystallization is facilitated when protein is pure enough. Impurity can induce lattice strain, internal stress, and rotation...

Annealing of Polymer Material PLA for Improved Properties

The aim of the work was to improve the properties of 3D printed products using annealing. The biggest problem that 3D printed products face is internal stress and poor tribological properties, but it can be eliminated by annealing. The material chosen for this work is PLA, which is the most used material for 3D printing. Stress reduction was performed by drying furnace, which is capable of gradually increasing the temperature and therefore does not cause unwanted thermal shock. The drying furnace is fully sufficient for annealing plastics as it is able to maintain temperatures up to 250°C. After annealing, the samples were placed into a UV chamber. With the help of heat and moisture, the deformation of annealed and non-annealed testing bodies was monitored.

Mass-ratio and Magnetic Flux Dependence of Modulated Accretion from Circumbinary Disks

Accreting supermassive binary black holes (SMBBHs) are potential multimessenger sources because they emit both gravitational-wave and electromagnetic (EM) radiation. Past work has shown that their EM output may be periodically modulated by an asymmetric density distribution in the circumbinary disk, often called an “overdensity” or “lump;” this modulation could possibly be used to identify a source as a binary. We explore the sensitivity of the overdensity to SMBBH mass ratio and magnetic flux through the accretion disk. We find that the relative amplitude of the overdensity and its associated EM periodic signal both degrade with diminishing mass ratio, vanishing altogether somewhere between 1:2 and 1:5. Greater magnetization also weakens the lump and any modulation of the light output. We develop a model to describe how lump formation results from internal stress degrading faster in the lump region than it can be rejuvenated through accretion inflow, and predicts a threshold value in specific internal stress below which lump formation should occur and which all our lump-forming simulations satisfy. Thus, detection of such a modulation would provide a constraint on both mass ratio and magnetic flux piercing the accretion flow.

Residual Stress and Tribological Performance of ZrN Coatings Produced by Reactive Bipolar Pulsed Magnetron Sputtering

In the past few decades, ZrN thin films have been identified as wear resistant coatings for tribological applications. The mechanical and tribological properties of ZrN thin layers depend on internal stress induced by the adopted deposition techniques and deposition parameters such as pressure, temperature, and growth rate. In sputtering deposition processes, the selected target voltage waveform and the plasma characteristics also play a crucial influence on physical properties of produced coatings. In present work, ZrN thin films, obtained setting different values of duty cycle in a reactive bipolar pulsed dual magnetron sputtering plant, were investigated to evaluate their residual stress through the substrate curvature method. A considerable progressive increase of residual stress values was measured at decreasing duty cycle, attesting the significant role of voltage waveform in stress development. An evident correlation was also highlighted between the values of the duty cycle and those of wear factor. The performed analysis attested an advantageous effect of internal stress, having the samples with high compressive stress, higher wear resistance. A downward trend for wear rate with the increase of internal residual stress was observed. The choice of suitable values of duty cycle allowed to produce ceramic coatings with improved tribological performance.