Influence Of Thermo-mechanical Stress Research Articles

The Influence of Thermal and Mechanical Stress on the Electrical Conductivity of ITO-Coated Polycarbonate Films.

The influence of thermomechanical stress on the conductivity of indium tin oxide (ITO)-coated polycarbonate (PC) films was investigated. PC is the industry's standard material for window panes. ITO coatings on polyethylene terephthalate (PET) films are the main commercially available option; as such, most investigations refer to this combination. The investigations in this study aim to investigate the critical crack initiation strain at different temperatures and crack initiation temperatures for two different coating thicknesses and for a commercially available PET/ITO film for validation purposes. Additionally, the cyclic load was investigated. The results show the comparatively sensitive behavior of the PC/ITO films, with a crack initiation strain at room temperature of 0.3-0.4% and critical temperatures of 58 °C and 83 °C, with high variation depending on the film's thickness. Under thermomechanical loading, the crack initiation strain decreases with increasing temperatures.

Plastic Deformation as an Origin of Dislocations in Cast Mono

The formation of dislocation clusters in cast mono ingots is investigated using etch pit density measurement and X-ray diffraction. The majority of detrimental dislocation clusters in the ingot originate in the seeding region.Beside the well-described dislocation source at the seed joints, a second origin of dislocation clusters is described in this work. Initial dislocation clusters appear in the seed by a rearrangement of dislocation cells to dislocation domains. It is demonstrated that a cell size below ∼ 50μm is required for this process. The dislocation density in these domains is about one order of magnitudes higher than in the cells. The high local dislocation density gains a very high shear stress. In consequence, the domain is able to penetrate the phase boundary between the remaining seed and the seeded material. Thus, the cluster is spreading unhindered into the ingot under the influence of thermo-mechanical stress during crystallization. X-ray diffraction measurements prove that the plastic deformation of the seeds leads in particular to such small cell sizes.