Increase In Surface Stress Research Articles

Wetting of soap bubbles on soft elastomers with surface stress and gravity

Surface stress and gravitational force have significant effects on the deformation of soft elastomers. By considering surface stress and gravity of the soft elastomer, we study wetting behaviors of soap bubbles on a semi-space elastomer through the surface Green’s function method. The normal surface displacement of the elastomer caused by the surface tension and Laplace pressure is calculated. The normal surface displacement in the contact zone monotonously increases from the center to the triple line, and the contact zone is divided into concave zone and convex zone. The results show that surface stress and gravity have significant influence on the normal surface deformation caused by the wetting of the soap bubble. In general, surface stress and gravity suppress the amplitude of the normal surface displacement. With the increase of surface stress, the amplitude of the normal surface displacement in the concave and convex zones decreases. However, with the increase of gravity, the amplitude of the normal surface displacement in the concave zone decreases, while that in the convex zone increases. This counterintuitive phenomenon can be understood by the superimposition of displacements. The results have potential applications in the fields of adhesion, indentation, evaporation, cell migration on soft materials, etc.

Effect of Critical Size on the Spontaneous of Tempered Glass Initiated by NiS Particle

Extrusion stress due to phase change of the NiS, internal stress due to CTE mismatch between the NiS and glass, and local concentrated stress around the NiS due to synergistic effects above were quantitatively calculated based on equal strength theory and the deformation coordination relation between NiS and glass in this work. The effects of NiS particle diameter, local strength of glass and ambient temperature on spontaneous breakage of tempered glass were analyzed. The critical diameter of NiS particles was determined as well. The results show that the fundamental reason for spontaneous breakage of tempered glass is the circumferential concentrated stress (tensile stress) near the NiS particle. There exists non-linear relations between circumferential stress and NiS particle diameter of which the circumferential stress decreases rapidly with the decrease of NiS particle diameter when it is less than 0.2 mm, but circumferential stress increases moderately when it is greater than 0.5 mm. The critical diameter of NiS particle which causes the spontaneous breakage of tempered glass decreases with the increase of surface stress in the tempered glass. It is difficult to induce spontaneous breakage of tempered glass when the diameter of NiS particle is less than 0.1 mm. The circumferential stress increases linearly with the increase of ambient temperature, and the stress increases slightly faster for the NiS with larger diameter.

Mechanism of wiggling enhancement due to HBr gas addition during amorphous carbon etching

The effect of gas chemistry during etching of an amorphous carbon layer (ACL) on wiggling has been investigated, focusing especially on the changes in residual stress. Although the HBr gas addition reduces critical dimension loss, it enhances the surface stress and therefore increases wiggling. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the increase in surface stress was caused by hydrogenation of the ACL surface with hydrogen radicals. Three-dimensional (3D) nonlinear finite element method analysis confirmed that the increase in surface stress is large enough to cause the wiggling. These results also suggest that etching with hydrogen compound gases using an ACL mask has high potential to cause the wiggling.

Oxygen-induced step ordering on Ni(119)

The presence of diffuse intensity in the LEED pattern of clean Ni(119), a stepped Ni(100) surface, indicates a disorder in the distribution of (100) terrace lengths. This diffuse intensity is attenuated upon adsorption of small amounts of oxygen, indicating an adsorbate-induced ordering of the surface, apparent at oxygen concentrations as low as θO = 0.03 ML. The physical origin of the oxygen-induced ordering is explored by considering two alternatives: an increase in repulsive interactions between surface steps and an inhibition of kink formation along step edges. The degree of surface ordering is found consistent with an increase in surface stress of 200 dyne cm or an increase in kink formation energy of just 40 meV. At an oxygen coverage matching the number of available step sites (θO ≈ 0.20 ML), a distinctive (9 × 1) oxygen overlayer pattern emerges which, upon additional oxygen exposure, transforms into the p(2 × 2) pattern typical of oxygen adsorption on Ni(100) at θO ≈ 0.25 ML. LEED “fingerprinting” of the I-V characteristics of both the (9 × 1)-O Ni (119) and p (2 × 2)-Ni (119) patterns was used to deduce the local oxygen chemisorption geometry. We conclude that oxygen in the (9 × 1) overlayer occupies 4-fold hollow sites near the step edge. Based upon this adsorption site, an oxygen-induced increase in the kink formation energy is the likely physical origin of the step ordering.