Determination of the stress-deformed state components of the rock mass around the mine opening fixed by anchors

The analytical investigation of the stress-deformed state of the rock mass around mine with random cross-section and anchorage is completed. The problem is solved in reliance on tangential stress, that arising in anchors

Coherent Phonons in Bismuth Film Observed by Ultrafast Electron Diffraction

The generation of coherent phonons in polycrystalline bismuth film excited with femtosecond laser pulse is observed by ultrafast time-resolved electron diffraction. The dynamics of the diffracted intensities from the (110), (202), and (024) lattice planes show pronounced oscillations at 130-150 GHz. The origin of these coherent acoustic phonons is discussed in view of optical phonon decay into two acoustic phonons. Different drop times in the intensity of the diffraction orders are observed and interpreted as anisotropy in the energy transfer rate of coherent optical phonons

Friction and Wear Characteristics of C/Si Bi-layer Coatings Deposited on Silicon Substrate by DC Magnetron Sputtering

The tribological behavior of carbon/silicon bi-layer coatings deposited on a silicon substrate by DC magnetron sputtering was assessed and compared to that of amorphous carbon and silicon coatings. The motivation was to develop a wear resistant coating for silicon using thin layers of amorphous carbon and silicon. Wear tests were conducted by sliding a stainless steel ball against the coating specimens under applied normal loads in the range of 20 * 50 mN. Results showed that the wear rate of the bi-layer coating was strongly dependent on the ratio of thickness between the carbon and silicon layers. The wear rate of the bi-layer coating with 25 nm thick carbon and 102 nm thick silicon layers was about 48 and 20 times lower than that of the single-layer amorphous carbon and amorphous silicon coating, respectively. In addition, the steady-state friction coefficient of the bi-layer coating could be decreased to 0.09 by optimizing the thickness of the layer. Finally, a model for the wear reduction mechanism of the carbon/silicon bi-layer coating was proposed

Structural transformation in C/Si multilayer after annealing

Amorphous C/Si multilayers were prepared by DC magnetron sputtering technique and investigated by transmission electron microscopy and low-angle x-ray diffraction methods after annealing at 650 and 950 °C. The amorphous interlayers of 0.5 − 0.6 nm thick were found at C/Si and Si/C interfaces being of different density and composition. Amorphous structure of the multilayer is stable up to 950 °C when crystallization of α-SiC occurs and voids form in α-Si layer.Изготовленные методом прямоточного магнетронного распыления аморфные многослойные композиции C/Si были исследованы методами просвечивающей электронной микроскопии и малоугловой рентгеновской дифракции после отжигов при температуре 650 и 950 °C. На границах раздела C/Si и Si/C обнаружены аморфные перемешанные зоны толщиной 0.5 – 0.6 нм c различными плотностью и составом. Аморфная структура многослойной композиции стабильна вплоть до 950 °C, когда наблюдается формирование пор в слоях α-Si и кристаллизация α-SiC.Виготовлені методом прямоточногомагнетронного розпилення аморфні багатошарові композиції C/Si було досліджено методами просвічувальної електронної мікроскопії та малокутової рентгенівської дифракції після відпалу при температурі 650 і 950 °C. На межах поділу C/Si та Si/C виявлені аморфні перемішані зони різної густини та складу завтовшки 0.5 – 0.6 нм. Аморфна структура багатошарової композиції є стабільною до 950 °C, коли спостерігається формування пор у шарах α-Si у та кристалізація α-SiC

Determination of the stress-deformed state components of the rock mass around the mine opening fixed by anchors

The analytical investigation of the stress-deformed state of the rock mass around mine with random cross-section and anchorage is completed. The problem is solved in reliance on tangential stress, that arising in anchors

States and properties of metallic systems at a threshold breakdown of the through holes under power laser action (part 2).

Threshold breakdown of the through holes by power laser radiation of metallic foils is considered as response of metallic system to laser radiation. Binding experimentally determined response to the absolute temperature scale allows to determine the value of the imaginary part of the generalized susceptibility depending on temperature, the critical temperature of the transition “liquid metal - gas”, states of the electronic subsystems at this temperature, and the reflectance coefficient values