![]() The best fit for all angles is obtained assuming 7.19 g cm −3 nominal chromium density, 0.5 nm roughness for all involved layers, and an oxide layer thickness of 25 nm with a carbon top coat of 50 nm to 100 nm. The correction factors are related to possible combinations of a varied chromium density, chromium oxidation and a carbon contamination layer. ![]() Fitting the mirror-based development rates to the white-light case as a reference, reflectivity correction factors are identified, and verified by experimental and numerical results of beam calorimetry. The rates vary from case to case, indicating that the actual mirror reflectivity deviates from that of clean chromium assumed for the experiments. Development rates cover almost five orders of magnitude for nominal exposure dose (deposited energy per volume) values of 1 kJ cm −3 to 6 kJ cm −3. In a systematic study, the surface conditions of the two mirrors are analyzed to determine the mirror reflectivity for DXRL process optimization, without the need for spectral analysis or surface probing: PMMA resist foils were homogeneously exposed and developed to determine development rates for mirror angles between 6 mrad and 12 mrad as well as for white light in the absence of the mirrors. At the Synchrotron Laboratory for Micro and Nano Devices (SyLMAND), Canadian Light Source, a chromium-coated grazing-incidence X-ray double-mirror system is applied as a tunable low-pass filter. ![]() Post-machining annealing at 275 C for one hour in a vacuum furnace was also performed to remove deformation remaining from the machining processes.In deep X-ray lithography (DXRL), synchrotron radiation is applied to pattern polymer microstructures. Three machining methods were analyzed: lathe turning, fly-cutting, and electrical discharge machining (EDM). Therefore, a study was conducted to find a test specimen preparation method that would minimize subsurface deformation. The samples should have a minimal amount of subsurface deformation prior to testing, so the deformation due to sliding will not be obscured. These features would complicate our efforts to study the changes produced by impact with sliding. This revealed substructures consistent with extensive subsurface. Transmission Electron Microscopy (TEM) was done on cross-sections of the as-machined annular OFHC copper samples. The new pin/disk wear testing system can achieve sliding speeds up to 1 m/s in a range of environments and contact times as small as 0.1 s. The experimental work at OSU has focused on three tasks: (1) designing and building an improved system for sliding tests at intermediate velocities, (2) developing appropriate pre-testing surface preparation and (3) developing post-test characterization techniques. The dependence of friction force on sliding velocity, v, shows two regimes: a low speed regime in which friction force rises with v and a high speed regime in which it decreases. The results show extensive plastic deformation and, in some cases, the formation of nanocrystals at the sliding interface. The LANL team has also performed molecular dynamics (MD) simulations of sliding for Cu/Cu and Al/Ta using embedded atom potentials as well as simpler systems using Lennard-Jones potentials (also used at OSU). If the number of microvoids was large, grain growth could only occur if the grain size was smaller than the size usually existing at that more » temperature or if recrystallization or an allotropic transformation occurred during bonding. At high temperatures the driving force to straighten the irregularly shaped interface was sufficient to provide grain growth across the bond region if there were only a few microvoids. Grain growth across the bond region was found to be dependent upon the presence or absence of microvoids. The pressure required is inversely proportional to the surface roughness and directly proportional to the number of points of contact raised to the n-2/n power where n is the Meyer coefficient. A pressure of 0.59 of the Vickers hot hardness was required to obtain intimate contact for the model studied in detail. In OFHC copper the pressure required to place the surfaces in intimate contact is equivalent to the Meyer hot hardness at which the penetration of the indenter is equal to the average depth of the surface asperities. The effects of pressure, temperature, grain size, and surface roughness were evaluated. The pressure bonding of OFHC copper was studied, and the mechanism of the solid-phase bonding of two components under the application of heat and pressure was established.
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