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Rock abrasivity causes the tool wear in rock excavation or drilling. The understanding of wear mechanism is important for the cost estimation and planning of projects. In this study, the effects of textural properties of grains such as aspect ratio, roundness, and diameter on the LCPC abrasivity coefficient (LAC) were investigated for coarse-grained igneous rocks. First, the LAC was correlated to the abrasive mineral content (AMC) and a good correlation was found between the two parameters. Then, the LAC was correlated to the AMC multiplied by the textural properties of grains, respectively. Compared to the correlation coefficient of the relation between the LAC and the AMC, the correlation coefficient was increased by including the textural properties of grains to the correlation. A combined parameter called shape and size coefficient (SSC) was defined in order to see the combined effect of the textural properties of grains on the LAC. The correlation coefficient of the relation between the LAC and the AMC multiplied by the SSC is very strong and fairly higher than that of the previous correlations derived. It can be concluded that the textural properties of loosened materials have a strong influence on the tool wear. 相似文献
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The metastable pitting behavior of 316L stainless steel with different surface roughness in 0.01 M NaCl solution was studied using potentiostatic and potentiodynamic polarization methods and statistical treatments. As surface roughness decreased, the nucleation rate of metastable pits decreased. The peak current of metastable pits also decreased, but the average growth rate of metastable pits showed a slight increase. The aspect ratio of surface groove, w/d, was suggested to characterize the openness of surface grooves, in which w is the width of the groove at the opening and d the depth of the groove. Bigger w/d value indicates more smooth surface, and it is more difficult for micro-pit to nucleate. Under certain conditions of solution and potential, there is a critical w/d value. Metastable pits may nucleate only on those surfaces whose w/d values are less than the critical value. As the aspect ratio w/d increases, the nucleation rate of metastable pits decreases linearly, and both metastable pitting potential Em and pitting potential Ep move in the positive direction. 相似文献
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John P. Ranieri Frederick S. Lauten Donald H. Avery 《Journal of Electronic Materials》1995,24(10):1419-1423
The aspect ratio (joint area/joint thickness) of thin (0.001-0.006 in.) surface mount solder (60S-40Pb) joints plays an important
role in determining the mechanical properties and fracture behavior of the joints. This study demon-strates that plastic constraint
of a large aspect ratio 60Sn-40Pb solder joint can develop triaxial (hydrostatic) stresses several times greater than the
average tensile strength of the bulk solder material. A four to sixfold increase in average joint stress and up to a tenfold
increase in peak stress was measured on joints with aspect ratios ranging from 400 to 1000. Although a direct relationship
of the aspect ratio to the average tensile stress is shown, as the Friction Hill model predicts, the observed stress increase
is not nearly as high but proportional to the classical prediction. This is attributed to the existence of internal defects
(oxide particles and micro-voids) and transverse grain boundaries which fail producing internal free surfaces. Thus, the actual
aspect ratio is thickness/d2, where d equals the distance between internal surfaces. The fracture of these constrained joints was brittle, with the separation
occurring between a tin-rich copper tin intermetallic at the interface and the solder matrix. Voids within the solder joint
are shown to relieve the plastic constraint and lower the average tensile stress of the joint. The Friction Hill model may
play an important role in explaining the small percentage of atypical solder joint failures which sometimes occur on electronic
assemblies. In particular, the sudden failure of a thin joint in a strain controlled environment may be attributed to the
development of a large hydrostatic stress component. Therefore, a flaw free, plastically constrained joint which develops
a high stress state will be a high risk candidate for failure. 相似文献
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We have investigated the selective etching of 50 μm diameter via-holes for etch depth >200 μm using 30 μm thick photo resist mask in Inductively Coupled Plasma system with Cl2/BCl3 chemistry. Resultant etch rate/etch profiles are studied as a function of ICP process parameters and photo resist mask sidewall profile. Etch yield and aspect ratio variation with process pressure and substrate bias is also investigated at constant ICP power. The etch yield of ICP process increased with pressure due to reactant limited etch mechanism and reached a maximum of ∼19 for 200 μm depth at 50 mTorr pressure, 950 W coil power, 80 W substrate bias with an etch rate ∼4.9 μm/min. Final aspect ratio of etched holes is increased with pressure from 1.02 at 20 mTorr to 1.38 at 40 mTorr respectively for fixed etch time and then decreased to 1.24 at 50 mTorr pressure. The resultant final etch profile and undercut is found to have a strong dependence on the initial slope of photo resist mask sidewall angle and its selectivity in the pressure range of 20-50mTorr. 相似文献
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Y. F. Hsieh Y. C. Hwang J. M. Fu Y. M. Tsou Y. C. Peng L. J. Chen 《Microelectronics Reliability》1999,39(1):15
Ion implantation into contact holes has been widely used to dope the specific contact area and to reduce the contact resistance. In this study, mask edge defects were observed at the edge area of small contact holes with high aspect ratio, which resulted in multiplied dislocations penetrating into Si substrate for more than 0.3 μm after back-end processings. Those dislocations were identified to be Schockley partial dislocations and stair rod dislocations lying on 4 sets of inclined {111}Si planes. 相似文献