Papers by Keyword: Surface Precipitation

Abstract: Surface precipitation calculation and application is a complex problem. It involves not only how to calculate, and more importantly, a broad range of issues of calculation and results which are both closely integrated with application. It mainly includes the reliability, representativeness and consistency of surface precipitation; the calculation of surface rainfall depth and rainfall amount in general different durations, rainfall area and its corresponding total amount in different durations, specified range and different degrees; the calculation of characteristic index of surface rainfall location, area, rain depth, total amount, and the corresponding shape, mobile, development within rain district or fixed area to analysis surface rainfall characteristics and changes. Taken sediment formation and variation of the midstream of the Yellow River as research objectives, this paper presents the flood control design and flood resource application research with larger flood to satisfy the requirement of engineering hydrological calculations, and briefly describes the surface precipitation calculation and research results.

Abstract: Long term service of the materials under stresses and at attacking environments causes material damages, leading to fractures. Among a lot of the material damages, creep cavity and fatigue crack are principal targets to be self healed autonomously during actual service of materials. Since the creep cavity and the fatigue crack are generally too fine to be detected during actual service and difficult to be repaired at the service sites. Recently self healing of creep cavity and fatigue crack has been developed. In the developed methods, segregation and precipitation of solute atoms were applied to self healing of the damages. The self healing methods are comparatively simple and low cost, which may make it easy to be applied to many materials.

Abstract: This paper presents a model for the analysis of the surface nucleation and growth of Ni silicide on silicon wafers contaminated by Ni. The model can additionally be used to characterize the gettering reaction of Ni induced by oxygen precipitates. We also discuss the relation between the surface precipitation of Ni silicide and the gettering ability of oxygen precipitate. The surface precipitation of Ni silicide depends on the total surface area of oxide precipitates. When the total surface area of the oxide precipitates exceeds the critical value, the surface precipitation is rapidly suppressed. Our model can explain the phenomenon of the gettering threshold in the following manner. 1) The gettering of Ni by oxygen precipitates is a reaction-limited process at the interface between oxygen precipitate and silicon, as Sueoka proposed. 2) The residual Ni concentration in this reaction-limited gettering process continuously decreases as the total surface area of the oxide precipitates increases. 3) The surface precipitation of Ni silicide is rapidly suppressed when the residual Ni concentration falls below the critical concentration. Our calculation results correspond well with the experimental results.