Study On The Effect Of Trace Impurity Elements On Crystallization Behavior Of Quartz Fiber

With the rapid development of aerospace technology,the demand for new ultra-lightweight,high-temperature materials is urgent.With the advantages of low thermal conductivity,reusable,etc.,ceramic insulation tile is an important thermal insulation material in the thermal protection system.Its main component is quartz fiber.However,due to the existence of crystallization of quartz fiber itself,in the high temperature environment,ceramic insulation tile will be due to crystallization of quartz fiber and lead to comprehensive performance degradation,the impact of ceramic insulation tile high temperature dimensional stability,limiting the heat insulation tile insulation The performance of the efficient play,it is necessary for quartz fiber crystallization behavior research.In this paper,the basic principles and methods of molecular dynamics simulation are introduced,and the application of force field,temperature control and voltage control and structural analysis in the process of molecular dynamics simulation of quartz crystal crystallization are introduced in detail.It provides a good reference value and guidance for the detailed understanding of quartz molecular dynamics simulation.Based on molecular dynamics,the molecular dynamics of quartz fiber was simulated by Reax FF 6.0,and the bonding process was simulated by using the condensed state field COMPASS ?.Firstly,the quartz crystal was thawed by dynamic hot bath.The amorphous structure of quartz was obtained by quenching.The quartz amorphous/crystal structure was obtained by annealing.The atomic pattern of quartz crystal cell was recorded at different stages.The mechanism of amorphous/crystalline crystallization was discussed by structural analysis of XRD and RDF.The results show that with the addition of trace elements Cl-,Na+ and Fe2+ and Cl-,the contents of Cl-,Na+ and Fe2+,Cl-on the crystallization behavior of quartz are simulated at 1700 K,Atomic arrangement of the more clear and orderly,quartz crystal more significant.In this paper,the effects of trace impurity elements on the crystallization behavior of quartz fibers were studied.Pure quartz fibers were treated at different temperatures.At 1350 ? for 1h,the fiber sintered and melted.When the temperature was kept at 1380 ? for 1h,the fibers were crystallized and the precipitated phase was low temperature square quartz.The quartz fibers doped with trace sodium chloride are heat treated at high temperature.It can be found that the concentration of sodium chloride affects the sintering of quartz fibers.Sodium chloride promotes the crystallization of quartz fibers at high temperature,nucleation of the surface and the change of crystal form.The quartz fibers doped with ferrous chloride were heat treated at high temperature,and it was found that trace ferrous chloride promoted quartz fibers and precipitated crystals were low-temperature quartz while suppressing the sintering and melting of quartz fibers.The molecular modeling method provided in this paper has a good reference for other molecular modeling,The method and analysis of the molecular dynamics simulation process for the amorphous/crystal crystallization behavior of quartz have good guiding significance for the molecular dynamics simulation of other nonmetallic materials.The conclusion of the research on the development of ceramic insulation tile has the theory and practice.