SiC模具高温模压石英玻璃物相接触角的分子动力学模拟  

Molecular Dynamics Simulation of High Temperature Contact Angle for Molded Silica Glass in SiC Die

作　　者：吴悠 邹斌[1,2,3] 王俊成 黄传真[1,2,3] 朱洪涛[1,2,3] 姚鹏[1,2,3] WU You;ZOU Bin;WANG Juncheng;HUANG Chuanzhen;ZHU Hongtao;YAO Peng(Center for Advanced Jet Engineering Technologies, School of Mechanical Engineering, Shandong University, Jinan 250061, China;Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Shandong University, Ministry of Education, Jinan 250061,China;National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China)

机构地区：[1]山东大学机械工程学院先进射流工程技术研究中心,济南250061 [2]山东大学高效洁净机械制造教育部重点实验室,济南250061 [3]山东大学机械工程国家级实验教学示范中心,济南250061

出　　处：《硅酸盐通报》2020年第3期923-931,共9页Bulletin of the Chinese Ceramic Society

基　　金：山东省自然科学基金重大基础研究项目(ZR2018ZB0521)。

摘　　要：针对高温下石英玻璃纳米液滴在SiC模具表面接触角难以测量的问题,采用分子动力学方法,模拟研究了不同温度和粗糙表面面向模压的SiO2/SiC高温接触角以及SiO2熔体的界面结构。应用压力张量法发现了MS-Q势函数模拟的SiO2熔体表面张力较接近实际值,即SiO2高温表面特性模拟可优先采用MS-Q势函数。针对SiC模具纳米级表面的粗糙度,发现当粗糙度因子r>1.5时润湿模式由Wenzel变为Cassie-Baxter,此时Ra的变化对接触角值无明显影响,Rmr值减小使得接触面积分数f减小,接触角值随之增大。因此,保持r大于1.5的同时适当减小Rmr值有利于减小固液摩擦,降低石英玻璃工件和SiC模具界面上的脱模力。随着温度升高SiO2表面结构变得松散,导致其在SiC表面接触角减小。在超过2300 K时接触角值的变化率增大,为减小工件-模具界面的粘附,模压温度应选择2300 K以下。Due to the difficulties of measurement of contact angle when pressing silica glass nano-droplet in SiC die surface at high temperature,the SiO2/SiC high temperature contact angle at different temperature and rough surface as well as the surface structure of SiO2 melt were simulated by molecular dynamics.Using the pressure tensor method,it is found that the surface tension of SiO2 melt simulated by MS-Q potential function is close to the experimental value.Thus the MS-Q potential can be preferred in simulation of SiO2 high-temperature surface character.For the roughness of nanoscale surface of SiC die.When the roughness factor r exceeds 1.5,the wetting mode changes from Wenzel to Cassie-Baxter.At this time,the change of Ra has no significant impact on the contact angle,and the reduced Rmr value results in the decrease of contact area fraction f and the increase of contact angle.Therefore,keeping r greater than 1.5 while appropriately reducing Rmr value is conducive to reducing solid-liquid friction and reducing the stripping force on the interface between fused silica workpiece and SiC die.As the temperature increases,the surface structure of SiO2 become loose,resulting in its contact angle declining on the SiC surface.The change rate of the contact angle increases when temperature exceeds 2300 K.In order to reduce the adhesion of the workpiece with the die,the molding temperature should be below 2300 K.

关 键 词：石英玻璃 碳化硅 接触角 分子动力学 模压 

分 类 号：O647.1[理学—物理化学] TS943.65[理学—化学]