摘要
基于固体边缘效应,对碳化硅(SiC)表面激光加工圆环形沟槽的润湿特性进行实验研究,通过分析去离子水在圆环槽上的润湿性能及其在边缘处的铺展行为,获得了环槽深度与环槽宽度对液滴在边缘处最大表观接触角的影响规律.结果表明,SiC圆环槽阻碍液滴铺展,光滑基体表面上接触角为70°,激光加工圆环槽深度为290μm,宽度为1 mm时,接触角可达138.5°.随槽深的增大,接触角呈现先增大后趋于稳定的趋势,临界槽深为80μm.当槽深小于该极值时,接触角随槽深的增大而线性增大;当槽深大于该极值时,液滴处于稳定钉扎状态,接触角趋于稳定,其稳定值符合Gibbs不等式.环槽宽度存在一临界值40μm.当槽宽低于该值时,液滴接触环槽外缘后越过沟槽继续在平面上铺展;当槽宽大于该值时,接触角趋于稳定,液滴沿边缘铺展.
To reduce the run-off of fluid in sealing system,especially in the multiphase medium and extreme operating conditions,it is necessary to investigate the wetting and spreading behavior in silicon carbon(SiC) sealing face.Considering the sealing performance,ring-grooved structures with a varying depth(h) and width(w) are fabricated on SiC substrates by laser marking machine.The radius of structure’ inner surface is 1.5 mm,less than the capillary length of water.Then,experimental equipment is designed to observe the profile and the spreading behaviors of droplet on the surface,and the wetting performance and pinning effect are discussed,and the influences of depth and width of ring-grooves on the wetting performance can be obtained.The results show that the contact angle(CA) and the advancing contact angle(ACA) of smooth SiC surface are 70° and 76.5°,respectively.And the values decrease to CA 50° and ACA 54° after laser processing,which may be due to the average roughness(Ra) increasing from 0.1μm in smooth surface to 0.8μm in laser machined surface,making the hydrophilic surface more hydrophilic.The CA on the edge of ring-grooves increases to 138.5°,the control of fluid can be realized.When the droplet spreads along the radius direction before reaching the edge of groove,its CA keeps 76.5°.Once it reaches the edge,the position of contact line remains constant or changes slowly along the wall of groove(we are more inclined to the latter),and thus making the CA increase with the droplet volume increasing,until reaching a maximum apparent contact angle(θmax).And θmax in the experiment is less than that from the Gibbs equation,which is perhaps because of the mechanical vibration,the roughness of the wall or the liquid viscosity effect.After that,the droplet collapses,and spreads along the groove area,or even flows over the outer edge of the ring groove.The influences of h and w of groove are then studied,showing that θmaxfirst increases linearly and then tends to be stable with the increase of h,and the de
作者
于子恒
马春红
白少先
Yu Zi-Heng;Ma Chun-Hong;Bai Shao-Xian(College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,China;School of Mechanical and Energy Engineering,Zhejiang University of Science and Technology,Hangzhou 310023,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第4期248-255,共8页
Acta Physica Sinica
基金
浙江省自然科学基金(批准号:LQ19E050002)
国家自然科学基金(批准号:51775504)
浙江省属高校基本科研业务费专项资金(批准号:2019QN01)资助的课题.
关键词
SIC
圆环槽
液滴铺展
边缘效应
SiC
ring-grooved structures
droplet spreading
edge effect
