In this study, Mg–6.0Zn–3.0Sn–0.5Mn(ZTM630) magnesium alloy was pre-activated by colloidal Ti, oxalic acid, and phosphoric acid,and a phosphate conversion coating(PCC) was prepared on the alloy surface. The morphol...In this study, Mg–6.0Zn–3.0Sn–0.5Mn(ZTM630) magnesium alloy was pre-activated by colloidal Ti, oxalic acid, and phosphoric acid,and a phosphate conversion coating(PCC) was prepared on the alloy surface. The morphology and corrosion resistance of the prepared PCCs were investigated. Surface morphology studies showed that the phosphate crystals that formed the coating were the smallest for the sample pre-activated by phosphoric acid. The coating on the colloidal Ti and the phosphoric acid samples had the largest and the smallest thickness and surface roughness, respectively. The reason for the discrepancy was analyzed by comparing the surface morphologies of alloy samples immediately after the pre-activation treatment and various phosphating treatments. X-ray diffraction analysis revealed that all three PCCs contained the same compounds. The corrosion resistance time from the copper sulfate drop test and the electrochemical data from the potentiodynamic polarization curves showed that the coating pre-activated by phosphoric acid had the best corrosion resistance. Finally, the 1500 h neutral salt spray corrosion test confirmed that the phosphating treated magnesium alloy, which was pre-activated by phosphoric acid,exhibited excellent corrosion resistance and behavior.展开更多
As there are numerous physics formulas in addition to them being theoretical,college students generally consider the concepts of physics as abstract,in which they are not able to apply what they have learned.For 3D dy...As there are numerous physics formulas in addition to them being theoretical,college students generally consider the concepts of physics as abstract,in which they are not able to apply what they have learned.For 3D dynamic animation and visualization in the teaching of college physics,VPyton has many advantages,and it provides useful exploration for students to overcome obstacles in college physics learning.Taking the teaching of simple harmonic vibration,optics,molecular thermal motion,and electric field as examples,this article discusses the application of VPython in the humancomputer interactive teaching mode of college physics,which provides a beneficial exploration and new way to improve students?engineering skills and numeracy,as well as to respond to the national“new engineering education”reform in China.展开更多
We consider the inhomogeneous incompressible Navier-Stokes equation on thin domains T^(2)×∈T,∈→0.It is shown that the weak solutions on T^(2)×∈T converge to the strong/weak solutions of the 2D inhomogene...We consider the inhomogeneous incompressible Navier-Stokes equation on thin domains T^(2)×∈T,∈→0.It is shown that the weak solutions on T^(2)×∈T converge to the strong/weak solutions of the 2D inhomogeneous incompressible Navier-Stokes equations on T^(2)as∈→0 on arbitrary time interval.展开更多
基金financially supported by National Key Research and Development Program of China (Nos. 2017YFB0103904, 2016YFB0301105)National Natural Science Foundation of China (No. 51804190)+2 种基金Youth Science Funds of Shandong Academy of Sciences (No. 2020QN0022)Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities (No. 2020KJA002)Jinan Science & Technology Bureau (No. 2019GXRC030)。
文摘In this study, Mg–6.0Zn–3.0Sn–0.5Mn(ZTM630) magnesium alloy was pre-activated by colloidal Ti, oxalic acid, and phosphoric acid,and a phosphate conversion coating(PCC) was prepared on the alloy surface. The morphology and corrosion resistance of the prepared PCCs were investigated. Surface morphology studies showed that the phosphate crystals that formed the coating were the smallest for the sample pre-activated by phosphoric acid. The coating on the colloidal Ti and the phosphoric acid samples had the largest and the smallest thickness and surface roughness, respectively. The reason for the discrepancy was analyzed by comparing the surface morphologies of alloy samples immediately after the pre-activation treatment and various phosphating treatments. X-ray diffraction analysis revealed that all three PCCs contained the same compounds. The corrosion resistance time from the copper sulfate drop test and the electrochemical data from the potentiodynamic polarization curves showed that the coating pre-activated by phosphoric acid had the best corrosion resistance. Finally, the 1500 h neutral salt spray corrosion test confirmed that the phosphating treated magnesium alloy, which was pre-activated by phosphoric acid,exhibited excellent corrosion resistance and behavior.
基金the Wuhan Institute of Technology project titled,"The Reform and Practical Teaching of the New Engineering Education Visualization Teaching Mode of College Physics Based on Jupyter Lab/Notebook Platfbrm,5 and a top course of the online undergraduate courses of college physics in Hubei Province as well as Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302003).
文摘As there are numerous physics formulas in addition to them being theoretical,college students generally consider the concepts of physics as abstract,in which they are not able to apply what they have learned.For 3D dynamic animation and visualization in the teaching of college physics,VPyton has many advantages,and it provides useful exploration for students to overcome obstacles in college physics learning.Taking the teaching of simple harmonic vibration,optics,molecular thermal motion,and electric field as examples,this article discusses the application of VPython in the humancomputer interactive teaching mode of college physics,which provides a beneficial exploration and new way to improve students?engineering skills and numeracy,as well as to respond to the national“new engineering education”reform in China.
基金The research is supported by NSFC underGrant Nos.11571167,11771395,11771206 and PAPD of Jiangsu Higher Education Institutions.
文摘We consider the inhomogeneous incompressible Navier-Stokes equation on thin domains T^(2)×∈T,∈→0.It is shown that the weak solutions on T^(2)×∈T converge to the strong/weak solutions of the 2D inhomogeneous incompressible Navier-Stokes equations on T^(2)as∈→0 on arbitrary time interval.
