Optimization and design of pigments for heat-insulating coatings

This paper reports that heat insulating property of infrared reflective coatings is obtained through the use of pigments which diffuse near-infrared thermal radiation.Suitable structure and size distribution of pigments would attain maximum diffuse infrared radiation and reduce the pigment volume concentration required.The optimum structure and size range of pigments for reflective infrared coatings are studied by using Kubelka-Munk theory,Mie model and independent scattering approximation.Taking titania particle as the pigment embedded in an inorganic coating,the computational results show that core-shell particles present excellent scattering ability,more so than solid and hollow spherical particles.The optimum radius range of core-shell particles is around 0.3 ～ 1.6 μm.Furthermore,the influence of shell thickness on optical parameters of the coating is also obvious and the optimal thickness of shell is 100-300 nm.     

应用于热控的壳厚可控核壳结构SiO2@TiO2颗粒制备

利用St觟ber方法合成了平均粒径在800 nm,球形度、单分散性良好的SiO2微球,再将其作为制备核壳结构SiO2@TiO2颗粒的内核。利用钛酸四丁酯水解反应,在SiO2内核上包覆制备了壳厚在30～100 nm的TiO2壳层,TiO2壳层厚度可根据水解反应中钛酸四丁酯的量调控。将制得的SiO2@TiO2核壳结构颗粒在550℃煅烧1 h,氧化钛壳层的晶型转变为锐钛矿相,晶型转变为锐钛矿相的TiO2更适合作为填料应用于近红外反射涂层。本文合成厚度可控SiO2@TiO2微球的方法是一种改进的溶胶凝胶方法,即在溶胶凝胶方法的基础上增加水热合成工艺。另外,本合成方法工艺简单,无表面活性剂或者耦合剂的引入。     

Study of mechanical properties of amorphous copper with molecular dynamics simulation

The formation and mechanical properties of amorphous copper are studied using molecular dynamics simulation. The simulations of tension and shearing show that more pronounced plasticity is found under shearing, compared to tension. Apparent strain hardening and strain rate effect are observed. Interestingly, the variations of number density of atoms during deformation indicate free volume creation, especially under higher strain rate. In particular, it is found that shear induced dilatation does appear in the amorphous metal.     

Study of mechanical properties of amorphous copper with molecular dynamics simulation

The formation and mechanical properties of amorphous copper are studied using molecular dynamics simulation. The simulations of tension and shearing show that more pronounced plasticity is found under shearing, compared to tension. Apparent strain hardening and strain rate effect are observed. Interestingly, the variations of number density of atoms during deformation indicate free volume creation, especially under higher strain rate. In particular, it is found that shear induced dilatation does appear in the amorphous metal.