Ag-Mo-O ternary oxide has attracted growing attention because of its potential as a solid lubricant at high temperatures.This work designs and prepares NiCoCrAlYTa/Ag/Mo composite coating,performed using high velocity...Ag-Mo-O ternary oxide has attracted growing attention because of its potential as a solid lubricant at high temperatures.This work designs and prepares NiCoCrAlYTa/Ag/Mo composite coating,performed using high velocity oxy-fuel(HVOF)spraying technology.The environment temperature plays an important role in the microstructure and phases as well as lubricant properties of NiCoCrAlYTa/Ag/Mo coatings.When the environment temperature is above 600℃,the outer diffusion and oxidation of Ag and Mo lead to the formation of Ag2 MoO4 on the coating surface.Layer-like Ag2 MoO4 could form a continuous lubricant film at 800℃and consequently let the composite coating present the best tribological properties.Meanwhile,a small number of hard particles could play a good bearing role during friction and improve the tribological properties of the composite coating.展开更多
The creation of intergrown layer-like zeolite crystals is one route to form hierarchical zeolites.Faujasite-type(FAU-type)zeolites are among the industrially most important zeolites and the implementation of hierarchi...The creation of intergrown layer-like zeolite crystals is one route to form hierarchical zeolites.Faujasite-type(FAU-type)zeolites are among the industrially most important zeolites and the implementation of hierarchical porosity is a promising way to optimise their catalytic and adsorptive performance.After a short general survey into routes for the preparation of hierarchical pore systems in FAU,we will review the currently existing strategies for the synthesis of FAU with layer-like morphology.Those strategies are mainly based on the presence of morphology modifying agents in the synthesis mixture.However,a very recent approach is the synthesis of layer-like FAU-type zeolite crystals assembled in an intergrown manner in the absence of such additives,just by finely adjusting the crystallization temperature.This additive-free preparation route for layer-like FAU,which appears very attractive from an ecological as well as economic point of view,is highlighted in this review.Concluding,a comparison,including powder X-ray diffraction,scanning and transmission electron microscopy,nitrogen physisorption and elemental analysis,between conventional FAU and three layer-like FAU obtained by different synthesis routes was carried out to show the structural,morphological and textural differences and similarities of these materials.展开更多
类金刚石薄膜由于其独特的物理化学特性,使得该薄膜在光学、电学、机械、医学、航空航天等领域得到了广泛应用。等离子体增强化学气相沉积(plasma enhanced chemical vapor deposition,PECVD)制备类金刚石是近几十年兴起的新的制备类金...类金刚石薄膜由于其独特的物理化学特性,使得该薄膜在光学、电学、机械、医学、航空航天等领域得到了广泛应用。等离子体增强化学气相沉积(plasma enhanced chemical vapor deposition,PECVD)制备类金刚石是近几十年兴起的新的制备类金刚石薄膜的方法,因其对沉积温度要求低,对基底友好,同时还具有沉积速率快和无转移生长的优势,获得了越来越多的研究者关注。详细介绍了类金刚石薄膜优异的特性,阐述了在等离子化学气相沉积条件下,不同沉积条件对沉积类金刚石薄膜结构特性的影响。衬底的选择直接影响着沉积类金刚石薄膜的性能,不同的衬底直接决定着生成类金刚石结构中sp^(3)相的数量和质量;沉积参数是最为常见的控制条件,对沉积薄膜的总体效果影响也是最大的,改变沉积参数,沉积薄膜的表面将会变得更加光滑致密;常用的掺杂元素是硅和氮,掺杂元素的引入往往是为了降低沉积薄膜的内应力,提高与衬底间的结合力,延长使用寿命等;由于很难直接在金属上沉积类金刚石薄膜,所以常通过制备复合层来改善沉积效果。最后对类金刚石薄膜的发展以及今后研究方向进行了展望。展开更多
基金the financial supports of National Natural Science Foundation of China(Nos.51771214 and 51705481)the Youth Innovation Promotion Association(No.2014378)for Chinese Academy of Sciences。
文摘Ag-Mo-O ternary oxide has attracted growing attention because of its potential as a solid lubricant at high temperatures.This work designs and prepares NiCoCrAlYTa/Ag/Mo composite coating,performed using high velocity oxy-fuel(HVOF)spraying technology.The environment temperature plays an important role in the microstructure and phases as well as lubricant properties of NiCoCrAlYTa/Ag/Mo coatings.When the environment temperature is above 600℃,the outer diffusion and oxidation of Ag and Mo lead to the formation of Ag2 MoO4 on the coating surface.Layer-like Ag2 MoO4 could form a continuous lubricant film at 800℃and consequently let the composite coating present the best tribological properties.Meanwhile,a small number of hard particles could play a good bearing role during friction and improve the tribological properties of the composite coating.
文摘The creation of intergrown layer-like zeolite crystals is one route to form hierarchical zeolites.Faujasite-type(FAU-type)zeolites are among the industrially most important zeolites and the implementation of hierarchical porosity is a promising way to optimise their catalytic and adsorptive performance.After a short general survey into routes for the preparation of hierarchical pore systems in FAU,we will review the currently existing strategies for the synthesis of FAU with layer-like morphology.Those strategies are mainly based on the presence of morphology modifying agents in the synthesis mixture.However,a very recent approach is the synthesis of layer-like FAU-type zeolite crystals assembled in an intergrown manner in the absence of such additives,just by finely adjusting the crystallization temperature.This additive-free preparation route for layer-like FAU,which appears very attractive from an ecological as well as economic point of view,is highlighted in this review.Concluding,a comparison,including powder X-ray diffraction,scanning and transmission electron microscopy,nitrogen physisorption and elemental analysis,between conventional FAU and three layer-like FAU obtained by different synthesis routes was carried out to show the structural,morphological and textural differences and similarities of these materials.
文摘类金刚石薄膜由于其独特的物理化学特性,使得该薄膜在光学、电学、机械、医学、航空航天等领域得到了广泛应用。等离子体增强化学气相沉积(plasma enhanced chemical vapor deposition,PECVD)制备类金刚石是近几十年兴起的新的制备类金刚石薄膜的方法,因其对沉积温度要求低,对基底友好,同时还具有沉积速率快和无转移生长的优势,获得了越来越多的研究者关注。详细介绍了类金刚石薄膜优异的特性,阐述了在等离子化学气相沉积条件下,不同沉积条件对沉积类金刚石薄膜结构特性的影响。衬底的选择直接影响着沉积类金刚石薄膜的性能,不同的衬底直接决定着生成类金刚石结构中sp^(3)相的数量和质量;沉积参数是最为常见的控制条件,对沉积薄膜的总体效果影响也是最大的,改变沉积参数,沉积薄膜的表面将会变得更加光滑致密;常用的掺杂元素是硅和氮,掺杂元素的引入往往是为了降低沉积薄膜的内应力,提高与衬底间的结合力,延长使用寿命等;由于很难直接在金属上沉积类金刚石薄膜,所以常通过制备复合层来改善沉积效果。最后对类金刚石薄膜的发展以及今后研究方向进行了展望。
