冷冻扫描电子显微镜(cryogenic scanning electron microscopy,cryo-SEM)是观察样品含水状态下真实微观形貌不可替代的分析手段,其中样品的冷冻断裂步骤是获得理想测试结果的关键步骤之一.水凝胶样品由于含水量丰富,质地柔软难以成形,...冷冻扫描电子显微镜(cryogenic scanning electron microscopy,cryo-SEM)是观察样品含水状态下真实微观形貌不可替代的分析手段,其中样品的冷冻断裂步骤是获得理想测试结果的关键步骤之一.水凝胶样品由于含水量丰富,质地柔软难以成形,在利用常规冷刀断裂方法进行冷冻断裂时,存在难以获得理想断裂面、断裂效率低等问题.因此创新性地提出了一种竹纤维柱辅助断裂方法,在样品冷冻固定前,将细小的竹纤维柱插入水凝胶样品顶端.冷冻断裂时,冷刀不直接作用在样品上,而是通过撬动与样品相连的竹纤维柱,实现样品与纤维柱接触部位的冷冻断裂.可轻松获得大范围可观测断裂面,且样品应力损伤小,无表面样品碎屑干扰,还可实现多个样品一次性同时断裂,是一种高质、高效的水凝胶冷冻断裂方法.展开更多
Study of the surface morphology of gas hydrate is of great importance in understanding its physical properties and occurrence.In order to investigate the surface morphology of different types(sI and sII)and occurrence...Study of the surface morphology of gas hydrate is of great importance in understanding its physical properties and occurrence.In order to investigate the surface morphology of different types(sI and sII)and occurrences(pore-filling and fracture-filling)of gas hydrate,both lab-synthesized and drilled-gas hydrate samples were measured using cryo-scanning electron microscopy(cryo-SEM).Results showed that the surface of s I hydrate was relatively smooth,and spongy nano-pores(200–400 nm)gradually occurred at the surface during continuous observation.The surface of sII hydrate was more compact,showing a tier-like structure.Hydrate occurred in quartz sand and usually filled the pores of the sediments and both hydrate and sediments were cemented with each other.SEM observation of the gas hydrates collected from the South China Sea showed that the surface morphology and contact relation with sediments varied with hydrate occurrence.For instance,hydrates dispersed in sediments mainly filled the pores of the sediments.The existence of microorganism shells,such as foraminifera,was beneficial to the formation of gas hydrate.When hydrate occurred as a massive or vein structure,it was easily distinguished from the surrounding sediments.The surface of hydrate with massive or vein structure showed two distinct characters:one was dense and smooth,the other is porous(several to tens of micrometers in diameter).The occurrence of different hydrate morphologies was probably caused by the supplement rates of methane gas.展开更多
文摘冷冻扫描电子显微镜(cryogenic scanning electron microscopy,cryo-SEM)是观察样品含水状态下真实微观形貌不可替代的分析手段,其中样品的冷冻断裂步骤是获得理想测试结果的关键步骤之一.水凝胶样品由于含水量丰富,质地柔软难以成形,在利用常规冷刀断裂方法进行冷冻断裂时,存在难以获得理想断裂面、断裂效率低等问题.因此创新性地提出了一种竹纤维柱辅助断裂方法,在样品冷冻固定前,将细小的竹纤维柱插入水凝胶样品顶端.冷冻断裂时,冷刀不直接作用在样品上,而是通过撬动与样品相连的竹纤维柱,实现样品与纤维柱接触部位的冷冻断裂.可轻松获得大范围可观测断裂面,且样品应力损伤小,无表面样品碎屑干扰,还可实现多个样品一次性同时断裂,是一种高质、高效的水凝胶冷冻断裂方法.
基金financially supported by the National Natural Science Foundation of China(No.41976205)the National Key R&D Program of China(No.2018YFC031 0000)the Open Funding of Qingdao National Laboratory for Marine Science and Technology(No.QNLM20 16ORP0203)
文摘Study of the surface morphology of gas hydrate is of great importance in understanding its physical properties and occurrence.In order to investigate the surface morphology of different types(sI and sII)and occurrences(pore-filling and fracture-filling)of gas hydrate,both lab-synthesized and drilled-gas hydrate samples were measured using cryo-scanning electron microscopy(cryo-SEM).Results showed that the surface of s I hydrate was relatively smooth,and spongy nano-pores(200–400 nm)gradually occurred at the surface during continuous observation.The surface of sII hydrate was more compact,showing a tier-like structure.Hydrate occurred in quartz sand and usually filled the pores of the sediments and both hydrate and sediments were cemented with each other.SEM observation of the gas hydrates collected from the South China Sea showed that the surface morphology and contact relation with sediments varied with hydrate occurrence.For instance,hydrates dispersed in sediments mainly filled the pores of the sediments.The existence of microorganism shells,such as foraminifera,was beneficial to the formation of gas hydrate.When hydrate occurred as a massive or vein structure,it was easily distinguished from the surrounding sediments.The surface of hydrate with massive or vein structure showed two distinct characters:one was dense and smooth,the other is porous(several to tens of micrometers in diameter).The occurrence of different hydrate morphologies was probably caused by the supplement rates of methane gas.
