环文蛤贝壳微观形貌及摩擦学行为特性

环文蛤贝壳具有优异的力学性能，对其进行仿生设计并开发新材料已经成为研究热点。该文以辽宁营口的环文蛤贝壳为研究对象，应用JSM-6700F冷场发射扫描电子显微镜对环文蛤贝壳各层微观形貌结构进行了观察，发现角质层表面比较光滑，背面布满大量无规则的球形颗粒，而棱柱层表面存在大量孔洞，颗粒与孔洞提高了二者的有效接触面积，增强了结合强度，环文蛤的分泌黏液通过这些孔洞到达角质层表面，当粒径与孔洞处于嵌合状态时，在黏液的作用下使角质层与棱柱层紧密结合在一起，能够进一步地提高环文蛤贝壳的机械强度；采用微观摩擦磨损试验机UMT对环文蛤贝壳的摩擦性能进行测量，试验表明，试验因素对摩擦因数的影响大小依次为砂纸规格、法向载荷、时间、滑动速度；对磨损量的影响大小依次砂纸规格、时间、滑动速度、法向载荷。采用JSM-6360LV扫描电子显微镜对环文蛤贝壳磨损表面微观形貌进行观察，环文蛤贝壳的主要磨损机理为较低试验载荷条件下的磨料磨损和轻微剥层磨损，以及在较高试验载荷条件下的磨料磨损和严重剥层磨损。

Micro morphology and properties of tribological action for shell in Cyclina sinensis

Abstract: Shells of Cyclina sinensis have excellent mechanical properties, and they have become a hot research topic for bionic design and materials development. Cyclina sinensis shells in the City of Yingkou, Liaoning Province were our research subject. The micromorphology of different layers of Cyclina sinensis shells was observed by using JSM-6700F cold field scanning electron microscope (SEM), and it was shown that the surface of the periostracum was comparatively smooth, and its back was covered by a large number of irregular, spherical particles. There are lots of holes on the surface of the prismatic layer, and the secreted mucus of Cyclina sinensis shells arrives at the surface of the periostracum through those holes. When the particle size and pore size of the prismatic surface coincide was in the same scope with good chimeric, periostracum and prismatic layers were closely together under secreted mucus. Tribological properties of the Cyclina sinensis shell was studied by using UMT micro-friction and a wear-testing machine. The experiment showed that the relative order of influence on the friction coefficient is sand paper, normal load, time, and sliding speed; the relative order of influence on the wear rate is sand paper, time, sliding speed, and normal load. The smallest wear rate was observed when the time was 5 min, the normal load was 20 N, the sliding speed was 0.188 m/s, and the sandpaper specification was 1000 meshes. Under those conditions the wear performance of Cyclina sinensis shell was best. According to the results of an orthogonal experiment, under the conditions of friction time 1000 s, sliding speed 0.188 m/s, and sandpaper specification of 1000 meshes, sample data and worn surface micromorphology were analyzed under the conditions of two normal loads, 20 N and 25 N. When the normal load was 20 N, in the early portion of the experiment the Cyclina sinensis shell had a larger friction coefficient, and the periostracum and sandpaper began to contact with each other. The periostracum was worn away after 25 s, the prismatic layer and sandpaper began to contact with each other, so the friction coefficient briefly decreased, after which the friction coefficient began to increase again, reaching a stable value at about 300 s. When the normal load was 20 N at the beginning of the friction surface the complex microstructure under high load was damaged because of excessive pressure. Micro morphology of worn surface for shells of Cyclina sinensis was observed using JSM-6360LV cold field scanning electron microscope (SEM), the major worn mechanism for shell of Cyclina sinensis were abrasive wear and mild delamination wear under low test load condition, as well as abrasive wear and serious delamination wear under higher test load condition.