The effect of SiC particles reinforcement with average size of 1, 5, 20 and 50 μm and volume fraction of 5%, 10% and 15% on the microstructure and tribological properties of Al-based composite was investigated. Compo...The effect of SiC particles reinforcement with average size of 1, 5, 20 and 50 μm and volume fraction of 5%, 10% and 15% on the microstructure and tribological properties of Al-based composite was investigated. Composites were produced by applying compocasting process. Tribological properties of the unreinforced alloy and composites were studied using pin-on-disc wear tester, under dry sliding conditions at different specific loads. The influence of secondary mechanical processing with different rolling reductions on the dry sliding wear characteristics of Al matrix composites was also assessed. Hardness measurement and scanning electron microscopy were used for microstructural characterization and investigation of worn surfaces and wear debris. The proper selection of process parameter such as pouring temperature, stirring speed, stirring time, pre-heated temperature of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chemical reaction between the reinforcement and matrix should be avoided.展开更多
The NiCoCrAlY coatings strengthened by three nano-particles with the same addition were prepared on a Ni-base super alloy using laser cladding technique. The dry frictional wear behaviors of the coatings at 500 ℃ in ...The NiCoCrAlY coatings strengthened by three nano-particles with the same addition were prepared on a Ni-base super alloy using laser cladding technique. The dry frictional wear behaviors of the coatings at 500 ℃ in static air were investigated. The comparison was made with the coating without nano-particles. The results show that the wear mechanism of the NiCoCrAlY coatings with nano-particles, like the coating without nano-particles, is the delamination wear due to the strong plastic deformation and oxidative wear. However, the frictional coefficient of the coatings increases and presents the decrease trend with the increase of sliding distance after adding nano-particles. Moreover, the wear rate of the coatings with nano-particles is only 34.0%-64.5% of the coating without nano-particles. Among the three nano-particles, the improvement of nano-SiC on the high temperature wear resistance of the coating is the most significant.展开更多
目的建立小鼠钛颗粒诱导骨溶解动物模型。方法 30只雄性BALB/c小鼠随机分为对照组和钛颗粒刺激组,每组15只。采用手术方法建立植骨气囊的动物模型,钛颗粒刺激组注射0.3 m L钛颗粒,对照组注射0.3 m L PBS液。气囊植入颅骨骨块14d后取出...目的建立小鼠钛颗粒诱导骨溶解动物模型。方法 30只雄性BALB/c小鼠随机分为对照组和钛颗粒刺激组,每组15只。采用手术方法建立植骨气囊的动物模型,钛颗粒刺激组注射0.3 m L钛颗粒,对照组注射0.3 m L PBS液。气囊植入颅骨骨块14d后取出颅骨及其周围囊壁组织,分别进行大体、组织病理学及超微结构观察。结果大体观察钛颗粒刺激组小鼠植骨骨块与气囊组织之间出现红肿、渗出并伴有新生血管增生,炎性反应明显;对照组的炎性反应较轻。组织病理学见钛颗粒刺激组植入气囊内的骨块表面出现骨吸收现象,并且有明显的炎性反应;对照组无明显骨表面骨吸收的改变,炎性反应较轻。超微结构观察钛颗粒刺激组细胞胞浆内出现钛颗粒浸润,细胞胞浆内高尔基体生长活跃,植骨气囊周围可见增生活跃的破骨细胞前体细胞;对照组破骨细胞内细胞器完整,基质比较丰富。结论在钛颗粒刺激下建立磨损颗粒诱导骨溶解动物模型,可为人工关节无菌性松动导致的假体周围骨溶解的研究提供有效的实验基础。展开更多
文摘The effect of SiC particles reinforcement with average size of 1, 5, 20 and 50 μm and volume fraction of 5%, 10% and 15% on the microstructure and tribological properties of Al-based composite was investigated. Composites were produced by applying compocasting process. Tribological properties of the unreinforced alloy and composites were studied using pin-on-disc wear tester, under dry sliding conditions at different specific loads. The influence of secondary mechanical processing with different rolling reductions on the dry sliding wear characteristics of Al matrix composites was also assessed. Hardness measurement and scanning electron microscopy were used for microstructural characterization and investigation of worn surfaces and wear debris. The proper selection of process parameter such as pouring temperature, stirring speed, stirring time, pre-heated temperature of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chemical reaction between the reinforcement and matrix should be avoided.
基金Project(20060287019)supported by the Research Fund for Doctoral Program of Higher Education of ChinaProject(kjsmcx07001)supported by the Opening Research Fund of Jiangsu Key Laboratory of Tribology,ChinaProject(BK2010267)supported by the Jiangsu Provincial Natural Science Foundation of Jiangsu Province,China
文摘The NiCoCrAlY coatings strengthened by three nano-particles with the same addition were prepared on a Ni-base super alloy using laser cladding technique. The dry frictional wear behaviors of the coatings at 500 ℃ in static air were investigated. The comparison was made with the coating without nano-particles. The results show that the wear mechanism of the NiCoCrAlY coatings with nano-particles, like the coating without nano-particles, is the delamination wear due to the strong plastic deformation and oxidative wear. However, the frictional coefficient of the coatings increases and presents the decrease trend with the increase of sliding distance after adding nano-particles. Moreover, the wear rate of the coatings with nano-particles is only 34.0%-64.5% of the coating without nano-particles. Among the three nano-particles, the improvement of nano-SiC on the high temperature wear resistance of the coating is the most significant.
文摘目的建立小鼠钛颗粒诱导骨溶解动物模型。方法 30只雄性BALB/c小鼠随机分为对照组和钛颗粒刺激组,每组15只。采用手术方法建立植骨气囊的动物模型,钛颗粒刺激组注射0.3 m L钛颗粒,对照组注射0.3 m L PBS液。气囊植入颅骨骨块14d后取出颅骨及其周围囊壁组织,分别进行大体、组织病理学及超微结构观察。结果大体观察钛颗粒刺激组小鼠植骨骨块与气囊组织之间出现红肿、渗出并伴有新生血管增生,炎性反应明显;对照组的炎性反应较轻。组织病理学见钛颗粒刺激组植入气囊内的骨块表面出现骨吸收现象,并且有明显的炎性反应;对照组无明显骨表面骨吸收的改变,炎性反应较轻。超微结构观察钛颗粒刺激组细胞胞浆内出现钛颗粒浸润,细胞胞浆内高尔基体生长活跃,植骨气囊周围可见增生活跃的破骨细胞前体细胞;对照组破骨细胞内细胞器完整,基质比较丰富。结论在钛颗粒刺激下建立磨损颗粒诱导骨溶解动物模型,可为人工关节无菌性松动导致的假体周围骨溶解的研究提供有效的实验基础。
