医用炭/炭复合材料表面梯度CVD热解炭涂层的摩擦性能研究

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倪昕晔, 汤晓斌, 林涛, 耿长冉, 蔡雷铭, 顾卫东, 陈达. 医用炭/炭复合材料表面梯度CVD热解炭涂层的摩擦性能研究. 无机材料学报, 2012, 27(5): 545-549
NI Xin-Ye, TANG Xiao-Bin, LIN Tao, GENG Chang-Ran, CAI Lei-Ming, GU Wei-Dong, CHEN Da. Friction of Pyrolytic Carbon Coating Prepared by Gradient CVD on Medical Carbon/Carbon Composites Surface. Journal of Inorganic Materials, 2012, 27(5): 545-549 复制到剪切板

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医用炭/炭复合材料表面梯度CVD热解炭涂层的摩擦性能研究

倪昕晔^1,², 汤晓斌¹, 林涛², 耿长冉¹, 蔡雷铭², 顾卫东², 陈达¹

1．南京航空航天大学材料科学与技术学院, 南京 210016

2. 南京医科大学附属常州第二人民医院, 常州 213003

陈达, 教授. E-mail:dachen@nuaa.edu.cn

倪昕晔(1975-), 男, 博士研究生. E-mail:nxy2000@yahoo.com.cn

基金:江苏省常州市社会发展基金(CS20102019); 南京航空航天大学基础科研业务费专项基金(Y1065-0630);

摘要

采用医用炭/炭复合材料并通过梯度化学气相沉积法(CVD)在其表面制备热解炭涂层, 研究分析了涂层的显微结构、摩擦系数、磨损情况. 结果发现, 该热解炭涂层表面被直径约20 μm热解炭球致密覆盖, 在断口处呈现紧密、多层的热解炭. 与用沥青浸渍/炭化法制备的炭/炭复合材料相比, 在干摩擦时, 热解炭涂层样品的摩擦系数更大; 在模拟人体关节的湿摩擦时, 它的摩擦系数低; 在干摩擦和湿摩擦的情况下, 它的磨损要小很多. 这些结果表明利用梯度的化学气相沉积法(CVD)制备医用炭/炭复合材料的涂层可以提高其表面的耐磨性.

关键词: 炭/炭复合材料; 化学气相沉积; 梯度; 摩擦

中图分类号:TB332 文献标志码:A 文章编号:1000-324X(2012)05-0545-05

Friction of Pyrolytic Carbon Coating Prepared by Gradient CVD on Medical Carbon/Carbon Composites Surface

NI Xin-Ye^1,², TANG Xiao-Bin¹, LIN Tao², GENG Chang-Ran¹, CAI Lei-Ming², GU Wei-Dong², CHEN Da¹

1. College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

2. Second People#cod#x02019;s Hospital of Changzhou, Nanjing Medical University, Changzhou 213003, China

Fund:Municipal Social Development Project of Changzhou City, Jiangsu Province (CS20102019); Special Research Projects of Nanjing University of Aeronautics and Astronautics (Y1065-0630);

Abstract

Pyrolytic carbon coating was prepared by gradient chemical vapor deposition (CVD) on medical carbon/carbon composites surface. Microstructure, friction coefficient and wear capacity of the pyrolytic carbon cating were investigated. The results show that the pyrolytic carbon coating is covered densely by spherical pyrdytic carbon with dimension of about 20 μm, and close, multi-layer pyrolytic carbon is shown on the fracture. Compared with carbon/carbon composite prepared by asphalt impregnated/carbonization, the friction coefficient of the byrolytic carbon coating is higher in the dry friction whereas in wet friction of simulated human joints, its friction coefficient is lower. The wear loss of the pyrolytic carbon coating is much smaller than that of the latter in dry and wet friction. It suggests that medical carbon/carbon composites surface prepared by gradient CVD can improve the wear resistance of the carbon/carbon composites.

Keyword: carbon/carbon composites; CND; gradient; friction

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碳是组成有机物质的主要元素之一, 也是构成人体的重要元素^{[ 1]}. 炭材料已在心脏瓣膜、骨骼、齿根、血管、肌腱等诸多人工材料方面获得应用和发展. 炭/炭复合材料克服了单一碳材料的脆性, 具有高强度、高韧性、耐腐蚀、耐高温等优点^{[ 2, 3]}, 炭/炭复合材料是以炭纤维增强炭基体的新型复合材料, 是一种极有潜力的新型生物医用材料. 炭/炭复合材料弹性模量与人骨相当, 是具有良好应用前景的人工关节、骨假体材料^{[ 4]}. 但是炭/炭复合材料颗粒易脱落^{[ 5]}, 有研究表明炭/炭复合材料表面游离的颗粒会被附近组织中的淋巴细胞或巨噬细胞吞噬^{[ 6]}. 通过提高石墨化温度^{[ 7]}、改变热解炭织构^{[ 8]}、改变纤维排列^{[ 9]}、提高湿度、提高热处理温度^{[ 10]}等方法可以提高炭/炭复合材料的耐磨性. 有报道对炭/炭复合材料制成的人工关节的磨损进行了研究^{[ 11]}, 但是用梯度CVD法制备医用炭/炭复合材料表面涂层来提高人工骨摩擦性能未见相关报道. 本研究通过梯度CVD法改变医用炭/炭复合材料表面热解碳的结构分布来提高摩擦性能, 分析了用梯度CVD法制备医用炭/炭复合材料表面涂层的微观结构,及其在模拟人工股骨头的受力情况及工作环境下摩擦学性能.

1 实验材料及方法

实验分对照组和实验组进行. 对照组为沥青浸渍／碳化的医用炭/炭复合材料, 炭/炭复合材料为2.5维PAN基的炭/炭复合材料, 用真空泵把泡沫碳预制体孔隙中的空气排出, 然后将沥青溶化的沥青倒入放泡沫碳的容器中并将泡沫碳覆盖, 再通入氮气, 对浸渍沥青的泡沫碳预制体进行碳化高温热处理, 把材料放在真空碳化炉中, 在真空状态下, 以一定的升温速率, 升温到1000~1200℃, 并保温1~2 h, 再2800~3200℃进行石墨化, 来消除炭/炭复合材料的有毒杂质. 实验组为利用梯度的化学气相沉积法(CVD)制备医用炭/炭复合材料的表面, 来提高表面的摩擦性能, 具体方法就是在沥青浸渍/碳化基础上, 在相对低温时通入低密度的碳源气体, 以一定的升温速率来提升炉的温度, 碳源气体的密度随着温度的升高而增大, 最终升温到1200~1300℃.

对对照组炭/炭复合材料表面和梯度CVD法制备的炭/炭复合材料的涂层进行XRD、SEM和EDS表征, 采用德国布鲁克产的D8型X射线衍射仪进行XRD测试, 衍射仪的测试条件为管电压40 kV, 管电流40 mA, 步长0.01°, 扫描范围10°~90°. 采用日本电子JSM-6360LA型扫描电镜进行SEM、EDS测试, 加速电压为15 kV.

本研究的摩擦学实验在球盘摩擦实验机上进行, 球盘摩擦实验机为南京航空航天大学自制, 模拟人工股骨头的磨损, 下试样为炭/炭复合材料, 放在圆盘上, 对偶件为φ8 mm的GCr15轴承钢球(上海钢球厂), 钢球硬度62~66 HRC, 表面粗糙度 R_a=0.025, 载荷为100 g, 转速为100 r/min, 钢球在垂直载荷的作用下与下试样圆盘接触, 钢球固定不动, 而圆盘状试样受驱动绕垂直轴转动. 由电涡流传感器测得力臂的变形得到摩擦力, 再换算成摩擦系数, 并由计算机直接给出测得的摩擦系数曲线, 读取数据的频率为0.1 s.

步频, 即脚步的频率, 竞走或跑步时两腿在单位时间内交替的次数. 窦文浩等对北京体院运动系6名男子中长跑运动员进行步频统计,其平均值为170步/分钟^{[ 12]}, 换算成单腿的步频的平均值为 85步/分钟, 故本研究中球盘摩擦实验机球盘的转速为100 r/min来模拟实际的步频.

人在走路时(速度为1.5 m/s), 髋关节最大受力约为2.5倍本人体重, 而当跑步时(速度为3.5 m/s), 关节最大受力约为5~6倍本人体重^{[ 13]}. 髋关节把受力传递给股骨头, 股骨头表面近似一个半球面, 郭云良等对26具男性的成人骨骼标本的股骨头表面积进行测量, 平均值为46.87 cm^{2[ 14]}, 如果球面压强平均分布, 那么压强 , F为压力, S为股骨头表面积, m为人的体重, 以80 kg为例, g为9.8 N/kg, n为运动方式所对应的参数, 跑步时压强为1.0 MPa. 实际上球面的压强是不均匀的, 在球的顶端即股骨头顶点的上方存在压强的极点, 且关节也不是一个标准的半球面, 人在奔跑时的速度会大于3.5 m/s, 再加上体重的差异, 因此综合考虑定义人工股骨头承受的最大压强为5.0~9.0 MPa.

通过在干燥状态的预实验, 发现球盘摩擦实验机的钢球与下试样的接触半径为0.02 cm, 利用公式来计算接触面的表面积, r为钢球的半径, 为0.4 cm, h为钢球的球冠高, , r₁为钢球与下试样的接触半径, h为5×10^-4cm, 从而得到 S₁为1.26×10^-3cm², 根据公式得到载荷 m₁的质量为64~115 g, 在本研究中选择摩擦实验机的载荷为100 g.

摩擦实验模拟的是人体关节实际的工作状态, 用干摩擦和湿摩擦来模拟关节液少和多的两种情况, 干摩擦为钢球与下试样间没有液体, 湿摩擦为下试样浸入在生理盐水中. 实验完成后通过日本KEYENCE公司VHX-500FE数码显微镜观察炭/炭复合材料表面磨损情况.

2 结果与讨论

2.1 梯度CVD法制备的炭/炭复合材料的表征

对对照组表面和梯度CVD法制备的炭/炭复合材料涂层进行SEM表征, 对照组表面较平坦, 热解炭覆盖不致密, 有空隙存在; 梯度CVD法制备的炭/炭复合材料表面较粗糙, 表面被直径约20 μm球面小球致密覆盖, 如图1(a)、(b)所示. 对两组分别进行断口观察, 对照组有疏松的不规则的热解炭炭片覆盖, 而梯度CVD法制备的炭/炭复合材料的断口有规则、紧密、多层似树年轮状的热解炭覆盖, 如图1(c)、(d)所示. 通过能谱分析(EDS)发现对照组表面和梯度CVD法制备的炭/炭复合材料涂层的碳含量分别为65.97%、70.06%, 如图1(a)、(b)插图. 炭/炭复合材料的XRD图谱如图2所示, 两者的衍射峰相似, 梯度CVD法制备的炭/炭复合材料涂层的石墨化程度更高.

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	图1 炭/炭复合材料的SEM表面和断面形貌及其对应能谱分析Fig. 1 Surface and fracture SEM images of carbon/carbon composites(a,c) Reference carbon/carbon composites; (b,d) Carbon/carbon composites surface coating prepared by gradient CVD

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	图2 炭/炭复合材料表面XRD图谱Fig. 2 XRD patterns of carbon/carbon composites surface(a) Reference carbon/carbon composites surface; (b) Carbon/carbon composites surface coating prepared by gradient CVD

2.2 实时摩擦系数

在干摩擦的状态下, 对照组和梯度CVD法制备的炭/炭复合材料涂层的摩擦系数在20 min内平均值分别为0.175、0.229, 如图3所示. 对照组炭/炭复合材料摩擦系数在一定时间内有所变化, 1、2、3、4、5、10 min内平均摩擦系数分别为0.161、0.166、0.168、0.169、0.170、0.173, 摩擦系数在摩擦初期有升高趋势, 随着摩擦时间的延长摩擦系数趋于平稳. 梯度CVD法制备的炭/炭复合材料涂层摩擦系数在一定时间内也有所变化, 1、2、3、4、5、10 min内平均摩擦系数分别为0.221、0.223、0.223、0.225、0.225、0.228, 摩擦系数在摩擦初期有升高趋势, 随着摩擦时间的延长摩擦系数较快趋于平稳. 在干摩擦的状态下, 对照组炭/炭复合材料表面摩擦系数比梯度CVD法制备的炭/炭复合材料摩擦系数低, 原因主要有两方面: (1)梯度CVD法制备炭/炭复合材料涂层表面摩擦系数高与热解炭小球所造成相对粗糙有关, (2)对照组炭/炭复合材料表面摩擦系数低与其表面涂层较松弛、易脱落产生自润滑磨屑有关.

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	图3 干摩擦的实时摩擦系数Fig. 3 Real dry friction coefficients of carbon/carbon composites surface(a) Reference carbon/ carbon composites surface; (b) carbon / carbon composites surface coating prepared by gradient CVD

在湿摩擦的状态下, 对照组和梯度CVD法制备炭/炭复合材料的涂层摩擦系数在20 min内的平均值分别为0.126、0.071, 如图4所示. 对照组炭/炭复合材料摩擦系数在一定时间内也有变化, 1、2、3、4、5、10 min内平均摩擦系数分别为0.103、0.106、0.106、0.107、0.109、0.115, 摩擦系数在摩擦初期有升高趋势, 随着摩擦时间的延长摩擦系数趋于平稳. CVD法制备炭/炭复合材料的涂层摩擦系数在一定时间内有所变化, 1、2、3、4、5、10 min内平均摩擦系数分别为 0.212、0.202、0.176、0.157、0.144、0.104, 摩擦系数在摩擦初期有降低趋势, 随着摩擦时间的延长摩擦系数趋于平稳. 在湿摩擦的状态下, 对照组炭/炭复合材料表面的摩擦系数比梯度CVD法制备的炭/炭复合材料涂层的摩擦系数高近1倍, 两者的摩擦系数都比在干摩擦状态下的摩擦系数低, 生理盐水起到了润滑的作用, 湿摩擦是混合摩擦. 梯度CVD法制备的炭/炭复合材料涂层的摩擦系数比干摩擦时摩擦系数下降明显的原因主要是: (1) 梯度CVD法制备的炭/炭复合材料涂层表面的微型球面使摩擦容易产生流体动压润滑; (2)微型球面之间的凹坑起到储油器的功能, 能够及时在摩擦表面形成润滑膜. 对照组炭/炭复合材料表面摩擦系数有渐升高且稳定的趋势, 梯度CVD法制备炭/炭复合材料涂层的摩擦系数有渐减低且稳定的趋势.

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	图4 湿摩擦的实时摩擦系数Fig. 4 Real wet friction coefficients of carbon/carbon composites surface(a) Reference carbon/carbon composites surface; (b) carbon/carbon composites surface coating prepared by gradient CVD

人体关节的工作是在关节液中进行的, 湿摩擦的模拟状态比干摩擦的模拟状态更接近于实际工作状态, 梯度CVD法制备炭/炭复合材料涂层的摩擦系数特性适合人工关节的要求.

2.3 摩擦的表面磨损形貌

在干摩擦的状态下, 在对照组的表面发现有明显凹痕, 凹痕的直径为0.4 mm, 炭纤维受损现象严重, 大量纤维束剪断磨损; 梯度CVD法制备的炭/炭复合材料涂层表面没有凹痕, 炭纤维束排列整齐、没有断裂发生, 如图5所示.

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	图5 干摩擦的表面磨损照片Fig. 5 Surface wear morphologies of dry friction(a, c) reference carbon/carbon composites surface(50×, 500×); (b, d) carbon/carbon composites surface coating prepared by gradient CVD (50×, 500×)

在湿摩擦的状态下, 在对照组的表面发现有明显凹痕, 凹痕的直径为0.2 mm, 炭纤维受损现象较严重, 发现部分纤维束剪断磨损; 梯度CVD法制备的炭/炭复合材料涂层表面没有凹痕, 炭纤维束排列整齐、没有断裂发生, 如图6所示.

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	图6 湿摩擦的表面磨损照片Fig. 6 Surface wear morphologies of wet friction(a,c) reference carbon/carbon composites surface (50×,500×); (b,d) carbon/carbon composites surface coating prepared by gradient CVD (50×,500×)

在干摩擦、湿摩擦状态下, 梯度CVD法制备的炭/炭复合材料涂层表面几乎没有磨损的原因与其表面涂层微型球面的组织致密有关, 这些涂层的硬度较高起到了抗磨作用, 使其耐磨性提高.

3 结论

1)梯度CVD法制备的炭/炭复合材料涂层在仿人体股骨头工作状态下, 即载荷为100 g、转速为100 r/min、生理盐水状态下, 20 min内的平均摩擦系数为0.071, 小于沥青浸渍/碳化的炭/炭复合材料的摩擦系数0.126; 且其摩擦时间越长, 摩擦系数越低. 梯度CVD法制备的炭/炭复合材料涂层磨损远小于沥青浸渍/碳化的炭/炭复合材料.

2) 梯度CVD法制备炭/炭复合材料涂层可以提高医用炭/炭复合材料的耐磨性能.

参考文献

View Option

[1]	Gott V L, Whiffen J D, Dutten R C. Heparin bonding colloidal graphite surfaces. Science, 1963, 142(3597): 1279-1298. [本文引用:1]
[2]	Brückman H, Hüttinger K J. Carbon, a promising material in endoprosthetics. Part 1: the carbon materials and their mechanical properties. Biomaterials, 1980, 1(2): 67-72. [本文引用:1] [JCR: 7.604]
[3]	侯向辉, 陈强, 喻春红, 等. 碳/碳复合材料的生物相容性及生物应用. 功能材料, 2000, 31(5): 460-463. [本文引用:1]
[4]	ZHANG Lei-Lei, LI He-Jun, LI Ke-Zhi, et al. Effect of surfare roughness of carbon/carbon composites on Osteob casts. Journal of Inorganic Materials, 2008, 23(2): 341-345. [本文引用:1] [JCR: 0.531] [CJCR: 1.106]
[5]	Shimmin A, Beaulé P E, Campbell P. Metal-on-metal hip resurfacing arthroplasty. J. Bone Joint Surg. Am. , 2008, 90(3): 637-654. [本文引用:1] [JCR: 3.234]
[6]	Brand wood A, Noble K R, Schindhelm K. Phagocytosis of carbon particles by macrophages in vitro. Biomaterials, 1992, 13(9): 646-648. [本文引用:1] [JCR: 7.604]
[7]	黄荔海, 李贺军, 胡志彪. 石墨化度对2. 5D 炭/炭复合材料在低能条件下的摩擦学性能影响. 材料科学与工程学报, 2005, 23(5): 487-490. [本文引用:1]
[8]	Xiong Xiang, Huang Baiyun, Li Jianghong, et al. Friction behaviors of carbon/carbon composites with different pyrolytic carbon textures. Carbon, 2006, 44(3): 463-467. [本文引用:1] [JCR: 5.868]
[9]	Huttona T J, Johnsona D, McEnaney B. Effects of fibre orientation on the tribology of a model carbon-carbon composite. Wear, 2001, 249(8): 647-655. [本文引用:1] [JCR: 1.262]
[10]	胡志彪, 李贺军, 陈强, 等. 炭/炭复合材料摩擦学性能及摩擦机制研究进展. 材料工程, 2004, 12: 59-62. [本文引用:1]
[11]	ZHANG Lei-Lei, HU Tao, LI He-Jun, et al. Wear partiles of carbon/carbon composite artifical hip joints. Journal of Inorganic Materials, 2010, 25(4): 349-353. [本文引用:1] [JCR: 0.531] [CJCR: 1.106]
[12]	窦文浩, 翟士岭, 孙克宜. 一定速度下中长跑步频变化对跑步效率的影响. 北京体育学院学报, 1990, 47(1): 44-50, 57. [本文引用:1]
[13]	胡侦明, 罗先正. 髋关节的生物力学. 中华骨科杂志, 2006, 26(7): 498-500. [本文引用:1]
[14]	郭云良, 刘丰春, 李相民. 股骨头的直径、表面积和体积的计算及其意义. 佳木斯医学院学报, 1993, 16(3): 6-8. [本文引用:1]

1963

0.0

Science. 1963, 142(3597):1279-1298

Heparin bonding colloidal graphite surfaces

Gott V L , Whiffen J D , Dutten R C

Experiments on clotting, both in vitro and in vivo, showed that a colloidal graphite surface, when rinsed with a cationic, surface-active agent, was capable of bonding heparin. The resistance of this graphite-heparin surface to the formation of clots was far greater than plastic or silicone surfaces in comparable studies.

... 碳是组成有机物质的主要元素之一, 也是构成人体的重要元素^[1] ...

1980

7.604

0.0

... 炭/炭复合材料克服了单一碳材料的脆性, 具有高强度、高韧性、耐腐蚀、耐高温等优点^[2,3], 炭/炭复合材料是以炭纤维增强炭基体的新型复合材料, 是一种极有潜力的新型生物医用材料 ...

2000

0.0

. 2000, 31(5):460-463

碳／碳复合材料继承了碳材料固有的生物相容性，又具有优良的力学性能。在生物医用材料领域有很大的应用前景。本文总结了医用碳／碳复合材料的研究现状．评述了碳／碳复合材料的生物相容性特点。并详细讨论了碳／碳复合材料生物医用所涉及到的模量、界面及表面改性等问题。对碳／碳复合材料的医用前景进行了展望。

2008

0.531

1.106

Journal of Inorganic Materials. 2008, 23(2):341-345 DOI:10.3724/SP.J.1077.2008.00341

Effect of surfare roughness of carbon/carbon composites on Osteob casts

School of Materials Science, Northwestern Polytechnical University, Xi’an 710072, China

The aim of this study is to investigate the role of surface roughness of carbon/carbon (C/C) composites on osteoblasts morphology, adhesion and proliferation. C/C composites were prepared by chemical vapor infiltration and three different values of surface roughness were created by treatment with two kinds of grinding paper and mechanical polishing. The
surface roughness of C/C composites was measured by Talysurf profilometer, and cell culture was performed with MG-63 osteoblasts. The adhesion rate, morphology and proliferation rate were assessed. The results show that the adhesion rate increase and the proliferation rate decrease with the increase of roughness. The orientation of the osteoblasts is affected by the roughness, the higher the roughness, the greater the effect. As surface roughness increasing, the morphology of the osteoblasts changes from shuttle and strip shape to slice shape.

采用化学气相沉积工艺制备了碳/碳(C/C)复合材料, 用表面轮廓仪检测了表面粗糙度, 用MG-63成骨细胞进行了细胞试验, 研究了C/C复合材料表面粗糙度对成骨细胞形貌、粘附和增殖的影响规律. 结果表明: C/C复合材料表面粗糙度越高则成骨细胞在其表面的粘附率越高, 增殖率越低; C/C复合材料表面粗糙度对成骨细胞的生长方向和形貌具有诱导作用, 粗糙度越高则方向诱导作用越明显, 且细胞附着形貌呈梭形或长条状, 立体感强, 反之成骨细胞则呈现片状, 铺展状态好.

... 炭/炭复合材料弹性模量与人骨相当, 是具有良好应用前景的人工关节、骨假体材料^[4] ...

2008

3.234

0.0

J. Bone Joint Surg. Am.. 2008, 90(3):637-654

Metal-on-metal hip resurfacing arthroplasty

Shimmin A , Beaul#cod#x000e9; P E , Campbell P

The main advantage of hip resurfacing is bone conservation for patients likely to outlive a primary conventional hip replacement.

Previous attempts at hip resurfacing failed predominantly because of the consequences of a high amount of wear of thin polyethylene acetabular components and poor femoral component fixation.

With correct patient selection, surgeon education, and operative technique, survivorship at five years is comparable with that of traditional hip replacements.

Hip resurfacing has its own unique set of complications, including a fractured neck of the femur. It is necessary to understand the risk factors prior to performing the procedure.

... 但是炭/炭复合材料颗粒易脱落^[5], 有研究表明炭/炭复合材料表面游离的颗粒会被附近组织中的淋巴细胞或巨噬细胞吞噬^[6] ...

1992

7.604

0.0

Biomaterials. 1992, 13(9):646-648

Phagocytosis of carbon particles by macrophages in vitro

Brandwood A , Noble K R , Schindhelm K

Particles of known size ranges of carbon fibre-reinforced carbon were presented to in vitro cultures of murine macrophages. Particles of up to 20 μm diameter were phagocytosed. Larger particles were not phagocytosed but became surrounded by aggregations of macrophages, some of which migrated on to the particle surfaces. Mean rates of phagocytosis up to 2.5 particles per hour were observed. Cells presented with a large excess of particles became rounded, detached from the substrate and some underwent lysis. The implications of these findings for the fate of particulates released from implanted medical devices is discussed. It is argued that a mechanism exists where particles in the size range 8–20 μm, released from medical devices, are small enough to be phagocytosed by macrophages and transported to the lymphatics and subsequently to the vascular circulation but large enough to lodge in capillary beds of tissues remote from the implant site.

... 但是炭/炭复合材料颗粒易脱落^[5], 有研究表明炭/炭复合材料表面游离的颗粒会被附近组织中的淋巴细胞或巨噬细胞吞噬^[6] ...

2005

0.0

... 通过提高石墨化温度^[7]、改变热解炭织构^[8]、改变纤维排列^[9]、提高湿度、提高热处理温度^[10]等方法可以提高炭/炭复合材料的耐磨性 ...

2006

5.868

0.0

Carbon. 2006, 44(3):463-467 DOI:10.1016/j.carbon.2005.08.022

Friction behaviors of carbon/carbon composites with different pyrolytic carbon textures

Abstract

Friction and wear properties of carbon/carbon (C/C) composites with a smooth laminar (SL), a medium textured rough laminar (RL) and a high textured RL pyrolytic carbon texture were investigated with a home-made laboratory scale dynamometer to simulate airplane normal landing (NL), over landing (OL) and rejected take-off (RTO) conditions. The morphology of worn surfaces at different braking levels was observed with scanning electron microscopy. The results show that C/C composites with RL have nearly constant friction coefficients, stable friction curves and proper wear loss at different braking levels, while friction coefficients of C/C composites with SL pyrolytic carbon decrease intensely and their oxidation losses increase greatly under OL and RTO conditions. Therefore, C/C composites with a high and medium textured RL pyrolytic carbon may satisfy the requirements of aircraft brakes. The good friction and wear properties of C/C composites with RL are due to the properties of RL, which leads to a uniform friction film forming on the friction surface.

... 通过提高石墨化温度^[7]、改变热解炭织构^[8]、改变纤维排列^[9]、提高湿度、提高热处理温度^[10]等方法可以提高炭/炭复合材料的耐磨性 ...

2001

1.262

0.0

Wear. 2001, 249(8):647-655

Effects of fibre orientation on the tribology of a model carbon-carbon composite

Huttona T J , Johnsona D , McEnaney B

Wear rates and friction coefficients were measured for a PAN fibre–CVI matrix carbon–carbon composite with different fibre orientations at the wear faces. A constant torque dynamometer operating at rotational speeds in the range 1800–8000 rpm (3.5–15.7 m s⁻¹ average linear sliding velocity) was used in a ring on ring configuration sliding wear test. Fibre orientations parallel to the wear face favour the formation of friction films by easy shear deformation of the graphitic CVI sheaths around the fibres. Fibre ends emerging at the wear face inhibit formation of a friction film at low rotational speeds. The resulting high wear rates suggest that particulate debris forms by microfracture of fibre ends emerging at the wear face. At faster rotational speeds, the wear face temperatures and shear forces are sufficiently high to allow friction films to develop. Different wear rates for stators and rotors were found when different fibre orientations were exposed at the two wear faces. The largest differences in wear were seen where fibre ends emerged at the rotor wear face when sliding against a parallel fibre orientated stator. This was also attributed to transverse microfracture of the fibre ends.

... 通过提高石墨化温度^[7]、改变热解炭织构^[8]、改变纤维排列^[9]、提高湿度、提高热处理温度^[10]等方法可以提高炭/炭复合材料的耐磨性 ...

2004

0.0

... 通过提高石墨化温度^[7]、改变热解炭织构^[8]、改变纤维排列^[9]、提高湿度、提高热处理温度^[10]等方法可以提高炭/炭复合材料的耐磨性 ...

2010

0.531

1.106

Journal of Inorganic Materials. 2010, 25(4):349-353 DOI:10.3724/SP.J.1077.2010.00349

Wear partiles of carbon/carbon composite artifical hip joints

1. School of Materials Science, Northwestern Polytechnical University, Xi’an 710072, China; 2. Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China

The carbon/carbon composite wear particles generated from a hip joint simulator were separated. The size, morphology and thickness of the particles were tested by laser particle size analyzer, scanning electron microscope and 3-D profiler, respectively. The results show that the particles are 0.3-93.9μm in size and the morphology and the thickness of the particles distributes regularly according to their sizes. The particles whose sizes are larger than 30μm are carbon fibers with a constant thickness. The particles whose thicknesses are in a broad range with medium size (3-30μm) show irregular morphology and complex boundary. The particles whose thicknesses are in the range of submicrometers are less than 3μm in size and have a spherical or circular shape. Based on the experimental results, the evolvement of the wear particles in the wear process is explained.

分离提取了炭/炭复合材料在髋关节模拟试验机中形成的磨损颗粒. 采用激光粒度仪考察了磨损颗粒的尺寸分布, 借助扫描电镜分析了磨损颗粒的形貌特征, 采用三维轮廓仪检测了磨损颗粒的厚度规律. 结果表明, 炭/炭复合材料磨损颗粒的尺寸分布在0.3～93.9μm之间, 其形貌和厚度依据颗粒尺寸呈现规律性的分布, 大尺寸（＞30μm）颗粒基本是破损的碳纤维, 厚度稳定; 中尺寸（3~30μm）颗粒的外形不规则, 边界轮廓复杂, 厚度分布范围广泛; 小尺寸（＜3μm）颗粒呈现圆片形或球形, 厚度分布在亚微米级别. 同时根据实验结果, 揭示了炭/炭复合材料磨损颗粒在磨擦过程中的演变过程.

... 有报道对炭/炭复合材料制成的人工关节的磨损进行了研究^[11], 但是用梯度CVD法制备医用炭/炭复合材料表面涂层来提高人工骨摩擦性能未见相关报道 ...

1990

0.0

. 1990, 47(1):44-50, 57

本文利用心脏、呼吸测定分析系统及每次运动都进行血乳酸测定的方法,测定了中长跑运动员在一定速度下步频变化对跑步效率的影响.研究发现,步频与耗氧量、每公斤体重耗氧量、能量消耗、血乳酸等值的变化有关,表现为自由步频消耗最低,效率最高.因此,在确认一定速度情况下,自由步频应为最佳步频.这为在跑步实践中避免能量的多耗提供了科学依据.

... 窦文浩等对北京体院运动系6名男子中长跑运动员进行步频统计,其平均值为170步/分钟^[12], 换算成单腿的步频的平均值为 85步/分钟, 故本研究中球盘摩擦实验机球盘的转速为100 r/min来模拟实际的步频 ...

2006

0.0

. 2006, 26(7):498-500

髋关节由凹状的髋臼与凸状的股骨头构成，属于球窝结构，具有内在稳定性。通过髋关节头、臼软骨面相互接触传导重力，支撑人体上半身的重量及提供下肢的活动度。在众多的可动关节中，髋关节是最稳定的，其结构能够完成日常生活中所需的大范围动作，如行走、坐和蹲等。球窝关节排列紊乱可导致关节软骨和骨内的应力分布发生改变，引起退行性关节炎等损害，并因关节承受巨大的力而逐渐加剧。

... 5 m/s), 关节最大受力约为5~6倍本人体重^[13] ...

1993

0.0

. 1993, 16(3):6-8

本文在47套(男26,女21)内蒙古通辽地区出土的干燥成人骨骼标本上测量了股骨头的底径和高度,并通过公式计算了股骨头的直径、表面积和体积。股骨头的底径:男4.58±0.03cm,女4.10±0.03cm;高度:男3.11±0.02cm,女2.89±0.02cm;直径:男4.80±003cm,女4.35±0.03cm;表面积:男46.87±0.59cm~2,女39.28±0.59cm~2;体积:男41.58±0.80cm~3,女31.87±0.80cm~3。所有指标均有显著性性别差异,并对股骨颈骨折内固定方法的选择和人工股骨头置换具有指导意义。

... 87 cm^2[14], 如果球面压强平均分布, 那么压强 , F为压力, S为股骨头表面积, m为人的体重, 以80 kg为例, g为9 ...