空气/氮气气氛下电流和摩擦速度对C/C复合材料载流摩擦磨损性能的影响

在空气/氮气气氛下研究了电流、摩擦速度、载荷等试验参数对C/C复合材料载流磨损率和摩擦因数的影响,并对磨损表面的形貌和成分进行了观察和分析。结果表明:随着电流和摩擦速度增大,C/C复合材料的磨损率和摩擦因数均增大;相较于空气气氛,氮气气氛下的摩擦因数较高,磨损率较低;空气气氛中炭材料的氧化加剧了材料的磨损,使得磨损率较高,而摩擦过程中材料表面形成的氧化膜使得摩擦因数较低。     

氮化硅陶瓷表面DLC膜的制备及摩擦性能研究

利用等离子体基离子注入与沉积技术,在氮化硅陶瓷片表面制备200～400nm的类金刚石碳膜。测试薄膜的厚度、表面形貌、结构、膜基结合力,利用球盘试验机考察DLC膜的摩擦性能。结果表明:沉积薄膜均匀光滑;薄膜的硬度和弹性模量与基体差异较小,膜基结合力强;DLC膜具有较低的摩擦因数,抗磨性能优异。     

碳纤维粉增强氟橡胶复合材料摩擦学性能研究

采用液相氧化法对碳纤维进行不同时间表面刻蚀,利用扫描电镜分析碳纤维的表观形貌;采用开炼共混和平板硫化方法制备改性后碳纤维/氟橡胶复合材料,研究改性碳纤维用量对复合材料硫化特征、力学性能和摩擦磨损性能的影响。结果表明：随着氧化时间的增加,碳纤维表面沟槽纹路变深变宽,从而与橡胶基体有更好的界面结合性;随着碳纤维用量的增加,复合材料交联密度增大,而拉伸性能降低;碳纤维的加入使复合材料摩擦磨损性能明显提高,最高可使材料摩擦因数降低近45%,耐磨性提高近1倍;经过表面改性的碳纤维能使复合材料的摩擦因数和磨损率更低,耐磨性能更好。     

碳纤维粉增强氟橡胶复合材料的摩擦学性能

采用液相氧化法对碳纤维进行不同时间表面刻蚀,利用扫描电镜分析碳纤维的表观形貌;采用开炼共混和平板硫化方法制备改性后碳纤维/氟橡胶复合材料,研究改性碳纤维用量对复合材料硫化特征、力学性能和摩擦磨损性能的影响。结果表明:随着氧化时间的增加,碳纤维表面沟槽纹路变深变宽,从而与橡胶基体有更好的界面结合性;随着碳纤维用量的增加,复合材料交联密度增大,而拉伸性能降低;碳纤维的加入使复合材料摩擦磨损性能明显提高,最高可使材料摩擦因数降低近45%,耐磨性提高近1倍;经过表面改性的碳纤维能使复合材料的摩擦因数和磨损率更低,耐磨性能更好。     

非平衡磁控溅射制备Cr掺杂DLC复合薄膜的高温摩擦学性能

元素掺杂是提升DLC薄膜摩擦学性能和耐温性能的重要途径。采用直流磁控溅射技术在304不锈钢基体表面沉积了含氢DLC薄膜,同时利用射频磁控溅射技术完成Cr元素的掺杂,研究Cr元素掺杂对DLC薄膜的力学性能及摩擦学性能的影响。采用纳米压痕仪测试薄膜硬度并利用划痕试验测试膜基结合力,采用拉曼光谱分析薄膜sp²和sp³键含量的变化和转移膜的生成。采用UMT多功能摩擦磨损试验机评价薄膜在常温和高温环境下的摩擦磨损性能,并利用扫描电镜观察磨损表面,分析其磨损机制。结果表明,Cr元素掺杂会显著提高薄膜的膜基结合力,但会使薄膜硬度有一定的下降。常温摩擦学性能测试显示,DLC薄膜的摩擦因数随着Cr含量的增加呈现出先下降后上升的趋势,在Cr质量分数为3.34%时达到最低;但薄膜的磨损率随Cr含量的增加略有升高。高温摩擦学性能测试表明,Cr元素掺杂显著改善了DLC薄膜的高温摩擦学性能,未掺杂的DLC在150℃以上摩擦时会失效,Cr元素掺杂使薄膜在250℃下也能保持较低的摩擦因数和较长的抗磨寿命。Cr元素的加入能够提高DLC薄膜的膜基结合力,降低摩擦因数,并提高薄膜...     

高能离子源清洗对AlCrN刀具涂层结构及性能的影响

采用自主研发的离子源增强多弧离子镀设备,研究涂层沉积前不同清洗工艺对基材表面粗糙度以及所制备的AlCrN涂层的表面形貌、硬度、膜基结合力、摩擦磨损和切削性能的影响。研究结果表明,高能Ar⁺清洗可以更有效清洁基材表面。与传统弧源清洗技术相比,经高能离子源清洗后的基体表面粗糙度降低,沉积态涂层的表面粗糙度更低。相比于传统弧源清洗工艺,高能Ar⁺清洗可以显著提高膜基结合强度,达到48.7 N,摩擦因数和磨损率均降低,涂层刀具寿命提高了3倍。     

添加不同固体润滑剂橡胶复合材料的力学及摩擦磨损性能

制备了添加不同固体润滑剂(鳞片石墨、超高分子量聚四氟乙烯、尼龙6、硅脂、白色减摩剂)的纤维增强丁腈橡胶/丁苯橡胶/复合材料,研究了橡胶复合材料的硫化性能、力学性能和摩擦磨损性能。结果表明：添加超高分子量聚四氟乙烯润滑剂的橡胶复合材料的综合硫化性能最佳;润滑剂为鳞片石墨时,复合材料邵氏硬度,拉伸强度最大;润滑剂为超高分子量聚四氟乙烯时,复合材料的动摩擦因数、动摩擦因数稳定度波动幅度、磨损率、干/湿环境下动摩擦因数差值最低,分别为0.27～0.29、2%、1.4×10^-7 g·J^-1、0.01,耐磨性能和干湿环境交替稳定性最佳。     

不同温湿度下风电轴承表面防护DLC薄膜微动摩擦特性

针对湿热环境下风电绝缘轴承的微动磨损失效问题，采用等离子体增强化学气相沉积工艺在绝缘涂层Al₂O₃表面沉积类金刚石碳(DLC)薄膜，研究温湿度对其微动摩擦特性的影响。结果表明：DLC薄膜在适当高温下均具有良好的摩擦学性能，在湿度为80%RH时的平均摩擦因数较小；温湿度较高的环境有利于降低DLC薄膜的微动磨损程度，提高绝缘轴承的防护程度；对磨痕处进行拉曼光谱分析表明摩擦过程中DLC薄膜磨痕表面杂化键sp²/sp³比值均大幅上升，且薄膜发生了石墨化转变。DLC薄膜在高温下的低摩擦行为主要是由于DLC薄膜表面石墨化过渡层和磨损表面石墨化的协同作用。     

稀土化合物改性复合材料在油润滑下的摩擦学性能

以竹纤维为增强相,通过稀土化合物改性制备一种树脂基复合材料;采用环块式摩擦磨损实验,研究稀土化合物改性复合材料在油润滑状态下载荷、转速对试样摩擦学性能的影响,以及稀土化合物改性对复合材料试样摩擦学性能的影响;比较干摩擦状态和油润滑状态下复合材料的摩擦学性能,观察和分析试样磨损表面形貌,探讨其磨损机制。实验结果表明:油润滑条件下,稀土化合物改性复合材料的摩擦因数和磨损率都随着载荷的增大而增加;较高载荷下摩擦因数随着转速的增大先增加后减小,而磨损率则呈现逐步增加的趋势;稀土化合物的改性使竹纤维和基体界面结合更为紧密,提高摩擦因数的同时降低了磨损率;在油润滑作用下,试样磨损由干摩擦时的磨粒磨损和疲劳磨损转变成为轻微的疲劳磨损;在油润滑状态下,复合材料处于边界润滑状态,故摩擦因数和磨损率均低于干摩擦。     

改性玄武岩纤维增强橡胶基摩擦材料的摩擦学性能

采用热压成型工艺制备改性玄武岩纤维增强橡胶基复合材料,考察其力学性能和摩擦学性能,采用扫描电镜(SEM)和能谱仪(EDS)对摩擦表面和磨料粉尘进行表征。结果表明,与憎水剂和硅烷偶联剂改性玄武岩短纤维及硅烷偶联剂改性玄武岩纤维增强复合材料相比,由于玄武岩纤维碎片的参与,聚醋酸乙烯酯和硅烷偶联剂改性玄武岩纤维增强橡胶基复合材料的摩擦表面上形成了完整且稳定的摩擦膜,这有助于稳定摩擦因数以及降低磨损率,因此表现为具有更好的摩擦学性能。     

碳碳复合材料界面热力学研究

化工材料是化工业及工业生产制造的基本元素,各种材料的性能特点决定了复合产品加工制造质量的好坏。分析碳碳复合材料界面热力学特点,主要是为了保证化工材料性能的正常发挥,使得化工生产的流程更加顺利。采用了理论研究与生产实践相结合的方式分析了碳碳复合材料的基本性质与优势,从四大热力学定律分析了材料详细的热学特点,得出了温度高低变化是影响复合材料性能的重要因素。     

Effect of Resin-Derived Carbon on the Friction Behavior of Carbon/Carbon Composites

Three different C/C composites with rough laminar (RL) pyrocarbon, RL pyrocarbon with added resin-derived carbon, and pure resin-derived carbon have been evaluated and tested for friction performance. A laboratory dynamometer was used to simulate different braking speeds utilizing a single stator and rotor pair. The morphologies and microstructures of the raw materials, wear surfaces, and wear debris at different braking levels were observed by polarized light microscopy, scanning electron microscopy, and transmission electron microscopy. The results have shown that the friction coefficients of the three C/C composites display the same characteristics with increasing braking speed. They increased to a maximum value at medium braking speed and thereafter decreased with increasing braking speed, and their mean values under the same braking conditions were similar. The C/C composite with pure resin-derived carbon showed the highest loss due to wear under all conditions, while the C/C composite with the RL pyrocarbon showed the lowest loss. Resin-derived carbon in C/C composites does not have a significant effect on the friction coefficient, but the wear rate increases greatly with increasing resin-derived carbon content. Wear debris is composed of flocculent particles with polycrystalline structure, along with the matrix carbon, which is worn off directly from the composites.     

基体炭对炭/炭复合材料摩擦磨损性能的影响

采用液相浸渍-炭化法制备了沥青基炭/炭复合材料(P-C/C)和沥青-酚醛树脂双基体炭/炭复合材料(D-C/C),研究了它们的增密效率、抗弯强度和摩擦磨损性能的差别。结果表明:P-C/C的增密效率高于D-C/C的;在体积密度基本相同的情况下,两种复合材料的抗弯强度相近;D-C/C的摩擦因数较大,磨损较严重;基体炭结构和性能的差别是造成两种复合材料摩擦磨损性能不同的主要原因。     

沥青基碳/碳复合材料的弯曲性能

采用三点弯曲法测试了单向和三维四向碳纤维增强的两种沥青基碳/碳(C/C)复合材料(1D-C/C和3D-C/C)在室温及1 800℃高温时的弯曲性能,分析了增强体结构、温度对C/C复合材料弯曲性能的影响,并探讨了其弯曲断裂时的界面机制。结果表明:3D-C/C的弯曲模量高于1D-C/C的,但其抗弯强度却明显低于1D-C/C的;1D-C/C的弯曲断裂呈脆性断裂,而3D-C/C的弯曲断裂则表现出明显的假塑性特征;对同一种增强体结构的沥青基C/C复合材料,在1 800℃时的弯曲性能高于其在室温时的。     

MG63 Osteoblast-like Cells Growth Behaviour on Carbon/Carbon Composites with Different Carbon Matrixes

During the process that implant materials are used for bone replacement,the cell responses to implant materials determine the long-term stability of bone replacement.The microstructure of implant materials is considered as a critical factor that influences the cell responses.Carbon/Carbon composites(C/C composites) are novel implant materials,but there are few reports on the effect of their microstructure,especially the carbon matrixes and holes,on cell behavior.In this paper,C/C composites with different carbon matrixes are prepared by chemical vapor infiltration and pressure impregnation carbonization technique,respectively.The structure of holes is analyzed.The cell responses to C/C composites with different carbon matrixes are evaluated with MG63 osteoblast-like cells.The morphologies of MG63 osteoblast-like cells on the surface of C/C composites,especially in the holes are assessed by scanning electron microscope,and cell proliferation behavior is evaluated by 3-[4,5-dimethylthiozol-2-yl]-2,5-diphenyltetrazolium bromide(MTT) assay. The results show that MG63 osteoblast-like cells have a lamellar morphology with similar sizes and spreading areas as well as the same proliferation behaviors for C/C composites with different carbon matrixes.Carbon matrix shows unapparent influence on the cell growth behavior.Besides,MG63 osteoblast-like cells have various interactions with the holes of C/C composites.The cells stride over the holes with 6～8μm in size,and connect with each other or grow along the curvature wall of the holes with a size of 30-40μm;the cells present three-dimensional morphologies inside the holes and display circular shapes along the ridge of the holes.Diverse cell-material interactions are found according to the size and position of the holes,which provides theoretical foundation for the microstructure design of clinical C/C composites.     

催化FBCVI制备碳纳米纤维增强碳/碳复合材料的组织与力学性能研究

采用薄膜沸腾气相沉积(film-boiling chemical vapor infiltration,FBCVI)工艺,制备原位碳纳米纤维增强碳/碳复合材料(carbon nanofibers-reinforced carbon/carbon composites,CNFs-C/C))。研究了致密化过程中CNFs的生长情况和催化剂的引入对材料组织结构和力学性能的影响。研究表明,致密化前期,原位生长CNFs困难;随着沉积时间延长,CNFs大量增多并被碳基体包覆,CNFs主要为碳纳米线(carbon nanowires,CNWs)。CNFs-C/C的碳基体结构为粗糙层(RL),且存在大量的生长锥。相比于未加催化剂的试样,CNFs-C/C的弯曲强度和模量分别提高了30.9%和39.1%,断裂模式为假塑性断裂。     

密度梯度碳/碳复合材料的制备及性能

采用强制流动热梯度化学气相渗透法在1000～1 250℃制备了密度梯度碳/碳复合材料;借助三点弯曲试验和激光闪烁法测定了复合材料的弯曲性能与导热系数,用偏光显微镜及扫描电子显微镜观察了基体热解碳的组织结构及断口形貌。结果表明:该复合材料上层的最大密度为1.65g·cm~(-3),下层的最小密度为1.10g·cm~(-3),具有明显的密度梯度;复合材料的密度越大,抗弯强度越高;其导热系数也随密度的增加而增大;沉积温度是影响基体热解碳组织的主要因素,高温有利于粗糙层热解碳的生成,而低温有利于光滑层热解碳的生成。     

The Solid Particle Erosion Behavior of Carbon/Carbon and Carbon/Phenolic Composite Used in Re-entry Vehicles

Several engineering components made of carbon-based heat-resistant composites are subjected to severe erosive wear. In view of the above, the solid particle erosion behavior of two and four dimensionally reinforced carbon/carbon (C/C) composites as well as that of carbon/phenolic (C/P) composite has been characterized at the ambient temperature. The investigated C/C composites have been produced through a liquid-phase infiltration method followed by hot isostatic pressing, while the C/P composite prepegs have been cured inside an autoclave. The erosion rates of these composites have been determined for two different impact angles and two different impact velocities using silica sand with average particle diameter of 200 μm. The morphologies of as-received and eroded surfaces of test specimens have been examined with the help of scanning electron microscopy to understand the mechanism of material removal. The erosion response, erosion efficiency, and erosion micromechanisms of these composites have been studied in detail. While the erosion resistance of the C/P composite is found to be superior to that of the investigated C/C composites, the four dimensionally reinforced C/C composite have shown the highest erosion efficiency. All the composites have exhibited a semi-ductile erosion response. Their mechanical properties have little correlation with the erosion rates.     

碳/碳复合材料基体上羟基磷灰石涂层的体外生物活性

通过分析碳/碳复合材料表面等离子喷涂羟基磷灰石(简称HA)涂层在模拟体液中浸泡后的钙离子浓度和pH值的变化,涂层表面沉积物的微观结构、相组成和钙、磷原子数比,研究了该涂层的体外生物活性。结果表明:随着浸泡时间的延长,浸泡液的钙离子浓度降低,pH值升高,涂层表面的CaO完全溶解,α-TCP和β-TCP轻微溶解;涂层表面的沉积物主要是晶相HA,涂层具有良好的体外生物活性。     

热梯度化学气相沉积工艺制备炭/炭复合材料

阐明了热梯度化学气相沉积工艺(CVI)的优越性和用于制备炭／炭复合材料的热梯度化学气相沉积工艺原理；壁冷式热梯度CVI工艺克服了等温化学气相沉积易形成闭孔的缺陷，实现了快速均匀致密化；热梯度CVI工艺设备简单且安全系数高，所制备的炭／炭复合材料密度均匀性好，通过控制工艺参数，利用热梯度CVI工艺可以制备不同微观组织结构的热解炭。