国产PAN基炭纤维增强炭基体复合材料的制动摩擦行为

分别采用国产聚丙烯腈基(即PAN基)炭纤维CCF700(A)和CCF300(B)及日本东丽PAN基炭纤维T300(C)编织二维针刺毡预制体,通过化学气相沉积结合树脂浸渍炭化增密技术制备飞机刹车副用炭/炭复合材料,在HJDS-Ⅱ型地面惯性台上测试这3种炭/炭复合材料的制动摩擦特性。结果表明:用国产炭纤维制备的炭/炭复合材料样件的整体石墨化度低于用进口炭纤维制备的样件。在模拟正常着陆能载下,国产炭纤维增强样件的减速率高于进口纤维增强样件。其中,采用CCF700炭纤维制备的材料A的摩擦因数较高、波动明显,而采用CCF300炭纤维制备的材料B的摩擦因数稳定在0.28左右。同时,刹车盘A和B的刹车过程相对平稳,刹停时间短,但刹车盘C在刹车结束前有明显的刹车力矩回升,有利于刹车过程的稳定性。材料A表面形成较厚的摩擦层,而材料B的摩擦表面摩擦层较薄,这与CCF300炭纤维具有良好的耐磨性有关。     

准单向纤维排布环形炭/炭复合材料的组织与性能

以PAN基炭纤维无纬布为主体,与短切网胎纤维交互叠层制备准单向纤维排布环形炭预制体,然后采用等温化学气相渗透工艺,在丙烯与氮气分压比为1.2:1,系统压力为1.5 kPa的条件下进行增密,制备准单向纤维排布环形C/C复合材料,研究气相渗透温度对增密效率的影响,并对复合材料进行组织观察与导电导热性能测试。结果表明:在980℃温度下化学气相渗透效率最高,480 h后获得密度为1.84 g/cm~3、孔隙率为6.4%的准单向纤维排布C/C复合材料;准单向纤维排布环形C/C复合材料沿轴向方向具有高纤维取向,并且材料沿轴向具有较高的导电与导热性能,其电阻率为20.3μ?·m,热导率为72.8 W/(m·K)。热解炭组织为高织构粗糙层,热解炭生长良好,石墨化度为60.1%。     

炭化工艺对C/C-SiC制动材料摩擦磨损性能的影响

以短炭纤维、Si粉、炭粉和树脂为原料,通过均匀混合、温压成形,在1 500℃原位反应最终制得C/C-SiC复合材料.测试试样的开孔隙率、热扩散率及摩擦磨损性能,研究制备工艺过程中后续炭化对摩擦磨损性能的影响,并对摩擦表面及磨屑进行扫描电镜观察和X射线衍射分析.结果表明:采用树脂浸渍炭化工艺制备的C/C-SiC制动材料具有适中的摩擦因数和较低的磨损率;经后续炭化,树脂转变为树脂炭,以磨粒的形式增大摩擦力,同时有效地降低了磨损率.     

X射线实时成像技术在炭纤维预制体及其复合材料中的应用

炭纤维预制体及其复合材料在制备和使用过程中可能产生不同程度的缺陷,对其进行无损检测非常重要。本工作采用X射线实时成像技术对炭纤维预制体及炭/炭复合材料进行无损检测。结果表明：X射线实时成像技术对炭纤维预制体中可能存在的缺陷和夹杂以及炭/炭复合材料的结构均匀性进行无损检测是有效的。炭纤维预制体中存在锥状断针和局部结构疏松缺陷,采用X射线实时成像技术分析得到的密度分布与取样实测的密度分布结果相吻合,这为炭/炭复合材料制备过程中的无损检测提供了快速、可靠手段。     

热解炭结构对C/C复合材料摩擦磨损性能的影响

以炭纤维整体毡为预制体,采用热梯度化学气相渗透(CVI)工艺制备了2种不同结构基体炭的C/C复合材料,即粗糙层结构材料与光滑层结构材料。研究了2种不同结构基体炭的C/C复合材料在沉积态和热处理态的显微结构、热物理性能及摩擦磨损性能。研究结果表明,在沉积态,2种结构材料都产生严重的氧化磨损,提高材料的石墨化度可显著降低材料的氧化磨损;不管是在沉积态还是在热处理态,RL结构材料的刹车性能曲线都明显优于SL结构材料的刹车性能曲线,这表明热解炭的微观结构不同是造成C/C复合材料摩擦性能差异的根本原因。     

CF/CVD/树脂炭复合材料的摩擦性能

采用针刺炭纤维整体毡作为骨架，经CVD致密，树脂浸渍固化增密及炭化，石墨化后制得C/C复合材料，研究了CVD炭和树脂炭含量对摩擦性能的影响。实验结果表明：CVD炭具有典型显微组织是材料具有良好摩擦性能的保证；C/C复合材料中加入适量的树脂炭不会影响材料的摩擦性能；摩擦系数大小不一定和摩损率成对应关系。     

新型隔热炭/炭复合材料的制备工艺

针对国内对高性能隔热材料的广泛需求,以炭纤维毡为预制体、热固性树脂为先驱体,采用浸渍-固化-炭化的方法制备新型低密度隔热炭/炭复合材料.研究浸渍液的浓度、树脂和毡体的类型、层间粘接剂的浓度和类型、固化时所加的外部压力等因素对材料密度的影响,并借助扫锚电镜观察、分析样品的微观结构.实验结果表明,采用长纤维毡作预制体、呋喃树脂作先驱体,浸渍液浓度为8%,层间粘接剂选用环氧树脂,固化压力为1 200 MPa时,炭/炭复合材料的密度为0.17 g/cm3,热导率为0.19 W/(m·K).     

浸渍模压与CVD复合工艺制备质子交换膜燃料电池用炭纸

以干法成形技术制备的炭纤维坯体为预制体,酚醛树脂作粘结剂,通过浸渍、模压、炭化、CVD和石墨化制备质子交换膜燃料电池用炭纸.借助扫描电镜(SEM)观察炭纸表面形貌,用四探针法测试炭纸面电阻.研究结果表明:浸渍模压与CVD复合工艺在炭纤维表面形成连续均匀的热解炭层,增强纤维与基体的结合,减少裂纹缺陷,提高炭纸的导电性能;炭纸横向和纵向的面电阻分别为0.34 Ω和0.37 Ω,小于日本东丽炭纸的面电阻0.43Ω和0.70Ω.     

新型浆料注射法制备C/C复合材料的显微组织及力学性能

采用浆料注射法将天然鳞片石墨粉添加到纤维预制体中,并结合化学气相渗透工艺(CVI)制备C/C复合材料。通过X射线无损检测、扫描电镜、偏光显微镜和材料力学性能测试,研究石墨浆料注射对C/C复合材料显微组织与力学性能的影响。结果表明:石墨浆料注射可将石墨引入到纤维预制体中,替代部分热解炭,并为热解炭提供新的形核位点和沉积表面,加速CVI致密化进程;且石墨的加入有利于粗糙层热解炭的形成,提高材料的可石墨化度。经80 h等温CVI制得密度为1.68 g/cm~3的C/C复合材料,抗弯强度为69.07 MPa,与传统等温CVI工艺相比,抗弯强度相近,平均增密速率提高近3倍;热解炭将纤维和石墨连成一个整体,材料表现出一定的假塑性断裂。     

SiC/C-Cu复合材料的载流磨损性能

采用粉末冶金法制备SiC/C-Cu复合材料,研究SiC颗粒含量对该材料组织结构与物理性能的影响,并在HST-100载流摩擦磨损试验机上进行载流磨损试验,研究摩擦速度、电流密度与SiC颗粒含量对SiC/C-Cu复合材料磨损率的影响以及磨损机理的变化。结果表明:SiC颗粒均匀分布于铜基体中。随SiC含量增加,复合材料的硬度和孔隙率都逐渐增大,密度和导电率降低。添加SiC颗粒可增强C-Cu复合材料的抗磨损性能,材料的磨损率随摩擦速度和电流密度增加而增加,随SiC含量增加呈先降低后上升的趋势,含2%SiC(质量分数)的SiC/C-Cu复合材料具有优异的抗载流磨损性能。添加SiC颗粒可减少摩擦磨损过程中铜基体的粘着磨损,磨损机理主要为磨粒磨损和电弧侵蚀磨损。     

Chinalco Signed Framework Agreement for Strategic Cooperation with Harbin Municipal Government

正Last month,Chinalco signed framework agreement for strategic cooperation with Harbin Municipal Government in Harbin Xiong Weiping,Chairman of Chinalco,said that based on the strategic deployment to build world top-class mining company with the highest growth potential,Chinalco was now concentrating all efforts on making strategic transition and structural adjustment,strategic cooperation with the local governments where     

Jiangxi Promotes Jiangxi Copper Corporation To Become The World's Most Competitive Mining Company

<正>According to the latest info from Jiangxi Province State-owned Assets Supervision and Administration Commission,Jiangxi Copper Corporation was approved to become the first pilot enterprise for deepening reform.Contents of the pilot work is"Three Self"(self expansion,self decision-making,self     

Journal of Rare Earths Contents List of Vol.32(2014)

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Contributions to Baosteel Technical Research wanted

正Baosteel Technical Research,a quarterly journal,which is issued domestically and abroad,is run and sponsored by Baosteel Group Corporation.Baosteel Technical Research mainly reports the achievements in technological innovation,academic research,new product development and industrial equipment improvement by Baosteel.It will continue to follow up on hot topics and serve the company’s technological development and progress.Its readers include experts in     

Ministry of Industry and Information Technology: No Short Term Solution For Our Country’s Excess Nonferrous Metal Smelting Capacity

【正】According to the Ministry of Industry and Information Technology,the Ministry has released the 2013 Operation Report on China’s Industrial Communication Indu...     

Chinalco Signed Framework Agreement for Strategic Cooperation with Gansu Province

正Recently,Chinalco and Gansu Provincial People’s Government signed"Framework Agreement for Strategic Cooperation on Reform,Restructuring and Transition Development of Chinalco’s Electrolytic Aluminum Enterprises in Gansu",signifying that the strategic cooperation between Chinalco and Gansu Province had made new substantive progress.     

Unavoidable Economic Cycle:30% Of Nonferrous Metal Companies Were Involved In Restructuring

正Owing to continual downturn in real estate and bulk commodity markets,a number of traditional industries in China suffered unfavorable impact in performance.With the progressive disclosure of third quarter report,the no-pleasant-surprise performance of     

Baotou Rare Earth Became the World's Biggest High Performance Magnetic Material Base

正The High Performance Magnetic Material Phase II Project,an industry upgrading project implemented by Inner Mongolia Baotou IronSteel Rare Earth(Group)Hi-tech Co.,Ltd,recently basically finished equipment commissioning,signifying that the enterprise had developed the production capacity of15000 t/a Nd-Fe-B strip casting alloy and 5000t/a Nd-Fe-B magnet,thus becoming the world’s     

Introducing Two Central Enterprises to Integrate Rare Earth Industry,Shandong Rare Earth Group Breaks Surface

正With the signing of"Letter of intention for Propelling Integration of Shandong Rare Earth Enterprises"between Shandong Province Commission Of Economy and Informatization,China IronSteel Research Institute Group("China Steel Institute"),and China Rare MetalsRare Earth Co.,Ltd("China Rare Earth"),the"Shandong Rare Earth Group"jointly set up by the 3 units thus broke surface.On August 9,reporters of the China Economic Herald learned from Shandong Province     

Aluminium Production by Province or City in 2014

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