CuxSiy改性C/C-SiC复合材料的制备及其性能

以针刺整体炭毡为预制体,采用化学气相渗透法(CVI)增密制备C/C多孔体,然后采用反应熔体浸渗法(RMI),将Cu与Si同时熔渗进C/C坯体中制备CuxSiy改性C/C-SiC复合材料.研究CuxSiy改性C/C-SiC复合材料的组织结构、力学性能和摩擦磨损性能,并与C/C-SiC复合材料进行对比.结果表明:CuxSiy改性C/C-SiC复合材料的弯曲强度和冲击韧性略低于C/C-SiC复合材料的;采用30Cr钢作对偶时,CuxSiy改性C/C-SiC复合材料的摩擦因数约为0.24,线磨损率小于4 μm·side-1·cycle-1,均与C/C-SiC复合材料的相近,但其摩擦表面温度降低约50 ℃;以自身材料作对偶时,CuxSiy改性C/C-SiC复合材料的摩擦磨损性能略低于C/C-SiC复合材料的.     

不同频率下C/C复合材料的往复式滑动摩擦特性

制备了两种具有不同基体炭类型的C/C复合材料,测试其与GCr钢在40 N时配副时的往复式摩擦行为.结果表明:随滑动频率的增加,两种试样的摩擦因数先增加,均在400 r/min时达到最大,之后除在1 200 r/min时略有反弹外,基本表现出线性下降趋势.在相同频率下,具有光滑层结构热解炭基体材料(SL)的摩擦因数低于另一种具有粗糙层结构热解炭和树脂炭混合基体(RL/RC)材料的.其中,RL/RC基体材料的摩擦因数在0.183～0.063之间;而SL基体材料的摩擦因数在0.150～0.059之间.随时间的延长,所有试样的摩擦因数均逐渐趋于稳定.Raman检测结果表明,随滑动频率增大,材料摩擦表面的微区石墨化度增加.但SEM形貌表明,随滑动频率增大,材料摩擦表面形貌由光滑变得粗糙,磨粒磨损加剧.     

C／C-SiC陶瓷基复合材料刹车副摩擦性能研究

以不同孔隙率的C／C复合材料为预制体，以甲基三氯硅烷（CH3SiCl3）为反应源气，以氩气为载气，高纯氢气为稀释气体，用化学气相渗透法（CVI）制备一系列C／C—SiC复合材料。通过在MM-2000摩擦磨损实验机上的摩擦试验，对该系列材料的摩擦磨损性能进行了研究，详细分析了不同压力和摩擦环境（湿态和干态）对材料摩擦性能的影响。结果表明，在外界条件相同的情况下，随着压力的增大，材料的摩擦系数先增大后降低；随着SiC含量增加，材料摩擦磨损性能先增强后下降，SiC含量在40％左右具有最好的摩擦磨损性能。在湿态环境下材料的平均动摩擦性能明显衰退，但是当压力增大时这种衰退的影响减小。     

C/C-SiC陶瓷基复合材料刹车副摩擦性能研究

以不同孔隙率的C/C复合材料为预制体,以甲基三氯硅烷(CH3SiCl3)为反应源气,以氩气为载气,高纯氢气为稀释气体,用化学气相渗透法(CVI)制备一系列C/C-SiC复合材料.通过在MM-2000摩擦磨损实验机上的摩擦试验,对该系列材料的摩擦磨损性能进行了研究,详细分析了不同压力和摩擦环境(湿态和干态)对材料摩擦性能的影响.结果表明,在外界条件相同的情况下,随着压力的增大,材料的摩擦系数先增大后降低;随着SiC含量增加,材料摩擦磨损性能先增强后下降,SiC含量在40%左右具有最好的摩擦磨损性能.在湿态环境下材料的平均动摩擦性能明显衰退,但是当压力增大时这种衰退的影响减小.     

短炭纤维增强C/C-SiC制动材料的摩擦磨损性能

采用温压？原位反应法制备C/C-SiC复合材料,利用QDM150型摩擦试验机研究短炭纤维（SCF）长度和纤维体积分数对C/C-SiC制动材料摩擦磨损性能的影响。结果表明：C/C-SiC制动材料能够保持较高且稳定的摩擦因数;SCF的体积分数将影响C/C-SiC制动材料的摩擦磨损性能,纤维体积分数为10%时,材料具有适中的摩擦因数和较低的磨损率;SCF长度对C/C-SiC制动材料的摩擦磨损性能有显著影响,炭纤维长度为12 mm时,材料具有最佳的摩擦磨损性能。     

模压技术制备C/C-BN复合材料的摩擦学特性

以h-BN、石墨、短切PAN炭纤维和酚醛树脂为原料,采用单向模压结合呋喃树脂浸渍炭化技术制备C/C-BN复合材料。在M2000型实验机上测试不同取向的C/C-BN试样与表面镀Cr的40Cr钢配副时的摩擦磨损行为。结果表明:在平行于压制方向的试样(试样1)中,抗压强度达82.43 MPa,高于垂直于压制方向试样(试样2)的(51.47MPa)。摩擦实验结果表明:随载荷增加,试样1、试样2的摩擦因数均先增加后降低,试样1的摩擦因数在120 N时达到峰值0.157,而试样2在100 N时达到峰值0.152;随载荷增加,试样1的体积磨损除150 N外,基本为增加态势,最高达2.07 cm3;而试样2的体积磨损则呈现三段式增加趋势,最高值为1.66 cm3。SEM形貌表明,在实验后,试样1的摩擦膜更完整、致密。其中,在60 N时,试样1的摩擦膜表层因粘着发生卷曲撕裂,而试样2则形成了网络状裂纹。     

RMI法制备穿刺C/C-SiC复合材料的微结构及烧蚀性能研究

以无纬布/网胎0°/90°叠层穿刺预制体为增强体,采用化学气相渗(Chemical vapor infiltration,CVI)、树脂浸渍碳化(Polymer infiltration carbonization,PIC)与反应熔渗(Reactive melt infiltration,RMI)复合工艺制备穿刺C/C-SiC复合材料,研究其微观组织及在C₂H₂-O₂焰中的烧蚀行为。结果表明：无纬布、穿刺纤维束由CVI+PIC制备的碳基体填充而形成致密C/C区域,RMI生成的SiC主要位于网胎层中,其含量37.3wt%。复合材料表面因过量硅化而形成了SiC富集层。烧蚀距离20mm、O₂:C₂H₂=2:1时,烧蚀600s后材料X-Y、Z向线烧蚀率分别为：0.8×10^_-4 mm/s、3.6×10^_-4 mm/s,比PIP工艺制备C/C-SiC材料烧蚀率小一个数量级。烧蚀面SiC富集层保护及被动氧化作用是材料具有优异抗氧化烧蚀性能的主要原因。随烧蚀距离由20mm向10mm减小,复合材料烧蚀率先缓慢变化后快速增大,烧蚀率快速增长阶段复合材料发生主动氧化烧蚀。     

润滑状态对C/C复合材料摩擦磨损特性的影响

在M-2000型摩擦磨损实验机上,对3种C/C复合材料与40Cr钢配副分别在干态、水润滑、油润滑3种条件下的摩擦磨损行为进行了研究.结果表明:在3种润滑条件下,干态摩擦试样的摩擦系数最大,体积磨损最小;基体炭为树脂浸渍炭的试样在3种试样摩擦系数最高,约为0.141～0.205;水润滑时试样的摩擦系数最小,为0.05～0.10,但体积磨损最大,最高可达7.75 mm3油润滑时试样的摩擦系数和体积磨损均介于干态和水润滑之间;干摩擦时,试样的摩擦系数随着载荷增加而缓慢降低,水润滑和油润滑的摩擦系数则随着载荷的增加而先增加后减少;干态摩擦时材料表面形成了完整的摩擦膜,水润滑和油润滑条件下摩擦膜很薄且不完整;所有润滑条件下试样均以磨粒磨损或犁削磨损为主.     

C/C-SiC摩擦材料的研究进展

综述了C/C-SiC摩擦材料的研究现状,以及C/C-SiC摩擦材料的发展历程。详细分析C/C-SiC摩擦材料的摩擦磨损性能影响因素及机理,介绍了C/C-SiC摩擦材料的改性及应用现状,并对未来的研究重点进行了展望。     

C/C-SiC复合材料的制备及其层间剪切强度分析

采用先驱体浸渍裂解结合液硅渗透的方法制备C/C-SiC复合材料。通过X射线衍射和扫描电镜分析了材料的成分和微结构,采用压缩双切口试样法分别在室温和1600℃下测试其层间剪切强度,分析了微观剪切破坏机理。结果表明:碳纤维表面的热解碳(PyC)与液硅反应生成一层SiC,保护纤维不受残余Si的损伤。树脂碳和液硅反应生成的SiC填充了多孔C/C的孔隙。材料的高温层间剪切强度是室温下的2倍左右。室温下基体存在残余热应力,界面结合强度低,材料属于脆性断裂,高温下基体残余热应力得到释放,界面结合强度增大,基体裂纹部分闭合,该复合材料可承受更大的剪切应力。     

Influence of load on sliding tribology of C/C composite with 40Cr steel couple coated by Cr

With the 40Cr steel couple coated by Cr, the sliding tribology behavior of two kinds of C/C composites with different matrix was tested using a M2000 wear tester. The results show that with the increasing of load, the friction coefficients of the composite with resin carbon matrix（RC） decrease quickly from 0.156 under 60 N to 0.123 under 150 N, while those of the composite with rough lamination/smooth lamination/resin carbon （RL/SL/RC） change only between 0.122 and 0.101. The wear volume loss of the two composites increases except for under 100 N. The SEM morphology shows that with the increasing of load, the worn surface of the composite with RC becomes more and more integrated while the size of the debris becomes less and less. The Raman spectrum shows that the graphitization on the worn surface of the fibers draws down after 100 N, the graphitization of the boundary between the fiber and the matrix carbon rises up to 150 N, but the graphitization of the matrix carbon draws down all the while. With the increasing of load, the graphitization on the worn surface of all the worn areas becomes closer and closer, which indicates the worn surface of the different component has the similar friction ability. The composites with RL/SL/RC have better tribological characteristic than the composite with RC.     

Rapid fabrication of C/C/SiC composite by PIP of HMDS

The C/C/SiC composite was fabricated within several days by the method of precursor impregnation and pyrolysis (PIP) using hexamethyldisilazane (HMDS) as the precursor. The carbon fiber plates, woven and punctured with two-dimensional orthogonal continuous carbon bundle and short carbon fiber, were used as the reinforced preforms. The characters of the C/C/SiC composite were analyzed using XRD, EDS and SEM, and three-point-bending test. The results indicated that pyrolyzed substance of the precursor contained excessive carbon, followed by silicon, and a small amount of nitrogen. There were micro-cracks on the massive matrix. The phase composition was difficult to distinguish, primarily considered as the Si–C–N composite. The structure of C/C/SiC was dense and homogeneous with some pores whose sizes were less than 5 μm between fibers and less than 100 μm between the carbon fiber bundles, respectively.

Fiber pull-out was observed on the bending fracture surface. The stress–strain curve of both at room temperature and 1300 °C appeared ascending zigzag. Flexural strength was 150 MPa at 1300 °C, higher than 121 MPa at room temperature.     

Al2O3/Mo composite and its tribological behavior against AISI201 stainless steel at elevated temperatures

Al₂O₃-reinforced molybdenum (Mo) composites were successfully prepared by powder metallurgy to improve the wear resistance of Mo components at high temperature. The reinforced Al₂O₃ particles are uniformly distributed in the Mo matrix; thus, the Al₂O₃/Mo composite is harder than monolithic Mo. The friction coefficients of both monolithic Mo and the Al₂O₃/Mo composite decrease by 37% and 42%, respectively, at 700 °C compared with those at room temperature (self-lubricating phenomenon). This phenomenon is attributed to the formation of very soft MoO₃ and FeMoO₄ metal oxides on the friction surface at high temperature. The Al₂O₃/Mo composite has better wear resistance than monolithic Mo at both room temperature and at 700 °C. The notable resistance of the composite particularly at 700 °C can be attributed to its increased hardness and the soft tribofilm forming on the worn surface.     

1.6%C超高碳钢的电致超塑性压缩行为及其与40Cr钢的电致超塑性焊接

以热机械处理获得的超细晶1.6%C超高碳钢为研究对象,借助电致超塑性压缩试验研究了电场强度和初始应变速率对超高碳钢超塑性的影响,并探讨了其与40Cr钢电致超塑性焊接的可行性.实验结果表明,在压缩温度780℃、初始应变速率(0.5-5.0)×10-4 s-1,试样接正极环状电极接负极条件下,超高碳钢的应力应变曲线呈现出明显的超塑性压缩流变特征,其应变速率敏感性指数为0.46;当电场强度为3 kV/cm时,其超塑稳态流变应力降低10%以上.在焊接温度780℃、初始应变速率1.5×10-4 s-1、预压应力56.6MPa、电场强度3 kV/cm条件下,超高碳钢与40Cr钢实现了电致超塑性焊接,其接头拉伸强度达到533 MPa,比不加电场时增加15%.     

40Cr钢的动态再结晶数学模型

利用单道次热压缩试验在Gleeble-1500热模拟试验机上,通过控制变形温度:973、1023、1073和1123 K,应变速率:0.01、0.1、1和5 s-1研究了40Cr钢的动态再结晶行为,根据应力应变曲线分析了40Cr钢的动态再结晶规律,采用回归法确定了双曲线本构方程中的材料常数和激活能(366.7 kJ/mol),建立了40Cr钢的本构方程;同时确定了40Cr钢的临界应变、峰值应变、峰值应力、稳态应力和动态软化量Ω等关键物理量。     

40Cr钢表面电火花沉积WC的界面行为

以WC合金作为电极,氩气为保护气体,采用电火花沉积技术在40Cr钢表面沉积WC合金层,通过显微硬度计、扫描电镜(SEM)及能谱分析(EDS),X射线衍射等测量方法,研究了40Cr钢表面电火花沉积WC层的显微硬度、表面状态、界面行为及相结构组成.结果表明,WC合金电火花沉积层存在微裂纹及气孔,主要由W、Fe6W6C、Fe3C和Cr23C6等相组成;沉积层显微硬度达820 HV,为基体的4.5倍;沉积层断面连续、致密,厚度为30 μm;沉积层与基体之间发生了元素的相互扩散与合金化过程,呈冶金结合,无明显界面.     

钒对Cr12Mo模具钢渗氮层及其摩擦学行为的影响

在Cr12Mo和Cr12MoV模具钢表面进行气体渗氮处理,对比分析了V对Cr12Mo模具钢渗氮层显微结构及其摩擦学行为的影响。结果表明,气体渗氮后两种模具钢的表面均制备出深度约120 μm的渗氮层,由表及里依次为渗氮层、扩散层和基体;V提高了模具钢的耐磨性,Cr12MoV表现出较好的耐磨效果;相比V对模具钢基体和扩散层硬度的提升而言,V对渗氮层最大硬度值附近区域的硬度提升幅度更为明显;V对两种模具钢渗氮层耐磨性的影响并不明显,但V的主要贡献在于促进了渗氮时N的有效渗入,大大提高了渗氮层与扩散层间的界面结合力,避免了渗氮层与扩散层间的开裂,促使磨损机制由疲劳磨损转变为黏着磨损,进一步提高了渗氮层的服役寿命。     

双连续复合材料SiC/Fe-40Cr与SiC/Al2618合金干摩擦磨损行为的实验研究与数值分析(英文)

利用环环式摩擦磨损试验机研究双连续复合材料SiC/Fe40Cr与SiC/2618Al合金在滑动速度30~105m/s,载荷1.0~2.5MPa条件下的干摩擦磨损性能。实验结果表明,在较高的载荷和滑动速度下,SiCn/2618Al复合材料的磨损机制是两体磨料磨损和氧化磨损。作为增强相的连续网络结构的SiC陶瓷可避免通常发生在传统的粒子增强复合材料上的第三体磨损现象。机械混合层(MML)极大地控制了复合材料的磨损速率和摩擦系数。在进行较高的滑动速度测试时,由于机械混合层的间歇的生形和消除,复合材料表现出较高的摩擦系数和波动。为了便于有限元模型(FEM)计算,用一个连续结构单元来代表三维碳化硅结构增强铝基复合材料的微观结构。利用有限元模型(FEM)预测的复合材料磨损和应力应变数据与实验数据一致     

Characterization and tribological properties of composite 3Cr13/FeS layer

The 3Cr13 coating was prepared on the surface of 1045 steel by high velocity arc spraying method, and then treated by low temperature ion sulfuration to obtain the solid lubrication composite 3Cr13/FeS layer. SEM was used to observe the surface, cross-section and worn scar morphologies. XRD was utilized to analyze the phase structure. X-ray stress determinator was utilized to measure its residual stress. The nano-hardness and elastic modulus of composite 3Cr13/FeS layer were surveyed by the nano-indentation tester. The tribological properties were investigated on a ball-on-disk wear tester under dry and oil lubrication conditions. The results showed that the friction coefficient and wear scar depth of the composite 3Cr13/FeS layer were always lower than those of FeS film and 1045 steel under dry and oil lubrication conditions. Therefore the composite 3Cr13/FeS layer had excellent Friction-reduction and anti-wear properties.     

C／C坯体对RMI C／C—SiC复合材料组织的影响

以PAN基炭纤维（Cf）针刺整体毡为预制体，用化学气相渗透（CVI）、浸渍炭化（IC）方法制备了不同炭纤维增强炭基体的多孔C／C坯体，采用反应熔渗（RMI）法制备C／C—SiC复合材料，研究了渗Si前后坯体的密度和组织结构。结果表明：不同C／C坯体反应溶渗硅后复合材料的物相组成为SiC相、C相及单质Si相；密度低的坯体熔融渗硅后密度增加较多；密度的增加与开口孔隙度并不是单调增加的关系，IC处理的坯体开口孔隙度低，但渗硅后复合材料的密度增加较多；IC坯体中分布分散的树脂C易与熔渗Si反应，CVI坯体中的热解C仅表层与熔渗Si反应，在Cf和SiC之间有热解C存在；坯体密度相同时，IC处理的坯体中SiC量较多，单质Si相含量少且分散较好，而CVI坯体中SiC量较少，单质Si相的量较多；制备方法相同时，高密度的C／C坯体，渗硅后C相较多。