共查询到20条相似文献,搜索用时 31 毫秒
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通过分析C/SiC在高温(1250、1300和1350℃)空气氧化过程中质量、强度、物相、气孔率、微观形貌演变规律, 并同时采用动态热机械分析仪测得内耗的变化趋势, 研究了氧化对其内耗行为的影响规律, 进而为以内耗表征复合材料的氧化行为奠定基础。为明确C/SiC各组元在氧化与内耗行为对应关系中所发挥的作用, 进一步研究了SiC陶瓷在1300℃、空气中的氧化与内耗行为之间的对应关系。结果表明: SiC陶瓷氧化对其内耗行为的影响规律不明显且影响程度较弱; C/SiC在氧化过程中的内耗行为受C相的氧化损伤控制, 且作用规律明显, 其内耗保持率曲线均出现峰值, 其中1250、1300和1350 ℃的峰值分别为6.65、3.48和1.59。 相似文献
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界面相对3D-SiC/SiC复合材料静态力学性能及内耗特征的影响 总被引:1,自引:0,他引:1
采用先驱体浸渍裂解工艺制备无界面、SiC、PyC和PyC/SiC等界面相SiC/SiC复合材料,研究了SiC/SiC复合材料的微观结构及静态力学性能,并通过强迫振动法系统分析了界面相对复合材料内耗行为的影响。研究结果表明,引入界面相有效改善了复合材料的微观结构及力学性能,并降低了复合材料的内耗。其中, PyC/SiC复相界面中亚层SiC限制了PyC界面相与纤维的结合及塑性形变,提高了复合材料的力学性能;同时,界面相对SiC/SiC复合材料内耗行为有显著影响,材料内耗水平与界面剪切强度成反比。对比50和350℃时的材料内耗变化率发现,随界面剪切强度增大,材料内耗呈降低的趋势,且含有PyC的PyC/SiC界面复合材料具有较低的内耗变化率,说明PyC/SiC复相界面的SiC/SiC复合材料更适于高温振动环境。 相似文献
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碳纤维增强的纳米碳化硅陶瓷基复合材料力学性能优良,且具有一定的生物相容性,因此可作为一种新型的可取代钛合金的全尺寸整体人工骨骼。研究了具有三向正交结构的T300和M30碳纤维预制体对C/SiC复合材料制备过程和抗弯强度的影响规律。以聚碳硅烷为先驱体,以二乙烯基苯为溶剂和交连剂,采用聚合物浸渍热解法制备了C/SiC复合材料,采用阿基米德排水法测量其密度和气孔率,采用三点抗弯法测量其抗弯强度。M30 C/SiC抗弯强度比T300 C/SiC高6.7%,表明碳纤维弹性模量对复合材料基体开裂强度有显著影响,并通过增加纤维径向强度以及承担载荷的比例提高了复合材料的断裂强度。 相似文献
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为研究预制体结构及界面对三维编织SiC/SiC复合材料拉伸性能的影响,采用先驱体浸渍裂解法(PIP)分别制备了三维四向和三维五向SiC/SiC复合材料,并引入热解炭/碳化硅(PyC/SiC)复合界面层,进行拉伸性能测试和断口形貌观察。结果表明,三维五向SiC/SiC复合材料拉伸性能优于三维四向SiC/SiC复合材料,三维五向SiC/SiC复合材料的拉伸强度、模量和断裂应变分别是三维四向SiC/SiC复合材料的1.22倍、1.25倍、1.43倍,且比三维四向SiC/SiC复合材料具有更好的强度可靠性。这是由于三维五向SiC/SiC复合材料增加了受力方向的纤维含量,限制了纤维在外力作用下的转动和变形,起到定型和稳固作用。添加PyC/SiC复合界面层,三维五向SiC/SiC复合材料的拉伸强度、模量及断裂应变分别提高了21.7%、15.0%和11.0%。界面的存在可以保护纤维,调节纤维与基体之间的热应力,受力时诱使裂纹偏转和分叉,消耗能量,提高三维五向SiC/SiC复合材料的拉伸性能。 相似文献
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反应熔体渗透C/SiC复合材料的摩擦性能 总被引:4,自引:0,他引:4
以不同结构类型及密度的C/C复合材料为预制体,采用反应熔体渗透法制备了C/SiC复合材料,研究了不同结构C/SiC复合材料的密度、组分含量、热扩散系数与摩擦性能相互之间的关系.结果表明随着碳含量的降低,复合材料的密度增加;短切纤维C/SiC、低密度针刺C/SiC与高密度针刺C/SiC复合材料的平均摩擦系数分别为:0.28,0.28与0.42;随着热扩散系数的增加,复合材料的摩擦稳定性系数升高;并且对于短切纤维C/SiC,摩擦实验后基本形成了连续光亮的摩擦面. 相似文献
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《Materials Letters》2007,61(19-20):4114-4116
Performance of three kinds of continuous fiber reinforced SiC matrix composites prepared by chemical vapor infiltration (CVI) method, i.e. 2D C/SiC, 3D C/SiC and 3D SiC/SiC composites, have been investigated in the high temperature combustion environment gas with various creep stresses. The relationship between the life time of composite and the normalized peak strength, defined by the ratio of the test stress to the material strength, was studied. The life time of composites decreased with increasing the normalized peak strength following an exponential relationship. The oxidation resistance of the SiC/SiC composite was the best and that of the 2D C/SiC composite was the worst in the high temperature combustion environment with an applied stress. The experimental results suggested that there was a critical normalized peak strength which controls the oxidation mechanism of C/SiC. Below the critical normalized peak strength, the degradation of C/SiC in the combustion environment was controlled by the diffusion of oxygen and water vapor through the cracks in the composite. Above the critical normalized peak strength, the degradation was controlled by the oxidation of C fibers. 相似文献
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In this paper, a numerical model which incorporates the oxidation damage model and the finite element model of 2D plain woven composites is presented for simulation of the oxidation behaviors of 2D plain woven C/SiC composite under preloading oxidation atmosphere. The equal proportional reduction method is firstly proposed to calculate the residual moduli and strength of unidirectional C/SiC composite. The multi-scale method is developed to simulate the residual elastic moduli and strength of 2D plain woven C/SiC composite. The multi-scale method is able to accurately predict the residual elastic modulus and strength of the composite. Besides, the simulated residual elastic moduli and strength of 2D plain woven C/SiC composites under preloading oxidation atmosphere show good agreements with experimental results. Furthermore, the preload, oxidation time, temperature and fiber volume fractions of the composite are investigated to show their influences upon the residual elastic modulus and strength of 2D plain woven C/SiC composites. 相似文献
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结合复合材料氧化质量损失率模型和混合率公式, 发展了单向C/SiC复合材料在无应力氧化下的弹性模量预测方法。对400~700 ℃和700~900 ℃两种氧化机制下C/SiC复合材料的弹性模量进行了预测, 分析了氧化温度、氧化时间和纤维体积含量对C/SiC复合材料弹性模量的影响。开展了单向C/SiC复合材料在650 ℃和800 ℃空气环境下的无应力氧化试验, 建立了复合材料质量损失率与氧化时间的变化关系, 得到了氧化后材料拉伸应力-应变曲线。同时, 将理论预测值与试验结果进行对比, 发现理论值与试验值基本吻合, 从而验证了该方法能够有效地预测无应力氧化下陶瓷基复合材料的弹性性能。 相似文献
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Defects created during the manufacture of an oxide/oxide and two non-oxide (SiC/SiNC and MI SiC/SiC) ceramic matrix composites (CMCs) were categorized as follows: (1) Intra-yarn defects such as dry fibers, (2) Inter-yarn defects such as those at crossover points, matrix voids, shrinkage cracks and interlaminar separation, and (3) Architectural defects such as layer misalignment. Their impact on elastic properties was analytically investigated using a stiffness averaging approach considering the defects to have volumetric and directional influences. In-plane tensile and shear moduli as well as the through-thickness compressive modulus were experimentally evaluated. Results of analytical model were around 7% on average from the mean value of the experimental data. It was observed that interlaminar separation drastically reduced the through-thickness modulus by about 63% for the SiC/SiNC, 40% for the MI SiC/SiC and around 32% for the oxide/oxide composites. Shrinkage cracks in oxide/oxide composite reduced the in-plane tensile and shear moduli by 14% and 8.8%, respectively. 相似文献
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以SiC或Al2O3磨粒为颗粒增强相,氯丁橡胶(CR)或丙烯酸酯橡胶(ACM)为基体制备了不同种类、不同质量比的磨粒与橡胶共混的颗粒/橡胶复合材料。当SiC与CR质量比小于50∶100时,同一配比多次重复实验,颗粒/橡胶复合材料杨氏模量值波动不明显,标准差最大值为1.09。针对橡胶的黏弹性导致工件与不同颗粒/橡胶复合材料动静态应力不一致的问题,通过振动测试和动态力学分析(DMA),发现在加工所需温度区间20~50℃,SiC/CR或Al2O3/CR复合材料与SiC/ACM复合材料相比,其动静态应力的最大偏差值分别为2.5%和16%,下降幅度明显,且DMA结果显示,SiC/CR或Al2O3/CR复合材料的损耗因子tanδ小于0.3,因此优选CR为梯度功能研磨抛光盘颗粒/橡胶复合材料的基体。 相似文献
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The effects of the ceramic particle material on the flexural Weibull modulus, characteristic flexural strength, and damage parameters of particulate-reinforced metal-matrix composites were studied. Three high volume fill composites were fabricated using the pressure infusion casting technique: they were reinforced with SiC, B4C, and -Al2O3 particles. Four-point bend testing determined the effects of particle material on flexural strength and elastic modulus. It was found the B4C and SiC composites had similar flexural Weibull modulus, low deflection, and similar damage parameters. The -Al2O3 reinforced composite had the largest flexural Weibull modulus, highest deflection at failure, and largest damage parameter. Extensive microstructural and SEM fractographs were taken of the as-processes and fractured specimens. The mechanisms leading to the dominant failure modes are discussed. 相似文献
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通过化学气相渗透法(CVI)结合反应熔体浸渗法(RMI)制备了三维针刺,C/SiC刹车材料 , 利用 MM21000型摩擦磨损试验机系统研究了C/SiC刹车材料的摩擦磨损性能,采用光学显微镜和扫描电子显微镜分别对摩擦表面和磨屑形貌进行了观察。结果表明:干态刹车条件下,当初始刹车速度相同时,摩擦系数随着刹车压力的升高而逐渐降低;当刹车压力相同时,摩擦系数随着初始刹车速度的增加先升高后降低。湿态摩擦性能衰减小(衰减约8 %) 、恢复快;静态摩擦系数高(为0. 56~0. 61),摩擦系数随着初始刹车温度的升高而显著降低。当刹车压力相同时,磨损率随着初始刹车速度的增加而增大;当初始刹车速度大于20 m/s时,刹车压力的增大使磨损率显著增加。 相似文献
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Yanzhi Cai Shangwu FanHeyi Liu Litong ZhangLaifei Cheng Benxing DongJuan Jiang 《Composites Science and Technology》2009
Three-dimensional (3D) needled carbon/carbon (C/C) composites with a lowest porosity of 15.6% were achieved after 1 cycle of impregnation by phenolic resin slurry containing graphite filler, hot-pressing curing and pyrolysis. Carbon/silicon carbide (C/SiC) composites were obtained by liquid silicon infiltrating C/C composites. The aim was to incorporate cost effectiveness and excellent performance of C/SiC braking material. Using filler content not exceeding 30 wt% in the slurry promised undamaged C/C segments in C/SiC composites. The linear wear rate of C/SiC using 30 wt% filler was 0.33 μm side−1 cycle−1 and displayed a fourfold decrease; its weight wear rate was 2.46 mg side−1 cycle−1 and minus 171%, compared with the previously reported values of C/SiC without filler, at a braking velocity of 28 m/s. Its friction coefficients and friction stability coefficients appeared relative insensitive to changes in braking velocities and displayed higher values at high braking velocities compared with the previous values. 相似文献
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《Materials Letters》2006,60(25-26):3197-3201
Oxidation behavior of a three dimensional (3D) Hi–Nicalon/SiC composite with CVD SiC coating was investigated in the simulated air using a thermogravimetric analysis (TGA) device. Below 1100 °C, the oxidation kinetics was controlled by gas diffusion through the defects in the SiC matrix and coating and resulted in the consumption of PyC interphase. The residual flexural strength did have not a remarkable fluctuation and the relationship between the residual strength to temperature and weight change to temperature of the 3D Hi–Nicalon/PyC/SiC composite indicated the same regularity. Above 1200 °C, the oxidation kinetics was controlled by oxygen diffusion through the SiO2 scale formed on the SiC coating and matrix. And the residual flexural strength of the composites was governed by the strength degradation of the Hi–Nicalon fiber. After oxidation, the fracture displacement in flexural tests increased with the weight loss increasing and the fracture mode showed a non-brittle pattern. 相似文献
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Li Longbiao 《Applied Composite Materials》2016,23(5):913-952
In this paper, the comparison of fatigue life between C/SiC and SiC/SiC ceramic-matrix composites (CMCs) at room and elevated temperatures has been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S–N curves and fatigue limits of cross-ply, 2D and 3D C/SiC and SiC/SiC composites at room temperature, 550 °C in air, 750 °C in dry and humid condition, 800 °C in air, 1000 °C in argon and air, 1100 °C, 1300 °C and 1500 °C in vacuum, have been predicted. At room temperature, the fatigue limit of 2D C/SiC composite with ECFL of 20 % lies between 0.78 and 0.8 tensile strength; and the fatigue limit of 2D SiC/SiC composite with ECFL of 20 % lies between 0.75 and 0.85 tensile strength. The fatigue limit of 2D C/SiC composite increases to 0.83 tensile strength with ECFL increasing from 20 to 22.5 %, and the fatigue limit of 3D C/SiC composite is 0.85 tensile strength with ECFL of 37 %. The fatigue performance of 2D SiC/SiC composite is better than that of 2D C/SiC composite at elevated temperatures in oxidative environment. 相似文献
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Li Longbiao 《Applied Composite Materials》2016,23(2):101-117
This paper presents an experimental analysis on the fatigue behavior in C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply and 2.5D woven, at room and elevated temperatures in air atmosphere. The experimental fatigue life S???N curves of C/SiC composites corresponding to different stress levels and test conditions have been obtained. The damage evolution processes under fatigue loading have been analyzed using fatigue hysteresis modulus and fatigue hysteresis loss energy. By comparing the experimental fatigue hysteresis loss energy with theoretical computational values, the interface shear stress corresponding to different peak stress, fiber preforms and test conditions have been estimated. It was found that the degradation of interface shear stress and fibres strength caused by oxidation markedly decreases the fatigue life of C/SiC composites at elevated temperature. 相似文献
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