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1.
    
《Ceramics International》2020,46(5):6182-6190
The SiC/Si3N4 composites were fabricated with sintering process. To produce SiC/Si3N4 composite components, slurry mixtures containing Si/SiC powders were used by the slip casting method. In order to investigate the effect of dispersants and additives on the rheological properties and the body casted, slurries with concentration of 70% solid weight were prepared. It included a mixture of silicon and silicon carbide with weight ratios of 30 wt% and 70 wt%, respectively, and various weight percentages of Ball clay as lubricant and Tiron (sodium salt of benzene disulfonic acid) as dispersant at pH value of 7. After preparing the green bodies by slip casting method by using plaster mold, the samples were sintered at 1450 °C inside an atmospheric-controlled furnace under a pressure of 0.12 MPa of nitrogen gas for 2 h. By examining the rheological properties of the slurry and the sintering properties, it was concluded that the best slurry was obtained in terms of viscosity, density, porosity and strength using 5 wt% Ball clay and 0.5 wt% Tiron. Phase transformations, microstructure and morphology of the sintered specimens were accomplished by Field Emission Scanning Electron Microscopy (FESEM) examination and X-ray diffraction experimental analysis. XRD and FESEM results demonstrated that the composite fabricated by slurry containing 5 wt% Ball clay and 0.5 wt% Tiron had the least porosity without SiO2 phase.  相似文献   

2.
影响凝胶注模成型SiAlON-SiC复相材料坯体性能的因素   总被引:2,自引:0,他引:2  
选用Al粉、Si粉、SiO2 等活性原料与较大颗粒的SiC ,采用凝胶注模成型工艺制备了SiAlON-SiC复相耐火材料的坯体 ,并研究了有机单体、分散剂和引发剂的加入量以及催化剂、胶凝温度等因素对坯体性能的影响。最终 ,在有机单体AM加入量为 1.8% (质量分数 ,下同 ) ,交联剂MBAM加入量为 0 .6‰ ,引发剂过硫酸铵溶液的最佳加入量为 0 .9% (体积分数 ) ,胶凝温度在 6 0℃左右 ,不加催化剂的条件下 ,制备出了抗折强度达到 32MPa ,密度为 2 .5g·cm- 3的均匀致密的SiAlON -SiC复相材料坯体。  相似文献   

3.
Petroleum coke, graphite, gas carbon and lower sulfur carbon black were used to prepare reaction-bonded silicon carbide. The influences of different carbon containing materials on properties of carbonaceous precursors, sintering process, and microstructure of the prepared SiC were researched. The results show that : ( 1 ) With the density of carbon containing materials increasing, the porosity of carbonaceous precursors decreases and the infiltrating process of liquid silicon is more difficult. (2) The reaction between carbon containing materials and liquid silicon, the volume effect is more obvious with the density of carbon containing materials increasing. (3) As the carbon containing materials density decreasing, residual carbon in reaction bonded SiC also decreases.  相似文献   

4.
SiCp/Al复合材料的自发熔渗机理   总被引:1,自引:0,他引:1  
以Mg为助渗剂,采用液态铝自发熔渗经氧化处理的SiC粉体压坯的方法,制备出高增强体含量的SiCp/Al复合材料.通过考察铝液在SiC粉体压坯中的渗入高度与温度、时间的关系来研究铝液的熔渗机理,并对SiCp/Al复合材料进行X射线衍射、能量散射谱和金相分析.结果表明:在熔渗前沿发生的液-固界面化学反应促进两相润湿,毛细管力导致铝液自发渗入到SiC多孔陶瓷中;熔渗高度与时间呈抛物线关系.熔渗激活能为166 kJ/mol,这表明渗透过程受界面反应控制.经氧化处理的SiC粉体均匀地分布在金属基体中,其轮廓清晰.在SiCp/Al复合材料中未发现Al4C3的存在.  相似文献   

5.
运用扫描电镜(SEM)技术,研究了氮化硅结合碳化硅耐火材料在钢水中的腐蚀行为。结果表明,金属与氮化硅结合碳化硅材料之间的界面清晰,基体内部无任何金属渗入,但氧化的材料表面有氧化物粘附。  相似文献   

6.
本文介绍了光刻机用碳化硅陶瓷结构件的特点及其对材料的要求,分析了碳化硅陶瓷在光刻机中作为结构件材料使用的优势,着重介绍了中国建筑材料科学研究总院在精密碳化硅结构件的制备领域所取得的技术成果,列举了精密碳化硅结构件在光刻机等集成电路制造关键装备中的应用。  相似文献   

7.
连续纤维增韧碳化硅陶瓷基复合材料研究   总被引:27,自引:6,他引:27  
采用化学气相浸渗法制造了连续碳纤维和碳化硅纤维增韧碳化硅陶瓷基复合材料,并对复合材料的显微结构和力学性能进行了研究,C/SiC/SiC复合材料的密度分别为2.1g/cm^3和2.5g/cm63,在断理解过程中表现出明显的非线性和非灾难性的断裂行为和规律,C/SiC和SiC/SiC弯曲强度分别为450MPa和850MPa,从室温至1600℃强度不发生降低;断裂韧性为20MPa.m^1/2和41.5MPa.m^1/2,断裂功为10kJ.m^-2和28.1kJ.m^-2,冲击韧性为62.0kJ.m^-2和36.0kJ.m^-2,C/SiC和SiC/SiC复合材料具有优异的抗热震性能,经1300℃→←3000℃,50次热震后,强度保持率高达96.4%,热震不是材料性能损伤的控制因素,而SiC/SiC复合材料优异的抗氧化性能,对温度梯度不敏感,得合材料喷管在液体火箭发动机上成功地通过了地面实验。  相似文献   

8.
    
A direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5-6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively.  相似文献   

9.
反应烧结碳化硅研究进展   总被引:7,自引:0,他引:7  
对有关反应结合碳化硅(RBSC)材料的研究进展作了综述,并对存在的问题和今后可能的发展方向提出了自己的见解,包括:进一步提高性能;降低游离硅含量,提高使用温度;提高材料的可靠性和稳定性;低成本化.  相似文献   

10.
The melt infiltration method was used to fabricate a SiC-mullite composite at high temperature. Mullite was successfully obtained from a SiO2 and Al2O3 powder mixture by melting above 1830°C in a BN crucible with a lid. When infiltrated into a porous SiC preform, the mullite significantly reacted with SiC to form gaseous SiO and CO, even at the lowest investigated temperature of 1830°C, consuming SiO2 and leaving Al2O3 and silicon phases in the sample. The relevant reactions were studied in detail. A closed system was adopted to suppress the reaction, and a dense composite was successfully obtained.  相似文献   

11.
以工业用黑色碳化硅砂、硅粉为主要原料,研制出了导热性能优良、抗热震性好、耐高温、耐侵蚀及耐磨损,且生产工艺较简单、成本较低的氧氮化硅结合的碳化硅制品.该产品已广泛应用于冶金炉、化工设备及发电用锅炉的内衬,并取得了较满意的效果。  相似文献   

12.
本文论述了影响SiC泥浆性能的几个主要因素,运用SiC粉料Zeta电位随PH值变化曲线作指导,通过PH值调整和改变分散介质,着重研究了SiC泥浆稳定性、泥浆浇注样品的性能和显微结构,获得了浇注性能好、长时间稳定不沉淀的泥浆。分析了浇注过程中的各种影响因素,讨论了泥浆性状对浇注性能及样品烧结后力学性能的影响,最终浇注出大尺寸SiC陶瓷部件。  相似文献   

13.
    
《Ceramics International》2022,48(16):22975-22984
A silicon carbide ceramic counter-flow heat exchanger with integrated headers was printed by binder jetting additive manufacturing process. Multiple phenolic binder infiltration cycles (3 or 5) followed by pyrolysis were conducted to increase the net carbon content of the printed SiC specimens. Subsequently, to attain full densification, silicon melt infiltration was used. The microstructure and mechanical properties were comprehensively characterized on the densified material. The chemical compositions and visual distribution of the various regions in the specimens were determined via scanning electron microscopy, while X-ray diffraction and synchrotron μ-computed tomography were used to provide a quantitative assessment of the volume fractions of the identified phase regions. Microhardness measurements showed dependence on the local microstructure. The fracture strength of the material was correlated with the specimen density and agreed with the reported values in the literature. High-temperature exposure at 750 °C for up to 200 h did not degrade the strength for the specimens with three phenolic-binder infiltrations; however, the strengths degraded for ones with five phenolic-binder infiltrations. The associated fracture toughnesses of the specimens were ~3.4 MPam1/2 at room temperature and 750 °C, and the thermal conductivities varied from >150 W/mK at room temperature to ~45 W/mK at 750 °C. Hence, this study validated the use of the binder-jetting printed SiC ceramic materials for high-temperature heat exchanges. Finally, we also present in this work the first successful fabrication of a binder-jetting printed one-piece dense SiC ceramic heat exchanger body with unblocked channels that can be used for the flow of heat transfer fluids.  相似文献   

14.
To improve the reliability, especially the toughness, of the reaction bonded silicon carbide (RBSC) ceramics, silicon carbide whiskers coated with pyrolytic carbon layer (PyC-SiCw) by chemical vapor deposition (CVD) were introduced into the RBSC ceramics to fabricate the SiCw/RBSC composites in this study. The microstructures and properties of the PyC-SiCw/RBSC composites under different mass fraction of nano carbon black and PyC-SiCw were investigated methodically. As a result, a bending strength of 550 MPa was achieved for the composites with 25 wt% nano carbon black, and the residual silicon decreased to 11.01 vol% from 26.58 vol% compared with the composite of 15 vol% nano carbon black. The fracture toughness of the composites reinforced with 10 wt% PyC-SiCw, reached a high value of 5.28 MPa m1/2, which increased by 39% compared to the RBSC composites with 10 wt% SiCw. The residual Si in the composites deceased below to 7 vol%, resulting from the combined actively reaction of nano carbon black and PyC with more Si. SEM and TEM results illustrated that the SiCw were protected by PyC coating. A thin SiC layer formed of outer surface of whiskers can provide a suitable whisker-matrix interface, which is in favor of crack deflection, SiCw bridging and pullout to improve the bending strength and toughness of the SiCw/RBSC composites.  相似文献   

15.
    
The flexural strength variability of α$alpha$-SiC$text{SiC}$ based ceramics at elevated temperatures creates the need for an Integrated Computational Materials Engineering (ICME) framework that relates the strength of a specimen directly to its manufacturing process. To create this ICME framework, a model must first be developed which establishes a relationship between the chemical vapor infiltration (CVI) process and parameters, the resulting mesoscale pores, and the overall macroscale flexural strength. Here, a nonlinear single-pore model of CVI is developed used in conjunction with a four-way coupled thermo-mechanical damage model. The individual components of the model are tested and a sample system under a four-point bending test is explored. Results indicate that specimens with an initial porosity greater than 30% require temperatures below 1273 K to maintain structural integrity, while those with initial porosities less than 30% are temperature-independent, allowing for optimization of the CVI processing time without compromising strength.  相似文献   

16.
The infiltration of liquid Fe3Si (mp of ∼1300°C), Fe5Si3 (mp of ∼1210°C), and FeSi (mp of ∼1410°C) into SiC powder preforms was performed at various infiltration temperatures for 60 min under either argon flow or dynamic vacuum. The amount of infiltration under various infiltration conditions was studied as a function of infiltration temperature. For the preforms as-pressed from raw SiC powder, the amount of infiltration of the three silicides under argon flow was independent of their melting points, but suddenly increased within a common temperature range from 1450° to 1550°C. Thermodynamic analyses indicated that the common temperature range corresponded to the temperature at which the SiO2 on the surface of the SiC particles was decreased under argon flow. Infrared spectroscopy showed SiO2 on the surfaces of as-received SiC powder particles, but not on the surfaces of the SiC powder particles fired under argon at 1600°C. The amount of infiltration of the as-pressed SiC under vacuum and of fired SiC under argon and vacuum exhibited an obvious dependence on the silicide melting points. This was attributed to the SiO2 reduction taking place at temperatures lower than the melting points of the silicides. The amount of infiltration was then controlled by the melt viscosity.  相似文献   

17.
无压浸渗法制备碳化硅颗粒增强铝基复合材料工艺研究   总被引:4,自引:0,他引:4  
用有预制型的无压浸渗法制备了体积分数高达75%的碳化硅颗粒增强铝基复合材料.研究了各工艺参数对复合材料制备过程与性能的影响.结果表明:SiO2氧化膜、N2气氛和充分的保温时间有利于浸渗;浸渗温度选择1000℃比较合适;Mg的质量分数为10%时浸渗能顺利进行.  相似文献   

18.
对反应熔渗法制备C/C-SiC复合材料过程中Si的渗入行为以及Si/C的反应机理和动力学进行了综合评述.分析了高温下Si的密度、粘度、表面张力及Si/C润湿角对渗入能力的影响.概括了Washburn公式及其改进模型在液Si渗入行为方面的研究进展,给出了渗入时间、SiC生成速率与渗入高度之间的关系.对控制Si/C反应的溶解-沉淀机理和扩散机理进行了阐述,总结分析得出:不同阶段Si/C反应发生的区域不同,因而控制反应的机理也不同.最终的SiC相是由不同反应机理共同作用形成的.  相似文献   

19.
周璇  朱冬梅  桂佳  罗发  周万城 《硅酸盐学报》2012,40(3):340-341,342,343,344
以纳米SiO2为填料,采用先驱体浸渍裂解法制备2.5D-SiCf/SiC(D为维数,SiCf为SiC纤维)复合材料,研究了前驱液中纳米SiO2含量对复合材料力学性能的影响。结果表明,纳米SiO2的添加能有效抑制先驱体裂解过程中的体积收缩,提高致密度,但过量引入易导致浸渍液黏度过高,浸渍效率降低。纳米SiO2含量对材料力学性能有较大影响,添加纳米SiO2后材料的抗弯强度和断裂韧性均高于没有添加的样品,材料抗弯强度随纳米SiO2含量的增加先增大后降低。当浸渍液中纳米SiO2含量为6%时,复合材料具有优异的力学性能,抗弯强度达到211.1MPa。  相似文献   

20.
2.5维碳化硅纤维增强碳化硅复合材料的力学性能   总被引:1,自引:0,他引:1  
采用低压化学气相渗透法制备了具有热解碳界面层的2.5维SiCf/SiC复合材料.研究了界面层厚度和基体制备工艺对材料力学性能的影响.结果表明:0.1μm厚的界面层使材料的弯曲强度提高了104.2%从144增加到294MPa),材料表现为非灾难性断裂;界面层厚度进一步增加(到0.161μm),纤维的增强效果减弱,材料的断裂行为变差.基体制备温度由1050℃降到950℃时,材料强度增加了≈45%(从188增加到274MPa):制备压力由8kPa增加到16kPa时,气孔率升高,SiC基体晶粒形状由菱形变为球形.基体的球形晶粒有利于提高材料的承载能力,虽然复合材料的气孔率较高,但其弯曲强度却稍有增加.  相似文献   

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