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氮化铝相在SiC-AIN-Y2O3复相陶瓷中起着至关重要的作用。在2050℃高温时,AIN颗粒表面发生固相蒸发现象,并聚集到SiC颗粒周围最终形成固溶体,改善了SiC颗粒周围最终形成固溶体,改善了SiC陶瓷的晶界结构,使该复相材料具有良好的机械性能,其室温抗折强度为610MPa,这一强度可持续至1400℃高温,断裂韧性达到8.1MPa.m^1/2。 相似文献
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碳化硅质耐火材料以其优异的抗热震,耐高温和抗氧化等特性而广泛地应用于冶金,钢铁和硅酸盐等工业领域中,并日益引起人们的重视。本文对各种碳化质耐火材料的制备方法,性能特点及其应用两头进行了综合评述。 相似文献
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Dense Sic ceramics were obtained by pressureless sintering of β-Sic and α-Sic powders as starting materials using Al2 O3 -Y2 O3 additives. The resulting microstructure depended highly on the polytypes of the starting SiC powders. The microstructure of SiC obtained from α-SiC powder was composed of equiaxed grains, whereas SiC obtained from α-SiC powder was composed of a platelike grain structure resulting from the grain growth associated with the β→α phase transformation of SiC during sintering. The fracture toughness for the sintered SiC using α-SiC powder increased slightly from 4.4 to 5.7 MPa.m1/2 with holding time, that is, increased grain size. In the case of the sintered SiC using β-SiC powder, fracture toughness increased significantly from 4.5 to 8.3 MPa.m1/2 with holding time. This improved fracture toughness was attributed to crack bridging and crack deflection by the platelike grains. 相似文献
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刚玉基复相陶瓷材料具有高硬度、高强度及耐磨性等优异的力学性能,是结构陶瓷领域研究的热点之一,具有广阔的应用前景.以α-Al2O3、SiC和ZrO2为原料,掺杂少量稀土氧化物La2O3,采用无压埋烧工艺,制备了稀土掺杂刚玉基复相陶瓷.通过XRD、SEM等手段研究La2O3添加量对复相陶瓷微观结构和性能的影响.结果表明:掺杂La2O3可将复相陶瓷的烧结温度降低至1540℃,经1540℃烧结的掺杂复相陶瓷强度和硬度分别为183 MPa和18.46 GPa.La2O3位于晶界处抑制晶粒长大,促进晶粒细化,利于样品的致密化,同时其晶界强化作用有利于复相陶瓷强度的提高. 相似文献
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采用非氧化物AlN和Re2O3作为复合烧结助剂(Re2O3-La2O3与Y2O3)进行碳化硅液相烧结得到了致密的烧结体.烧结助剂占原料粉体总质量的20%,其中:AIN与(La0.5Y0.5)2O3的摩尔比为2:1,在30MPa压力下,1850℃保温0.5h热压烧结的碳化硅陶瓷,抗弯强度>800MPa,断裂韧性>8MPa·m1/2,明显高于同组分1 950℃无压烧结0.5h的碳化硅陶瓷的抗弯强度(433.7MPa)和断裂韧性(4.8MPam·m1/2.热压烧结的陶瓷晶粒呈单向生长,断裂模式为沿晶断裂.同组分无压烧结碳化硅陶瓷的显微结构可以观察到核壳结构. 相似文献
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稀土氧化物对钛酸铝陶瓷显微结构和力学性能的影响 总被引:8,自引:0,他引:8
研究了添加稀土氧化物Y2O3和Y2O3+Nd2O3对钛酸铝陶瓷的烧结温度、力学性能和显微结构的影响.结果表明,添加1%的稀土氧化物可以降低钛酸铝陶瓷的烧结温度,改善其显微结构,提高其力学性能,尤其是添加1%的复合稀土氧化物(Y2O3+Nd2O3)后,钛酸铝陶瓷的抗折强度和断裂韧性是未添加的试样的1.96倍和1.82倍.其性能提高的主要原因是由于稀土元素的细晶强化、净化界面、固溶强化、自增韧补强等作用. 相似文献
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以AlN、Pr2O3做为SiC陶瓷液相烧结的复合助剂,选定不同的助剂含量(5wt%~ 20wt%)和不同的助剂摩尔比例(Pr2O3/AlN=1/3、1/1、3/1),在1800~2000℃温度下,采用热压和无压烧结的方法制备SiC陶瓷样品,并对这些陶瓷样品的性能进行了研究.实验结果表明,助剂比1/3组的样品显示出更有效地促进SiC陶瓷致密化,该组样品无压烧结最大相对密度为87%,热压烧结具有最高的相对密度96.1%、维氏硬度23.4 GPa、抗弯强度549.7MPa、断裂韧性5.36 MPa·m1/2,显微结构中可观察到晶粒拔出现象,断裂模式为沿晶断裂. 相似文献
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Shi C. Zhang Greg E. HilmasWilliam G. Fahrenholtz 《Journal of the European Ceramic Society》2011,31(5):893-901
ZrB2 ceramics containing 10-30 vol% SiC were pressurelessly sintered to near full density (relative density >97%). The effects of carbon content, SiC volume fraction and SiC starting particle size on the mechanical properties were evaluated. Microstructure analysis indicated that higher levels of carbon additions (10 wt% based on SiC content) resulted in excess carbon at the grain boundaries, which decreased flexure strength. Elastic modulus, hardness, flexure strength and fracture toughness values all increased with increasing SiC content for compositions with 5 wt% carbon. Reducing the size of the starting SiC particles decreased the ZrB2 grain size and changed the morphology of the final SiC grains from equiaxed to whisker-like, also affecting the flexure strength. The ceramics prepared from middle starting powder with an equiaxed SiC grain morphology had the highest flexure strength (600 MPa) compared with ceramics prepared from finer or coarser SiC powders. 相似文献
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Longyang Liu Xianzhi Chen Qiyu Li Shuaifeng Chen Yongjun Chen Jianbao Li Changjiu Li Lijie Luo 《International Journal of Applied Ceramic Technology》2020,17(5):2083-2093
Zirconia-toughened alumina (ZTA) ceramics with high mechanical properties were sintered by hot-pressing method using SiC particles (SiCp) and SiC whiskers (SiCw) as the reinforcing agents simultaneously. The influences of sintering temperature, SiCp, and SiCw contents on the microstructure and mechanical properties of ZTA ceramics were investigated. It was found that both SiCp and SiCw could contribute to grain refinement significantly and promote the mechanical properties of the ceramics. However, the excess addition of SiCp or SiCw led to the formation of pores with large sizes and degraded the mechanical properties instead. When 13 wt% SiCp was introduced, the maximum flexural strength of 1180.0 MPa and fracture toughness of 15.9 MPa·m1/2 were obtained, whereas the maximum flexural strength of 1314.0 MPa and fracture toughness of 14.7 MPa·m1/2 were achieved at 20 wt% SiCw. Interestingly, the simultaneous addition of SiCp and SiCw could further improve the mechanical properties, and the highest flexural strength of 1334.0 MPa and fracture toughness of 16.0 MPa·m1/2 were achieved at a SiCw/SiCp ratio of 16/4. The reinforcement mechanisms in the ceramics mainly included the phase transformation toughening of ZrO2, the crack deflection and bridging of SiCp and SiCw, and the pull-out of SiCw. 相似文献