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1.
B4C陶瓷的协同增韧   总被引:7,自引:0,他引:7  
采用热压工艺制备的B4C-35vol%TiB2复相陶瓷的断裂韧性值从单体B4C的3.6MPa-m^1/2以6.5MPa.m^1/2, 游离碳后的韧性进一步提高,达7.6MPa.m^1/2,显微结构观察表明,材料韧性的改善是因第二相颗粒的TiB2和基体B4C之间的热膨胀系数不匹配而产生的残余应力导致的偏转和游离碳的 产生的微开明纹协同增韧的结果,游离碳的存在削弱了界面的结合强度,在很强的残余应力的和  相似文献   

2.
本文采用热压工艺制备TiC和Al2O3共同补强Y-TZP基复相陶瓷,研究了复相陶瓷的相组成。力学性能及显微结构,发现复相陶瓷的高温强度得到显著提高,1000℃时,组成为30vol%TiC-(25vol%,Al2O3/1.8Y-TZP)复相陶冷饮 抗弯强度高达614MPa,TiC颗粒补强机制在高温下发挥了重要作用。  相似文献   

3.
本文采用热压工艺制备TiC和Al_2O_3共同补强Y-TZP基复相陶瓷,研究了复相陶瓷的相组成、力学性能及显微结构.发现复相陶瓷的高温强度得到显著提高,1000℃时,组成为30vol%TiC-(25vol%Al2O3/1.8Y-TZP)复相陶瓷抗弯强度高达614MPa.TiC颗粒补强机制在高温下发挥了重要作用.  相似文献   

4.
晶内型Al2O3—SiC纳米复合陶瓷的制备   总被引:36,自引:5,他引:31  
研究了沉淀法制备Al2O3-SiC纳米复合陶瓷的工艺过程,利用Al2O3从γ相到α相的蠕虫状生长过程,使大部分纳米SiC颗粒位于Al2O3晶粒内,用沉淀法制得的、含有5vol%SiC的Al2O3-SiC纳米复合陶瓷,其强度为467MPa,韧性为4.7MPa.m^1/2,与一般的Al2O3陶瓷相比有较大的提高,显示了沉淀法制备Al2O3-SiC纳米复合陶瓷的优点。  相似文献   

5.
本文介绍了用化学共沉淀和在适当温度下煅烧以直接制备YAG-Al2O3纳纳米复合粉体的新方法。XRD结果表明,所得粉体具纯的YAG和α-Al2O3相,因此其化学组成符合配料的组分设计,用本方法制备的25vol%YAG-Al2O3复合粉体经热压烧结,所得的致0密体材料为晶内型纳米复合材料,其抗弯强度达612MPa,断裂韧性为4.54MPam^-1/2,都比单相Al2O3陶瓷有大幅度提高。  相似文献   

6.
通过对无压烧结、热压烧结和热等静压烧结SIC陶瓷以及热压烧结的SiC粒子补强Al2O3基复相陶瓷(SiCp-Al2O3)和SiC粒子与SiC晶须共同增强的Al2O3基复合材料(SiCp-SiCw-Al2O3)在氮气氛中进行高温氮化处理,成功地实现了这些材料的开口气孔表面裂纹的愈合。研究表明:热等静压氯化工艺可以显著提高SiC和Al2O3陶瓷的抗弯强度,对断裂韧性也有较大的改善作用。对于热等静压烧结SiC陶瓷,在1850℃和200MPa氮气压力下氯化处理1小时后,其抗弯强度和断裂韧性分别由582MPa和5.7MPa·m1/2提高到907MPa和8.4MPa·m1/2;对于热压烧结的SiCp-Al2O3复相陶瓷和SiCp-SiCw-Al2O3复合材料,在1700℃和150MPa氮气压力下氮化处理1小时后,其室温抗弯强度分别由460和705MPa提高到895和1033MPa。  相似文献   

7.
通过热压烧结技术,SiC、AlN和Y2O3粉末混合体在1920 ̄2050℃、Ar气氛下形成了致密的复相陶瓷。在室温下SiC-AlN-Y2O3复相材料的抗弯强度和断裂韧性分别达到600MPa和7MPa·m^1/2以上。运用XRD、SEM和TEM分析致密样品的断裂裂纹、形貌和组成。SiC-AlN-Y2O3复相陶瓷在1370℃氧化试验30h,其氧化产物为莫来石。  相似文献   

8.
非均相沉淀法制备Al2O3-YAG复相陶瓷   总被引:1,自引:0,他引:1  
本文测量了YAG粉体的ξ电位,通过调节pH值获得均匀分散的YAG水悬浮液.采用非均相沉淀方法获得YAG分布均匀的Al2O3-YAG复合粉体.通过热压烧结得到致密烧结体,YAG的加入对烧结温度的影响不大.Al2O3-5vol%YAG复相陶瓷的抗弯强度为485MPa,断裂韧性为4.2MPa·m1/2,均高于单相Al2O3陶瓷,数据的重复性好于球磨混合所制备的样品.通过TEM观察,YAG颗粒均匀分布于整个样品中,表明通过非均相沉淀制粉可以获得YAG颗粒分布均匀的Al2O3-YAG复相陶瓷.  相似文献   

9.
通过热压烧结技术,SiC、AlN和Y2O3粉末混合作在1920~2050℃、Ar气氛下形成了致密的复相陶瓷.在室温下SiC-AlN-Y2O3复相材料的抗弯强度和断裂韧性分别达到600MPa和7MPa·m1/2以上运用XRD、SEM和TEM分析致密样品的断裂裂纹、形貌和组成.SiC-AlN-Y2O3复相陶瓷在1370℃氧化试验30h,其氧化产物为莫来石.  相似文献   

10.
SiO2-Si3N4复合材料的力学性能及其增韧机理   总被引:11,自引:0,他引:11  
采用热压工艺制备了SiO2-Si3N4复合材料,其抗弯强度和断裂韧性达到143MPa和1.7MPa.m^1/2,比基体SiO2材料分别提高107%和70%,复合材料改善是由于高弹性模量的Si3N4引入以及SiO2和Si3N4热膨胀系数不匹配导致的残余应力。  相似文献   

11.
本文研究了原位生成的TiC/TiB2/MoSi2三相复合材料的一种新的显微结构及其对力学性能的影响,结果表明,当热压金属Ti,B4C和MoSi2的混合粉末时,在MoSi2的基体内生成由TiC和TiB2组成的空心粒子。  相似文献   

12.
TiC-TiB2/Cu复合材料的自蔓延高温合成研究   总被引:4,自引:0,他引:4  
采用SHS/PHIP工艺制备了TiC-TiB2/Cu复合材料,通过实验研究了该系列复合材料的微观结构特征和力学性能.结果表明,TiC-TiB2/Cu复合材料中只有TiC、TiB2和Cu相存在;随着Cu含量的增加,燃烧温度下降,材料的颗粒尺寸变小;TiC-TiB2/Cu复合材料的相对密度、抗弯强度和断裂韧性均随Cu含量的增加呈先增后减趋势,当Cu含量为20%时强度最高为580MPa,Cu含量为40%时韧性最高为8.1MPa.m1/2.  相似文献   

13.
Monolithic B4C, TiB2 and B4C-TiB2 particulate composites were consolidated without sintering additives by means of pulsed electric current sintering in vacuum. Sintering studies on B4C-TiB2 composites were carried out to reveal the influence of the pressure loading cycle during pulsed electrical current sintering (PECS) on the removal of oxide impurities, i.e. boron oxide and titanium oxide, hereby influencing the densification behavior as well as microstructure evolvement. The critical temperature to evaporate the boron oxide impurities was determined to be 2000 °C. Fully dense B4C-TiB2 composites were achieved by PECS for 4 min at 2000 °C when applying the maximum external pressure of 60 MPa after volatilization of the oxide impurities, whereas a relative density of 95-97% was obtained when applying the external pressure below 2000 °C. Microstructural analysis showed that B4C and TiB2 grain growth was substantially suppressed due to the pinning effect of the secondary phase and the rapid sintering cycle, resulting in micrometer sized and homogeneous microstructures. Excellent properties were obtained for the 60 vol% TiB2 composite, combining a Vickers hardness of 29 GPa, a fracture toughness of 4.5 MPa m1/2 and a flexural strength of 867 MPa, as well as electrical conductivity of 3.39E+6 S/m.  相似文献   

14.
碳纳米管-TiB2陶瓷基复合材料的制备与性能研究   总被引:1,自引:0,他引:1  
研究了用热压烧结(HP)方法制备TiB2-xwt%CNTs-5wt%Ni(x=0.1、0.3、0.5、1、4)复合材料的工艺条件、力学性能和微观结构.用XRD研究了其相组成,用SEM观察了复合材料的断口形貌和裂纹扩展.研究表明碳纳米管的加入使复合材料的硬度、弯曲强度和断裂韧性得到明显的提高,并且在碳纳米管含量为0.5wt%左右时,复合材料的硬度达到20.5GPa,弯曲强度为496MPa,断裂韧性达7.25MPa·m1/2;断口形貌分析表明碳纳米管主要分布于TiB2颗粒的晶界处,复合材料的增韧机制主要是碳纳米管的拔出机制和桥联机制.  相似文献   

15.
Densities up to 99% of the theoretical value were achieved by hot-pressing of TiB2-B4C composites at 1700° C for 1 h using 1 vol % Fe as a sintering aid. The microstructure consists of dispersed B4C particles in a fine-grained TiB2 matrix. Addition of B4C particles increases the fracture toughness of TiB2 (to 7.6 MPa m1/2 at 20 vol % B4C) and yields high fracture strength (to 700 MPa at 10 vol % B4C). Microstructural observations indicate that the improved strength is a result of a higher density, smaller grain size and intergranular fracture, and the toughness increase is a result of crack deflection around the B4C particles.  相似文献   

16.
The B4C/BN ceramics composites were fabricated by the hot-pressing process. In this paper, the mechanical property and R-curves behavior of the B4C/BN composites were investigated. The fracture strength and fracture toughness of the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increasing content of h-BN. The fracture strength and fracture toughness of the B4C/BN nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The damage resistance and R-curves behavior of the B4C monolith and the B4C/BN composites were evaluated by the indentation-strength in bending technique (ISB). The fracture strength of the B4C monolith, the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increase of the indentation load. The B4C/BN nanocomposites retained relative higher fracture strength in comparison with the B4C monolith and the B4C/BN microcomposites under the equivalent indentation load. The B4C monolith, the B4C/BN microcomposites and the B4C/BN nanocomposites all exhibited the rising R-curves behavior. The B4C/BN nanocomposites exhibited the higher rising R-curve behavior than that of the B4C monolith and the B4C/BN microcomposites. The toughness mechanisms of the composites were investigated. The B4C/BN composites with the h-BN content more than 20 wt.% exhibited excellent machinability. The slowly rising R-curves behavior remarkably improved the machinability of the composites.  相似文献   

17.
Reactive hot-press (1800-1880 °C, 30 MPa, vacuum) is used to fabricate relatively dense B4C matrix light composites with the sintering additive of (Al2O3 +Y2O3). Phase composition, microstructure and mechanical properties are determined by methods of XRD, SEM and SENB, etc. These results show that reactions among original powders B4C, Si3N4 and TiC occur during sintering and new phases as SiC, TiB2 and BN are produced. The sandwich SiC and claviform TiB2 play an important role in improving the properties. The composites are ultimately and compactly sintered owing to higher temperature, fine grains and liquid phase sintering, with the highest relative density of 95.6%. The composite sintered at 1880 °C possesses the best general properties with bending strength of 540 MPa and fracture toughness of 5.6 MPa m1/2, 29 and 80% higher than that of monolithic B4C, respectively. The fracture mode is the combination of transgranular fracture and intergranular fracture. The toughening mechanism is certified to consist of crack deflection, crack bridging and pulling-out effects of the grains.  相似文献   

18.
热压烧结TiB2陶瓷的显微结构和力学性能研究   总被引:4,自引:1,他引:3  
以Y2O3-Al2O3为烧结助剂,通过热压制备了TiB2陶瓷,研究了烧结温度,烧结时间和晶化处理对材料的显微结构和力学性能的影响。实验结果表明,随着烧结温度的升高,烧结体失重增加,其抗弯强度和断裂韧性降低,烧结时间延长,其显微结构的均匀性降低,对力学性能不利。晶粒直径对TiB2陶瓷的力学性能有重要影响,晶化处理能够导致晶界析出YAG相,从而提高TiB2陶瓷的高温抗弯强度。  相似文献   

19.
高能球磨制备TiB2/TiC纳米复合粉体   总被引:8,自引:0,他引:8  
研究了通过高能球磨制备TiB2/TiC纳米复合粉体的反应过程和机理,对粉体的显微结构进行了表征。实验结果表明,采用金属Ti和B4C为原料,在球磨过程中,TiC先于TiB2形成。球磨5h后Ti与B4C反应生成TiB2和TiC,在随后的长时间高能球磨过程中TiB2和TiC两相保持稳定。球磨30h后,直径约8nm的TiC纳米粒子分布在100-200nm的TiB2粒子中,形成均匀分布的纳米TiB2/TiC复合粉体。  相似文献   

20.
A three-layer structure material, consisting of B4C/Al, B4C/TiB2 and B4C composites, was obtained using a two-step method for both hot pressing and aluminum infiltration in vacuum. The three-layer B4C/Al–B4C/TiB2–B4C composite showed good interfacial bonding. Before aluminum infiltration the B4C porous layer in the three-layer preform looked like a three-dimensional network of interconnected capillaries. The microstructures of both B4C/TiB2 and B4C layers showed no apparent changes before and/or after aluminum infiltration. The three-layer composite showed improved fracture toughness than that of B4C material and higher comprehensive hardness than that of B4C/Al material.  相似文献   

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