Effects of metal binder on the microstructure and mechanical properties of Al2O3-based micro-nanocomposite ceramic tool material

The Al2O3?(W,Ti)C composites with Ni and Mo additions varying from 0vol% to 12vol% were prepared via hot pressing sintering under 30 MPa. The microstructure was investigated via X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Mechanical properties such as flexural strength, fracture toughness, and Vickers hardness were also measured. Results show that the main phases A12O3 and (W,Ti)C were detected by XRD. Compound MoNi also existed in sintered nanocom-posites. The fracture modes of the nanocomposites were both intergranular and transgranular fractures. The plastic deformation of metal particles and crack bridging were the main toughening mechanisms. The maximum flexural strength and fracture toughness were obtained for 9vol% and 12vol% additions of Ni and Mo, respectively. The hardness of the composites reduced gradually with increasing content of metals Ni and Mo.     

Effects of metal binder on the microstructure and mechanical properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-based micro-nanocomposite ceramic tool material

The Al₂O₃-(W,Ti)C composites with Ni and Mo additions varying from 0vol% to 12vol% were prepared via hot pressing sintering under 30 MPa. The microstructure was investigated via X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Mechanical properties such as flexural strength, fracture toughness, and Vickers hardness were also measured. Results show that the main phases Al₂O₃ and (W,Ti)C were detected by XRD. Compound MoNi also existed in sintered nanocomposites. The fracture modes of the nanocomposites were both intergranular and transgranular fractures. The plastic deformation of metal particles and crack bridging were the main toughening mechanisms. The maximum flexural strength and fracture toughness were obtained for 9vol% and 12vol% additions of Ni and Mo, respectively. The hardness of the composites reduced gradually with increasing content of metals Ni and Mo.     

Microstructure and mechanical properties of Nb–Mo–ZrB2 composites prepared by hot-pressing sintering

Nb–Mo–ZrB₂ composites (V(Nb)/V(Mo)=1) with 15vol% or 30vol% of ZrB₂ were fabricated by hot-pressing sintering at 2000℃. The phases, microstructure, and mechanical properties were then investigated. The composites contain Nb-Mo solid solution (denoted as (Nb, Mo)ss hereafter), ZrB, MoB, and NbB phases. Compressive strength test results suggest that the strength of Nb–Mo–ZrB₂ composites increases with increasing ZrB₂ content; Nb–Mo–30vol%ZrB₂ had the highest compressive strength (1905.1 MPa). The improvement in the compressive strength of the Nb–Mo–ZrB₂ composites is mainly attributed to the secondary phase strengthening of the stiffer ZrB phase, solid-solution strengthening of the (Nb, Mo)ss matrix as well as fine-grain strengthening. The fracture toughness decreases with increasing ZrB₂ content. Finally, the fracture modes of the Nb–Mo–ZrB₂ composites are also discussed in detail.     

SiC_W—ZTA陶瓷基复合材料增韧、增强机理的分析

采用国产SiC晶须(SiC_W)制备SiC_W-ZTA陶瓷基复合材料,研究了SiC晶须含量对复合材料的抗弯强度及断裂韧性的影响;并分析了晶须增韧和ZrO_2相变增韧两种机制协同作用的条件。     

添加BN对TiB_2-Al复合材料显微组织与力学性能的影响

对金属浸渗法制备的TiB2-Al复合材料进行物相、显微组织以及力学性能方面的检测,研究了添加BN对于TiB2-Al复合材料力学性能与显微组织的影响.物相分析发现,添加的BN与金属Al进行了界面反应生成了AlN;显微组织分析发现,AlN产生于TiB2与Al界面;力学检测发现,随着BN添加量的增加,抗折强度逐渐下降,断裂韧性先增加再下降,硬度逐渐增加.浸入预制体中Al的量是影响材料断裂韧性的主要原因;当BN的添加量为10%时,TiB2-Al显现出较好的力学性能,抗折强度、断裂韧性和硬度(HRC)分别为538.48 MPa,7.14MPa.m1/2和21.2.     

B_4C-ZrB_2-Al复合材料的真空熔渗法制备与性能分析

通过在B4C-ZrB2多孔预烧体中真空熔渗Al制备了B4C-ZrB2-Al复合材料,研究了该复合材料的物相组成和力学性能.结果表明:ZrB2的生成量影响B4C-ZrB2-Al复合材料的物相组成;随着ZrB2生成量的增加,复合材料的硬度先增大后降低,抗折强度和断裂韧性先降低后增大;延性Al的渗入是造成材料断裂韧性提高的主要原因.当ZrB2生成量为35%(质量分数)时,复合材料主要由B4C,ZrB2和Al组成,其气孔率、硬度HRA、抗折强度和断裂韧性分别为1.06%,82.2,521.5MPa和8.6MPa.m1/2.观察材料断口形貌可见较多的韧窝和金属撕裂棱,表明其断裂行为主要为沿晶和穿晶混合断...     

CuO/Al反应自生复合材料的机械性能研究

采用液态搅拌法制备了反应自生 Al2 O3增强金属基复合材料并研究了它的机械性能 .采用 X衍射和扫描电镜分析了相组成和断口形貌 .与基体合金比较 ,复合材料的强硬性得到较大提高 ,其中 10 % Cu O复合材料的抗拉强度提高了 5 2 .3% ,硬度提高近一倍 .复合材料中的拉伸断裂特征为韧性断裂 ,铸造缺陷渣气孔是主要的裂纹源     

Si3N4-Ti(C0.12N0.88)复合材料的制备与性能

在Si3N4基体中添加第二相粒子Ti(C0.12N0.88），研究Ti(C0.12N0.88）添加量对Si3N4-Ti(C0.12N0.88）复合材料性能的影响。结果表明，在Si3N4-Ti(C0.12N0.88）复合材料中，Ti(C0.12N0.88）在Si3N4基体中能够稳定存在，并能起到增韧初强的作用，添加适量的Ti(C0.12N0.88），Si3N4-Ti(C0.12N0.88）复合材料的抗弯强度和断裂韧性都有不同程度的提高。     

Ti3SiC2/TiC复合材料的制备及力学性能研究

弓网系统中,各种类型的受电弓滑板承担着传输电能的重要功能,其严酷的工作条件对受电弓滑板材料的性能提出了非常苛刻的要求。目前最主要的受电弓滑板有：粉末冶金滑板,纯碳滑板和浸金属碳滑板。其中碳滑板材料性能较好但价格昂贵,粉末冶金滑板材料价格便宜,但性能明显逊于前者。Ti3SiC2/TiC是一种兼具陶瓷与金属性质的新型材料,与碳滑板材料相比,其电阻率低,且具有良好的抗氧化性和自润滑减摩性,因此Ti3SiC2/TiC将可能成为一种工艺简单、成本更低、而性能则更高的新型受电弓滑板材料。本研究以Si、Ti和C为原料,利用熔渗反应烧结技术制备出Ti3SiC2/TiC复合材料,研究结果表明,制备样品的弯曲强度与硬度分别达到 423MPa~564MPa 和169~249HB。同时,本文对Ti3SiC2/TiC复合材料的断裂机理进行了研究。     

Enhanced performance of nano-sized SiC reinforced Al metal matrix nanocomposites synthesized through microwave sintering and hot extrusion techniques

In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol%) reinforced aluminum (Al) metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM), mechanical (nanoindentation, compression, tensile) and thermal properties (co-efficient of thermal expansion- CTE) of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile) of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites.     

冷却工艺对低碳Ti微合金化热轧超高强钢组织性能的影响

对实验钢采用低碳高Ti微合金化的成分设计,进行了控轧控冷实验,通过控制不同的冷速和卷取温度,研究了过冷度和原子扩散速率对钢组织演变及(Ti,Mo)C粒子的析出行为的影响.研究结果表明,冷速为30℃/s,卷取温度为420℃时,实验钢屈服强度大于690MPa,抗拉强度为820MPa,断后伸长率达18%,并具有良好的低温冲击韧性.显微组织性能研究表明,多边形铁素体、针状铁素体、细小M/A岛及弥散的(Ti,Mo)C析出粒子的混合组织可实现强度和韧性的良好匹配.     

高硼多组分铸铁的组织及相元素分布

这种新提出的新型铸铁的化学成分为在0.7C–5W–5Mo–5V–10Cr–2.5Ti (wt%)中分别添加1.6wt% B和2.7wt% B。这项工作的目的是研究硼的含量对合金的结构状态和阶段元素分布对耐磨结构成分的形成影响。结果表明,当B含量为1.6wt%时,合金由三种共晶组成:(a) “M₂(C,B)₅+铁素体”具有“汉字”形貌 (89.8vol%), (b) “M₇(CB)₃+奥氏体”具有“莲座”形貌,(c) “M₃C+奥氏体”具有“莱氏体”形貌 (2.7vol%)。当硼含量为2.7wt%时,基体硬度由HRC 31提高到HRC 38.5。组织中出现了平均显微硬度为HV 2797的初生碳化物M₂(C,B)₅,体积分数为17.6vol%。共晶体(a)和(b,c)的体积分数分别降低到71.2vol%和3.9vol%。基体为“铁素体/奥氏体” (1.6wt% B) 和“铁素体/珠光体”(2.7wt% B),两种铸铁均含有致密析出碳化物(Ti,M)C和碳硼化物(Ti,M)(C,В),体积分数为7.3%–7.5%。基于能量色散X射线能谱,给出了元素相的分布和相应的相公式。     

化学镀碳纤维增强钛酸铝莫来石基复合材料

通过化学镀方法,在碳纤维表面分别镀上Ni、Cu和Cu+Ni镀层,以这种表面改性碳纤维与钛酸铝 莫来石陶瓷复合,制备表面改性碳纤维增强钛酸铝 莫来石基复合材料,研究不同质量分数的碳纤维对复合材料抗弯强度、断裂韧性、尺寸变化率和孔隙率等的影响规律·结果表明,碳纤维可以显著地提高材料的性能,表面改性碳纤维可以进一步提高材料性能,尤其是铜镍复合镀碳纤维的效果更好,其抗弯强度可达基体抗弯强度的2 8倍,断裂韧性可达基体断裂韧性的2 74倍,增强后的复合材料的尺寸变化率和孔隙率变化不大·     

Al_2O_3对B_4C-Al_2O_3-Al显微组织与力学性能的影响

在B4C-Al2O3预烧体中真空熔渗铝制备了B4C-Al2O3-Al复合材料,分析了w(Al2O3)对复合材料显微组织和力学性能的影响.结果表明:B4C-Al2O3-Al复合材料主要由B4C,Al2O3,Al,Al3BC和AlB2等相组成;随着w(Al2O3)的增加,复合材料的HRA硬度先增大后减小,材料的抗弯强度和断裂韧性均先减小后增大,当w(Al2O3)为25%时,复合材料具有较好的综合性能,它的气孔率、硬度、抗弯强度和断裂韧性分别为2.06%,84.4HRA,440.36 MPa和6.53 MPa.m1/2;延性铝的加入、裂纹的偏转和分叉、晶粒的细化、增韧相AlB2的生成及热膨胀的不匹配...     

B_4C陶瓷材料的无压烧结与性能

以碳化硼微粉作为原料,选用SiC和C为烧结助剂,研究了SiC和C对无压烧结B4C材料的体积密度、硬度、抗折强度和断裂韧性等性能的影响.结果表明,最佳烧结温度为1975℃,保温时间是30min.SiC和C的质量分数对材料密度、硬度和抗折强度的影响都是先增大后减小.烧结助剂SiC和C的最佳添加量分别为6%和5%(质量分数)时,得到相应的无压烧结B4C陶瓷材料的最佳力学性能:体积密度为2.45g/cm3,维氏硬度为35GPa,抗折强度为240MPa,断裂韧性为3.0MPa.m1/2     

SiCpl-BAS复合材料的显微组织与力学性能

用热压烧结法工艺制备碳化硅片晶增强BAS（BaOAl2O32SiO2)玻璃陶瓷基复合材料（SiCpl-BAS)，并对其组织结构与力学性能进行了研究，结果表明，当碳化硅片晶体积分数达到0．30时，SiCpl-BAS复合材料的断裂韧性和抗弯强度分别从纯基体的100．3MPa和1．49MPa.m^1/2，提高到181．0MPa和3．20MPa.m^1／2，主要的增强增韧机理为裂纹的偏转,分岔和片晶的拔出。     

热压烧结C-SiC-B_4C复合材料组织与性能(Ⅰ)

以Cfg,SiC,B4C,TiO2为原料,热压工艺为1750~1 900℃×30 min,25 MPa,制备了C-SiC-B4C复合材料,并研究了材料的组织与性能.结果表明随热压温度升高,复合材料的体积密度、抗折强度、断裂韧性均升高;相同热压温度下随Cfg含量增加,其抗折强度降低、断裂韧性升高.在1 900℃热压,原料质量配比(质量分数,%)为Cfg20,SiC 61.7,B4C 12.3和TiO26时,复合材料的综合力学性能最佳,抗折强度为142.5MPa,断裂韧性为4.8 MPa.m21.复合材料的主晶相为层状结构的Cfg,在Cfg层间为SiC,B4C和原位生成的TiB2颗粒.复合材料的增...     

晶须改性氰酸酯树脂/玻璃纤维布复合材料的研究

为了改善氰酸酯树脂基复合材料的层间性能,研究了不同类型晶须材料,即硼酸铝晶须、钛酸钾晶须和硫酸钙晶须对氰酸酯树脂的增韧改性作用,并探讨了硼酸铝晶须对氰酸酯树脂/玻璃纤维布复合材料的力学性能和耐湿热性的影响.研究结果表明:3种晶须材料均可显著提高氰酸酯树脂的弯曲强度和冲击强度,硼酸铝晶须改性效果最佳;硼酸铝晶须添加到氰酸酯树脂/玻璃纤维布复合材料中,复合材料的层间剪切强度和弯曲性能大幅增强,耐湿热性能明显提高.SEM分析表明:晶须在材料破坏过程中,能起到"锚钉"和阻止微裂纹扩展的作用,是氰酸酯树脂的韧性以及复合材料的层间剪切强度得到改善的主要原因.     

粉末冶金制备钛基复合材料的组织与性能

在工业条件下，采用球磨混料、机械压模成型以及真空粉末冶金法制备钛基复合材料。通过测量不同组分和烧结温度条件下试样的弯曲强度和硬度，以及观察其微观组织，结果发现：钛基复合材料的组分对其三点弯曲强度影响较大，三点弯曲强度167．4～602．9MPa，Ti／15W的三点弯曲强度达到602．9MPa；烧结温度对其硬度影响相对较大，洛氏硬度（HRC）31．4～63．8，Ti-3．5Mo-3．4Fe-1．1AI／12TiB的洛氏硬度达到63．8。     

Effects of Cr and Mo elements on the microstructures and compressive properties of the in situ (TiC_xN_y–TiB_2)/Ni cermets

In-situ(TiC_xN_y–TiB_2)/Ni cermets with 70 wt%TiC_xN_y–TiB_2 were successfully fabricated by combustion synthesis and hot pressing sintering in Ni-Ti-B_4C-BN powder systems.The microstructures,density,compressive properties,and hardness of the TiC_xN_y–TiB_2/Ni cermets with the addition of 0–8 wt%Cr/Mo to the Ni-Ti-B_4C-BN powder systems were compared and analysed.The results showed that the ceramic particles distributed uniformly in the cermets,and the size of the ceramic particles reduced with the Cr/Mo addition.Both Cr and Mo addition can improve the hardness,compressive properties,and fracture strains of the cermets.The hardness,compressive strength,and fracture strain of the(TiC_xN_y–TiB_2)/(Ni+Cr)cermets increased from 1561 HV,2.94 GPa,and 2.9%to 1864 HV,3.65 GPa,and 3.4%,respectively when the Cr content increased to 5 wt%.The hardness and compressive strength of the(TiC_xN_y–TiB_2)/(Ni+Mo)cermets increased from 1561 HV and 2.94 GPa to 1902 HV and 3.43 GPa,respectively when the Mo content increased to 8 wt%.The cermets with Cr had better compressive properties than the cermets with Mo.