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1.
Wear behavior of Al/Al 2O 3/C hybrid metal matrix composites fabricated by squeeze casting method was characterized. The effects of volume fraction of carbon fiber on wear behavior of hybrid composites was investigated. Wear behavior of Al/Al 2O 3/C composites was characterized by the dry spindle wear test under various sliding speeds. The wear resistance of Al/Al2O3/C composites was remarkably improved over Al/Al2O3 composites by adding carbon fibers to Al/Al2O3/C composites. Specifically, at the intermediate sliding speed the wear resistance of Al/Al2O3/C composites containing 8 vol.% carbon fiber was found to be better than that of the rest of the carbon hybrid composites. From fractographic studies, damaged sections in wear surfaces of hybrid composites at intermediate sliding speed were not observed due to the formation of solid lubrication film. The solid lubrication film which was formed as a result of adding carbon fibers improved the wear resistance of carbon hybrid composites because this film reduced the high friction force between MMCs and counter material. 相似文献
2.
TiB 2–Al 2O 3 composites with Ni–Mo as sintering aid have been fabricated by a hot-press technique at a lower temperature of 1530 °C for 1 h, and the mechanical properties and microstructure were investigated. The microstructure consists of dispersed Al 2O 3 particles in a fine-grained TiB 2 matrix. The addition of Al 2O 3 increases the fracture toughness up to 6.02 MPa m 1/2 at an amount of 40 vol.% Al 2O 3 and the flexural strength up to 913.86 MPa at an amount of 10 vol.% Al 2O 3. The improved flexural strength of the composites is a result of higher density than that of monolithic TiB 2. The increase of fracture toughness is a result of crack bridging by the metal grains on the boundaries, and crack deflection by weak grain boundaries due to the bad wetting characters between Ni–Mo and Al 2O 3. 相似文献
3.
The effects of volume fraction, Al 2O 3 particle size and effects of porosity in the composites on the abrasive wear resistance of compo-casting Al alloy MMCs have been studied for different abrasive conditions. It was seen that porosity in the composites is proportional to particle content. In addition, process variables like the stirring speed, and the position and diameter of the stirrer affect of the porosity content in a way similar to that observed for particle content. In addition, the abrasive wear rates of composites decreased more rapidly with increase in Al 2O 3 volume fraction in tests performed over 80 grade SiC abrasive paper than in tests conducted over 220 grade SiC abrasive paper. Furthermore, the wear rates decreased with increase in Al 2O 3 size for the composites containing the same amount of Al 2O 3. Hence, it is deduced that aluminium alloy composites reinforced with larger Al 2O 3 particles are more effective against abrasive wear than those reinforced with smaller Al 2O 3 particles. At the same time the results show that the beneficial effects of hard Al 2O 3 particles on wear resistance far surpassed that of the sintered porosity in the compocasting metal-matrix composites (MMCs). Nevertheless, the fabrication of composites containing soft particles such as graphite favors a reduction in the friction coefficient. For this reason graphite and copper were used in the matrix in different amounts to detect their effect on wear resistance. Finally, it was seen that wear rate of the composites decreased considerably with graphite additions. 相似文献
4.
Al/Al 2O 3 composite coating was prepared by plasma spraying and characterized by XRD and SEM. Some thermal–mechanical properties of the composite coating including thermal diffusivity, microhardness, fracture toughness and sliding wear rate were measured. The results showed that the Al/Al 2O 3 composite coating, compared with Al 2O 3 coating, exhibits denser structure and developed splat interface. The coexistence of Al metal phase and Al 2O 3 ceramic phase effectively increased the fracture toughness and thermal diffusivity of composite coating, in spite of the slight decrease in microhardness. Furthermore, the wear resistance of Al/Al 2O 3 composite coating is superior to that of Al 2O 3 coating. 相似文献
5.
热处理可显著提高镀层的硬度和耐磨性能。采用化学镀的方法在45钢表面制备了Ni-P-纳米A12O3复合镀层,并以不同温度对其热处理,研究了镀层热处理前后的物相、硬度和耐磨性能。结果表明:400℃热处理后,Ni-P-A12O3复合镀层达到稳态,稳定相是Ni+Ni3P+NiO+A12O3;镀层的显微硬度随热处理温度的升高而先... 相似文献
6.
The C40 Mo(Si 0.75Al 0.25) 2/Al 2O 3 composites were prepared by spark plasma sintering (SPS) of mechanically alloyed (MA) powders. The Mo(Si 0.75Al 0.25) 2/0–20 vol.% Al 2O 3 materials, showing micron and submicron composite structure, possess a hardness of 13.9–14.6 GPa but a poor toughness of 1.78–1.80 MPa m 1/2. The addition of 30 vol.% Al 2O 3 leads to the formation of the micron C40 Mo(Si 0.75Al 0.25) 2/Al 2O 3 composite with an intergranular distribution of Al 2O 3, that results in a drop of the hardness to 10.2 GPa and an improvement of the toughness to 3.67 MPa m 1/2. The transition of the cleavage facets to the intergranular fracture with the addition of Al 2O 3 is assumed as the main toughening mechanism. 相似文献
7.
首先,以15vol%或25vol%的TiC0.5N0.5粉体为导电第二相,利用热压烧结法制备了TiC0.5N0.5/Si3N4复相陶瓷;然后,分别通过物理气相沉积(PVD)和化学气相沉积(CVD)技术在TiC0.5N0.5/Si3N4陶瓷刀具表面沉积了CrAlN和TiN/Al2O3/TiN涂层;最后,通过对TiC0.5N0.5/Si3N4刀具进行连续切削灰铸铁实验,研究了TiC0.5N0.5含量和涂层类型对刀具磨损特征的影响,并探讨了刀具的磨损机制。结果表明:TiC0.5N0.5含量的增加有利于提高TiC0.5N0.5/Si3N4复相陶瓷刀具基体的硬度和电导率,但对耐磨性和切削寿命的影响较小;采用PVD技术沉积CrAlN涂层时,随着TiC0.5N0.5含量的增加,涂层的厚度、结合强度和硬度都得到提高,涂层刀具的磨损性能显著提高,切削寿命也明显延长;而采用CVD技术沉积TiN/Al2O3/TiN涂层时,TiC0.5N0.5含量的变化对涂层的厚度、结合强度和硬度基本没有影响,TiN/Al2O3/TiN涂层刀具整体切削性能变化不大。CrAlN涂层和TiN/Al2O3/TiN涂层都可明显改善TiC0.5N0.5/Si3N4复相陶瓷刀具的耐磨性和切削寿命;相对于TiN/Al2O3/TiN涂层,CrAlN涂层具有更高的涂层硬度和粘着强度,但TiN/Al2O3/TiN涂层具有较大的涂层厚度,TiN/Al2O3/TiN涂层刀具表现出更加优异的耐磨性和切削寿命。TiC0.5N0.5/Si3N4复相陶瓷刀具的磨损机制以机械摩擦导致的磨粒磨损为主,伴随有少量的粘结磨损。 相似文献
8.
Joining of bulk ceramics by plastic flow has been demonstrated for several fine-grained ceramics. We have joined, for example, submicrometer 3 mol% Y 2O 3 partially stabilized ZrO 2 (YSZ) and YSZ-toughened Al 2O 3. The interlayers in these cases consisted of dense, submicrometer-grain-sized pieces of ceramics that have been shown to exhibit superplastic flow. We have extended the joining work to include incorporation of 15 vol.% SiC or 20 vol.% TiC whiskers within the bond layer. Unlike YSZ/Al 2O 3, because of the presence of the whiskers, YSZ/Al 2O 3/SiC and YSZ/Al 2O 3/TiC do not deform superplastically. However, virtually perfect YSZ/Al 2O 3 joints with and without whiskers could be made by compressing at 1300–1350 °C and stresses of <20 MPa. 相似文献
9.
采用共沉积法在TA15合金表面制备了Ni-SiC复合镀层, 分析了Ni-SiC复合镀层对基体合金硬度和磨擦磨损性能的影响, 并对其摩擦磨损机制进行了讨论。结果表明: 所制备的Ni-SiC复合镀层组织致密且与基体结合紧密, 硬度明显高于TA15合金基体。摩擦磨损实验结果表明, Ni-SiC复合镀层能为TA15合金提供良好的摩擦磨损抗力, 在相同的摩擦条件下, Ni-SiC复合镀层的磨损率明显低于TA15合金。TA15合金与GCr15球和Al 2O 3球对磨的磨损机制均主要为犁削磨损、粘着磨损, 同时伴随有氧化磨损和轻微的磨粒磨损; Ni-SiC复合镀层与GCr15磨球对磨的磨损机制主要为镀层组织的拔出及GCr15钢球在其表面上的涂抹, 与Al 2O 3磨球对磨时的磨损机制主要为疲劳磨损和削层磨损。 相似文献
10.
通过对比分析Ti 3AlC 2-Al 2O 3/TiAl 3复合材料在纯腐蚀、纯磨损及熔蚀-磨损三种条件下的材料流失特征,研究了Ti 3AlC 2-Al 2O 3/TiAl 3复合材料在Al液中的熔蚀-磨损行为及熔蚀与磨损的交互作用机制。结果表明,Ti 3AlC 2-Al 2O 3/TiAl 3复合材料在Al液中的熔蚀-磨损体积损失比H13钢的体积损失低了两个数量级,随着载荷和转速的上升,Ti 3AlC 2-Al 2O 3/TiAl 3复合材料的磨损由磨粒磨损逐渐向黏着磨损转变。Ti 3AlC 2-Al 2O 3/TiAl 3复合材料的熔蚀、磨损交互作用率的最大值为47.5%,在低载荷或低转速条件下由于铝熔体的润滑作用,Ti 3AlC 2-Al 2O 3/TiAl 3复合材料甚至表现出负的交互作用。这一方面是由于Ti 3AlC 2-Al 2O 3/TiAl 3复合材料在Al液中腐蚀时不生成其它界面产物,而仅为极少量Ti元素的溶解;另一方面则是由于TiAl 3基体与Al 2O 3二者所形成的空间网络状结构改善了Ti 3AlC 2-Al 2O 3/TiAl 3复合材料在Al液中的耐磨损性能。 相似文献
11.
Dense TiC–Al 2O 3–Al composite was prepared with Al, C and TiO 2 powders by means of electric field-activated combustion synthesis and infiltration of the molten metal (here Al) into the synthesized TiC–Al 2O 3 ceramic. An external electric field can effectively improve the adiabatic combustion temperature of the reactive system and overcome the thermodynamic limitation of reaction with x < 10 mol. Thereby, it can induce a self-sustaining combustion synthesis process. During the formation of Al 2O 3–TiC–Al composite, Al is molten first, and reacted with TiO 2 to form Al 2O 3, followed by the formation of TiC through the reaction between the displaced Ti and C. Highly dense TiC–Al 2O 3–Al with relative density of up to 92.5% was directly fabricated with the application of a 14 mol excess Al content and a 25 V cm −1 field strength, in which TiC and Al 2O 3 particles possess fine-structured sizes of 0.2–1.0 μm, with uniform distribution in metal Al. The hardness, bending strength and fracture toughness of the synthesized TiC–Al 2O 3–Al composite are 56.5 GPa, 531 MPa and 10.96 MPa m 1/2, respectively. 相似文献
12.
采用往复式滑动摩擦磨损(SRV)试验机研究了高铬铸铁及三维网络结构Al 2O 3陶瓷增强高铬铸铁复合材料的干摩擦磨损性能,测量了高铬铸铁和Al 2O 3陶瓷/高铬铸铁复合材料在不同摩擦频率及载荷下的摩擦系数和磨损率;用扫描电镜观察磨损表面形貌,并分析了三维网络Al 2O 3陶瓷对复合材料磨损机制的影响。结果表明:陶瓷Al 2O 3与高铬铸铁基体之间具有良好的界面结合,复合材料的摩擦系数随摩擦频率和载荷的变化保持稳定,耐磨性远优于高铬铸铁,而且随着摩擦频率和载荷的增加,Al 2O 3陶瓷/高铬铸铁复合材料的抗磨损性能明显提高,这是由于复合材料中Al 2O 3与高铬铸铁相之间三维空间结构和良好的界面结合有利于摩擦载荷的传递;三维Al 2O 3陶瓷骨架在磨损表面形成硬的网络突体并起承载作用,能有效保护金属基体;磨损机制为氧化磨损及磨粒磨损共同作用。 相似文献
13.
本研究在ZrO 2基体表面涂覆一薄层Al 2O 3涂层, 利用基体与涂层之间热膨胀系数不匹配, 在Al 2O 3-ZrO 2预应力陶瓷(简称A CZ S预应力陶瓷)表层引入压应力。采用维氏压痕法评价残余应力对A CZ S预应力陶瓷的表层和基体中裂纹扩展阻力的影响。理论分析结合实验结果表明: 表层的压应力使得A CZ S预应力陶瓷的裂纹扩展阻力增大, 最终导致强度和损伤容限提高; 且A CZ S预应力陶瓷表层的压应力和裂纹扩展阻力随着基体截面积与涂层截面积比值的增加而增大。当ZrO 2基体表层的Al 2O 3涂层厚度为40 μm时, 表层压应力使A CZ S预应力陶瓷的弯曲强度达到(1207±20) MPa, 相比于同种工艺下制备的ZrO 2陶瓷强度提高了32%, 同时也是Al 2O 3强度的3倍。此外, A CZ S预应力陶瓷也表现出很好的抗热震性能。 相似文献
14.
采用刷涂法在Al 2O 3基多孔隔热材料表面制备Al 2O 3/MoSi 2涂层,涂层以硅溶胶作为粘结剂,纳米Al 2O 3与Al 2O 3纤维作为耐高温组分,MoSi 2为高发射率组分。通过SEM、XRD对Al 2O 3/MoSi 2涂层微观表面结构、物相组成进行分析。研究纳米Al 2O 3与Al 2O 3纤维的质量比和MoSi 2含量对Al 2O 3/MoSi 2涂层耐温性能的影响,并对Al 2O 3/MoSi 2涂层的抗热震性能、发射率进行表征。结果表明,当纳米Al 2O 3与Al 2O 3纤维的质量比小于1∶1时,热考核后Al 2O 3/MoSi 2涂层表面无裂纹产生;当纳米Al 2O 3与Al 2O 3纤维的质量比在1∶2~1∶4之间时,Al 2O 3/MoSi 2涂层中的纤维网络较完整。MoSi 2的含量为20%时,Al 2O 3/MoSi 2涂层抗热震实验循环25次后表面保持完好,热考核后在2.5~25 μm波段的平均发射率在0.85左右,具有较高的发射率。 相似文献
15.
向SiO 2基体粉料中添加Al 2O 3纤维,采用热压注法制备Al 2O 3/SiO 2陶瓷型芯。分析Al 2O 3纤维含量对陶瓷型芯性能的影响。研究结果表明:Al 2O 3纤维含量对Al 2O 3/SiO 2陶瓷型芯的线收缩率、体积密度和抗弯强度均有较大的影响。当Al 2O 3纤维含量大于1wt%时,Al 2O 3/SiO 2陶瓷型芯的线收缩率大幅度降低,稳定在0.335%左右,体积密度随之降低,稳定在1.790 g · cm -3左右;当Al 2O 3纤维含量为1wt%时,陶瓷型芯抗弯强度达最大值20.48 MPa。分析了Al 2O 3纤维对Al 2O 3/SiO 2陶瓷型芯烧结收缩的阻滞作用机制。 相似文献
16.
采用叠层模压法制备了纳米Al 2O 3-碳纤维织物多尺度增强聚酰胺基(nano Al 2O 3-CFF/PA6)复合材料层压板。借助场发射扫描电子显微镜(FESEM)、同步热分析仪(TGA/DSC)和FTIR,研究了模压温度、压力和纳米Al 2O 3加入量等因素对nano Al 2O 3-CFF/PA6复合材料力学性能的影响。研究表明:在模压温度为230℃、模压压力为3 MPa和保压时间为15 min时,CFF/PA6层压板的弯曲强度为250.3 MPa,层间剪切强度为87.6 MPa,平行层厚方向的冲击强度为41.2 MPa,垂直层厚方向为9.6 MPa。当基体中的Al 2O 3含量达到6wt%时,nano Al 2O 3-CFF/PA6层压板的弯曲强度为387.6 MPa,层间剪切强度为35.7 MPa,平行和垂直层厚方向的冲击强度分别为80.3 MPa和25.6 MPa。 相似文献
17.
采用水热法制备片状纳米Al 2O 3,经过偶联剂改性后与环氧树脂复合,通过溶液混合法制备了不同填充量的片状纳米Al 2O 3/环氧树脂复合材料,研究了片状纳米Al 2O 3用量对片状纳米Al 2O 3/环氧树脂复合材料介电性能和热性能的影响,利用SEM对复合材料的断口形貌进行了表征。结果表明: 片状纳米Al 2O 3在环氧树脂基体中分散良好;随着片状纳米Al 2O 3填充量的增加,复合材料的起始热分解温度升高、介电强度增大,当片状纳米Al 2O 3的填充量为7wt%时,复合材料的介电强度为 29.58 kV/mm,比纯环氧树脂的介电强度提高了30%;复合材料的介电常数(3.8~4.5)和介电损耗(0.015)比纯环氧树脂稍有增大,但仍维持在较好的介电性能范围内。 相似文献
18.
采用球磨-转喷微注相结合的新工艺制备纳米Al 2O 3颗粒(Al 2O 3p)/Al(7075)复合材料,设计一种转喷微注装置,该装置能将连续、微量的纳米Al 2O 3p注入到Al熔体中。观察纳米Al 2O 3增强相对Al(7075)基体合金材料微观组织的影响,并测试Al(7075)基体和纳米Al 2O 3p/Al(7075)复合材料的磨损特性。对纳米Al 2O 3p/Al(7075)复合材料和Al(7075)基体在不同载荷(15 N、25 N和35 N)下的磨损特性进行对比研究。结果表明:球磨-转喷微注法制备的纳米Al 2O 3p/Al(7075)复合材料晶粒较小,且增强相在基体中分布均匀且结合良好;随着载荷增大,纳米Al 2O 3p/Al(7075)复合材料磨损量的上升趋势慢于Al(7075)基体。载荷为35 N时,纳米Al 2O 3p/Al(7075)复合材料的磨损量较Al(7075)基体少,磨屑尺寸较小,其耐磨性能明显改善,这主要得益于纳米Al 2O 3p的支撑作用和材料的细晶强化作用。 相似文献
19.
以稻草纤维及丙烯腈-丁二烯-苯乙烯(ABS)为原料,分别以活性炭、Al 2O 3、SiO 2和硅烷偶联剂为增强改性剂,通过混炼-模压工艺制备了改性剂-稻草/ABS复合材料,对比研究了几种不同增强改性剂的增强效果及其增强机制。结果表明:硅烷偶联剂对稻草/ABS复合材料的增强效果较差,活性炭、Al 2O 3和SiO 2对稻草/ABS复合材料的增强均优于硅烷偶联剂,其中Al 2O 3的增强效果最佳。当Al 2O 3的添加量(Al 2O 3∶ABS质量比)为5%时,Al 2O 3-稻草/ABS复合材料的拉伸、弯曲及冲击强度分别达到最大值27.719 MPa、61.05 MPa和26.53 kJ/m 2;当无机物添加量(无机物∶ABS质量比)为5%时,复合材料的耐水性能表现为:5% Al 2O 3 > 5%活性炭 > 5% SiO 2 > 未添加,与复合材料的力学性能梯度相符;改性剂-稻草/ABS复合材料的流变性能则表现为:5%活性炭 > 5% Al 2O 3 > 5% SiO 2 > 未添加。 相似文献
20.
采用SRV摩擦磨损试验机研究了球墨铸铁及三维网络Al 2O 3增强球墨铸铁基复合材料的干摩擦磨损性能, 测量了球墨铸铁和复合材料在不同摩擦频率及载荷下的摩擦系数和磨损率; 用扫描电镜观察磨损表面形貌, 并分析了三维网络Al 2O 3对复合材料磨损机制的影响。结果表明: 陶瓷与金属基体之间具有良好界面结合的三维网络Al 2O 3/球墨鋳铁复合材料, 其摩擦系数随载荷和摩擦频率的变化保持稳定; 复合材料的耐磨性能远优于球墨铸铁, 而且随着摩擦频率和载荷的增加, 复合材料的抗磨损性能明显提高。这是由于复合材料中陶瓷与金属相之间三维空间结构和良好的界面结合有利于摩擦载荷的传递; 金属基体中的石墨减摩作用保持摩擦系数的稳定; 三维陶瓷骨架在磨损表面形成硬的微突体并起承载作用, 制约了基体的塑性变形和高温软化, 有利于磨损表面氧化膜的留存。 相似文献
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