Effect of graphite particle size on wear property of graphite and Al_2O_3 reinforced AZ91D-0.8%Ce composites

The graphite particles and Al_2O_3 short fibers reinforced AZ91D-0.8%Ce composites were fabricated by squeeze-infiltration technique.The researches about the effects of different graphite particle sizes on the microstructure and wear property of the composites were performed under the condition of constant contents of graphite particles and Al_2O_3 short fibers.The results reveal that the grain size of the composites changes less when the graphite particle size descends.Moreover,Ce enriches around the gr...     

Effect of graphite content on wear property of graphite/Al_2O_3/Mg-9Al-1Zn-0.8Ce composites

Using squeeze-infiltration technique, Mg-9Al-1Zn-0.8Ce composite reinforced by graphite particles and Al2O3 short fibers was fabricated. The reinforcing phases combined closely with the matrix and no agglomeration was observed. The microstructure, hardness and wear property of the composites with the graphite content of 5%, 10%, 15% and 20% were investigated, respectively. The results reveal that Ce tends to enrich around the boundaries of graphite particles and Al2O3 short fibers, and forms Al3Ce phase. Wh...     

Microstructures and properties of graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites

Graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites were fabricated by perform squeeze-infiltration route. The effects of the volume of graphite particles on the microstructure, mechanical properties and tr/bological behavior were investigated under the conditions of constant size of graphite particle and volume of Al2O3 short fiber. The results reveal that the uniform distribution of the reinforced graphite particles and Al2O3 short fiber can be obtained by this technique, and they have strong bonding with the metal matrix. Increasing graphite volume results in decrease in hardness, the ultimate tensile strength whereas the Al2O3 short fiber makes contribution to the increase in hardness of the composite. The composite exhibits good wear resistance, small wear mass loss and low coefficient of friction as compared with the metal matrix. The wear mechanisms transit from oxidation wear, abrasion wear into delamination wear as the applied load is increased, and a film of lubricant covering almost entire surface of specimen, is found to be formed, which separates the wear surfaces from metal to metal contact and thus improves the tribological properties.     

废弃玻璃／铝基复合材料的组织和性能

利用搅拌熔铸法将废弃玻璃颗粒加入到熔融的基体合金ZL105中,制备出了废弃玻璃／铝基复合材料,研究了复合材料的微观组织,力学性能及断裂机理,结果表明,玻璃颗粒较均匀地分布于基体中,与基体发生界面反应;与基体合金相比,废弃玻璃颗粒的加入提高了复合材料的硬度和抗拉强度,在低载荷下,复合材料的摩擦性能优于基体合金,由于玻璃颗粒形状较尖锐,尺寸大小不均,并存在加工缺陷,有碍于大幅度提高复合材料的性能。     

半固态B4C/Y112复合材料磨损性能研究

研究了机械搅拌法制备的半固态B4C/Y112复合材料在不同载荷下的磨损性能.采用SEM对磨损面和磨屑显微组织进行了观察与分析,讨论了不同质量分数的B4C颗粒对磨损机制的影响.结果表明,基体和复合材料磨损质量损失都是随着载荷的增加而增加,磨损质量损失随B4C颗粒含量增加而减少.随着载荷增加,材料从轻微磨损向严重磨损转变.总体上讲,复合材料比基体的耐磨性好.     

T6热处理对SiCp/Al复合材料摩擦磨损性能的影响

采用粉末冶金法制备出不同SiC颗粒体积分数(30%、35%和40%)的SiCp/Al复合材料。采用MMU-5GA微机控制真空高温摩擦磨损试验机对比研究SiCp/Al复合材料在不同体积分数以及T6热处理前后情况下平均摩擦因数和磨损率的变化,通过扫描电镜分析了SiCp/Al复合材料表面磨损形貌,探讨了摩擦磨损机理。试验结果表明,SiC颗粒体积分数在30%~40%变化时,随其体积分数增加耐磨性下降。SiC颗粒体积分数在30%~35%范围内,SiC颗粒与基体结合较好,SiC颗粒作为硬质点起到抵抗磨损和限制基体合金塑性变形产生磨损的双重作用;但SiC含量过多时,颗粒与基体的结合不紧密,磨损时颗粒极易脱落,复合材料耐磨性降低;T6热处理后复合材料的平均摩擦因数和磨损率均降低,这是由于热处理后试样强度及硬度提高,从而提高了试样的耐磨性;常温下复合材料在磨损初期的磨损机理主要以磨粒磨损为主,而在磨损期则为磨粒磨损与剥落磨损共存。     

富Ce混合稀土对铝基混杂复合材料耐磨性能的影响

用挤压铸造法制备Al2O3短纤维石墨颗粒混杂增强ZL109复合材料,并研究富Ce混合稀土对该混杂复合材料耐磨性能的影响。结果表明:适量稀土元素可在一定程度上改善该混杂复合材料的耐磨性能,特别在低载荷下,其作用更为显著;稀土对复合材料磨损机制的影响与载荷有关,在较低的载荷下,犁沟磨损是复合材料的主要磨损机制,并存在轻微的剥层破坏;但在较大载荷下,稀土元素加入后,特别是稀土含量高于0.6%后,复合材料的磨损机制由犁沟磨损转变为严重的剥落磨损,复合材料耐磨性反而降低,这可能与稀土含量高时富含稀土的针状相析出有关。     

Casting fabrication of in situ Al3Ti-Al composites and their wear behaviors

The Al3li intermetallic reinforced pure Al, Al-13Si and Al-17Cu matrix composites were prepared by casting method. Their microstructures and dry sliding wear behaviors at room temperature and 100℃ were particularly investigated. The results indicated that the Al3Ti phases in these composites were all in flaky form. But the aspect ratio of the Al3Ti platelets decreased with the increase of Ti content in the pure AI, Al-Cu and Al-Si matrix composites, in order of effectiveness. The effect of Si on the Al3Ti morphology seemed to be greater than that of Cu. The distributions of the Al3Ti platelets were different in the different matrix composites, leading to different grain refining effects. Except for the sub-wear regime of adhesive wear, the plastic deformation induced wear was a dominant wear mechanism for all of the composites at room temperature and 100℃. Increasing the testing temperature, decreasing the Al3Ti content or the hardness of materials could enhance these two wear mechanisms, and thus increase the wear rate. The Al-Cu matrix composite had the best wear resistance, while the pure Al matrix composite showed the worst for the same Ti content. These differences or changes were attributed to the differences in materials' hardness or the strengthening effects of the Al3Ti platelets.     

Superior Tribological Properties of Particulate Aluminum Matrix Nano Composites

Aluminum is the best metal for producing metal matrix composites which are known as one of the most useful and high-tech composites in our world. Combining aluminum and nano Al₂O₃ particles will yield a material with high mechanical properties. Characterization of tribological properties revealed that the presence of nano particles significantly increased wear resistance of the composite. In case of unreinforced Al alloy, the depth of penetration is governed by the hardness of the specimen surface and applied load. But, in case of Al matrix composite, the depth of penetration of the harder asperities of hardened steel disk is primarily governed by the protruded hard ceramic reinforcement. The hard Al₂O₃ particles act as a protrusion over the matrix, carries a major portion of the applied load and protect the abrasives from penetration into the specimen surface.     

电磁铸造法制备的(Al2O3+Al3Zr)p/A359复合材料的磨损行为

利用A359-Zr(CO3)2体系原位反应合成法制备(Al2O3 Al3Zr)p/A359颗粒增强铝基复合材料,在制备过程中施加低频交变电磁场进行搅拌以提高复合材料的耐磨性能.干滑动摩擦磨损试验表明:复合材料的耐摩擦性比纯基体合金明显提高,施加电磁搅拌后复合材料的耐摩擦性进一步提高,特别是在较大载荷下的耐摩擦性大幅提高,从轻微磨损到急剧磨损的临界转变载荷由58.8 N提高到78.8 N.磨损表面的SEM分析显示:纯基体合金为粘着磨损和剥层磨损,复合材料的磨损为以磨粒磨损为主和少量的剥层磨损,施加电磁搅拌后的复合材料为纯磨粒磨损.     

固溶处理对TiB2/6061复合材料硬度及耐磨性的影响

采用氟盐法制备了TiB₂质量分数为3%的原位合成TiB₂/6061复合材料,研究了固溶温度和固溶时间对复合材料硬度和耐磨性能的影响。结果表明:TiB₂颗粒弥散分布在6061铝合金基体中,明显细化6061铝合金基体晶粒。当固溶温度一定时,随固溶时间延长,复合材料的硬度和耐磨性可获得明显提高,但固溶时间在6~10 h时,复合材料的性能变化不显著。当固溶时间一定时,随固溶温度升高,复合材料硬度和耐磨性呈现先上升后下降的趋势。3wt%TiB₂/6061复合材料经530 ℃×10 h固溶处理后,硬度和耐磨性能最佳,相较于铸态硬度值提高了79.5％,磨损量减少了59.1%。固溶处理后复合材料的磨损表面犁沟变细变浅,材料脱落现象减少。     

摩擦条件对化学混杂复合镀层Ni-P-Gr-SiC摩擦性能的影响(英文)

研究化学复合镀层Ni-P-Gr-SiC的摩擦磨损性能,主要研究石墨复合量、载荷及转速对复合镀层摩擦性能的影响。采用SEM和EDAX对磨损表面和截面进行磨痕形貌和成分分析。结果表明,由于石墨和碳化硅两相颗粒的协同作用,复合镀层显示出良好的减摩性能和耐磨性。分析表明,摩擦试样的亚表层形成的富石墨机械混合层对摩擦体系保持良好的摩擦性能起到重要作用,同时碳化硅颗粒的承载作用有效避免富石墨机械混合层在摩擦剪切力作用下的断裂。     

Dry sliding wear behavior of Al 2219/SiCp-Gr hybrid metal matrix composites

The dry sliding wear behavior of Al 2219 alloy and Al 2219/SiCp/Gr hybrid composites are investigated under similar conditions. The composites are fabricated using the liquid metallurgy technique. The dry sliding wear test is carried out for sliding speeds up to 6 m/s and for normal loads up to 60 N using a pin on disc apparatus. It is found that the addition of SiCp and graphite reinforcements increases the wear resistance of the composites. The wear rate decreases with the increase in SiCp reinforcement content. As speed increases, the wear rate decreases initially and then increases. The wear rate increases with the increase in load. Scanning electron microscopy micrographs of the worn surface are used to predict the nature of the wear mechanism. Abrasion is the principle wear mechanism for the composites at low sliding speeds and loads. At higher loads, the wear mechanism changes to delamination.     

Effect of Hot Working on Structure and Tribological Properties of Aluminium Reinforced with Aluminium Oxide Particulates

Al-Al₂O₃ (18%) composite was prepared by stir-cast melt technique. The microstructures showed uniform distribution of particulates, dispersed in the matrix. There exists discontinuity (~0.25???m) in the interface between particulates and matrix. The composite was hot forged. Hot working resulted in fine recrystallized microstructure with particulates dispersed along grain boundaries. Formation of pancake microstructure with some inhomogeneity in the microstructure along three faces of the forged composite was observed. The discontinuity across the interface between Al-Al₂O₃ was reduced to 0.125???m after forging. The as-cast and forged Al-Al₂O₃ composites showed higher wear resistance than pure Al. In lubricant media, there was no significant wear observed for either the as-cast or forged composite, whereas Al had shown higher wear at 50?N load.     

磁化学熔体反应法合成TiB2/7055复合材料的组织和性能

通过磁化学熔体反应法在7055(Al?3%B)?Ti反应体系中成功制备TiB2/7055复合材料。利用XRD、OM和SEM等分析检测技术研究复合材料的相组成和微观组织。结果表明,脉冲磁场作用下生成的TiB2颗粒呈多边状或近球形,尺寸小于1μm,均匀分布于基体中。与未施加脉冲磁场的复合材料相比,施加磁场后α(Al)晶粒平均尺寸从20μm减小到约10μm,第二相从连续的网格状分布变为非连续性分布。在磁场作用下,复合材料的抗拉强度从310 MPa提高到333 MPa,伸长率从7.5%提高到8.0%。此外,与基体相比,在载荷为100 N,磨损时间为120 min时,复合材料的磨损量从111 mg降低到78 mg。     

玄武岩颗粒增强7A04铝基复合材料的界面结构及力学行为

采用喷射成形技术制备7A04铝合金及玄武岩颗粒增强7A04铝合金复合材料,利用金相显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和能谱(EDS)分析复合材料微观组织和界面结构,对比研究复合材料的力学性能。结果表明:玄武岩颗粒在铝基体中弥散分布,并与铝基体形成强力结合界面,玄武岩颗粒边缘的SiO2不断被反应生成的Al2O3取代,形成一层几十纳米厚度的高温反应层,反应生成的Al2O3强化玄武岩颗粒与铝基体的结合界面;弥散分布的玄武岩颗粒促进基体中位错增殖、空位形成和析出相的析出,析出相主要以板状的η(MgZn2)相和亮白色条状或椭球状的T(Al2Mg3Zn3)相为主,结合界面、高位错密度及弥散分布的第二相显著提高复合材料的力学性能,添加玄武岩颗粒的7A04铝合金复合材料的屈服强度和极限拉伸强度分别达667 MPa和696 MPa,与未添加玄武岩颗粒的7A04铝合金相比分别提高10.4%和10.1%。     

熔铸法制备原位内生Al3Tip/AZ91D复合材料

采用熔铸法制备了Al3Tip体积分数分别为4%和8%的AZ91D复合材料,研究了其显微组织和物相,测试了其致密度、硬度及磨损性能。结果表明,复合材料组织致密,原位内生的Al3Ti颗粒尺寸细小,呈球形且在基体中分布较均匀,与基体结合紧密;随Al3Ti体积分数的增加复合材料的致密度降低,硬度升高,但其耐磨性反而有所降低。与基体AZ91D合金相比,Al3Tip/AZ91D基复合材料的硬度和耐磨性均得到明显提高。     

添加NH_4AlO（OH）HCO_3原位生成Al_2O_3/Al复合材料的制备及其性能

碳酸铝铵与熔融的铝液反应原位生成颗粒增强铝基复合材料,对复合材料的力学性能和摩擦磨损行为进行研究。结果表明：在搅拌的铝熔体中碳酸铝铵发生分解反应生成γ-Al2O3;该原位反应的增强颗粒比直接添加的Al2O3在铝熔体中分布得更均匀;复合材料的密度和硬度随着增强相加入量的增加而提高,而强度则随着增强相加入量的增加而降低;磨损率随着增强相加入量的增加和载荷的增加而提高;原位反应生成的复合材料的力学性能和耐磨性明显优于直接添加Al2O3颗粒形成的复合材料的。     

原位合成Al_3Ti颗粒增强铝基复合涂层(英文)

以直径200μm、纯度99.5%的钛丝丝网为反应源,通过熔渗-原位反应法制备一种Al3Ti金属间化合物颗粒增强铝基表面复合涂层。差热分析结果表明,在890°C下,Ti丝和Al熔体间发生反应。采用XRD、SEM以及显微硬度和磨损测试对所得到的复合涂层进行表征。结果表明:当保温时间为20min时,钛丝反应完全,原位合成为块状和条状的Al3Ti颗粒;颗粒的显微硬度大约为基体显微硬度的4.5倍;在载荷10N的干滑动磨损条件下,与没有增强的Al基体相比较,保温20min所制备的复合涂层表现出较好的耐磨性,其磨损机制为粘着磨损和磨粒磨损共存。     

Characteristics and wear behavior of cenosphere dispersed titanium matrix composite developed by powder metallurgy route

The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in α-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al₂O₃, SiO₂, TiO₂ and α-Ti. The average microhardness of the composite (matrix) varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti–6Al–4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl (mass fraction) solution shows that corrosion potential (φ_corr) shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti–6Al–4V alloy.