流变成形压力对Al2Y/AZ91镁基复合材料摩擦磨损行为的影响

采用销盘式摩擦副,在转速为100 r/min干摩擦条件下,结合OM、SEM结果,考察了不同载荷与成形压力对流变成形Al2Y/AZ91镁基复合材料(质量分数2%Y)摩擦磨损性能的影响,并探究耐磨性与材料显微组织、力学性能之间的关系.研究表明:在相同的实验载荷下,随着制备复合材料流变成形压力的增加,材料的磨损质量和摩擦系数减少,本实验条件下最大成形压力为100 MPa时磨损量和摩擦系数最小,摩擦磨损性能较佳;对于在相同成形压力下制备的镁基复合材料,磨损质量随着载荷的提升而增大,而摩擦系数有所降低.当载荷较小时,Al2Y/AZ91镁基复合材料的磨损机制以磨粒磨损为主;随着载荷的增大,磨损机制逐步发生转变;当载荷较大时,磨损机制以剥层磨损为主.     

Mg_2B_2O_(5W),SiC和Gr颗粒增强6061Al基复合材料的摩擦磨损行为

采用粉末热挤压法制备2%Mg2B2O5w/6061Al,2%Gr/6061Al,2%SiCp/6061Al,2%Mg2B2O5w+2%Gr/6061A,2%Mg2B2O5w+2%SiCp/6061Al,2%Mg2B2O5w+2%Gr+2%SiCp/6061Al单一及混杂增强的铝基复合材料,并对其耐磨性和摩擦行为进行研究。结果表明:随着载荷的增大,各种复合材料的磨损率均增大,石墨的添加增大了铝基复合材料的磨损率;复合材料的摩擦因数随载荷的增大而降低并趋于稳定,摩擦因数均介于0.22~0.32之间。未加入石墨的复合材料的磨损机制以磨料磨损和轻微的黏着磨损为主,加入石墨后复合材料的磨损机制转变为剧烈的黏着磨损。     

纳米Al2O3改性玻璃纤维增强复合材料低温力学性能研究

简述了纳米Al2O3改性玻璃纤维增强环氧树脂基复合材料的制备,并对其常温、低温力学性能进行实验。结果表明,常温、低温下,复合材料的力学性能随着纳米Al2O3含量的增加都呈现先增强后减弱的趋势。低温处理使复合材料的力学性能得到提升,并且低温下Al2O3的引入对复合材料强度的改善效果比常温下明显,Al2O3含量为1%(质量分数)时,拉伸强度提高比例高达16.61%。其原因是低温下基体强度增大,另外基体热膨胀系数大,收缩明显,界面粘接强度增大,纳米Al2O3颗粒在界面处与树脂基体结合更深入,从而使纳米粒子阻碍微裂纹扩展的能力更强。     

三维网络Al2O3增强球墨铸铁基复合材料摩擦磨损性能

采用SRV摩擦磨损试验机研究了球墨铸铁及三维网络Al₂O₃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Al₂O₃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Al₂O₃/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。     

三维网络Al2O3增强球墨铸铁基复合材料摩擦磨损性能

采用SRV摩擦磨损试验机研究了球墨铸铁及三维网络Al2O3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Al2O3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Al2O3/球墨铸铁复合材料,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.     

Al2O3-TiC/Al2O3-TiC-CaF2复合叠层陶瓷材料摩擦磨损性能

将Al2O3-TiC陶瓷材料与具有固体润滑特性的Al2O3-TiC-CaF2陶瓷材料进行叠层,通过真空热压烧结制备Al2O3-TiC/Al2O3-TiC-CaF2复合叠层陶瓷材料.在环盘式摩擦磨损试验机上进行摩擦磨损实验,研究该材料在不同载荷、转速条件下的摩擦系数和磨损率,分别用SEM及EDS观察材料磨损前后的微观形貌和分析其成分组成,研究其磨损机制.结果表明:在相同载荷条件下,Al2O3-TiC/Al2O3-TiC-CaF2复合叠层陶瓷材料的摩擦系数和磨损率随着转速的升高而下降,在相同转速条件下,其摩擦系数和磨损率随着载荷的增加而下降;Al2O3-TiC/Al2O3-TiC-CaF2复合叠层陶瓷材料的磨损机制主要是磨粒磨损和黏着磨损.     

Al2O3-TiC/Al2O3-TiC-CaF2复合叠层陶瓷材料摩擦磨损性能

将Al₂O₃-TiC陶瓷材料与具有固体润滑特性的Al₂O₃-TiC-CaF₂陶瓷材料进行叠层, 通过真空热压烧结制备Al₂O₃-TiC/Al₂O₃-TiC-CaF₂复合叠层陶瓷材料。在环盘式摩擦磨损试验机上进行摩擦磨损实验, 研究该材料在不同载荷、 转速条件下的摩擦系数和磨损率, 分别用SEM及EDS观察材料磨损前后的微观形貌和分析其成分组成, 研究其磨损机制。结果表明: 在相同载荷条件下, Al₂O₃-TiC/Al₂O₃-TiC-CaF₂复合叠层陶瓷材料的摩擦系数和磨损率随着转速的升高而下降, 在相同转速条件下, 其摩擦系数和磨损率随着载荷的增加而下降; Al₂O₃-TiC/Al₂O₃-TiC-CaF₂复合叠层陶瓷材料的磨损机制主要是磨粒磨损和黏着磨损。     

SiO2基酸化剂高温消解转炉钢渣中游离CaO的研究

转炉钢渣中游离CaO的水化膨胀是导致转炉钢渣体积安定性不良的重要原因。通过高温配加SiO_2基酸化剂,改变w(SiO_2)/w(CaO)对转炉钢渣进行稳钙改质处理。利用化学检测分析、X射线衍射和场发射扫描电子显微镜对SiO_2基酸化剂高温消解转炉钢渣中游离CaO的效果和特征进行研究。结果表明,改质后的转炉钢渣的w(SiO_2)/w(CaO)在0.37以上,就能满足钢渣中f-CaO低于3%的水泥和混凝土行业使用标准,且消解率达到60%以上,而当w(SiO_2)/w(CaO)为0.67时,f-CaO低于1%,且消解率达到90%以上;改质前后转炉钢渣的矿相组成有明显差异,改质后转炉钢渣以硅酸二钙、镁黄长石、镁铁尖晶石、磁铁矿和铁铝酸钙相为主,并且镁黄长石相随着w(SiO_2)/w(CaO)的增大而增多;转炉钢渣酸化稳钙前f-CaO被紧密包裹在矿相基体中,高温酸化改质后,团簇状聚集的f-CaO颗粒会嵌在硅酸盐相间,无明显包裹现象,尺寸为0.5~2μm。     

三维网络结构Al2O3陶瓷/高铬铸铁复合材料干摩擦磨损性能

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Al₂O₃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Al₂O₃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Al₂O₃陶瓷对复合材料磨损机制的影响。结果表明：陶瓷Al₂O₃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,Al₂O₃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Al₂O₃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Al₂O₃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。     

纳米-Al2O3/SiO2加入量对MgO-Al2O3-SiO2复相陶瓷烧结机理的影响

为了探究纳米-Al₂O₃/SiO₂加入量对MgO-Al₂O₃-SiO₂复相陶瓷烧结行为的作用机理。以微米级MgO、纳米级Al₂O₃和SiO₂为主要原料制备陶瓷基复合材料。通过XRD和 SEM等检测手段对烧后试样的物相组成和微观结构进行测试与表征,重点研究Al₂O₃/SiO₂的加入对复相陶瓷物相组成、微观结构及烧结性能的影响。结果表明:随着Al₂O₃/SiO₂加入量的增大,试样烧后相对密度和烧后线变化率呈先增大后减小再增大的趋势,加入15%Al₂O₃/SiO₂(质量分数)的试样经1 500 ℃烧结后,其相对密度可以达到94%。引入的Al₂O₃/SiO₂与基体中的MgO生成镁铝尖晶石与镁橄榄石相,原位反应伴随的体积膨胀,抵消部分烧结过程中的体积收缩。Al₂O₃/SiO₂加入量为75%(质量分数)的试样经1 400 ℃烧结后,基体中有大量堇青石相生成,随着煅烧温度提高到1 500 ℃,堇青石分解所产生的高温液相促进了试样的烧结收缩。     

石墨烯/纳米Al2O3增韧Ti(C,N)基金属陶瓷的力学及摩擦磨损性能

采用真空热压烧结工艺制备了石墨烯(GNPs)和纳米Al₂O₃增韧的Ti(C,N)基金属陶瓷复合刀具材料(TAG)。研究了GNPs和纳米Al₂O₃对复合陶瓷材料微观结构、力学性能和摩擦磨损性能的影响。研究表明,GNPs和纳米Al₂O₃的添加对复合陶瓷材料的力学性能有明显的提高,当GNPs和纳米Al₂O₃含量(质量分数)为1%和5%时,复合刀具陶瓷材料(TA5G1)综合力学性能最优,其硬度、抗弯强度和断裂韧性分别为21.50 GPa、810.80 MPa和10.51 MPa·m^1/2。研究了复合刀具材料的摩擦磨损性能和磨损机理,研究结果表明,在TAG复合刀具材料中,TA5G1的摩擦磨损性能最优,其摩擦系数和磨损率分别为0.338和4.921×10^-6 mm³/(N·m),复合刀具材料的主要磨损形式为磨粒磨损和黏着磨损。     

Cr2AlC复合材料的研究进展

Cr2AlC是一种可加工三元层状结构材料,兼具金属和陶瓷的优异性能。将Cr2AlC作为增强相与基体材料复合,可以有效地改善基体材料的综合性能,克服基体单一材料的部分缺点,扩大基体材料的应用范围。固溶强化和颗粒弥散增强Cr2AlC基复合材料相对于Cr2AlC单相材料,具有更高的硬度、耐磨性、强度和韧性,但损失了部分可加工性。Cr2AlC作为强化层与基体形成的层状复合材料,可以有效抑制微裂纹扩展,从而获得具有极高耐磨性的层状陶瓷复合材料。     

碳纳米管掺杂Fe3Al基复合摩阻材料的摩擦磨损特性研究

采用冷压烧结法制备了CNTs-Fe3Al基复合摩阻材料。经添加0.5%~5%CNTs、1%~5%Al2O3,研究了掺杂物含量及摩擦载荷对摩阻材料摩擦磨损性能的影响,并采用SEM对材料初始表面形貌及磨损形貌进行了观测。结果表明,随着CNTs及Al2O3含量的逐渐增加,磨损方式将由磨粒磨损向疲劳磨损转变。添加CNTs时,摩擦系数先降低后升高再降低;添加Al2O3时,摩擦系数不断升高。加入0.5%CNTs、3%Al2O3可制备平均摩擦系数0.7,硬度295.8HV的摩阻材料。     

Friction stir processing strategies to develop a surface composite layer on AA6061-T6

Friction stir processing (FSP) has been used to produce metal matrix composites by incorporating reinforcement particles in an AA6061-T6 matrix. Two types of particles (Al₂O₃ and SiC) were tested. Powder was placed into a mechanized square section groove on a plate surface and then sealed before FSP. This study investigates the effect of several strategies for reinforcement (number and direction of FSP passes) on the wear resistance behavior of friction stir-processed Al-SiC/Al₂O₃ composites. The distribution and size of the particles in the friction stir-processed zone were studied by optical and scanning electron microscopy. Ball-on-disk test was performed on both base material and surface metal matrix composites (SMMCs), and both friction coefficient and specific wear rate (SWR) were correlated with particle distribution and metallurgical effects on the metallic matrix. For all strategies and for both types of reinforcing particles used in this study, the friction coefficient decreases with respect to the base material. Moreover, the SWR is reduced for the conditions of one single FSP pass and two passes with opposite directions, when SiC are used. However, this positive effect has not been detected with Al₂O₃. Wear mechanisms in base metal and in SMMCs are compared and discussed in detail.     

硼酸酯改性Mg2B2O5W/PP复合材料界面及其力学性能

为了提高聚丙烯(PP)的强韧性能,采用熔融共混法分别制备了质量分数为0～15%的Mg2B2O5晶须(MBOw)和硼酸酯偶联剂(BE)改性MBOw填充PP基复合材料,测试了PP及其复合材料的拉伸、冲击性能,并通过红外光谱、接触角测试、扫描电镜分析等对复合材料界面作用机理进行了研究.结果表明:MBOw与BE之间存在化学和物理吸附层;PP与BE处理前后的MBOw之间不存在化学键合;BE改性MBOw/PP复合材料中PP与MBOw之间的粘附功和表面张力之比由BE表面处理前的8.7增至处理后的315.0,明显改善了基体中MBOw的分散性及其界面结合性能,提高了BE改性MBOw/PP复合材料的拉伸及冲击性能.     

Torsional wear behaviours of TiO2/PMMA film against Ti6Al4V alloy and alumina femoral head ball in dry condition

The torsional fretting wear tests of Ti₆Al₄V alloy flat against alumina femoral ball in dry condition were carried out on a new high-precision torsional fretting-wear tester. The TiO₂/P-methoxymethamphetamine (PMMA)/Ti₆Al₄V pair showed higher contact stiffness, friction torque, wear damage and material transfer than that of the presentation of TiO₂/PMMA/Al₂O₃ pairs. The mechanisms of torsional wear under different counterbodies were discussed in detail. The mechanisms of torsional fretting wear of aluminium alloy are mainly oxidative wear, abrasive wear and delamination in the three fretting regimes. The torsional fretting running regimes transferred from partial slip regime (PSR) to SR were analysed; however, the mixed fretting regime was never appeared in this test. In PSR (lower angular displacement amplitudes), only a dint was found after the tests. The kinetics behaviours and damage mechanism of Ti₆Al₄V alloy under different angular displacement amplitudes with friction torque and dissipation energy, which are strongly dependent upon the imposed angular displacement amplitudes and presented in three stages, were discussed in detail.     

SPS制备氮化硅/锌铝基复合材料的组织和性能研究

通过放电等离子烧结工艺制备了氮化硅/锌铝基复合材料,重点探讨了氮化硅添加量对氮化硅/锌铝基复合材料致密度、硬度和摩擦性能的影响.采用扫描电子显微镜(SEM)及电子探针X射线显微分析仪(EPMA)对样品的微观组织进行了分析,并使用显微硬度仪、旋转摩擦试验仪对其性能进行了研究.结果表明:氮化硅在样品中分散均匀,且氮化硅的加入能够明显提高样品的致密度和硬度.当在锌铝合金中加入质量分数为20％氮化硅时,氮化硅/锌铝基复合材料致密度达到95.53％,同时与高锌铝合金烧结试样相比,其硬度提高了 58.5％,达到162.56HV.氮化硅/锌铝基复合材料的耐磨性随着氮化硅的添加呈现先增加后下降的趋势,添加量为20％时摩擦系数达到最佳为0.210 3,磨损量为0.003 37 mm3.     

Preparation of super-high strength nanostructured B4C reinforced Al-2Cu aluminum alloy matrix composites by mechanical milling and hot press method: Microstructural,mechanical and tribological characterization

In this research, super-high strength nanostructured B₄C reinforced Al-2Cu aluminum alloy matrix composites produced by mechanical milling and hot press method. Nanostructured Al-2Cu powder containing 4, 6 and 10?wt.% B₄C reinforcement particles synthesized using a high-energy attritor under argon atmosphere. Results showed that with increasing the content of B₄C particles the matrix grain size decreased. Since the compressibility of mechanically milled powders is very low, hot press processing used for consolidation of nanostructured Al-2Cu/B₄C powders. The hot pressed Al-2Cu/10?wt.%B₄C nanocomposite, when tested in compression, exhibited extremely high strength (1.1?GPa) which is 735?MPa higher than that of coarse grain Al-2Cu sample. Moreover, the hardening capacity (H_c) of hot pressed nanocomposites decreased with the increase in the content of B₄C particles. According to Orowan strengthening mechanism, since B₄C particles act as a barrier to the dislocations movement, the increase of B₄C particles leads to the increase of barriers and as a result, Δσ_Orowan increases. Therefore, the strength of composite increases but work hardening capacity (H_c) decreases. The results of wear test indicated that wear rate and friction coefficient declined gradually as the B₄C particles fraction increased. Based on this result, hot-pressed sample containing 10?wt.% B₄C showed the lowest wear rate and friction coefficient (1.9?×?10^?5 mm³/m and 0.48 respectively).     

Effect of secondary processing on the microstructure and wear behavior of spray formed Al–30Mg2Si–2Cu alloy

In the present work, Al–30Mg₂Si–2Cu alloy has been spray formed and subsequently hot pressed for densification. The alloy is then subjected to solutionizing and isothermal aging treatments. The microstructural features, hardness and wear behavior of spray formed and secondary processed alloys have been evaluated individually and compared with that of as-cast alloy. The microstructure of spray formed alloy showed refined and globular shaped primary Mg₂Si intermetallic particles and Al₂Cu precipitate particles uniformly distributed in Al matrix. The microstructure was refined further after hot consolidation. The microstructure after solution heat treatment appeared similar to that of the spray formed alloy but aging led to a further refinement in the microstructure compared to that of the hot pressed alloy. The evaluation of wear behavior of these alloys, under dry sliding condition, showed that the age hardened alloy exhibits maximum wear resistance and minimum coefficient of friction over the entire range of applied load (10–50 N) at a sliding speed of 2 ms⁻¹ followed by hot pressed, spray formed and solution heat treated alloys. The as-cast alloy showed the least wear resistance and highest coefficient of friction. Similar trend has been observed even in their hardness values too. The wear resistance of the alloys is discussed in light of their microstructural modifications induced during spray forming and subsequent secondary processing and also the topography of worn surfaces.