AA6061/ZrB_2原位复合材料的干滑动磨损行为(英文)

通过往铝熔体中添加K2ZrF6和KBF4制备AA6061/ZrB2原位复合材料,并对该复合材料的干滑动磨损形为进行研究。构建了一数学模型来预测该复合材料的磨损速率。采用4因素5水平的中心复合旋转设计方法来减少实验工作量。考察滑动速度、滑动距离、载荷和ZrB2质量分数这4个因素对制备的复合材料的磨损速率的影响,通过观察磨损表面形貌分析这些因素的影响。结果表明,原位生成的ZrB2颗粒改善了复合材料的磨损性能。该复合材料的磨损速率随着滑动速度、滑动距离和载荷的增加而增加。     

6061铝合金/岩粉复合材料的干滑动磨损行为(英文)

研究岩粉尺寸(10~30μm)和质量分数(5%~15%)对搅拌铸造法制备6061铝合金/岩粉复合材料密度、硬度和干滑动磨损行为的影响。在不同载荷、不同滑动速率和滑动距离条件下在销盘摩擦试验机上对复合材料进行干滑动摩擦磨损试验。采用Taguchi法进行正交试验(L27)设计,并对实验结果进行方差分析。结果表明,载荷和增强相(岩粉)尺寸是影响复合材料样品比摩损率的主要因素,其次为增强相的质量分数、滑动速率、滑动距离,且其影响程度分别为47.61%、28.57%、19.04%、9.52%和4.76%。对所得回归方程的预测精度进行实验论证,结果显示,此回归方程能用于复合材料的磨损率的预测且预测误差很小。复合材料磨损表面的SEM结果表明,以岩粉作为增强相能改善铝合金材料的耐磨性能。     

硼酸镁晶须增强6061铝基复合材料的干摩擦磨损行为(英文)

研究搅拌铸造工艺制备的硼酸镁晶须增强6061铝基复合材料在干滑动条件下的摩擦磨损性能。复合材料的体积分数为2%,根据增强体种类,材料分别记为:Al基体、Mg2B2O5w/6061Al、ZnO/Mg2B2O5w/6061Al和CuO/Mg2B2O5w/6061Al;讨论磨损速率和摩擦因数之间的关系。结果表明:在4种材料中,ZnO/Mg2B2O5w/6061Al复合材料的磨损率最低。随着载荷和滑动速度的增大,基体和复合材料的摩擦因数和磨损率降低,摩擦磨损机制由轻微磨损机制转向严重磨损机制。     

润滑条件下Mg2B2O5/6061Al基复合材料摩擦磨损性能研究

采用自制的机械-超声混合搅拌设备制备出Mg2B2O5/6061Al铝基复合材料,复合材料的体积分数为2%。研究了载荷和滑动速度对基体以及复合材料的摩擦磨损性能的影响。实验结果表明,基体和复合材料摩擦系数总体上随着载荷和滑动速度的增加而减小。基体和复合材料的磨损率随载荷和滑动速度的增加而明显的增大,且基体和复合材料均存在一个临界载荷和临界滑动速度。当载荷和滑动速度到达临界值后,磨损率均急剧增大,此时试样摩擦磨损机制由微观疲劳磨损和磨粒磨损向粘着磨损与剥离磨损转变。     

增强相对铝基复合材料耐磨性的影响（英文）

通过考虑不同的参数,包括滑动距离(6 km)、压力(0.14~1.1 MPa)和滑动速度(230~1480 r/min),研究增强相对金属基复合材料(MMC)磨损机理的影响。在一台销-盘式磨损试验机上,对比研究相同实验条件下MMC和相应基体材料的磨损机理。销由6061铝基合金或者10%Al2O3(体积分数)颗粒(6~18μm)增强的6061铝基复合材料组成,盘由钢铁组成。得到以下主要结论:MMC比相应的基体材料具有更优的耐磨性;与基体材料不同,MMC的磨损性是线性的和可预测的;除了MMC的三体磨粒磨损外,两种材料的磨损机理相似;增强相能抗磨损并限制MMC的变形,从而导致MMC具有更优的耐磨性。所得结果显示了增强相颗粒在提高MMC耐磨性方面的作用,并为更好地控制其磨损提供了有效指导。     

WC颗粒增强铜的载流摩擦磨损行为北大核心CSCD

采用粉末冶金法制备了碳化钨颗粒增强铜(WC/Cu)复合材料,研究了WC含量对WC/Cu)复合材料力学性能和微结构的影响,并考察了复合材料载流摩擦磨损性能。结果表明:随着WC质量分数增加,复合材料相对密度逐渐降低,硬度缓慢增大,电导率快速下降。WC含量较低时,大部分WC颗粒能较均匀分布于铜基体上;而WC含量较高时,WC颗粒的团聚现象较严重,团聚所形成的颗粒团体积较大。载流摩擦磨损测试中,随着WC质量分数增加,体积磨损率逐渐减小;未加载电流时,体积磨损率随载荷增大而增大;一定载荷和滑动速率时,复合材料体积磨损率随载流密度增加而增大。     

WC颗粒增强铜的载流摩擦磨损行为

采用粉末冶金法制备了碳化钨颗粒增强铜(WC/Cu)复合材料,研究了WC含量对WC/Cu)复合材料力学性能和微结构的影响,并考察了复合材料载流摩擦磨损性能。结果表明:随着WC质量分数增加,复合材料相对密度逐渐降低,硬度缓慢增大,电导率快速下降。WC含量较低时,大部分WC颗粒能较均匀分布于铜基体上;而WC含量较高时,WC颗粒的团聚现象较严重,团聚所形成的颗粒团体积较大。载流摩擦磨损测试中,随着WC质量分数增加,体积磨损率逐渐减小;未加载电流时,体积磨损率随载荷增大而增大;一定载荷和滑动速率时,复合材料体积磨损率随载流密度增加而增大。     

添加铝对AlNp/Cu复合材料组织与热性能的影响

为提高高体积分数AlNp/Cu复合材料的致密度,采用粉末冶金液相烧结工艺制备了含10vol%Al的AlNp/Cu复合材料,与未添加Al的AlNp/Cu复合材料以及AlN颗粒表面镀铜的AlNp/Cu复合材料进行了组织与热性能的比较.X射线衍射与显微组织观察表明,添加的Al在烧结过程中扩散至铜基体形成固溶体,并能有效的提高AlNp/Cu复合材料的致密度,添加10vol%Al的复合材料相对密度与未添加Al的AlNp/Cu复合材料相比提高了3.5%.热膨胀试验表明:50～550℃之间,40% AlNp/Cu复合材料、添加10vol%Al的40%AlNp/Cu复合材料及AlN颗粒表面镀铜的40%AlNp/Cu复合材料的平均热膨胀系数分别为15.7、13.4和13.4,热循环后的残余应变分别为0.51%、0.18%和0.24%.Al的添加及AlN颗粒表面镀铜都能有效地降低AlNp/Cu复合材料的热膨胀系数和热循环后的残余应变.与表面镀铜的AlNp/Cu复合材料相比,Al的添加在一定程度上降低了AlNp/Cu复合材料的热传导性能,但材料的制备成本显著降低.     

搅拌铸造工艺参数对AA6061/TiC铝基复合材料抗拉强度影响的预测（英文）

采用搅拌铸造工艺制备AA6061/15%TiC(质量分数)铝基复合材料。构建一个经验公式用于预测搅拌铸造工艺参数对AA6061/TiC铝基复合材料极限抗拉强度的影响。采用有4因素、5水平组成的中心旋转组合设计方案来减少搅拌铸造实验次数。实验因素包括搅拌速率、搅拌时间、搅拌叶片角度和铸造温度。采用所建立的经验公式和显微组织观察分析这些因素对AA6061/TiC铝基复合材料极限抗拉强度的影响。分析结果表明:上述各因素均显著影响复合材料的极限抗拉强度。复合材料极限抗拉强度的变化归因于孔隙率、团簇的形成、TiC颗粒在晶界的偏析及其在铝基体中的均匀分布。     

固体润滑颗粒增强铝基复合材料的高温摩擦学行为（英文）

通过搅拌铸造法制备AA6061-10wt.%B4C单一复合材料,Gr(Gr为石墨)颗粒含量为2.5、5、7.5 wt.%的AA6061-10wt.%B4C-Gr混杂复合材料,和Mo S2颗粒含量为2.5、5、7.5wt.%的AA6061-10wt.%B4C-Mo S2混杂复合材料。采用销-盘式摩擦试验机(对磨材料为EN31)研究温度对复合材料干滑动摩擦行为的影响。在30～100°C的温度范围内,由于摩擦保护层及其固体润滑相的共同润滑作用,Gr增强和Mo S2增强的混杂复合材料的磨损率和摩擦因数均下降。对磨损表面进行扫描电镜观察,结果表明,150、200和250°C下的磨损机制分别为重度粘着磨损、剥层磨损和磨粒磨损。透射电镜结果显示,150°C时,混杂复合材料中形成了变形带和精细的晶体结构,分别是由严重的塑性变形和动态再结晶造成的。     

Dry Sliding Tribological Studies of AA6061-B<Subscript>4</Subscript>C-Gr Hybrid Composites

The dry sliding behavior of stir-cast AA6061-10 wt.% B₄C composites containing 2.5, 5 and 7.5 wt.% graphite particles was studied as a function of applied load, sliding speed and sliding distance on a pin-on-disk tribotester. The wear rate and friction coefficient increased with increase in applied load and sliding distance. The increase in graphite addition reduced the increase in wear rate and friction coefficient in the sliding speed range 2-2.5 m/s. Scanning electron microscopy of the worn pin revealed a graphite tribolayer, and transmission electron microscopy revealed overlapping deformation bands under 30 N applied load. Upon increasing the applied load to 40 N, welded region with fine crystalline structure was formed due to dynamic recrystallization of AA6061 alloy matrix.     

Effect of partial melting on superplasticity ofAlNp/6061Al composite

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Dry sliding wear characterization of squeeze cast LM13/FeCu composite using response surface methodology

Dry sliding wear is one of the predominant factors to be considered while selecting material for automotive and aerospace applications. Researchers have been exploring novel aluminium matrix composites(AMC), which offer minimum wear rate for various tribological applications. In this present work, an attempt has been made to reinforce LM13 aluminium alloy with copper coated steel fibers(10 wt.%) using squeeze casting process and to perform dry sliding wear test using pin-on-disc tribometer. Microstructure of cast samples was examined using image analysis system to investigate the dispersion of reinforcement in matrix. Dry sliding wear test was performed by considering factors such as load(10–50 N), sliding velocity(1–5 m·s(-1)) and sliding distance(500–2,500 m). Wear test was performed according to the experimental design at room temperature. Three factors and five levels central composite design were used to design the experiments using response surface methodology. Based on the results of the experiments, a regression model was developed to predict the wear rate of composites and checked for its adequacy using significance tests, analyses of variance and confirmation tests. Worn surface of samples was investigated using field emission scanning electron microscope and reported with its mechanisms. Microstructure of cast samples revealed uniform dispersion of reinforcement throughout the matrix. Response surface plots revealed that wear rate of composites increases with increasing load up to 50 N with the velocity 1–5 m·s(-1) and a sliding distance up to 2,500 m. However wear rate decreasesd with increasing velocity at lower loads(up to 20 N) and increased after reaching transition velocity of 2 m·s(-1). Dry sliding wear process parameters were optimised for obtaining minimum wear rate and they were found to be a load of 18.46 N, velocity of 4.11 m·s(-1), sliding distance of 923 m. Worn surface of samples revealed a mild wear at lower loads(up to 30 N), and severe wear was observed at high loads(40–50 N) due to higher level of deformation on the surface.     

Fracture toughness of in situ TiCp–AlNp/Al composite

The effect of particle size, particle volume fraction, and matrix microstructure on the fracture initiation toughness of in situ TiCp–AlNp/Al composite was examined. The composites were Al matrix reinforced with 7.8–19.6 vol.% of TiC and AlN particles produced in situ by S-V-L reaction synthetics. The average particle diameters of TiC and AlN were 3.5 and 0.9 μm, respectively, which were distributed in the Al in a matrix dispersedly manner. The room-temperature plane-strain toughness measured using three-point bending specimens ranged from 12.7 to 37.5 MPa . Toughness was adversely affected by an increase in the TiCp–AlNp volume fraction. Fractography revealed that these composites failed in a ductile manner, with voids initiating at the in situ reinforcing TiC and AlN particles. The experimentally measured plane-strain toughness properties of in situ TiCp–AlNp/Al composite agrees with the Rice and Johnson model.     

激光熔覆TiC增强FeAl金属间化合物基复合材料涂层磨损性研究

利用激光熔覆技术在1Cr18Ni9Ti奥氏体不锈钢表面制得了以TiC为增强相、以FeAl 金属间化合物为基体的耐磨复合材料涂层，研究了激光熔覆。FiC／FeAl复合材料涂层在干滑动磨损条件下的耐磨性能及磨损机制。结果表明：随着载荷和滑动速率的增加，TiC／FeAl金属间化合物基复合材料涂层的磨损速率增加，其磨损机制随着载荷的增加逐渐由磨料磨损向粘着磨损转变；激光熔覆层中TiC体积分数的增加，一方面提高了涂层的磨料磨损抗力，另一方面降低了熔覆层表面与对磨材料之间的粘着倾向，提高了TiC／FeAl涂层的滑动磨损性能。激光熔覆TiC/FeAl金属间化合物基复合材料涂层具有优异的耐磨性能并随TiC体积分数的增加而提高。     

A novel approach for evaluation of load bearing capacity of duplex coatings on aluminum alloy using PLS and SVR models

Duplex NiP/TiN coatings consisting of the electroless intermediate layers and the physical vapor deposition (PVD) top layers were fabricated on the AA6061 aluminum alloy in order to enhance the load bearing capacity. The main objective of this study was to model the load bearing based on the thickness, adhesion and elastic modulus of the coatings. For this purpose, partial least square (PLS) and support vector regression (SVR) approaches were employed. The results showed that both models had an acceptable performance; however, the PLS model outperformed SVR. The correlation coefficients between thickness, adhesion and elastic modulus with load bearing were 0.841, 0.8092 and 0.7657, respectively; so, thickness had the greatest effect on the load bearing capacity. The composition and structure of the samples were evaluated using XRD and SEM. The load capacity of the coated samples was also discussed based on the wear and adhesion evaluations. Dry sliding wear tests, under a load of 2 N and a sliding distance of 100 m, demonstrated the complete destruction of the coated specimens with low load capacity. The samples with high load capacity showed not only a superior tribological performance, but also a remarkable adhesion according to the Rockwell superficial hardness test.     

Microstructure,mechanical properties and two-body abrasive wear behaviour of hypereutectic Al—Si—SiC composite

The microstructure, mechanical properties, and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al—Si—SiC composite and its matrix alloy were investigated. The hypereutectic Al—Si—SiC composite was prepared by stir casting route. The hardness, ultimate tensile strength and yield strength of the composite are increased by 17%, 38%, and 30% respectively compared with those of the matrix alloy, while the elongation of the composite is decreased by 48% compared with that of the matrix alloy. The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance. The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy (HR FESEM) and wear mechanism was analyzed for low and high load regimes.     

二硼化钛对Al2024−TiB2非原位复合材料摩擦磨损性能的影响

用搅拌铸造法制备不同质量分数二硼化钛(TiB2)颗粒增强的铝基复合材料,并研究其摩擦磨损性能.采用销?盘式摩擦试验机对Al2024?TiB2复合材料进行干滑动磨损试验.为了研究摩擦学参数对复合材料的影响,对载荷、滑动距离和滑动速度等参数进行调整.显微组织表征结果表明,TiB2颗粒分散均匀并与基体有良好的结合.实验结果表...