纳米碳化硅增强铜基复合材料的组织及其磨损性能

为了探求在常温下制备颗粒弥散增强金属基复合材料的方法,采用复合电铸工艺在室温下制备了纳米碳化硅粒子弥散增强铜基复合材料,对其表面形貌、微观组织结构进行了观察,对显微硬度、磨损性能及导电性能进行了测试。结果表明：纳米碳化硅粒子均匀弥散分布在铜基体中,且与基体结合良好;复合材料表面平整、细密;与电沉积纯铜材料相比,其显微硬度明显提高,磨损性能改善,导电性能下降幅度不大。     

消失模铸渗法制备SiC颗粒增强钢基表面复合材料

通过涂覆预制块的预置方法,利用消失模(V-EP)铸渗工艺制备了SiC颗粒增强钢基表面复合材料,着重研究碳化硅粒径对表面复合效果的影响.结果表明:碳化硅颗粒粒径在600～850 μm时,制备的复合材料表面复合效果好,铸渗复合层厚度可达4 mm左右,表面较平整;碳化硅颗粒粒径对SiC/钢复合材料表面质量有很大的影响,随着SiC颗粒粒径的增加,复合材料铸渗层的表面质量呈下降趋势.     

SiCp/Al复合材料旋转超声辅助磨削的试验研究

铝基碳化硅颗粒增强复合材料(SiCp/Al)有许多优异的特性,但其加工非常困难,限制了该种材料在工程中的应用。旋转超声辅助磨削加工非常适合中、高体分SiCp/Al复合材料的加工。针对增强体体积分数45%、增强颗粒尺寸3μm、基体材料A12的SiCp/Al复合材料进行了实验研究,分析了加工表面形貌、表面粗糙度和切削力随切削参数的变化规律。实验结果表明,工件加工表面质量较高,表面粗糙度Ra值在0.131~0.340μm之间;切削过程平稳,轴向切削力Fz值在23.33~51.31N。     

碳化硅及其颗粒增强铝基复合材料超精密加工研究进展

针对碳化硅及其颗粒增强铝基复合材料超精密加工的研究状况,重点关注了碳化硅超精密切削过程中的脆塑性转变以及铝基碳化硅的加工表面形成机理,对其加工过程中切削力、表面形成、刀具磨损、切屑形成等超精密加工过程中的机理以及各自超精密加工过程中的特点及各种其他影响因素进行了分析和总结,以期全面了解碳化硅及其颗粒增强铝基复合材料超精密加工的研究进展。     

铸渗过程粒度对碳化硅钢基表面复合材料的影响

采用负压铸渗的方法，以Q235钢为母材制备碳化硅颗粒增强钢基表面复合材料。研究碳化硅粒度对复合效果的影响。通过试验与分析表明碳化硅的粒度对碳化硅钢基表面复合材料的复合质量有很大的影响，且碳化硅粒度在350～850μm时可在钢表面形成结合良好的复合层。     

T6热处理对SiC_p/Al复合材料高速铣削加工性的影响

使用聚晶金刚石(PCD)刀具,在切削速度为1200m/min下对碳化硅颗粒增强铝基(SiCp/Al)复合材料进行铣削加工试验,研究SiCp/Al复合材料经T6热处理后对其高速铣削加工性的影响。结果表明:经T6热处理后,切削力/切削温度明显高于未热处理材料,切屑锯齿形明显,加工过程不稳定性增加,刀具承受冲击作用增大,导致PCD刀具发生较严重的崩刃、剥落、冲击裂纹等磨损形式,从而刀具使用寿命显著低于高速铣削未热处理材料。T6热处理材料高速铣削表面粗糙度Ra/Rz值一般低于未热处理材料,其加工表面变质层深度也显著低于未热处理材料,加工表面存在较少的坑洞、微裂纹、基体撕裂、基体涂覆等加工所致缺陷。     

SiC_p/Al复合材料高速铣削加工表面质量及切屑形成机制

使用聚晶金刚石(PCD)刀具,对碳化硅颗粒增强铝基复合材料(SiCp/Al)进行高速铣削加工,研究了加工表面质量及切屑的形成机制。结果表明:刀具进给波纹、工件材料塑性侧流、刀具-工件相对振动和增强颗粒去除过程留下的孔洞、微裂纹、基体撕裂等是SiCp/Al复合材料高速铣削加工表面的主要形成机制;增大切削速度、使用冷却液、降低增强颗粒体积分数、减小增强颗粒尺寸均有助于提高加工表面质量;切屑形态为不均匀锯齿状,增强颗粒体积分数、热处理状态等对切屑形成有显著影响,绝热剪切、孔洞/微裂纹动态形成和扩展是切屑的主要形成机制。     

金属基复合材料的摩擦学研究现状

金属基复合材料(MMC)的研究开始于本世纪60年代初期。70年代末期,开发了用廉价稻壳为原料制造β-SiC晶须的新技术,促进了SiC晶须增强铝基复合材料(SiC_w/Al)以及SiC颗粒增强铝基复合材料(SiC_p/Al)的研究。80年代初期,日本首次将纤维增强铝基复合材料试用于制造柴油发动机活塞,这使得金属基复合材料的开发应用开始了一个新阶段。航空、航天工业对新材料的要求,又进一步推动了MMC的发展。现在已开始应用于汽车工业、仪表工业及其它一些民用工业之中。但是,许多MMC仍处于研制开发阶段。 金属基复合材料是以金属为基体,添加颗粒、晶须或纤维作为增强相,通过特定方法复合而成。目前使用的金属基体有铝、钛、镁、铜、锰以及一些金属间化合物等,其中铝基复合材料研究最多,应用范围最广。所用增强相物质有碳化硅、碳化硼、碳化钛和氧化铝的颗粒;碳化硅、氮化硅、氧化铝和钛酸钾晶须;硼、石墨、碳化硅、氧化硅、氧化铝和氧化硼纤维;钛、钼、钨、不锈钢和铍金属丝以及金属条带如铍条带等。表1列出了MMC增强剂     

碳化硅颗粒增强铝基复合材料的制备及应用的研究

综述了碳化硅颗粒增强铝基复合材料（SiCp/Al基复合材料）的研究进展,重点阐述了国内外现阶段碳化硅颗粒增强铝基复合材料的常用制备方法,并结合其应用现状进一步分析了各种常用制备方法的优缺点和未来的研究方向,在此基础上展望了其未来的发展和应用前景。     

颗粒增强铝基复合材料摩擦磨损性能研究

对颗粒增强铝基复合材料及其基体与 4 0Cr钢摩擦材料组成的摩擦副的摩擦磨损特性进行了对比试验研究 ,并采用SEM对颗粒增强铝基复合材料及其基体磨损表面进行了观察 ,探讨了其磨损机理。试验表明 :复合材料具有较稳定的摩擦系数、低的磨损率 ;复合材料的主要磨损形式是磨粒磨损 ,基体材料的主要磨损形式是粘着磨损。     

Direct laser cladding of SiC dispersed AISI 316L stainless steel

The present study concerns development of SiC dispersed (5 and 20 wt%) AISI 316L stainless steel metal-matrix composites by direct laser cladding with a high power diode laser and evaluation of its mechanical properties (microhardness and wear resistance). A defect free and homogeneous composite layer is formed under optimum processing condition. The microstructure consists of partially dissociated SiC, Cr₃C₂ and Fe₂Si in grain refined stainless steel matrix. The microhardness of the clad layer increases to a maximum of 340 VHN (for 5% SiC dispersed) and 800 VHN (for 20% SiC dispersed) as compared to 150 VHN of commercially available AISI 316L stainless steel. Direct laser clad SiC dispersed AISI 316L stainless steel has shown an improved wear resistance against diamond surface with a maximum improvement in 20% SiC dispersed AISI 316L stainless steel. The mechanism of wear was predominantly abrasive in nature.     

The wear properties of an SiC-whisker-reinforced aluminium composite

The wear behaviour of an SiC-whisker-reinforced aluminium (SiC_w-Al) composite is studied by comparative testing. The experimental results show that the SiC_w-Al composite exhibits a fairly good wear resistance, especially for higher sliding velocities and/or higher loads in the test. The results are considered to be due to the high hardness of the SiC whiskers, the rotation of the SiC whiskers and the constraint of the SiC whisker in the aluminium matrix. It is also discovered by experiment that during the wear of oxides the wear volume of both the SiC_w-Al composite and the aluminium is small, but the wear volume of the former is a little larger than that of the latter. The reason may be that the compactness of the oxide on the surface of the specimen is damaged because of the existence of the SiC whiskers.     

Impact wear resistance of WC/Hadfield steel composite and its interfacial characteristics

A composite coating of WC/Hadfield steel was fabricated through centrifugal casting process to improve the impact wear resistance of Hadfield steel under the conditions of low or medium impact energy. The interfacial structure between WC ceramic particle and the steel matrix was analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The impact wear tests at different impact energy were carried out on a MLD-10 type impact wear rig to investigate the wear-resistant properties of three kinds of composites with different WC particle sizes. For comparison, the wear tests of Hadfield steel were also carried out under the same conditions. The results show that WC particles are partially dissolved in the steel during centrifugal casting. The elements W, C and Fe in steel react to form new carbides such as Fe₃W₃C or M₂₃C₆, which precipitate around former WC particles forming fine particles during subsequent solidification. So the interface between WC particles and Hadfield steel matrix is a strong metallurgical bonding. The composite reinforced with smaller WC particles has better impact wear resistance than that of Hadfield steel regardless of impact energy level. Whereas, the composite reinforced with larger WC particles has better impact wear resistance property than that of Hadfield steel when the impact energy is small but an opposite result is gained when the impact energy is higher. So, it is very essential to choose suitable size of WC particles as reinforcement in Hadfield steel to make the composite material more durable in the service conditions.     

Tribology at high-velocity impact

The tribological events taking place when a high-velocity projectile hits a SiC particulate reinforced AA 5083 composite material was examined under real conditions. The samples were cast in a disc shape by squeeze casting method. Different volume fractions of SiC particles were used. They were solidified under 180 MPa in a steel mould with a 650–700 °C temperature range. SiC particles with the size of 250–500 μm, and 30% and 45% in volume fraction were incorporated into the matrix material. The composites were machined to ensure a smooth surface and to obtain samples without burrs. The samples had a diameter and thickness of 140 and 20 mm, respectively. The terminal ballistic tests were carried out in an army zone under standard test conditions. An AP 7.62 mm armour piercing projectile with a speed of 710 m/s was used for testing the composite.The frictional characteristics and wear mechanisms caused by high-velocity impacts to the composite were determined by SE microscopy studies. The evaluations of the tribological events on both the hole and projectile tip surfaces resulting from high-velocity friction were carried on. As the projectile moved thorough the composite, some material broke from the matrix body and conglomerated along the path followed by the missile. Then these conglomerated blocks yielded and slided along the hole surface. There were also scratching and local melting on the hole surface. Similarly, some ploughing took place on the hole, some SiC particles were removed from the matrix body by the friction effect of projectile and these particles were conglomareted on the tip surface of the projectile. Thus, the nature of wear mechanism on the projectile surface was predominantly abrasive while those of the friction surfaces of the composites were predominantly abrasion and melt wear.     

稀土强韧化MoSi2材料的摩擦学性能

采用高温自蔓延和真空烧结合成了含0.8%（质量分数）稀土/MoSi2复合材料。在MRH-5A型环-块摩擦磨损试验机上,考察了其与调质45#钢配对时的摩擦磨损特性。运用带有微探针的KYKY2800型扫描电镜分析了其磨损表面形貌,探讨了该材料的磨损机制。结果表明：在干摩擦同等条件下,稀土/MoSi2复合材料比纯MoSi2材料具有更好的抗磨损性能,其磨损率比纯MoSi2至少降低了68%。低速（200r/min）时,RE/MoSi2复合材料的磨损机制主要是粘着磨损,随着载荷的增加,粘着磨损脱落更为严重;在高速（400r/min）和低载荷（78N）下,RE/MoSi2复合材料的磨损机制仍以粘着磨损为主,在重载荷（274N）下,RE/MoSi2复合材料的磨损机制主要为粘着磨损和疲劳脆性断裂。     

Abrasive wear behaviour of SiC/2014 aluminium composite

Aluminium alloy matrix reinforced with 15 wt% SiC particles were prepared by powder metallurgy (PM) method. Wear behaviour of the composite was investigated to find out effects of operating variables and hardness in terms of the Taguchi approach, on a pin-on-disc machine and compared with the previous work on the composite produced by liquid metallurgy method [1]. Analysis of variance (ANOVA) was also employed to investigate which design parameters significantly affected the wear behaviour of the composite. The results showed that abrasive grain size exerted the greatest effect on the abrasive wear, followed by the hardness, which supported the previous work, but the percentage contribution was very different. The percentage contributions of the grain size and hardness were about 81.57 and 11.09, respectively. This might be because of production method of PM, particle size, model used by not considering the interaction effects, and testing condition. Moreover, larger particle sizes of the composites showed more wear resistance than those of others. As for the case of earlier work the percentage contributions of the grain size and type of material (hardness) were about 29.90, 17.90, respectively. However, the percentage contribution of interaction of abrasive size and hardness was about 30.90 while interaction of other factors was pooled.     

Friction and wear behavior of laser composite surfaced aluminium with silicon carbide

The present study concerns the wear behavior of laser composite surfaced Al with SiC and Al + SiC particulates. A thin layer of SiC and Al + SiC (at a ratio of 1:1 and dispersed in alcohol) were pre-deposited (thickness of 100 μm) on an Al substrate and laser irradiated using a high power continuous wave (CW) CO₂ laser. Irradiation leads to melting of the Al substrate with a part of the pre-deposited SiC layer, intermixing and followed by rapid solidification to form the composite layer on the surface. Following laser irradiation, a detailed characterization of the composite layer was undertaken in terms of microstructure, composition and phases. Mechanical properties like microhardness and wear resistance were evaluated in detail. The microstructure of the composite layer consists of a dispersion of partially melted SiC particles in grain refined Al matrix. Part of the SiC particles are dissociated into silicon and carbon leading to formation of the Al₄C₃ phase and free Si redistributed in the Al matrix. The volume fraction of SiC is maximum at the surface and decreases with depth. The microhardness of the surface improves by two to three times as compared to that of the as-received Al. A significant improvement in wear resistance in the composite surfaced Al is observed as compared to the as-received Al. The mechanism of wear for as-received vis-à-vis laser composite surfaced Al has been proposed.     

Fretting wear of Al-Si alloy matrix composites

Ball-against-disk type fretting wear tests for Al-Si alloy matrix composites in contact with bearing steel were conducted in wet air to investigate the effects of relative slip amplitude on friction and wear of the composites. In the larger range of relative slip amplitude, the Al-Si alloy-impregnated graphite composite (ALGR-MMC) shows lower friction coefficients than those of alumina short fiber-reinforced composite (ASFR-MMC) and hollow silica particle-reinforced composite (HSPR-MMC). Although the wear rate of the ALGR-MMC is higher than that of the ASFR-MMC and HSPR-MMC, the composite hardly causes damage to the mating material due to adhesion of compacted films of graphite powder and Al-Si alloy wear particles.     

Materials transfer and formation of mechanically mixed layer in dry sliding wear of metal matrix composites against steel

The wear behavior of a composite of a pure Al matrix reinforced with 20 vol% SiC particles against quenched 1045 steel was investigated. Material was found to transfer from the counterface to the wear surface of the composite, where a mechanically mixed layer (MML) was produced. A new mechanism, named the debris burial mechanism, for the formation of the mechanically mixed layer (MML) is proposed and discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

SiCp增强铝基复合材料与Kevlar增强摩擦材料摩擦副摩擦磨损机理研究

采用盘销式摩擦磨损试验机，对SiCp含量为20vol％的铝基复合材料和Kevlar增强摩擦材料组成的摩擦副在于摩擦条件下的摩擦磨损机理进行了实验研究。结果表明：摩擦副在跑合过程中，铝基复合材料中的SiCp颗粒对较软的有机复合材料产生犁削和微观切削效应，磨损机理为铝基复合材料的硬质颗粒对较软的有机复合材料的磨粒磨损；在跑合后的磨损试验中，摩擦材料磨损表面呈现出粘着磨损和塑性变形特征，随着转动速度的增加，塑性流动加剧；摩擦副接触表面发生材料的相互转移，并在铝基复合材料表面形成转移膜，且在较高速度下转移膜更易形成；在高速条件下，摩擦材料表面可见从铝基复合材料的铝合金基体中脱离的SiCp颗粒和熔融迹象；摩擦材料的磨损机理主要为磨粒磨损、粘着磨损和塑性变形。