PCD刀具高速铣削SiCp／Al复合材料的表面粗糙度研究

通过切削实验,研究PCD刀具铣削SiC颗粒尺寸较大、体积比含量较高的SiCp／Al复合材料时,切削速度、每齿进给量、切削深度对已加工表面粗糙度的影响,根据对实验结果分析得出切削用量对已加工表面粗糙度的影响规律．     

磨削高体积分数SiCp/Al复合材料表面形成机制

针对高体积分数SiCp/Al复合材料精密加工问题,研究了磨削加工高体积分数SiCp/Al复合材料表面形貌的形成机制.使用金刚石砂轮在干式和湿式两种磨削条件下对高体积分数SiCp/Al复合材料进行磨削实验研究,通过表面粗糙度仪对表面粗糙度进行测量,运用扫描电镜对磨削加工的表面形貌进行观测研究.结果表明：该材料磨削表面的主要缺陷为SiC颗粒拔出、破碎、压入和Al基体的涂敷等,SiC颗粒的破碎和脱落是磨削加工该材料表面形成的主要机制.两种磨削条件下工件进给速度对表面粗糙度的影响比磨削深度更显著,湿式磨削无论是在工件已加工表面形貌和微观结构还是表面粗糙度上都好于干式磨削.     

超声振动高速铣削SiCp/Al复合材料的切削力及刀具磨损特性

颗粒增强铝基复合材料由于其优异的性能,在航空、航天及军事等领域得到广泛应用,但材料的难加工特性限制其进一步应用.采用超声高速铣削对高体分SiC颗粒增强铝基复合材料进行了实验研究,研究了超声切削参数对铣削力的影响,分析了超声加工时的刀具磨损情况和机理.研究发现采用超声铣削可以有效地减小切削力,得出了超声加工SiC颗粒增强铝基复合材料的合理切削用量.同时,超声铣削很大程度上降低了磨料磨损和粘结磨损,提高了刀具的使用寿命.     

超声辅助切削SiCp/Al复合材料棱边缺陷有限元仿真研究

对超声辅助切削SiCp/Al复合材料棱边缺陷进行了有限元仿真研究,分析了超声激励方式、切削参数对SiCp/Al复合材料棱边缺陷的影响。结果表明:相比于普通切削,超声辅助切削改善其棱边缺陷,其中刀具Y方向振动方式切削显著减小棱边缺陷,次之为椭圆振动方式切削和X方向振动方式切削;超声辅助切削时,大切深不利于形成优良的棱边质量;刀具Y方向振动方式切削下,小范围变化的前角对棱边缺陷几乎没有影响,而X方向振动方式切削下,刀具前刀面的磨损会导致棱边缺陷更加严重。     

A mesomechanical ductility model of SiCp/Al composite

1 INTRODUCTIONAl alloy matrix composites reinforced with SiCparticles are widely usedin aerospace , military andcivil industries because of their high specificstrength, modulus , wear resistance and fatigue re-sistance . With the increase of volume fraction ofSiC,the tensile ductility al ways decreases ,the e-lastic modulus increases ,and the strength changescomplexly .It is a noticeable issue to opti mize themechanical properties .Recently , many researchershave established some mechani…     

SiCp增强Al基复合材料浸润性的研究

利用半固态熔铸法制备ＳｉＣｐ／Ａｌ复合材料,探讨了在空气中将ＳｉＣｐ加入（纯Ａｌ＋添加剂）合金中时,ＳｉＣｐ的加入量、搅拌温度、浇注温度等因素对复合制备工艺的影响。结果表明,叶片在三层以上的搅拌器,以适当速度搅拌熔体时,可增加ＳｉＣｐ在体中的熔入量,且浸润性较好,分布均匀。     

不同应力比下SiCp/Al复合材料疲劳裂纹扩展行为

为了研究应力比对SiC颗粒增强铝基复合材料疲劳性能的影响,采用真空液态搅拌法制备了SiCp/Al复合材料,并对CT试样循环加载测定其裂纹扩展曲线.研究了三种不同应力比下的裂纹扩展行为,结果表明:随着应力比R增大,疲劳裂纹扩展速率da/dN降低.疲劳裂纹的断口形貌塑性断裂越明显,裂纹尖端塑性区增大,裂纹尖端钝化越显著,二次裂纹数量增加.     

切削SiCp/Al复合材料三相摩擦系数建模与模拟

为解决SiCp/Al复合材料切削力准确预测的问题,本文采用理论建模、有限元模拟和实验研究相结合的方法,研究了SiCp/Al复合材料切削过程中刀-屑接触摩擦状态。考虑基体材料与刀具接触摩擦、Si C颗粒的两体滑动摩擦和Si C颗粒的三体滚动摩擦对SiCp/Al复合材料刀-屑接触状态的影响,提出了SiCp/Al复合材料刀-屑接触三相摩擦系数模型。建立了SiCp/Al复合材料多颗粒随机分布模型,并基于刀-屑接触三相摩擦系数模型进行了SiCp/Al复合材料切削有限元模拟以及实验研究。结果表明:采用基于刀-屑接触三相摩擦系数模型进行SiCp/Al复合材料切削过程模拟,能够较准确地预测SiCp/Al复合材料的去除过程、切屑形成、刀具与颗粒之间的相互作用以及切削力。     

ZA22／Al2O3f复合材料的机械加工与表面粗糙度

通过对ＺＡ２２／Ａｌ２Ｏ３ｆ复合材料机械加工表面粗糙度的研究，得知合理选择切削参数是提高加工表面质量，降低表面粗糙度的重要手段。高的切削速度，小的进给量及小的切削深度对提高该复合材料的表面质量有益。     

基于单颗磨粒划切试验的SiCp/Al复合材料表面去除机理研究

碳化硅颗粒增强铝基（SiCp/Al）复合材料中含有不规则碳化硅颗粒使得材料内部形成大量非理想截面,为材料表面的有效去除带来困难. 为了揭示材料去除机理,进行SiCp/Al 复合材料单颗磨粒变切深划切的表面去除仿真分析和试验验证. 研究结果表明,界面破坏对表面创成有重要影响,存在铝合金基体撕裂、界面分离,碳化硅颗粒裸露、裂纹扩展、破碎脱落、压入铝合金基体、碎片滑擦材料表面等去除过程,碳化硅颗粒中部大面积破碎脱落形成凹坑,并在刀具推挤作用下对材料进行二次切削,使铝合金基体表面形成非连续裂纹. SiCp/Al复合材料中由于铝合金基体的存在,实际划切深度小于名义切削深度. 研究可以为SiCp/Al复合材料去除机理与加工研究提供一定借鉴.     

In-situ fabrication of particulate reinforced aluminum matrix composites under high-frequency pulsed electromagnetic field

Pulsed magnetic field is generated when imposing pulse signal on high-frequency magnetic field. Distribution of the inner magnetic intensity in induction coils tends to be uniform. Furthermore oscillation and disturbance phenomena appear in the melt. In-situ Al2O3 and Al3Zr particulate reinforced aluminum matrix composites have been synthesized by direct melt reaction using Al-Zr(CO3)2 components under a foreign field. The size of reinforced particulates is 2-3 μm. They are well distributed in the matrix. Thermodynamic and kinetic analysis show that high-frequency pulsed magnetic field accelerates heat and mass transfer processes and improves the kinetic condition of in-situ fabrication.     

Machining studies of die cast aluminum alloy-silicon carbide composites

Metal matrix composites(MMCs)with high specific stiffness,high strength,improved wear resistance,and thermal properties are being increasingly used in advanced structural,aerospace,automotive,electronics,and wear applications.Aluminum alloy-silicon carbide composites were developed using a new combination of the vortex method and the pressure die-casting technique in the present work.Ma-chining studies were conducted on the aluminum alloy-silicon carbide(SiC)composite work pieces using high speed steel(HSS)end-mill tools in a milling machine at different speeds and feeds.The quantitative studies on the machined work piece show that the surface finish is better for higher speeds and lower feeds.The surface roughness of the plain aluminum alloy is better than that of the aluminum alloy-silicon carbide composites.The studies on tool wear show that flank wear increases with speed and feed.The end-mill tool wear is higher on ma-chining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy.     

Aluminum matrix composites reinforced by molybdenum-coated carbon nanotubes

To extend the application of carbon nanotubes (CNTs) and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT (Mo-CNT)/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering.The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated.The results show that magnetic stirring is better tha...     

高速切削最佳工艺参数的选择

应用田口法时高速切削中切削参数最优化进行了分析．设计并实施了以切削速度、每齿进给量和切削深度为切削参数，表面粗糙度为测量指标的高速切削实验，并利用信号与干扰比、方差分析研究了各切削参数对表面粗糙度的影响，获得了最优切削参数组合。     

Fabrication and densification enhancement of SiC-particulate-reinforced copper matrix composites prepared via the sinter-forging process

The fabrication of copper （Cu） and copper matrix silicon carbide （Cu/SiCp） particulate composites via the sinter-forging process was investigated. Sintering and sinter-forging processes were performed under an inert Ar atmosphere. The influence of sinter-forging time, temperature, and compressive stress on the relative density and hardness of the prepared samples was systematically investigated and subsequently compared with that of the samples prepared by the conventional sintering process. The relative density and hardness of the composites were enhanced when they were prepared by the sinter-forging process. The relative density values of all Cu/SiCp composite samples were observed to decrease with the increase in SiC content.     

非连续增强铝基复合材料连接新工艺

介绍几种非连续增强铝基复合材料连接的新工艺，从不同途径改善了接头显微结构和提高接头力学性能，但仍存在一定问题，其目的旨在更多的工作者参与工艺完善和开发研究，加速先进材料焊(连)接技术革新，促进新材料应用．     

一种利用偏振干涉原理测量表面粗糙度的方法

近年来,对精加工表面质量的要求日益增高,使得表面粗糙度的测量具有越来越重要的地位.提出了一种新颖的,利用光的干涉原理测量光滑物体表面粗糙度的方法.该光路使用一个半波片改变一路光束的偏振态,避免了以前广泛使用的类似测量系统中光路具有可逆性的问题,保证了系统的稳定性.使用一个1/4波片使接收端的光束的偏振态方向一致,使干涉信号最强.采用两光束共光路、同心聚焦扫描方法可实现表面粗糙度的绝对测量.通过对一标准量块的测量验证了方案的可行性,结果表明该系统在实验室现有条件下可以测量轮廓算术平均偏差Ra为0.012 μm的粗糙度量块.     

Al2O3颗粒增强铝基复合材料储能焊接头微观组织及性能

对0.3 mm厚Al2O3颗粒增强铝基复合材料薄板进行了储能点焊连接研究试验。发现其微型点焊接头由熔核区、热影响区和熔核向热影响区过渡的熔合区（线）组成。由于储能焊极短的焊接时间,大的冷却速率达到106 K/s,使得熔核组织显著细化,具有快速凝固特征。熔核中增强相Al2O3颗粒发生偏聚现象,在熔核边缘区域出现了气孔缺陷。当焊接电容C=6600μF、电压U=80 V、电极压力F=18 N时,获得较高力学性能的焊接接头。     

Tool life modeling for evaluating the effects of cutting speed and reinforce-ments on the machining of particle reinforced metal matrix composites

The wear of cutting tools in the machining of 2024A1 alloy composites reinforced with Al2O3 particles using varying sizes and volume fractions of particles up to 23.3vol% was investigated by a turning process using coated carbide tools K10 and TP30 at different cut-ting speeds. Machining tests were performed with a plan of experiments based on the Taguchi method. The tool life model was developed in terms of cutting speed, size, and volume fraction of particles by multiple linear regressions. The analysis of variance (ANOVA) was also em-ployed to carry out the effects of these parameters on the cutting tool life. The test results show that the tool life decreases with the increase of cutting speed for both cutting tools K10 and TP30, and the tool life of the K10 tool is significantly longer than that of the TP30 tool. For the tool life, cutting speed is found to be the most effective factor followed by particle content and particle size, respectively. The predicted tool life of cutting tools is found to be in very good agreement with the experimentally observed ones.