Dry Sliding Wear Behavior of Tempered (T4 and T6) Hypereutectic Aluminum Alloy-Based Composites

Silicon - The present work describes the effect of tempering (T4 and T6) processes on the dry sliding wear properties of ilmenite reinforced aluminum alloy (LM30) composites, prepared through stir...     

Friction and Wear Behavior of AA 7075- Si3N4 Composites Under Dry Conditions: Effect of Sliding Speed

Silicon - In this paper, the effect of sliding speed on tribological properties of AA7075-Si3N4 composites has been investigated. The tribological testing was carried on a unidirectional pin on...     

TiB2涂层刀具制备及干铣削Ti-6Al-4V磨损行为研究?

由于切削过程中产生高温、刀具粘结与氧化严重,钛合金切削尤其是干切削,一直是刀具行业的重大挑战之一,而在刀具表面添加涂层是提高钛合金切削刀具寿命的有效途径。利用脉冲磁控溅射技术制备了TiB2涂层刀具,以相同基体的无涂层刀具为对照,干铣削Ti-6Al-4V钛合金,切削速度从30~100 m/min变化,研究TiB2涂层刀具的切削性能与失效机理。所制备的TiB2涂层具有(100)择优取向的六方晶体结构,组织致密。涂层硬度可高达4000 HV。切削实验发现,在30 m/min的低速时,TiB2涂层刀具的切削寿命超过无涂层刀具57%之多,当切削速度加倍到60 m/min时,刀具寿命未见下降。当切削速度增加到100 m/min时,TiB2涂层刀具与无涂层刀具切削寿命相当。TiB2涂层刀具表面氧化所产生的B2O3液化膜,起自润滑作用,可充分减少钛合金的粘结,降低摩擦力。因此,在TiB2或B2O3消失之前,TiB2涂层刀具均有良好表现。在100 m/min时,切削高温造成B2O3强烈挥发,且TiB2被氧化为多孔疏松的TiO2,刀具寿命急剧下降到无涂层刀具的水平。     

偶联修饰纳米碳化硅/聚四氟乙烯基复合材料的摩擦磨损性能

通过冷压烧结法制备了聚四氟乙烯(PTFE)与钛酸酯和硅烷偶联剂修饰的纳米碳化硅(nano-SiC)复合材料,采用45#钢为摩擦对偶件的MM-200型摩擦磨损试验机,在室温干摩擦条件下测试了复合材料的摩擦学性能,用扫描电子显微镜(SEM)对磨损表面进行了观察并分析了磨损机理。结果表明:纳米SiC的加入能提高PTFE复合材料的硬度和耐磨性;偶联修饰改善了复合材料的摩擦学性能;与硅烷相比,钛酸酯偶联修饰nano-SiC/PTFE复合材料的硬度和摩擦学性能更好。两种偶联修饰复合材料的表面磨损情况相似,主要表现为粘着磨损,而未经偶联处理nano-SiC的复合材料在粘着磨损的同时出现了疲劳磨损。     

Effect of Granite Particle Size on the Properties of Al-7%Si-0.3%Mg/Granite Particulate Composites

The present study aims at investigating the effect of granite particle size on the properties of Al-7%Si-0.3%Mg/granite particulate composites. The composites were fabricated with two different size fractions of granite (− 38 + 0.5 μm and − 0.5 μm). Al-Si-Mg/granite particulate composites were produced using stir casting method with varying amount of granite particles from 0 to 12 wt% at 3 wt% intervals. X-ray fluorescence (XRF) analysis on the granite particulates as well as determination of density and mechanical properties were conducted. The results showed that density of Al-Si-Mg/granite particulate reinforced composites decreased considerably with particles loading. The results further revealed that with increase in granite particulates, a considerable rise in hardness accompanied with a significant decrease in tensile and impact strengths except at 3 wt% addition is achieved. The microstructural analyzes of the produced composites were studied using optical microscope (OM) and Scanning Electron Microscope (SEM). Noticeably, in the micrographs and images obtained, Mg₂Si and eutectic Si in α-Al matrix with granite particulates were observed.

     

Abrasive Wear Behavior of a Si3N4-MoSi2 Composite

MoSi₂ particles (20 vol%) have been added to Si₃N₄ to form ceramic matrix-intermetallic composites. Benefits associated with the addition of the MoSi₂ to Si₃N₄ include higher strength, higher fracture toughness, no loss in oxidation resistance, and lower electrical resistivity. However, because the hardness of MoSi₂ is approximately half that of Si₃N₄, a decrease in the specific wear rate of the Si₃N₄-20 vol% MoSi₂ composite is expected to result from the incorporation of the MoSi₂ into the Si₃N₄. In this U.S. Bureau of Mines and Los Alamos National Laboratory study, it is found, however, that the specific wear rate of the composite during two-body abrasion by SiC particles is equivalent in magnitude to the specific wear rate of monolithic Si₃N₄. The specific wear rates of both the Si₃N₄-20 vol% MoSi₂composites and monolithic Si₃N₄ are four to five times less than that of monolithic MoSi₂.     

PPS／PTFE复合材料摩擦磨损性能研究

研究了聚苯硫醚（PPS）／聚四氟乙烯（PTFE）复合材料的摩擦因数、磨损体积、磨损后表面的微观形貌及损耗因子峰值、储能模量对摩擦因数的影响。结果表明，PTFE的加入显著改善了复合材料的摩擦学性能，摩擦因数由纯样的0．35降至复合材料的0．11。随着PTFE含量从5％（质量分数，下同）增至15％，复合材料的摩擦因数从0．26降至0．11；复合材料损耗因子峰值越大，摩擦因数越小；初始储能模量越大，摩擦因数越小。     

Effects of Molecular Weight and Thermal Treatment on Wear Behavior of Polyamide 6

Abstract

A series of polyamide 6 (PA 6) samples varying in their molecular weight (between 10000 and 50000) were annealed for 6 h in vacuum at various temperature (between 100 and 220°C) in order to create different morphological structures. The samples have been characterized with respect of their density, melting and crystallinity (from DSC), thermal expansion coefficient, humidity, predomination α- or γ-crystalline modification (from IR), shear melt viscosity and their tribological behaviour (the specific wear rate W_s ). It is found that density increases with increasing annealing temperature T_a but decrease with the rise of molecular weight (m.w.). The thermal expansion coefficient is more sensitive to T_a than to m.w. Contrary, shear-viscosity increases from 35 MPa for PA 6 with a m.w. of 10000 to 7200 MPa for samples with a m.w. of 50000. Concerning wear behavior it is concluded that the observed tendency for a decrease of W_s with an increase of T_a , particularly for samples with low m.w. is attributed to the formation of a more stable physical structure during annealed. This well defined tendency (except samples annealing at highest T_a ) is related to the observed drastic increase of shear melt viscosity with an increase of m.w.     

尼龙6/高岭土复合材料的非等温结晶行为研究

用差示扫描量热法研究了尼龙6/高岭土复合材料的熔融结晶行为,并用Jeziorny法、Ozawa法、Mo法对复合材料的非等温结晶动力学进行研究。结果表明,3种高岭土的加入均使复合体系的熔融峰变窄,熔点增加;结晶峰温和结晶起始温度提高,结晶速率增大;高岭土填料起到异相成核作用;Jeziorny法、Mo法均适合分析尼龙6及复合体系的非等温结晶动力学过程,而Ozawa法不适合。     

Investigation of Mechanical and Tribological Behaviour of Heat-Treated Functionally Graded Al-7Si/B 4 C Composite

The current study focuses on improving the mechanical and reciprocating wear characteristics of centrifugally cast functionally graded A356(Al-7Si-0.3      

聚氨酯/微米Si_3N_4复合材料的性能研究

对聚氨酯/微米Si3N4复合材料的性能进行了研究,实验表明：聚氨酯/Si3N4复合材料具有优异的性能,聚氨酯/微米Si3N4复合材料,其硬度、力学性能和抗冲蚀磨损性能比纯聚氨酯优异;在微米Si3N4含量为3%时,其硬度、力学性能最佳;在微米SiN含量为5%时,其抗冲蚀磨损性能最佳。     

微乳液法合成ZrSiO4/Cd(S1-xSex)包裹色料

以聚乙二醇辛基苯基醚(Triton X-100)/正己醇/环己烷/水相的反相微乳液体系合成了 ZrSiO4/Cd(S1–xSex)包裹色料。通过 X 射线衍射、透射电子显微镜以及色度测试对色料的物相、微观结构以及色度进行了表征和分析。结果表明:当烧成温度为 1 150 ℃,焙烧时间为 30 min,ZrSiO4与 Cd(S1–xSex)的摩尔比为 2.0,Si 与 Zr 的摩尔比为 1.5 时,合成的样品结晶性能好,ZrO2与 SiO2反应较完全且对 Cd(S1–xSex)包裹较好,色料具有较高的色度值。     

Effect of Si3N4 Ceramic Particulates on Mechanical,Thermal, Thermo-Mechanical and Sliding Wear Performance of AA2024 Alloy Composites

Silicon - In this investigation, hybrid AA2024 – Si3N4 (0–6 wt.% @ 2%) – SiC (2 wt.%) – graphite (2 wt.%) alloy composites have been fabricated as...     

Influence of Residual Stresses on the Wear Behavior of Alumina/Alumina–Zirconia Laminated Composites

Symmetric structures of laminated ceramic composites were produced by superimposing alternating layers of Al₂O₃ and Al₂O₃/ZrO₂ composite prepared by tape casting. The composites were designed to have an alumina surface layer on either side. This configuration caused residual compressive stresses to be induced on the surface due to the different thermal expansion coefficients of the various layers, leading to an increase in the apparent surface toughness. The amount of residual stress was determined using the indentation technique. The tribological behavior of these laminated structures was evaluated using the pin-on-disk method for different loads and sliding speeds. Comparison with the results obtained from stress-free alumina showed that, within the range of these experimental conditions, the improvement in surface toughness leads to a reduced friction coefficient and increased wear resistance of the composites. Possible wear mechanisms are proposed.     

Effect of MoS2 on the Wear Behavior of Aluminium (AlMg0.5Si) Composite

Silicon - Aluminium alloy with silicon as alloying element finds more comprehensive applications and this induces the development of aluminium composite with the matrix AA6063 (AlMg0.5Si) alloy....     

尼龙6/钨复合材料的制备及其流变性研究

采用注射成型方法制备了密度高达11.214 g/cm3的尼龙6/钨(PA6/W)复合材料,利用扫描电子显微镜观察了复合材料的微观形貌,用转矩流变仪研究了PA6,PA6与W粉的混合热历史过程及转速对混合物平衡转矩的影响。为了提高PA6/W复合材料的流变性,在PA6与W粉的混合过程中加入3种微量增塑剂季戊四醇硬酯酸酯(PETS)、N,N′-乙撑双硬脂酰胺(EBS)、邻苯二甲酸二辛脂(DOP),利用熔体流动速率(MFR)仪研究了增塑剂对PA6/W复合材料MFR的影响。结果表明,W颗粒被PA6基体包裹良好,且分散比较均匀;在温度为230℃、转速为35 r/min条件下,PA6和W粉混合效果理想;3种增塑剂都能明显改善复合材料的流变性,以EBS的改善效果最佳,并且复合材料属于假塑性流体,非牛顿指数n小于1。     

表面处理纳米Al2O3填充PTFE复合材料的磨粒磨损性能

利用自制销-盘式磨粒磨损试验机，测定聚四氟乙烯(PTFE)及其表面处理与未处理纳米氧化铝(Al2O3)填充聚四氟乙烯复合材料试件在干摩擦滑动条件下的磨粒磨损质量损失。考察了载荷、磨粒、转速等参数的变化对试件摩擦学性能的影响。采用扫描电子显微镜观察、分析试件磨损表面形貌及磨损机理。结果表明，纳米Al2O3可以提高PTFE耐磨性。表面处理纳米Al2O3在PTFE中能较均匀分散，其耐磨性比相同含量但未经表面处理的纳米Al2O3填充PTFE高。导致PTFE复合材料磨粒磨损的重要机理是犁切破坏。     

苯并噁嗪／不完全笼型倍半硅氧烷复合材料的固化动力学研究

采用非等温差示扫描量热法(DSC)比较了苯并噁嗪和苯并噁嗪/不完全笼型苯基三羟基七聚倍半硅氧烷(T7POSS)复合材料两种体系的固化特性.Kissinger和Ozawa方程计算了两体系的固化反应表观活化能、反应级数,并建立了固化动力学方程.结果表明T7POSS上的弱酸性官能团Si-OH对苯并噁嗪的固化反应具有催化作用,两种体系在特征固化温度、固化速率、反应热、反应级数以及表观活化能上存在明显的差别.     

The Effect of Maleic Anhydride Grafted Styrene-Ethylene-Butylene-Styrene on the Friction and Wear Properties of Polyamide6/Carbon Nanotube Composites

The friction and wear properties of polyamide6 (PA6), polyamide6/carbon nanotube (PA6/CNT) nanocomposites and PA6/maleic anhydride grafted Styrene-ethylene-butylene-styrene (SEBS-g-MA+CNT) nanocomposites was studied by means of a ring-on-block tribometer. The morphologies of the worn surfaces of specimens were observed with a scanning electron microscopy (SEM). All specimen wear increases with increasing load; meanwhile, the friction coefficient decreases. Wear of PA6/CNT is larger than that of PA6. Adding SEBS-g-MA to the PA6/CNT improves the wear resistance. The friction coefficient of PA6/CNT is slightly less than that of PA6 at various loads. The friction coefficient of PA6/(SEBS-g-MA+CNT) is the lowest among PA6, PA6/CNT and PA6/(SEBS-g-MA+CNT).