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.     

无压烧结Al2O3/ZrSiO4复相陶瓷的研究

以Al2O3颗粒为增强体,MgO-Y2O3为烧结助剂,采用无压烧结方法,在组分优化的基础上,制备的锆英石基复相陶瓷室温抗弯强度和断裂韧性分别可达371 MPa和3.4 MPa·m1/2;采用XRD、SEM分析样品的相组成和显微结构,结果显示:确定ZrSiO4为主要晶相,另外还有少量Al2O3和ZrO2的存在;确定复相陶瓷的强韧化是由Al2O3颗粒引发的裂纹偏转、微裂纹增韧和由ZrSiO4分解而来的ZrO2相变增韧共同作用而实现的,断裂方式主要为穿晶断裂.     

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.     

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      

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。     

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。     

ZrSiO4颗粒/Ca0.6Mg0.4Zr4P6O24基复相陶瓷的烧结行为及力学性能

本文对ZrSiO4颗粒/Ca0.6Mg0.4Zr4P6O24基复相陶瓷的烧结行为及力学性能进行了研究.发现引入ZrSiO4相,可促进Ca0.6Mg0.4Zr4P6O24基陶瓷的烧结,并抑制主晶相的晶粒长大.在Ca0.6Mg0.4Zr4P6O24中引入10vol%ZrSiO4,可获得一种具有较高抗弯强度(197MPa)和较低热膨胀系数(1.54×10-6/℃)的NZP基复相陶瓷材料.     

微乳液法合成ZrSiO_4/Cd(S_(1-x)Se_x)包裹色料(英文)

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。     

MCPA6/改性聚硅氧烷复合材料的摩擦磨损性能

采用阴离子聚合法制备了浇铸尼龙6(MCPA6)/改性羟基封端聚二甲基硅氧烷(MHPDMS)原位复合材料,研究了不同MHPDMS含量对复合材料在水润滑及干摩擦条件下的摩擦磨损性能影响。结果表明,在干摩擦条件下,复合材料的摩擦系数随滑动时间增加先增大后减小最后达到平衡,随着MHPDMS含量的增加,复合材料在稳定阶段的摩擦系数变化不大,但是磨损量逐渐减小,MHPDMS质量分数为4%的复合材料磨损量仅为MCPA6的25%;在水润滑条件下,复合材料的摩擦系数随滑动时间增加先增大后平衡,随着MHPDMS含量的增加,复合材料的稳定摩擦系数基本没有变化,磨损量先减小后增大,当MHPDMS质量分数为2%时,磨损量最小,为MCPA6的50%左右。复合材料在水润滑条件下的稳定摩擦系数比干摩擦条件下的小,但磨损量比干摩擦条件下的大很多。复合材料在干摩擦条件下的磨损机理主要是粘着磨损和疲劳磨损,而在水润滑条件下主要为犁削磨损和磨粒磨损。     

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...     

炭黑表面改性对硅酸锆包裹炭黑色料的影响

本文以无水四氯化锆和正硅酸乙酯为前驱体,氟化锂为矿化剂,炭黑为着色剂,研究了炭黑的硝酸氧化改性和表面活性剂改性对炭黑悬浮液的稳定分散和硅酸锆包裹炭黑(ZrSiO4/C)色料黑度的影响.电动电位(Zeta电位)、红外(FTIR)、白度仪、扫描电镜(SEM)、紫外-可见分光光度计分析测试的结果表明:硝酸氧化改性炭黑表面含氧官能团增多,并且颗粒表面带电量发生改变,有助于炭黑的悬浮和硅酸锫对炭黑的包裹;聚乙烯醇缩丁醛(PVB)的空间位阻作用和增大体系粘度的双重效应有利于炭粉在乙醇中的稳定悬浮;聚乙烯吡咯烷酮(PVP)、十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)通过静电机理和空间位阻作用使炭粉在水中稳定悬浮,但考虑到对炭黑悬浮液Zeta电位的改变,PVP和SDS更有利于硅酸锆溶胶对炭黑的包裹.     

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....     

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.