CuCrW(Al_2O_3) nanocomposite: mechanical alloying,microstructure, and tribological properties

The effect of alumina nanoparticle addition on the microstructure and tribological properties of a CuCrW alloy was investigated in this work. Mechanical alloying was carried out in a satellite ball mill. The tribological properties of the samples were evaluated using pin-on-disk wear tests with different pins(alumina, tungsten carbide, and steel pins). The results indicated that the tungsten carbide pin had a lower coefficient of friction than the alumina and steel pins because of its high hardness and low surface roughness. In addition, when the sliding rate was decreased, the weight-loss rate increased. The existence of alumina nanoparticles in the nanocomposite led to a lower weight-loss rate and to a change in the wear mechanism from adhesive to abrasive.     

CuCrW(Al<Subscript>2</Subscript>O<Subscript>3</Subscript>) nanocomposite: mechanical alloying,microstructure, and tribological properties

The effect of alumina nanoparticle addition on the microstructure and tribological properties of a CuCrW alloy was investigated in this work. Mechanical alloying was carried out in a satellite ball mill. The tribological properties of the samples were evaluated using pin-on-disk wear tests with different pins (alumina, tungsten carbide, and steel pins). The results indicated that the tungsten carbide pin had a lower coefficient of friction than the alumina and steel pins because of its high hardness and low surface roughness. In addition, when the sliding rate was decreased, the weight-loss rate increased. The existence of alumina nanoparticles in the nanocomposite led to a lower weight-loss rate and to a change in the wear mechanism from adhesive to abrasive.     

Cu-Zn-Al2O3 nanocomposites: study of microstructure,corrosion, and wear properties

Alumina nanoparticles were added to a Cu-Zn alloy to investigate their effect on the microstructural, tribological, and corrosion properties of the prepared alloys. Alloying was performed using a mixture of copper and zinc powders with 0vol% and 5vol% of α-Al nanopowder in a satellite ball mill. The results showed that the Cu-Zn solid solution formed after 18 h of mechanical alloying. The mechan-ically alloyed powder was compacted followed by sintering of the obtained green compacts at 750℃ for 30 min. Alumina nanoparticles were uniformly distributed in the matrix of the Cu-Zn alloy. The tribological properties were evaluated by pin-on-disk wear tests, which revealed that, upon the addition of alumina nanoparticles, the coefficient of friction and the wear rate were reduced to 20% and 40%, respectively. The corrosion properties of the samples exposed to a 3.5wt% NaCl solution were studied using the immersion and potentiodynamic polarization methods, which revealed that the addition of alumina nanoparticles reduced the corrosion current of the nanocomposite by 90%.     

Effect of different atmospheres on dry friction behavior of steel sliding against brass at high speed

The atmosphere components have an influence on tribological behaviors of tribo-pairs. Through changing the atmosphere component, the effect of atmosphere component on the tribological behaviors of CrNiMo steel against brass at high sliding velocity was investigated. The wear test was carried out on a high-speed friction and wear test rig whose test atmosphere could be controlled. The tests were performed at four sliding velocities （30, 40, 50, 60 m/s）, one contact pressure （1.33 MPa） and two atmosphere components （N2 or O2）. The morphologies of the worn surfaces of various pins were observed with a scanning electron microscope. The chemical compositions of the surfaces and subsurfaces for steels were determined with an energy dispersion spectroscopy. The results showed that the wear rate of the steel pins were low all the time with the sliding velocity increasing in oxygen atmosphere, and that the wear rate of the steel pin in nitrogen atmosphere was higher than that of the steel pin in oxygen atmosphere. It was found that the thin and compact oxidation layer formed on the worn surface of the steel in oxygen atmosphere played a key role in wear resistance. However, the wear rate of the steel pin increased rapidly with the sliding velocity increasing in nitrogen atmosphere, which was attributed to the thick and loose surface layer formed on the worn surface of the steel.     

等温淬火球墨铸铁在销——环法试验条件下的滑动磨损

用销环法研究了奥贝球铁与下贝球铁及具有奥贝组织与下贝组织的一种对比钢的滑动磨损性能，采用的载荷为1－20kgf，速度为0.61-1.54m/s。根据实验结果讨论了奥贝球铁与下贝球铁在不同条件下的磨损行为，得出了一个与传统观点不同的结论：等温淬火球铁中的石墨不利于耐磨性。获得的另一结论是：在描述或比较材料的耐磨性时，除磨损率外，单位载荷的磨损率与转折载荷都是重要的。     

Cu-Zn-Al2O3 nanocomposites:study of microstructure,corrosion,and wear properties

Alumina nanoparticles were added to a Cu-Zn alloy to investigate their effect on the microstructural, tribological, and corrosion properties of the prepared alloys. Alloying was performed using a mixture of copper and zinc powders with 0vol% and 5vol% of α-Al nanopowder in a satellite ball mill. The results showed that the Cu-Zn solid solution formed after 18 h of mechanical alloying. The mechanically alloyed powder was compacted followed by sintering of the obtained green compacts at 750℃ for 30 min. Alumina nanoparticles were uniformly distributed in the matrix of the Cu-Zn alloy. The tribological properties were evaluated by pin-on-disk wear tests, which revealed that, upon the addition of alumina nanoparticles, the coefficient of friction and the wear rate were reduced to 20% and 40%, respectively. The corrosion properties of the samples exposed to a 3.5wt% NaCl solution were studied using the immersion and potentiodynamic polarization methods, which revealed that the addition of alumina nanoparticles reduced the corrosion current of the nanocomposite by 90%.     

NiWC喷焊层冲蚀磨损性能的研究

本文通过对NiWC喷焊层的冲蚀实验以及扫描电镜分析,研究NiWC喷焊层的冲蚀性能.结果表明在Al_2O_3硬粒子冲蚀条件下,NiWC喷焊层显示介于延性、脆性材料之间的冲蚀特性.NiWC喷焊层的冲蚀率随WC%增加而增加.     

干摩擦条件下金刚石复合膜摩擦学性能

在干摩擦条件下利用 SRV磨损试验机比较了在硬质合金基体上金刚石薄膜、石墨 /金刚石复合膜以及硬质合金 3种试样的摩擦学性能。利用扫描电子显微镜观察了试样和磨痕的表面形貌。利用表面形貌仪测试了磨损体积。研究了振动频率对试样的摩擦学性能影响。结果表明 ,在干摩擦条件下 ,金刚石薄膜与石墨 /金刚石复合膜的摩擦学性能差别不大 ,二者的磨损机理均为微断裂磨损。在干摩擦条件下 ,高频时金刚石薄膜的耐磨性是硬质合金耐磨性的 8～ 10倍 ,其原因是硬质合金的磨损机理存在着从粘着磨损到微断裂磨损的转变     

碳纤维/石墨-铜基自润滑耐磨复合涂层的摩擦学性能

为提高45~#钢的摩擦学性能,采用热压烧结技术,在45~#钢表面制备了以Ni为中间连接层的铜基自润滑耐磨复合涂层。采用扫描电镜和能谱仪对涂层表面及截面的微结构进行了分析;采用球-盘式摩擦磨损试验机与GCr15球配副,在不同载荷和速度下,研究了铜基自润滑耐磨复合涂层和基体的干摩擦学性能,并分析了磨损机理。结果表明:在所有试验条件下,含4wt%碳纤维和2wt%石墨样品的摩擦系数和磨损率均比45~#钢低,且在15 N载荷、500 r/min转速下显示出最优的摩擦学性能。     

离子束轰击钨合金表面碳膜的AES和XPS分析

钨合金是一种重要的合金材料 ,由于它具有密度大、强度高及足够的韧性 ,因此 ,在医疗器械、军工装备等一些特殊使用的器件上有着重要的用途 [1 ,2 ] .但在实际使用中发现 ,其表面硬度及其耐磨性能尚有不足之处 [3] ,为此我们采用离子束表面强化技术 [4～ 6]以改善其表面性能 .具体做法是 :先在钨合金表面利用磁控溅射技术沉积碳膜 ,再用单一的或混合的离子束进行轰击 ,之后通过使用俄歇电子能谱 ( AES)及 X射线光电子能谱 ( XPS)对其表面进行分析研究 .实验结果表明 ,单独使用氮离子轰击可在钨合金表面形成碳化物 ,有利于提高钨合金的表…     

Effect of Al<Subscript>2</Subscript>O<Subscript>3sf</Subscript> addition on the friction and wear properties of (SiC<Subscript>p</Subscript>+Al<Subscript>2</Subscript>O<Subscript>3sf</Subscript>)/Al2024 composites fabricated by pressure infiltration

Aluminum (Al) 2024 matrix composites reinforced with alumina short fibers (Al₂O_3sf) and silicon carbide particles (SiC_p) as wear-resistant materials were prepared by pressure infiltration in this study. Further, the effect of Al₂O_3sf on the friction and wear properties of the as-synthesized composites was systematically investigated, and the relationship between volume fraction and wear mechanism was discussed. The results showed that the addition of Al₂O_3sf, characterized by the ratio of Al₂O_3sf to SiC_p, significantly affected the properties of the composites and resulted in changes in wear mechanisms. When the volume ratio of Al₂O_3sf to SiC_p was increased from 0 to 1, the rate of wear mass loss (K_m) and coefficients of friction (COFs) of the composites decreased, and the wear mechanisms were abrasive wear and furrow wear. When the volume ratio was increased from 1 to 3, the COF decreased continuously; however, the K_m increased rapidly and the wear mechanism became adhesive wear.     

Effect of Al_2O_(3sf) addition on the friction and wear properties of(SiC_p+Al_2O_(3sf))/Al2024 composites fabricated by pressure infiltration

Aluminum(Al) 2024 matrix composites reinforced with alumina short fibers(Al_2O_(3sf)) and silicon carbide particles(SiC_p) as wear-resistant materials were prepared by pressure infiltration in this study. Further, the effect of Al_2O_(3sf) on the friction and wear properties of the as-synthesized composites was systematically investigated, and the relationship between volume fraction and wear mechanism was discussed. The results showed that the addition of Al_2O_(3sf), characterized by the ratio of Al_2O_(3sf) to SiC_p, significantly affected the properties of the composites and resulted in changes in wear mechanisms. When the volume ratio of Al_2O_(3sf) to SiC_p was increased from 0 to 1, the rate of wear mass loss(K_m) and coefficients of friction(COFs) of the composites decreased, and the wear mechanisms were abrasive wear and furrow wear. When the volume ratio was increased from 1 to 3, the COF decreased continuously; however, the K_m increased rapidly and the wear mechanism became adhesive wear.     

MOSi2-淬火45#钢在油润滑下的摩擦学特性

利用M-200型磨损试验机考察了MoSi2-淬火45针仪分析讨论其磨损机理.结果表明:润滑油明显改善了MoSi2材料的摩擦学性能;MoSi2与淬火45#钢对摩在120～150 N载荷范围内表现出较好的摩擦磨损综合性能;其磨损机制主要表现为疲劳磨损、磨粒磨损和轻微粘着磨损.图4,参10.     

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. Machining 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 machining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy.     

Thin films of fullerene-like MoS2 nanoparticles with ultra-low friction and wear

The tribological properties of solid lubricants such as graphite and the metal dichalcogenides MX2 (where M is molybdenum or tungsten and X is sulphur or selenium) are of technological interest for reducing wear in circumstances where liquid lubricants are impractical, such as in space technology, ultra-high vacuum or automotive transport. These materials are characterized by weak interatomic interactions (van der Waals forces) between their layered structures, allowing easy, low-strength shearing. Although these materials exhibit excellent friction and wear resistance and extended lifetime in vacuum, their tribological properties remain poor in the presence of humidity or oxygen, thereby limiting their technological applications in the Earth's atmosphere. But using MX2 in the form of isolated inorganic fullerene-like hollow nanoparticles similar to carbon fullerenes and nanotubes can improve its performance. Here we show that thin films of hollow MoS2 nanoparticles, deposited by a localized high-pressure arc discharge method, exhibit ultra-low friction (an order of magnitude lower than for sputtered MoS2 thin films) and wear in nitrogen and 45% humidity. We attribute this 'dry' behaviour in humid environments to the presence of curved S-Mo-S planes that prevent oxidation and preserve the layered structure.     

钻头齿面堆焊用硬质合金耐磨性试验

为了选择更合适的钻头齿面强化材料,对多种粒度的球状烧结碳化钨和粒状铸造碳化钨堆焊层分别作了磨料磨损试验,以评价其抗磨性能。用Ni基合金作钎料,在高真空度下将硬质合金颗粒焊至20Ni4Mo表面。试验采用多种冲击能量,磨料介质为石英砂、水和少量悬浮剂,用天平称出磨损失重。结果表明:球状烧结碳化钨或不同类型和粒度混合的碳化钨堆焊层都比现行采用的粒状铸造碳化钨具有更好的抗冲击磨料磨损能力。用球状烧结碳化钨代替粒状铸造碳化钨作钢齿钻头齿面堆焊材料是提高齿面强化效果的有效途径。     

镍基碳化钨高温磨损特性的研究

本文用不同碳化钨含量的镍基自熔合金粉末喷焊层的试样,进行扫描电镜形貌观察和X光衍射分析,同时进行了高温磨粒磨损试验,试验结果发现粉末中碳化钨的含量对喷焊层的磨损特性及组织结构有重要的影响,其中以35%碳化钨喷焊层的高温耐磨性最佳.     

微晶二氧化硅粉体添加剂的抗磨减摩作用

为研究微晶SiO2粉体添加剂的抗磨减摩作用,采用微晶SiO2矿物粉体作为润滑油添加剂,利用AMSLER摩擦磨损试验机研究45#钢摩擦副在添加剂润滑油润滑下的摩擦学特性.磨损后钢环表面的形貌和成分通过扫描电子显微镜和X射线光电子能谱仪进行分析.结果显示:以微晶SiO2粉体为添加剂润滑时在摩擦副表面形成一层陶瓷保护层.相比基础油,在微晶SiO2添加剂润滑油润滑条件下,摩擦副的接触状态由金属之间的摩擦磨损转化为自修复膜层之间的摩擦磨损.添加剂润滑油较基础油润滑条件下的摩擦系数大.摩擦磨损过程中自修复膜层的形成,隔离了金属摩擦副的直接接触,降低了试样磨损失重,具有良好的耐磨性能.     

TiB_2弥散强化Al_2O_3陶瓷刀具的切削性能

研究了Al2O3－TiB2复合陶瓷的力学性能．结果表明，当TiB2含量为20wt％时，能获得较高的综合性能．用此配方制成的陶瓷刀具具有较高的耐磨性能．后刀面磨损量VBmax比YW1低1倍左右．陶瓷刀具的磨损以微区剥离为主要机制．此外，还对比了陶瓷刀具和硬质合金刀具的切削力变化情况．     

碳化钨基硬质合金的制备与力学性能研究

在碳化钨粉末中加入一定量的钴、碳化钽以及碳化铪,经过混料、球磨、冷压成型和热压烧结等步骤制备出硬质合金试样。利用1 000 N维式显微硬度计、三点弯曲试验、XJJ-5冲击试验机以及扫描电镜分别对试样硬度、抗弯强度、冲击韧性以及试样的微观形貌进行了研究,并对试样力学性能的提高机理进行了探讨。结果表明,碳化铪的加入可有效改善烧结质量,细化晶粒,改善试样力学性能。碳化铪质量分数为2%的试样力学性能最好。