石墨形态和铬含量对铸铁干摩擦学性能的影响

使用ＭＭ—２００磨损试验机研究了石墨形态和铬含量对铸铁与石棉基摩擦材料配副时的干摩擦学性能。结果表明,蠕墨铸铁的磨损率最低;摩擦系数由高到低依次为：片墨铸铁、蠕墨铸铁、球墨铸铁。蠕墨铸铁中,随着铬含量的增加,耐磨性能明显提高,摩擦系数略有降低。在高速、高载荷条件下,铬含量的质量分数达到１．５％时,耐磨性可达普通蠕墨铸铁的４倍以上;随着载荷的增加,蠕墨铸铁的摩擦系数降低,磨损率提高。在高速条件下,摩擦系数降低的幅度比在低速条件下小。铬改善蠕墨铸铁干摩擦学性能的效果在高速使用条件下更为突出。     

沙尘环境下含玻璃微珠铜基摩擦材料的摩擦磨损性能

利用MM-1000摩擦实验机,分别在沙尘环境与干摩擦情况下,研究不同玻璃微珠含量(质量分数)铜基摩擦材料的摩擦磨损性能。结果表明:在摩擦过程中,玻璃微珠含量通过影响摩擦膜的形成而影响材料的摩擦磨损性能;在沙尘环境下,沙尘破坏材料表面摩擦膜致使材料的摩擦因数高于干摩擦情况下的摩擦因数,且材料的制动稳定性较差,线性磨损量随着玻璃微珠含量增加而增加;综合不同环境下的摩擦实验结果表明,含6%玻璃微珠的材料具有良好的摩擦学性能;添加2%和4%玻璃微珠材料的磨损机制主要为磨粒磨损与剥层磨损,但添加6%和8%玻璃微珠的材料以粘着磨损和磨粒磨损为主要磨损机制。     

铸铁—铸铁、铸铁—镀铬层在纯油和加磨料润滑条件下磨损特性的研究

利用SRV高温磨损试验机测定了几种铸铁和镀铬层在油润滑和有磨料条件下不同温度时的摩擦系数和磨损率,同时利用SEM和EDX研究了材料去除机理以及表面层和第二相质点在磨损过程中的行为。研究结果表明,在油润滑条件下,镀铬层与铌铸铁配磨高温时以粘着磨损为主,而在较低温度下以疲劳剥落为主,该对摩擦副的磨损率比Cr-Mo-Cu/B铸铁副高;但在有磨料介入的条件下,镀铬层/铌铸铁副则表现出较好的耐磨性。     

石墨形态对含铸铁干摩擦磨损行为的影响

本文利用自制的干摩擦磨损试验机,系统地研究了不同石墨形态含磷铸铁在不同接触压力及不同摩擦速度条件下的干摩擦磨损行为。试验结果证明,合磷蠕墨铸铁具有最佳的耐磨性及最高的摩擦系数。随着接触压力的提高,含磷铸铁的磨损量呈直线增加,而随着摩擦速度的提高,含磷铸铁的磨损量首先增加,而后则大幅度下降。随着接触压力和摩擦速度的提高,含磷铸铁的摩擦系数首先大幅度降低,而后趋于一相对稳定值。随着石墨长宽比的增加,摩擦系数趋于相对稳定值的接触压力和摩擦速度呈直线增加。     

速度与载荷对无铅铜铋轴承材料摩擦学特性的影响

采用粉末冶金法制备无铅铜铋双金属轴承材料,并在HDM-20端面摩擦磨损实验机上进行油润滑条件下的摩擦磨损试验,分析速度、载荷对其摩擦学性能的影响。结果表明:摩擦因数随摩擦速度、载荷的增加而减小,其磨损量、摩擦副表面温度均随速度、载荷的增加而增大;摩擦磨损过程中低熔点组元铋的析出起着较好的减摩、抗粘着作用,并存在铋的析出、熔化、磨损脱落的循环过程。     

自润滑材料滑动摩擦失效分析

通过滑动摩擦磨损实验,评价试样的磨损性能,结合自润滑材料的摩擦特性（μ-n）曲线和自润滑滑动摩擦磨损机理,利用SEM研究摩擦磨机理,得知自润滑材料失效的实质是：在滑动摩擦的后期,自润滑向干摩擦过渡,最终转变为干摩擦,而干摩擦的磨损量比自润滑的高3个数量级,使材料的磨损量急剧升高,材料因磨损量过大而失效,其磨损机理粘着磨损。     

对偶材料对航空刹车副摩擦性能的影响

介绍了粉末冶金对偶和合金钢对偶对航空刹车副摩擦性能的影响,对进口刹车副原件和作者所研制的材料进行了摩擦性能试验,结果表明:在设计着陆和服役使用条件下,与粉末冶金对偶配对使用的刹车副摩擦因数较高;在中断起飞条件下,则与合金钢配对使用的刹车副摩擦因数要高一些,摩擦材料的磨损,在设计着陆条件下,与合金钢配对使用的材料磨损比与粉末冶金对偶配对使用的材料磨损大得多;在服役使用条件下,两者的磨损大体相当,作者对这种摩擦性能的差别进行了分析,并认为造成这种差别的主要原因是粉末冶金对偶含有较多的孔隙和石墨。     

对偶材料对航空刹车副摩擦性能的影响

介绍了粉末冶金对偶和合金钢对偶对航空刹车副摩擦性能的影响,对进口刹车副原件和作者所研制的材料进行了摩擦性能试验。结果表明,在设计着陆和服役使用条件下,与粉末冶金对偶配对使用的刹车副摩擦系数较高;在中断起飞条件下,则与合金钢配对使用的刹车副摩擦系数要高一些。摩擦材料的磨损,在设计着陆条件下,与合金钢配对使用的材料磨损比与粉末冶金对偶配对使用的材料磨损大得多;服役使用条件下,两者的磨损大体相当。作者对这种摩擦性能的差别进行了分析,认为造成这种差别主要原因是粉末冶金对偶含有较多的孔隙和石墨。     

45CrNiMoVA与PCrNiMo配副的摩擦磨损特性

 在自制的销盘式干滑动摩擦磨损实验机上研究了45CrNiMoVA与PCrNiMo配副的摩擦磨损特性。结果表明：材料的磨损率随着速度、载荷的增加而增大；摩擦因数随着载荷增加而减小；随着速度的改变磨损率的变化规律为：减小、增大、再减小；硬度对实验材料磨损率的影响与通常所用材料不同，磨损机理为磨粒磨损和粘着磨损。     

偶联剂改性硅灰棉对树脂基摩擦材料摩擦学性能的影响

硅灰棉是树脂基摩擦材料常用的主要组分之一,分别采用硅烷偶联剂CX-602与KH-550,以及钛酸酯偶联剂TCA-201与TCA-311w对硅灰棉进行表面改性,以期改善材料的摩擦磨损性能。利用D-MS150定速实验机和ZYMM-1000缩比台架试验机(1:6)对摩擦材料试样进行摩擦磨损性能测试,研究偶联剂改性硅灰棉对树脂基摩擦材料结构与摩擦学性能的影响。结果表明,用KH-550表面改性硅灰棉制备的树脂基摩擦材料的摩擦磨损性能最佳,高温摩擦因数比未改性的试样提高22%,并且摩擦因数的稳定性最好,热衰退率最低(14%),摩擦试验后的质量损失和厚度损失都最小,分别为1.38 g和1.04 mm。     

含钒蠕墨铸铁干摩擦学性能

研究了含钒蠕墨铸铁与钢盘对磨时的干摩擦学性能。结果表明，钒的加入降低了蠕墨铣的的磨损量，提高了接触压力和摩擦速度变化时磨损量的稳定性。含钒０．１％和０．３％时，提高了摩擦系数和高接触压力，高摩擦速度下降摩擦系数稳定性。     

Friction Surfaces and Wear Products of Sn–Sb–Cu-Based Composite Materials

The structure and the tribological properties of the composite materials based on an Sn–Sb–Cu alloy (B83 babbit) and fabricated by hot pressing of powders are studied under dry sliding friction conditions. Modified schungite and silicon carbide are chosen as reinforcing materials. The composite material fabricated by a powder technology and reinforced by silicon carbide and modified schungite particles is found to have the doubled wear resistance as compared to a cast B83 alloy at a comparable friction coefficient.     

Influence of deposition parameters of the Ti-Al-N/Zr-Nb-N-Cr-N multilayered nanostructured coating obtained by the arc-PVD method on their physicomechanical, tribological, and operational properties

Physicomechanical, tribological, and operational properties of the Ti-Al-N/Zr-Nb-N-Cr-N multilayered coatings obtained by the arc-PVD method are investigated. Dependences between the controlled deposition parameters (the bias potential across the substrate and the revolution rate of the sample relative to sputtered cathodes) and the characteristics of the coatings having hardness up to 37 GPa and adhesion strength of over 100 N are established. Comparative investigations into the tribological properties of multilayered coatings of various compositions showed that the developed coatings are characteristic of the lowest friction factor. A cutting tool with such coatings possesses high resistance properties in conditions of the interrupted and continuous cutting of gray cast iron (SCh30) and steels (St. 45, X18H10T).     

颗粒尺寸对真空浸渗SiC/Al复合材料性能的影响

采用无压浸渗法制备了SiC/Al复合材料,考察了复合材料中SiC颗粒尺寸对复合材料的组织结构、抗弯强度、摩擦磨损性能的影响.结果表明:随着SiC颗粒尺寸的减小,SiC/Al复合材料的残余气孔率逐渐减小,密度和抗弯强度逐渐增加;粒度配比有利于提高复合材料的抗弯强度.与灰铸铁配副时,材料的摩擦系数与磨损率明显依赖于碳化硅颗粒尺寸,二者均随颗粒尺寸的增大而先降低后增大.粒度配比能明显改善复合材料的干摩擦磨损性能.粗细颗粒的粒度配比具有相互强化的作用,有利于降低摩擦系数和磨损率,并使其趋于稳定.     

高铬白口铸铁低速重载条件下的干滑动摩擦磨损特性

研究了不同类型碳化物和不同基体组织的高铬白口铸铁在低速（滑动速度为0.4187～1.0467m/s），重载（接触应力为1～21MPa）条件下与淬火40Cr钢（硬度HRC51～53）配副的干滑动摩擦磨损特性，结果表明，在（Fe,Cr)7C3、（Fe,Cr）3C和（Fe,Cr）33C63种碳化物中，（Fe,Cr）7C3有利于提高高铬白口铸铁的耐磨性，（Fe,Cr）3C有利于降低摩擦系数，共析组织，奥氏体和马氏体3种基体相比，共析组织基体使合金具有较高的摩擦系数，而奥氏体基体合金的耐磨性最好，存在一个临界摩擦应力，当摩擦应力大于此值时，磨损率急剧上升。     

Tribological properties of centrifugally cast copper alloy-graphite particle composite

Centrifugal casting technique was used to impart better tribological properties to the inner periphery of centrifugal castings of a C90300 copper alloy originally containing 13 vol pct graphite particles. Microstructural observation of centrifugally cast copper alloy containing graphite particles shows that a graphite-free zone and a graphite-rich zone (25 vol pct) with a unique microstructure are formed near the outer and the inner periphery of the centrifugally cast cylinders, respectively. Wear tests were conducted using a pin-on-disc apparatus running against a cast-iron counterface under dry conditions at applied loads between 44.5 and 267 N and at a sliding speed of 1 m/s. The worn surfaces of pin and counterface were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. The wear rate (1.89×10⁻¹³ to 7.59 × 10⁻¹³ m³/m) and the temperature (50 °C to 170 °C) at the counterface for the pins from the graphite-rich zone of the centrifugal castings were found to be lower than the friction coefficient (0.52 to 0.75), the wear rate (6.32×10⁻¹² to 3.16 × 10⁻¹¹ m³/m), and the temperature (70 °C to 200 °C) at the counterface for the pins from the graphite-free zone (of the same centrifugal casting under similar conditions). A greater transfer of the copper phases from the pin to the cast-iron counterface was observed visually from the pin of the graphite-free zone than from the pin of the graphite-rich zone, which was also confirmed by EDX analysis. This leads to an increase in the weight of the counterface running against the pin from the graphite-free zone with an increase in the applied load. Despite the presence of graphite in cast iron, the presence of graphite in the matrix of mating copper alloys lead to improved tribological properties. The effect of graphite particles on tribological properties of the composites was discussed in terms of the transfer of iron and copper phases, the interparticle distance between graphite in cast-iron and copper-graphite alloys, and the deformability of the matrix containing graphite.     

Effect of Sintering Temperature on Microstructure and Mechanical and Bearing Properties of Iron Containig 15% Tribaloy

Abstract

Tribaloy particles with a microstructure of a hard Laves phase in ductile cobalt or nickel matrix can be incorporated in bronze and steel materials by powder metallurgical methods. The Tribaloy content and the compacting and sintering conditions determine the microstructure and the mechanical and tribological properties of these materials. In this investigation the influence of the sintering temperature on the properties of Fe–Tribaloy mixtures was studied. Higher sintering temperature improves the bonding between Tribaloy particles and iron matrix; however, it decreases the heterogeneity of the composite which is necessary for optimum performance under conditions of dry or mixed friction. The best bearing materials are produced at intermediate sintering temperatures where a compromise between mechanical strength and tribological performance can be achieved. PM/0180     

Sliding Wear Characteristics of Friction Stir Processed CAST ZK60 Magnesium Alloy Under Different Applied Loads

Wear resistance and poor friction are the two main draw backs of magnesium alloys that restricts structural applications. Therefore it is essential to enhance the tribological properties of magnesium alloys with the help of surface engineering without causing significant antagonistic effects on the properties of the base metal. Friction stir processing (FSP) is one of the promising thermo-mechanical processing techniques that alters the micro-structural and tribological properties of the material with low production at less period of time. Hence, this investigation enable us to study an effect of friction stir processing on wear characteristics of cast ZK60 magnesium alloy. A pin-on-disc wear testing machine was used to evaluate the wear resistance of surface modified ZK60 magnesium alloy. The result shows that the surface modification by FSP resulted in 26% increase in hardness compared to parent metal. The formation of finer grains and subsequent increase in hardness are the main reasons to improve wear resistance of FSPed ZK60 magnesium alloy.     

The Properties and Performance of Cast Iron Grinding Media

Cast iron balls have been used for decades as a grinding media in all types of grinding applications. Early applications of cast iron grinding balls in mineral processing operations were disastrous due to spalling and premature breakage. Better control and understanding of a high chromium cast iron metallurgical system have led to the use of high chromium cast iron balls in all types of grinding. This paper reviews the wear properties of cast iron grinding media materials during dry and wet grinding conditions. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed, giving special importance to the corrosion and abrasion properties of cast iron media materials.