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将3种不同直径的氮化硅球坯采用循环加工方法研磨成G5级轴承用陶瓷球。研究了研磨过程中陶瓷球的磨损行为并将磨损缺陷按光学显微镜下的形貌分成5类。采用扫描电子显微镜观察分析各种缺陷并用陶瓷材料断裂力学解释凹坑与裂纹缺陷的形成。研究结果表明,异常的磨粒作为尖锐压头产生凹坑。各种裂纹主要是由起钝压头作用的上研磨盘产生的。材料的晶体结构变化产生雪花缺陷,雪花缺陷抵抗磨粒磨损的能力较差。精研过程中不正确的加工压力和没有破碎的硬磨粒产生擦伤和划痕缺陷。提高球坯圆度,降低粗研加工的载荷和速度可以减少裂纹缺陷。提高磨粒质量可以减少精研中各种机械加工缺陷。 相似文献
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利用有限元软件LS-DYNA建立了单颗磨粒旋转冲击玻璃工件的模型,计算模拟出工件受冲击的材料去除过程,分析了材料去除机理。模拟结果表明:冲击瞬间,裂纹交汇,接触区材料大片剥落;冲击过程中,工件表面裂纹开叉扩展,内部裂纹发展成亚表面层裂,磨粒持续压溃材料;切削力小,随着切削深度的增加,切削力变大。利用有限元软件LSDYNA对金刚石磨粒冲击玻璃材料的过程进行数值模拟,计算冲击过程的形变和切削力,研究工件表面和内部裂纹的产生与扩展过程,分析材料去除机理。 相似文献
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在高速磨削中,磨粒高速冲击表层材料,在热力强场作用下表层材料产生的动态行为激变是高速磨削的一个重要特征。本文通过对高速磨削力场、温度场和绝热剪切、准流动相冲击成屑、材料本构关系、微裂纹扩展等高速磨削材料变化行为机理进行深入探讨,得出以下结论:在高速磨削过程中,材料的动态变化行为不同于普通磨削,需要基于对高速磨削热力强场作用的研究,揭示材料动态行为变化机制;需要对高速磨削过程中磨粒、磨屑和材料表层的热量分配比和温度场变化进行深入研究,以解释磨削温度在砂轮线速度超过某一临界值后开始下降的原因;需要深入研究高速磨削热力强场作用下塑性材料的微裂纹扩展机制,揭示塑性材料的塑脆转变行为。 相似文献
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氮化硅陶瓷球研磨去除机制试验与仿真研究 总被引:1,自引:0,他引:1
为研究研磨过程中氮化硅陶瓷球的材料去除形式及磨损行为,结合陶瓷材料动态压痕断裂力学理论,进行陶瓷球研磨加工试验,采用超景深三维显微镜和扫描电镜对研磨后陶瓷球表面进行观察,同时建立单颗金刚石磨粒冲击作用有限元模型并进行仿真研究。试验结果表明:氮化硅陶瓷球表面材料去除以脆性断裂去除和粉末化去除为主,陶瓷球表面残留有大量贝壳状缺陷和呈簇状随机分布的粉末化材料区域;研磨过程中,陶瓷球表面存在擦伤、划伤和凹坑等缺陷;磨粒冲击作用时,表面材料会受微切削作用产生破碎去除,同时也会受挤压作用产生脆性断裂去除,当磨粒以滚动方式作用在陶瓷球表面时,陶瓷球表面更容易形成粉末化去除,且材料去除率更高。仿真结果表明:各磨粒冲击作用方式产生的最大等效应力由大到小的顺序为滚动磨粒变切深、滚动磨粒定切深、磨粒挤压、滑动磨粒定切深,其中,滚动磨粒变切深产生的亚表面裂纹最深。 相似文献
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利用低温环境轮轨磨损模拟试验装置,研究了高速铁路车轮材料在室温及低温环境下的滚动接触疲劳损伤行为。结果表明:低湿度的低温环境导致车轮材料磨损率、塑性变形及疲劳损伤较室温下明显加重。随试验温度的降低,轮轨摩擦因数、磨损率及表面硬度均呈现先急剧上升后轻微下降趋势。室温工况下磨痕表面有严重的犁沟现象,而低温工况下车轮试样表面以疲劳裂纹及剥落损伤为主。随着温度的降低,磨损形式由氧化磨损、磨粒磨损逐渐向疲劳及粘着磨损转变。车轮材料裂纹主要沿较软的铁素体线扩展,室温下剖面损伤较轻微。低温工况下由于车轮材料发生脆化,珠光体呈现不同于室温下的形貌及分布特性。在低温下,表层裂纹扩展角度及次表层裂纹长度增加,同时表层裂纹易于汇合并产生分支。 相似文献
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《Wear》1986,108(4):385-399
The abrasion of nearly brittle materials can be considered as a multipoint scratching and indenting process. Knowledge of flow morphologies around the abrasive protuberances, the determination of the energy dissipated during single-contact scratching experiments and the estimation of the forces acting on the abrasive particles are therefore essential for a better understanding of the wear and finishing processes based on abrasion phenomena.Experiments using linear and pendular sclerometers were conducted on various materials such as glass, ceramics, metals and polymers. The results described in the present paper show the effects of the geometry, the speed and the rheology on the abrasive process. The forces induced and the morphologies of the scratches are studied. The behaviour of the abrasive contact is in particular very nicely described by a critical transition from ductile to brittle abrasion which is analysed in detail for soda-lime glass. This transition is itself correlated with the dynamic hardness and the dynamic toughness of the tested materials. The results have a bearing on the prediction of the behaviour of nearly brittle materials when used as bulk materials or surface coatings in tribological applications dealing with abrasive wear. 相似文献
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前混合磨料水射流切割脆性材料研究 总被引:3,自引:0,他引:3
提出在有防爆要求的场合下,利用前混合磨料水射流冷切割技术对混凝土等脆性材料进行切割.对脆性材料的切割机制进行研究,建立切割冲蚀模型,分析受冲击区的应力.对混凝土试块进行切割实验,并对分析同切割深度的不同形态所产生的因为.研究表明:在切割初始阶段,高速磨料以较小角度冲击、磨削材料,形成较光滑的切割磨削区;随切深的增加,材料在磨料粒子大角度冲击下形成斜条纹状的变形磨削区.前混合磨料水射流对混凝土等建筑脆性材料具有良好的切割效果,在易燃易爆等应急场合进行切割作业具有独特优势. 相似文献
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Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods 总被引:3,自引:0,他引:3
The aim of the present study is to evaluate the abrasive wear resistance of some potential abrasion resistant steels exposed to different types of abrasive wear contact conditions typical of mining and transportation applications. The steels investigated, include a ferritic stainless steel, a medium alloyed ferritic carbon steel and a medium alloyed martensitic carbon steel.The abrasive wear resistance of the steels was evaluated using two different laboratory test methods, i.e. pin-on-disc testing and paddle wear testing that expose the materials to sliding abrasion and impact abrasion, respectively. All tests were performed under dry conditions in air at room temperature. In order to evaluate the tribological response of the different steels post-test characterization of the worn surfaces were performed using optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Besides, characterization of the wear induced sub-surface microstructure was performed using optical microscopy.The results show that depending on the abrasive conditions a combination of high hardness and toughness (fracture strain) is of importance in order to obtain a high wear resistance. In the pin-on-disc test (i.e. in sliding abrasion) these properties seem to be controlled by the as-rolled microstructure of the steels although a thin triboinduced sub-surface layer (5–10 μm in thickness) may influence the results. In contrast, in the paddle wear test (i.e. in impact abrasion), resulting in higher forces acting perpendicular to the surface by impacting stones, these properties are definitely controlled by the properties of the active sub-surface layer which also contains small imbedded stone fragments. 相似文献
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I.M. Hlavacova V. Geryk 《The International Journal of Advanced Manufacturing Technology》2017,90(5-8):1217-1224
The paper discusses abrasive water-jet cutting of hard-to-cut materials represented by high carbon steel DIN norm No.1.2436 (CSN EN 19437) plate 61–mm-thick and high-strength concrete cube sized 150 mm. Four relatively hard minerals with different densities not commonly used in water-jet technology were tested and their cutting results compared to those of three types of almandine garnets: Ukraine, Australian, and sorted Australian. Cutting efficiency was evaluated utilizing declination angle. Dependence of cutting efficiency on abrasive density and hardness was investigated. High density of abrasive appeared to be disadvantageous in our experiment. Cutting efficiency dependence on hardness exhibited nearly linear course, the increase was much more significant for concrete than for steel. Evaluation of experimental results led to the conclusion that cutting mechanism in case of very thick samples is different from common abrasive waterjet cutting. The limit declination angle for thick samples is significantly smaller, it was found to be approximately 22°. This result represents entirely new finding. The most promising finding from the economical point of view appears to be behavior of corundum, when cutting concrete. Our experimental results promise 20 % increase in cutting speed for brittle materials. 相似文献
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爆炸硬化处理对高锰钢冲击磨损性能影响的研究 总被引:1,自引:0,他引:1
对Mn13Cr2高锰钢进行了爆炸硬化处理。并分别以玻璃砂、鹅卵石为磨料,在MLD.10动载磨料磨损试验机上对比研究了爆炸前、后Mn13Cr2高锰钢的冲击磨损性能。实验结果表明:在低硬度磨料(玻璃砂)冲击磨损时,爆炸硬化使高锰钢的冲击耐磨性提高20%-40%。在高硬度磨料(鹅卵石)冲击磨损时,在冲击功小于1.7J的条件下,爆炸硬化使高锰钢的冲击耐磨性提高30—50%。在冲击功大予1.7J的条件下,爆炸硬化则使高锰钢的冲击耐磨性降低。爆炸硬化使高锰钢表层硬化和冲击韧性降低是冲击耐磨性发生变化的主要原因。在冲击磨损条件下,爆炸硬化前、后高锰钢磨损面均出现磨料嵌入物及犁沟、凿削坑和剥落坑等形貌特征。爆炸硬化高锰钢适用予低硬度磨料的冲击磨损及高硬度磨料的低冲击功冲击磨损的工况条件。 相似文献
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This paper presents an attempt to model the abrasive waterjet (AWJ) turning process considering material removal from the circumference of a rotating cylindrical specimen. The methodology involves the use of Finnie's theory of erosion to estimate the volume of material removed by the impacting abrasive particles. The proposed model considers the impact of jet at an angle to the workpiece surface to account for the curvature of the workpiece. Unlike earlier works, this model considers the continuous change in local impact angle caused by the change in workpiece diameter. The flow stress of the workpiece material is determined using a novel experiment involving the same abrasive and workpiece materials. The adequacy of the proposed model is examined through AWJ turning tests under various process parameter combinations. The final diameters predicted by the model are found to be in good agreement with the experimental results. 相似文献
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Edge failure as a means of concurrently estimating the abrasion and edge fracture resistance of hard-metals 总被引:1,自引:0,他引:1
Fracture toughness is often the major limiting parameter governing the use of tools manufactured from hard materials and there is a need for research aimed at increasing toughness without sacrificing good wear resistance. To aid in this objective, a simple and reliable integrated testing method is needed in which a combined action involving both fracture and abrasion occurs. One such method currently developed is presented in this paper. The method is based on the concept of edge chipping during the initial transition stage of abrasion wear, which is controlled by a brittle fracture process. The limitation of the method for tougher materials, such as tool steel, as well as for very brittle materials such as ceramics is also indicated. The empirical relationship between mass loss as a result of edge chipping during the initial transitional stage of abrasive wear and fracture toughness is presented in the form of formulae. 相似文献
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通过对硬脆材料 (玻璃 )的切削试验 ,建立了硬脆材料的磨削模型 ,讨论了硬脆材料在磨粒作用下的塑性变形和断裂行为 相似文献
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采用往复磨损实验机完成了Zr-4合金/Al2O3摩擦副在Na2SO4溶液中的腐蚀磨损实验。试验在改变负荷及试样的阳极/阴极面积比时,对腐蚀磨损的影响作了分析。用三坐标表面粗糙度仪测量了磨损体积,利用脉冲电位评价磨损产生的新生面与磨损表面的关系。结果表明:随着负荷的增加,自然电位下降而磨损量成正比例增加。电化学腐蚀作用随试样阳极/阴极的面积比的减小而增大。磨损面损伤的主要表现为磨粒磨损和粘着磨损的共同作用。 相似文献