Oxidization resistance of Ni76Cr19AITi valve alloy at temperatures under operating mode of heavy-duty engines

The oxidization resistance of the Ni76Cr19A1Ti alloy was studied by a static oxidization experiment at 600-800℃. The results show that the oxidation behavior of the alloy can be explained by a kinetic equation： （△m/S）2 = Kpt ＋ C, where Kp is a kinetic constant of the nickel-base alloy. The higher the experimental temperature, the higher the value of Kp. It is discovered that the microstructure of the oxide scales is compact and the thickness of it is less than 10 μm The oxidization of the alloy is in the first grade. It is also found that the oxide scales are mainly composed of Cr2O3 and TiO2. Chrome and titanium react more easily with oxygen at temperatures under the operating mode.     

Oxidization resistance of Ni76Cr19AlTi valve alloy at temperatures under operating mode of heavy-duty engines

1. Introduction Wear can lead to failure of engine valves. The oxidization resistance of valve alloys has a direct ef-fect on its wear resistance [1-5]. Thin and compact oxide scales can avoid direct contact of the valve al-loy with the valve seat alloy. On the contrary, thick and porous oxide scales can accelerate wear of en-gine valves. Therefore it is necessary to study the oxidization resistance of the valve alloy at tempera-tures under operating mode. Ni76Cr19AlTi is a nickel-based allo…     

充填钻孔内管道磨损机理及易破损位置的确定

充填钻孔是充填法矿山的关键工程之一,容易受到充填料浆的冲击而造成破损。金川公司数字化钻孔电视观测结果表明,充填钻孔存在一个严重破损区域,该区域位于充填钻孔内空气和料浆的接触面上。充填料浆自由降落,具有较高的末期下落速度,而以较高的动量和冲量冲击充填钻孔的内套管管壁。因此,充填钻孔的严重磨损深度,即空气与料浆的接触面高度,可以根据充填钻孔的高度、水平管道的长度、浆体的密度和水力坡度进行估算。实例研究结果表明,该估算方法具有足够的精度,有利于充填钻孔的日常管理和维护。     

制备工艺对铁基粉末冶金气门座圈致密性和性能的影响

采用烧结、熔渗、热处理制备了高性能铁基粉末冶金气门座圈。研究不同工艺对气门座圈的孔隙变化、致密性、显微组织和力学性能的影响,确定气门座圈致密性的最佳工艺条件。结果表明：采用熔渗或提高烧结温度,可使孔隙的形状趋于球化,大大减少孔隙的数量和大小,明显提高气门座圈的致密性。获得气门座圈理想致密性的最佳工艺条件：均匀压入14%~15%（质量分数）的熔渗薄铜片,在1150 ℃下熔渗烧结2 h,然后进行620 ℃高温回火;回火后可得到大量综合性能良好的回火索氏体,明显提高了气门座圈的综合性能     

中锰高碳钢的冲击磨损性能及磨损机制

采用场发射扫描电镜(SEM)、MLD-10冲击实验机和硬度实验机等检测手段,对不同处理制度条件下的中锰高碳钢在中低冲击载荷条件下的耐磨性能与其磨损机制进行了研究。结果表明:低冲击载荷条件下,热轧态中锰高碳钢具有最优异的冲击磨损性能,远高于冷轧态与其他热处理制度下的中锰高碳钢,其磨损机制为剥削磨损与凿削磨损;在中等冲击载荷条件下,450℃保温15 min样品的冲击磨损性能最优越,且磨损机制为剥削磨损、凿削磨损与塑性变形。     

Tribological property and wear mechanism of undercooled Ni-Pb monotectic alloys

1　INTRODUCTIONMonotecticalloyshaveperfectphysicalandchemicalpropertiesandcanbeusedasself lubricatingmaterials ,electricalcontactmaterials ,superconductingmaterialsetc[13] .However ,itisverydifficulttofabricatemono tecticalloyswithhomogeneousstructuresbyemployingconventionalcasting ,becausetheparentliquiddecompos esquicklyintotwodistinctimmiscibleliquidsintheim miscibilitygap[4 6 ] .Theproblemhasdelayedtheutiliza tionofmonotecticalloysasindustrialmaterialsandsys tematicresearchonthesolidif…     

Wear mechanism of electrodeposited amorphous Ni-Fe-P alloys

1　INTRODUCTIONAmorphousalloysarecharacterizedbyhighwearandcorrosionresistance ,togetherwithmanyspecificphysicalproperties[1,2 ] .Theyhavebeenusedasfunc tionalmaterialsinmanyfieldsextensively .Theamor phousNi Palloyhasbeenappliedtoautomobile[3] ,aircraft,computer ,electronics ,food processing ,petroleum ,andsoon[4 ] .Electrodepositionorelectrolessplatingisoneofthemostsimple ,convenientandeconomicmethodstoobtainvariousamorphousalloys .Themostattractiveamorphousalloysconsistoftheelementsof…     

不同基体炭结构的C/C复合材料摩擦表面特性和摩擦磨损机理

与表面镀Cr的40Cr钢配副进行滑动摩擦实验后,在JSM 6360LV扫描电镜上观察6种具有不同基体炭结构的C/C复合材料的磨损表面形貌。结果表明:完全光滑层(SL)炭结构的C/C复合材料摩擦表面在任何载荷下均难以形成完整的磨屑膜;完全粗糙层(RL)炭结构、粗糙层/树脂炭(RL/RC)的材料摩擦表面在低载荷时能形成较厚的磨屑膜,在高载荷时表面摩擦膜均很薄;完全RC结构试样摩擦表面在低载荷时完整、致密,在高载荷时有显著的磨屑膜剥落;RL/SL/RC、SL/RC结构试样在低载荷时的表面摩擦膜薄,而高载荷时,RL/SL/RC材料的基体炭磨损比SL/RC的严重;RL/SL或SL炭在摩擦中的损伤呈现阶梯状磨损形貌,RL炭在摩擦后难以分辨出原始形貌,RC炭在部分摩擦表面则为条纹状磨损形貌;RL/SL/RC、SL/RC结构的C/C复合材料摩擦形貌的稳定性高,材料耐磨性好,在一定载荷范围内有利于降低材料的摩擦因数和体积磨损。     

Erosion wear behaviour and mechanism of abradable seal coating

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｌｅａｒａｎｃｅｂｅｔｗｅｅｎｔｈｅｒｏｔａｔｉｎｇｂｌａｄｅｓａｎｄｔｈｅｃａｓｉｎｇｓｈｏｕｌｄｂｅａｓｓｍａｌｌａｓｐｏｓｓｉｂｌｅｉｎｏｒｄｅｒｔｏｉｎｃｒｅａｓｅｔｈｅｅｆｆｉｃｉｅｎｃｙａｎｄｒｅｄｕｃｅｔｈ     

气门电热镦粗工艺的数值模拟

综合运用ANSYS和DEFORM软件对气门电热镦粗工艺的电镦加热过程和电镦变形过程进行了模拟 ,获得了整个电热镦粗过程的加热与变形的详细信息及分布规律 ,提出了消除缺陷的措施 ,为优化工艺参数提供了较为严密的理论依据。     

Tribological behavior and wear mechanism of resin-matrix contact strip against copper with electrical current

The resin-matrix pantograph contact strip （RMPCS）, which has excellent abrasion resistance with electrical current and friction-reducing function, was developed in view of the traditional contact strips with high maintenance cost, high wear rate with electrical current and severe damage to the copper conducting wire. The characteristics of worn surfaces, cross-section and typical elemental distributions of RMPCS were studied by scanning electron microscopy （SEM） and energy dispersion spectrometry （EDS）. The wear behavior and arc discharge of RMPCS against copper were investigated with self-made electrical wear tester. The results show that the electrical current plays a critical role in determining the wear behavior, and the wear rate of the RMPCS against copper with electrical current is 2.7-5.8 times higher than the value without electrical current. The wear rate of the contact strip increases with the increase of the sliding speed and electrical current density. The main wear mechanism of RMPCS against copper without electrical current is low stress grain abrasive and slightly adhesive wear, while arc erosion wear and oxidation wear are the dominate mechanism with electrical current, which is accompanied by adhesive wear during the process of wear.     

Tool wear mechanism in turning of novel wear-resisting aluminum bronze

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌｕｍｉｎｕｍｂｒｏｎｚｅｉｓａｎｉｍｐｏｒｔａｎｔｅｎｇｉｎｅｅｒｉｎｇｍａｔｅｒｉ ａｌｄｕｅｔｏｉｔｓｅｘｃｅｌｌｅｎｔｐｈｙｓｉｃａｌ ,ｍｅｃｈａｎｉｃａｌ,ａｎｔｉ ｃｏｒｒｏ ｓｉｏｎａｎｄｗｅａｒｒｅｓｉｓｔｉｎｇｐｒｏｐｅｒｔｉｅｓ .Ｏｕｒｒｅｓｅａｒｃｈｇｒｏｕｐｄｅ ｖｅｌｏｐｅｄａｓｐｅｃｉａｌｔｙｐｅｏｆｈｉｇｈｓｔｒｅｎｇｔｈ ,ｗｅａｒ ｒｅｓｉｓｔｉｎｇａ ｌｕｍｉｎｕｍｂｒｏｎｚｅ(ＫＫ ) ,ｗｈｉｃｈｉｓｅｘｃｅｐｔｉｏｎａｌｌｙｇｏｏｄｆｏｒ…     

Study on wear mechanism of CVD diamond graver for stone machining

This paper presents a new kind of CVD diamond machining object, we studied influence of cutting speed, feed variance analysis and regression analysis. The result indicated on tool life; feed rate ranked the second; depth of cut had graver for stone machining. Taking granite as rate and depth of cut on tool life by means of that cutting speed had a more remarkable effect no significant influence on tool life. Scanning electron microscope （SEM） was used to observe wear morphologies of gravers. It was found that abrasive wear was the main wear mechanism     

AuNiCu合金摩擦磨损的分子动力学模拟

通过分子动力学模拟的方法，研究了Au-7.5Ni-xCu合金的摩擦磨损性能。首先采用粗糙体-平面接触模型和Atomsk软件构造合金模型；再由lammps软件计算出合金的摩擦力、摩擦系数判断出合金的摩擦学特性；最后通过Ovito软件对摩擦磨损过程进行可视化分析，包括摩擦磨损过程中组织结构和位错的演变，磨损表面原子的堆积情况等。结果表明，合金摩擦系数随着Cu含量的增加而呈现上升趋势，磨损后基体表明呈“U”形堆积，当Cu含量为10%时，基体抗变形能力最强；磨损过程中观察到晶粒的分裂和合并现象，合金基体内部位错密度明显增加。     

离心铸造高铬合金铸铁气门座圈的组织及耐磨性能研究

采用离心铸造制备两种高铬合金铸铁气门座圈.利用X射线衍射仪(XRD)、金相显微镜、洛氏硬度计和扫描电镜(SEM),对气门座圈铸态及热处理态后的试样物相组成、金相组织、力学性能及拉伸断口形貌进行了观察和分析,同时在销盘式摩擦磨损试验机上对高铬合金铸铁气门座圈的耐磨性能进行了磨损试验.结果表明,热处理前高铬合金铸铁主要为由...     

Fe－B－C合金冲击磨料磨损性能及磨损机制的研究

以高铬铸铁为对比材料,采用MLD-10型冲击磨料磨损试验机,研究了Fe—B—C合金冲击磨料磨损性能：借助子扫描电镜,探讨了Fe—B—C合金的磨损机制。结果表明：Fe—B—C合金的硬度和冲击韧度与高铬铸铁相当,耐磨性能达到高铬铸铁水平,具有良好的性价比;Fe—B—C合金的磨损机制是以微观切削为主,同时存在微观断裂和微观犁沟的混合磨损。     

汽车发动机缸体用AZ91合金的表面改性与耐磨耐蚀性能

对汽车发动机缸体用AZ91合金表面进行了等离子熔覆改性处理,对比分析了AZ91合金基体、TiB2-Al2O3和三种不同比例的Al:(TiB2-Al2O3)改性层的显微组织和物相组成,并对改性层的硬度、耐磨性和耐腐蚀性能进行了研究。结果表明,随着距离改性层表面距离的增加,显微硬度整体呈逐渐降低的趋势,不同配比的改性层的显微硬度都高于AZ91合金基体(98 HV0.1),TiB2-Al2O3改性层的显微硬度最高,随着熔覆材料中Al含量的增加,改性层显微硬度呈现逐渐降低的趋势;经过等离子熔覆TiB2-Al2O3和Al:(TiB2-Al2O3) 改性处理后的发动机缸体的耐磨性与耐腐蚀性均有所提高,其中Al:(TiB2-Al2O3)=1:2改性层的耐磨性及耐腐蚀性能最好。     

基于数值模拟的堆焊模具耐磨性分析

采用Archard磨损模型,和有限元软件DEFORM-3D分析了不同回火温度下中间轴堆焊模具的磨损量。结果表明,材料的耐磨性并不与硬度成正比,当回火温度为500℃时,堆焊模具的耐磨性最好,磨损深度最小为9.98×10-5mm。     

W6Mo5Cr4V2铸钢气门阀座的真空热处理

观察和测试了铸钢W6Mo5Cr4V2气门阀座试样真空淬火和三次回火后的组织和硬度。结果表明,气门阀座试样经上述热处理后,组织为回火隐针马氏体+极少量残留奥氏体+断续网状分布的共晶碳化物+弥散析出的二次碳化物;显微组织较均匀,硬度52.0～54.0 HRC,畸变量可控制在要求范围内,满足技术要求。     

高硅铝合金及其原位复合材料干滑动磨损性能与机制

采用熔体反应法制备了(Al2O3 Al3Zr)p/Al-22%Si原位复合材料。探讨了高硅铝合金及其原位复合材料的干滑动磨损行为,并对其磨损表面和亚表面形貌进行了观察和分析。试验结果表明:复合材料的磨损量显著低于同条件下高硅铝合金的磨损量,且随颗粒体积分数的增大,复合材料的磨损量减小。磨损表面亚表面的SEM观察分析表明:高硅铝合金磨损表面存在与亚表面相连的撕裂纹和宽大的犁沟,其磨损机制为粘着磨损加磨粒磨损的混合型磨损;复合材料的磨损表面亚表面平整光滑,主要表现为磨粒磨损。