White Layer of Hard Turned Surface by Sharp CBN Tool

White layers in hard turned surfaces were identified and measured as a function of turning parameters based on the Taguchi method. It reveals that white layers generate on the machine surface in the absence of tool flank wear, and white layer depth varies with the different combinations of hard turning parameters. Turning speed has the most important impact on white layer depth, feed rate follows, and cutting depth at last. The white layer generation consequently suggests a strong couple relation to the heat generation and thermal process of hard turning operation. White layer disappears under an optimal combination of turning parameters by Taguchi method. It suggests that a superior surface integrity without white layer is feasible under some selected combinations of turning parameters by a sharp CBN cutting tool.

Flexible white top-emitting organic light-emitting diode with a MoO_x roughness improvement layer

In this paper, an MoOx film is deposited on a polyethylene terephthalate （PET） substrate as a buffer layer to improve the surface roughness of the flexible PET substrate. With an optimized MoOx thickness of 100 nm, the surface roughness of the PET substrate can be reduced to a very small value of 0.273 nm （much less than 0.585 nm of the pure PET）. Flexible white top-emitting organic light-emitting diodes （TEOLEDs） with red and blue dual phosphorescent emitting layers are constructed based on a low-reflectivity Sm/Ag semi-transparent cathode. The flexible white emission exhibits the best luminance and current injection characteristics with the 100-nm-thick MoOx buffer layer and this result indicates that a smooth substrate is beneficial to the enhancement of device electrical and electroluminescence performances. However, the white TEOLED with a 50-nm-thick MoOx buffer layer exhibits a maximum current efficiency of 4.64 cd/A and a power efficiency of 1.9 lm/W, slightly higher than those with a 100-nm MoOx buffer layer, which is mainly due to an obvious intensity enhancement but limited current increases in 50-nm MoOx-based white TEOLED. The change amplitudes of the Commission International de l’Eclairage （CIE） chromaticity coordinates are less than （0.016, 0.005） for all devices in a wide luminance range over 100 cd/m2, indicating an excellent color stability in our white flexible TEOLEDs. Additionally, the flexible white TEOLED with an MoOx buffer layer shows excellent flexibility to withstand more than 500 bending times under a curvature radius of approximately 9 mm. Research demonstrates that it is mainly attributed to the high surface energy of the MoOx buffer layer, which is conducible to the improvement of the surface adhesion to the PET substrate and the Ag anode.

Enhancement of Frster energy transfer from thermally activated delayed fluorophores layer to ultrathin phosphor layer for high color stability in non-doped hybrid white organic light-emitting devices

Fluorescence/phosphorescence hybrid white organic light-emitting devices（WOLEDs） based on double emitting layers（EMLs） with high color stability are fabricated.The simplified EMLs consist of a non-doped blue thermally activated delayed fluorescence（TADF） layer using 9,9-dimethyl-9,10-dihydroacridine-diphenylsulfone（DMAC-DPS） and an ultrathin non-doped yellow phosphorescence layer employing bis[2-（4-tertbutylphenyl）benzothiazolato-N,C2＇]iridium（acetylacetonate）（（tbt）_2Ir（acac））.Two kinds of materials of 4,7-diphenyl-1,10-phenanthroline（Bphen） and 1,3,5-tris（2-Nphenylbenzimidazolyl） benzene（TPBi） are selected as the electron transporting layer（ETL）,and the thickness of yellow EML is adjusted to optimize device performance.The device based on a 0.3-nm-thick yellow EML and Bphen exhibits high color stability with a slight Commission International de l＇Eclairage（CIE） coordinates variation of（0.017,0.009） at a luminance ranging from 52 cd/m^2 to 6998 cd/m^2.The TPBi-based device yields a high efficiency with a maximum external quantum efficiency（EQE）,current efficiency,and power efficiency of 10%,21.1 cd/A,and 21.3 lm/W,respectively.The ultrathin yellow EML suppresses hole trapping and short-radius Dexter energy transfer,so that Forster energy transfer（FRET）from DMAC-DPS to（tbt）_2Ir（acac） is dominant,which is beneficial to keep the color stable.The employment of TPBi with higher triplet excited state effectively alleviates the triplet exciton quenching by ETL to improve device efficiency.

水泥路面加铺Superlayer磨耗层应用技术浅析

水泥混凝土路面在行车荷载和环境因素的综合作用下,会出现不同程度的路面问题,影响道路行车安全与舒适性,通常需要采用"白改黑"技术对水泥混凝土路面进行提升改进。水泥路面加铺超薄磨耗层,具有节省材料与能源、施工速度快、路面改造效果好等特点。本文通过水泥路面加铺Superlayer磨耗层(超薄罩面)的应用实践,选取结构良好的水泥混凝土道路,对Superlayer磨耗层应用于水泥路面表面功能层的实施过程、技术特点进行总结,实践表明Superlayer磨耗层应用于城市道路提升改造效果良好,实践经验可为城市水泥路面提升改造提供经验参考。

White Organic Light-emitting Diodes with A Sr_2SiO_4:Eu^(3+) Color Conversion Layer

Abstract:Hybrid inorganic/organic white organic light emitting diodes(hybrid-WOLEDs)are fabricated by combi-ning the blue phosphorescent organic light emitting diodes(PHOLEDs)with red Sr2SiO4:Eu3+phosphor spin coatedas a color conversion layer(CCL)over the other side of glass substrate on the devices.The basic configuration of thePHOLEDs consists a host material,N,N'-dicarbazolyl-3,5-benzene(mCP)which doped with a blue phosphorescentiridium complexes iridium(Ⅲ)bis[(4,6-di-fluorophenyl)-pyridinato-N-C2'](FIrpic)to produce high efficient blueorganic light emitting diodes.The hybrid-WOLED shows maximum luminous efficiency of 22.1 cd/A,maximumpower efficiency of 11.26 lm/W,external quantum efficiency of 10.2%and CIE coordinates of(0.32,0.34).Mo-reover,the output spectra and CIE coordinates of the hybrid-WOLED have a small shift in different driving currentdensity,which demonstrate good color stability.

Tandem white organic light-emitting diodes adopting a C_(60) :rubrene charge generation layer

Organic bulk heterojunction fullerence(C60) doped 5, 6, 11, 12-tetraphenylnaphthacene(rubrene) as the high quality charge generation layer(CGL) with high transparency and superior charge generating capability for tandem organic light emitting diodes(OLEDs) is developed. This CGL shows excellent optical transparency about 90%, which can reduce the optical interference effect formed in tandem OLEDs. There is a stable white light emission including 468 nm and 500 nm peaks from the blue emitting layer and 620 nm peak from the red emitting layer in tandem white OLEDs. A high efficiency of about 17.4 cd/A and CIE coordinates of(0.40, 0.35) at 100 cd/m2 and(0.36, 0.34) at 1000 cd/m2 have been demonstrated by employing the developed CGL, respectively.

载荷对D2车轮钢滑动磨损表层微观组织和性能影响

目的研究滑动磨损条件下,载荷变化对D2车轮钢表层微观组织和磨损性能的影响。方法利用MRH-30(环块)滑动摩擦磨损试验机进行滑动磨损试验。使用金相显微镜(OM)、场发射扫描电镜(SEM)、X射线衍射仪(XRD)和场发射透射电镜(TEM)等设备,分析滑动磨损后表层微观组织、表面磨损形貌和硬度变化。结果不同载荷条件下,随着磨损时间的增加,轮轨试样磨损量逐渐增加。200 N载荷条件下,(环状)车轮试样的磨损量大于100 N车轮试样磨损量,但200 N钢轨(块状)试样的磨损量却低于100 N钢轨试样。滑动磨损后,在不同载荷条件下,车轮试样表面主要形成长条状白层和不连续的月牙状白层。在200 N载荷条件下,由于车轮试样的磨损量较高,其白层厚度和表面白层硬度都小于100 N载荷条件下的车轮试样。在200 N载荷条件下,车轮试样表面更易形成不连续的月牙状白层。由于轮轨试样表面存在微凸体,高载荷会加速车轮试样表面局部微凸体发生严重塑性变形,导致月牙状白层的形成。在白层内片状渗碳体发生明显溶解和铁素体晶粒显著细化。结论车轮表面白层对磨损性能有明显影响。滑动磨损过程中,高载荷条件下,月牙状白层和周边微观组织界面易形成裂纹,裂纹会逐渐沿着界面向内部扩展,导致不连续月牙状白层发生剥落,降低车轮试样表面的硬度,加速车轮试样磨损。另一方面,高载荷会加速无白层区域塑性变形,导致其形成棘轮失效,从而加速磨损。

电火花加工对H13钢表面完整性及力学性能的影响

对H13钢进行电火花加工,研究了电火花加工对其微观形貌、物相组成、残余应力、显微硬度和冲击性能的影响。结果表明:电火花加工后H13钢表面出现熔融颗粒、陨石坑、孔洞、微裂纹等缺陷,截面分为白亮层、热影响区、回火区和基体;白亮层中存在柱状晶、柱状树枝晶、等轴晶、共晶组织等,显微组织包括马氏体、残余奥氏体、Fe_(3)C、Fe_(7)C_(3)、(Cr,Fe)_(7)C_(3)、Fe_(0.3)Mn_(2.7)C等相;相比基体,白亮层中的碳元素和残余奥氏体含量增加;电火花加工后H13钢表层的残余应力和显微硬度均高于基体,且随着距表面距离增加,均先增大后减小,最大分别为575 MPa、647.3 HV;电火花加工后H13钢的冲击功比磨削加工后下降了35.56%,冲击断口出现大量撕裂棱,还有韧窝、解理面、大尺寸剥离面,为准解理断裂。

景区公路路面白改黑应用研究

以实际工程为例,探讨了水泥路面直接加铺沥青层方案的设计思路,并针对反射裂缝等问题提出了相应的处治措施,通过理论计算得出沥青加铺层最小厚度,结合实际施工条件提出设计要点。

A Three-layered Contrasting Analysis of the Theme in Once more to the lake

Once more to the lake is a representative work of the American Writer, Elwyn Brooks White, and has been acclaimed by people in the world. The paper offers a three-layered contrasting analysis of the essay. By detailed analysis of the contrasts running through the whole essay, the author finds that those contrasts are symbol of White's internal struggle and reflection for life.On the foundation of the three-layered contrasts, the paper presents the theme analysis and clarifies the content of the essay.

Fabrication of High-power White LEDs and White Light Uniformity Testing

As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated by a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al5O12∶Ce3+(in short: YAG∶Ce3+). The matching of the spectrum of the blue LED chips and the YAG∶Ce3+ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high-power single-chip-white-LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high-power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.

Efficient top-emitting white organic light emitting device with an extremely stable chromaticity and viewing-angle

In this paper,we report on the fabrication of a top-emitting electrophosphorescent p-i-n white organic lightemitting diode on the basis of a low-reflectivity Sm/Ag semi-transparent cathode together with a thickness-optimized ZnS out-coupling layer.With a 24-nm out-coupling layer,the reflectivity of the cathode is reduced to 8% at 492 nm and the mean reflectivity is 24% in the visible area.By introducing an efficient electron blocking layer tris（1phenylpyrazolato,N,C2 ＇）iridium（III）（Ir（ppz） 3） to confine the exciton recombination area,the current efficiency and the colour stability of the device are effectively improved.A white emission with the Ir（ppz） 3 layer exhibits a maximum current efficiency of 9.8 cd/A at 8 V,and the Commission Internationale de L＇Eclairage（CIE） chromaticity coordinates are almost constant during a large voltage change of 6 V-11 V.There is almost no viewing angular dependence in the spectrum when the viewing angle is no more than 45,with a CIE x,y coordinate variation of only（±0.0025,±0.0008）.Even at a large viewing angle（75）,the CIE x,y coordinate change is as small as（±0.0087,±0.0013）.

高速铣削参数对GH4169镍基高温合金加工表面变质层厚度的影响

在不同铣削速度(500~1000 m·min^(-1))和径向铣削深度(0.1~0.3 mm)下对GH4169镍基高温合金进行高速铣削加工,研究了铣削参数对切削力、切削温度、变质层和白层厚度以及表层硬度的影响。结果表明:随着铣削速度的增大,切削力降低,切削温度升高,铣削深度的增加会导致切削力和切削温度升高;在相同铣削深度下,当铣削速度由500 m·min^(-1)增大至1000 m·min^(-1)时,变质层厚度增大约30μm,白层厚度增大约5μm,表层显微硬度增大约200 HV,硬化层深度增大约100μm;在相同铣削速度下,铣削深度每增大0.1 mm,变质层厚度增大约30μm,白层厚度增大约3μm,表层硬度增大20 HV,硬化层深度增大约20μm。

基于梯度提升决策树的硬车表面白层预测方法

目的实现硬态车削过程中每个产品零件白层现象的实时在线检测,提高产品生产加工效率和加工质量,提出一种基于梯度提升决策树的硬态车削加工工件表面白层预测方法。方法首先,利用功率传感器、声发射传感器和振动传感器采集硬态车削过程中的动态切削信号数据,并对上述各种传感器信号数据进行特征提取;然后,结合特征重要性分析和梯度提升决策树建立硬态车削加工表面白层预测模型;最后,基于混淆矩阵提出一套评估梯度提升决策树模型预测性能的评价方法。结果与功率、振动信号等特征相比,声发射信号特征能够进一步提升模型的白层预测性能。实验结果表明,该方法的预测准确率达到90%,F1为92%,Auc为89%,与SVM、XGBoost分类方法所得结果相比,该方法能更准确有效地实现硬态车削加工工件表面白层现象的在线预测。结论该方法基于智能传感技术和梯度决策树模型对硬车过程中产生的白层现象进行了有效预测识别,对实现硬车过程白层现象的在线智能预测具有重要意义。

磨削诱导单晶高温合金微观组织演化机制研究

目的通过对零件磨削表面的微观组织进行表征,探讨高温和大应变条件下单晶高温合金晶体取向和位错的演化机制。方法采用场发射扫描电子显微镜对磨削亚表面微观组织形貌进行观察,通过X射线衍射技术对磨削前后表面晶体取向进行分析。利用聚焦离子束定向切割技术制备了磨削表面透射电子扫描样品,采用透射电子显微镜和透射菊池衍射方法对表面白层以及塑性变形层晶体取向以及位错分布进行了表征。结果磨削后单晶高温合金表面形成强烈塑性变形,原始单一取向发生改变,形成多晶衍射峰特征。磨削表面深度方向上形成具有不同晶粒尺寸和取向的梯度组织结构。选区衍射花样显示原始单晶材料的衍射斑点转变为多晶材料的衍射环。磨削表面由于强烈剪切变形和磨削热产生微纳尺度的动态再结晶现象,同时形成高密度位错结构。磨削表面产生强烈的剪切应变,使晶体向有利于剪切变形的方向旋转,形成了R-Cube织构和F剪切织构。结论单晶高温合金磨削表面微观组织演化是基于微纳尺度的动态再结晶和位错滑移运动进行的。

涂层刀具高速切削GH2132铁基高温合金加工表面变质层研究

加工表面变质层结构对零件使用性能起到重要作用,采用TiN/TiCN/TiAlN涂层硬质合金刀具对GH2132铁基高温合金进行高速切削试验,分析其加工表面变质层结构特征及形成机理。结果表明:经过涂层刀具高速加工的GH2132铁基高温合金表面变质层由白层和暗层组成,随着切削参数增加,加工表面塑性变形增大,晶粒细化,致使白层厚度增大;在加工表面微观结构电子背散射衍射(EBSD)分析中发现孪晶的存在,随着切削速度的提高,孪晶的数量增加,诱导材料组织发生相变,材料组织在转化过程中晶粒被拉长,促进塑性变形,从而引起加工表面组织再结晶。

通辽哈民忙哈遗址房屋地面白色铺垫材料的分析研究

为了达到最好的居住效果,古人运用长期积累的经验对房屋内部进行装修和改造。对内蒙东部通辽地区哈民忙哈遗址中F33和F50房址地面上的白色铺垫材料进行了分析,发现该遗址地面坚硬以及地面发白的原因是使用了白灰作为地面装饰层;并利用红外光谱峰在吸收强度上的变化,判断碳酸钙中原子无序度的信息,从而判断其制作工艺。结果表明,遗址白色铺垫材料中的方解石ν_(2)/ν_(4)的比值约在5左右,远远高于天然石灰石,反映了天然石灰石与人工制备石灰砂浆中方解石晶体结构无序性的差异,证明该遗址的白灰层是人工烧制而成的,说明我国古代先民在很久之前就开始使用人工烧制的石灰作为装饰建筑的材料。

覆盖层对顶发射白光微型OLED性能的影响研究

采用两种覆盖层CPL(Capping layer)材料Alq3和ZnSe制备了顶发射白光有机电致发光器件TE-OLEDs(Top emitting white organic light-emitting diodes),器件结构为ITO/NPB:LiQ(5%)(10 nm)/TCTA(20nm)/FIrpic+3.5%Ir(ppy)3+0.5%Ir(MDQ)2(acac)(25nm)/TPBI(10nm)/LiF(5nm)/Mg:Ag(10%)(12 nm)/CPL。实验结果表明,Alq3和ZnSe作为CPL可以增强TE-OLED器件的出光和调制光谱特性,并且ZnSe作为覆盖层制备的TE-OLED器件色坐标(CIEX,CIEY)随亮度变化更平稳,表现出良好的色稳定性。进一步,通过改变ZnSe厚度来优化器件,当ZnSe为45 nm时,器件获得了最佳的亮度和电流效率,分别为1461 cd/cm2和7.38 cd/A,色坐标为(0.30,0.33)。

38CrMoAl/QT600-3摩擦副摩擦磨损行为研究

目的研究实际工况下氮化处理的38CrMoAl/QT600-3摩擦副的磨损机理,为提高摩擦副的服役寿命提供指导。方法模拟实际工况,采用往复式摩擦磨损试验机进行摩擦磨损试验,结合显微维氏硬度计、金相显微镜、XRD分析摩擦副氮化处理后的硬度和组织,借助LSCM、SEM分析其磨损形貌,使用EDS分析其磨损表面化学成分。结果氮化处理后,38CrMoAl白亮层厚度为26μm,主要由ε相、γ′相组成,表面硬度平均为1112.8HV0.3,扩散层主要是α相,硬度呈梯度下降,即使白亮层磨损,扩散层依然具有较高的硬度;QT600-3白亮层厚度为16μm,主要由ε相、γ′相和石墨组成,表面硬度平均为960.4HV0.3,扩散层由α相和石墨组成,白亮层磨损后,扩散层硬度急剧下降,接近基体硬度。本试验条件下,38CrMoAl/QT600-3摩擦副磨损过程分3个阶段,即38CrMoAl白亮层对磨QT600-3白亮层、38CrMoAl白亮层对磨QT600-3扩散层、38CrMoAl扩散层对磨QT600-3扩散层,前2个阶段摩擦因数曲线稳定,摩擦因数介于0.5~0.6之间,磨损机理主要以磨粒磨损和疲劳磨损为主,其中第2阶段发生了氧化磨损,第3个阶段以黏着磨损和氧化磨损为主,此阶段摩擦副出现严重的擦伤、胶合,导致摩擦因数曲线噪音较大。结论提高白亮层的硬度、韧性以及厚度,可以增加摩擦副的服役寿命。

铝型材挤压模具开裂原因

某铝型材挤压模具在服役期间发生开裂。采用宏观观察、化学成分分析、硬度测试、非金属夹杂物评定、金相检验和扫描电镜分析等方法对模具开裂的原因进行分析。结果表明:电火花加工的工艺参数选择不当,使模具型腔表面产生很厚的白亮层,并伴有微裂纹,微裂纹延伸至热影响区,破坏了材料的连续性,降低了模具的耐疲劳性能;加工过程中尖端部位产生应力集中,在挤压力和热应力的作用下,裂纹不断萌生并扩展,最终导致模具发生开裂。