球墨铸铁表面激光堆焊层组织和性能的研究

借助光学显微镜、扫瞄电子显微镜,能谱仪对堆焊层显微组织及热影响区组织进行观察、分析,得知堆焊层显微组织特征是树枝状的V8C7分布在FeNi基体上,热影响区组织为细的莱氏体,堆焊层与基体结合良好.通过显微硬度计测试了堆一层的显微硬度为900～1 200,堆两层的HV为700～900,堆焊层数增加,裂纹倾向减少.     

焊接线能量对熔敷金属组织形成的影响

采用堆焊焊条CHR322,在A3钢基体上以不同的焊接工艺进行手工电弧堆焊试验。分析了堆焊熔敷金属的显微组织,研究了焊接线能量对堆焊层金属显微组织形成的影响。分析研究表明：堆焊金属与基体金属具有良好的冶金结合,第一层堆焊金属受基体金属的稀释程度影响明显。堆焊金属的显微组织与输入的焊接线能量的大小有关。     

40Cr曲面基体激光熔覆W6Mo5Cr4V2性能

为了利用激光熔覆技术实现模切机刀辊刀刃的增材制造,以曲率半径、熔覆轨迹、搭接率等为影响因素,在40Cr曲面基体上进行W6Mo5Cr4V2粉末的多道激光熔覆正交试验研究,并对熔覆层的残余应力、显微硬度以及显微组织结构进行分析。结果表明,保护气流量对残余应力变化影响显著,当工艺参数为激光功率1 800 W、扫描速度10 m/s、保护气流量400 g/min、曲率半径60 mm、搭接率30%、周向熔覆时,残余应力达到最小值。当残余应力满足成形要求时,显微组织的结晶形态从熔覆层顶部到结合区由平面晶向树状晶发展,熔覆层没有缺陷且与基体实现了良好的冶金结合。同时,显微硬度值从基体到熔覆层顶部呈阶梯状增长式分布,熔覆层的显微硬度平均值均在60HRC以上,满足模切机刀辊刀刃的硬度要求。     

Al基材表面激光制备Zn熔覆层的实验研究

利用波长为1．06μm，功率密度为10－20kW/cm^2的Nd:YAG激光器的聚焦光束为热源，在易氧化的纯铝表面制备了锌铝熔覆层，对熔覆工艺、熔覆层的微观组织、激光参数进行了实验研究。实验结果表明，强激光光辐照使基体材料铝表面熔覆高硬度、抗氧化的锌金属表面层是可行的。通过金相显微镜微观组织结构的分析，研究了激光工艺参数对Zn/Al熔覆层过渡区裂纹倾向的影响，只要选择合适的激光束参数，可获得理想的Zn/Al合金熔覆层。这对改进铝材表面物理、化学性能并进一步开发铝的用途具有实用价值。     

厚层激光熔覆层裂纹控制的综合实验研究与理论分析

采用5kW横流CWCO2激光器,对不同基体材料的核阀与石化高参数阀门密封面进行激光熔覆,所用合金粉为CoCrWB与NiCrFeBSi合金粉末,在研究解决了厚层单道熔覆裂纹问题基础上,得到了厚2－3．5mm,表达平整、无质量缺陷的激光熔覆层,结合激光熔覆阀门零件的试验研究,分析探讨了影响熔覆层,特别是厚层熔覆层裂纹形成的各种因素及其综合影响,提出了关于建立判断熔覆层裂纹形成的应力判据模型的思路。     

激光堆焊工艺对堆焊层组织性能的影响

在45钢的基体上,选用不同的激光功率、扫描速度、送丝速度等,用专用焊丝进行堆焊处理,结果表明当速度不变时,激光功率增加,其热影响区变大,组织由细变粗,硬度增加;当其它条件不变时,随着扫描速度的增加,堆焊层的稀释率下降,硬度增加,随着送丝速度的增加,堆焊层的组织均匀分布,硬度先增加,后下降.     

堆焊金属组织及其微动磨损研究

采用CHR207、CHR227和CHR237焊条，在45号钢基体上进行了手工电弧堆焊和不同堆焊层金属的微动摩擦试验。分析了堆焊熔敷金属的显微组织，研究了微动摩擦试验结果。分析研究表明，堆焊金属与基体金属具有良好的冶金结合，第一层堆焊金属受基体金属的稀释程度影响明显，界面处金属过渡层的宽度因焊条种类的不同而异。基体金属和堆焊层金属具有类似的摩擦特性图，微动均处于完全滑移区。     

Al基材表面激光制备Cu/Zn熔覆层的实验研究

利用Nd：YAG激光器的聚焦光束为热源，在易氧化的纯铝表面制备了铜锌铝熔覆层，分析讨论了激光功率、激光有效热利用率的最佳耦合，对熔覆工艺、熔覆层的微观组织、激光参数进行了实验研究。实验结果表明，Nd：YAG激光辐照Al基体可制备抗氧化的铜锌铝表面合金。通过JEOLJSM-5610LV扫描电镜对Cu／Zn／Al表面合金微观组织结构的分析，表明只要选择合适的激光工艺参数，而且采用与基体熔点相近的熔覆材料(如Zn、Cu)，可获得熔覆层、过渡区裂纹与徽洞较少的高质量Cu／Zn／Al合金。     

45钢堆焊金属组织及显微硬度研究

分别采用D237和D207两种堆焊焊条,以焊条电弧焊工艺在基体材料45钢上进行堆焊,对在相同焊接条件下获得的堆焊金属的显微组织和显微硬度进行了分析,并讨论了合金元素对堆焊层显微组织及显微硬度的影响.结果表明:堆焊层金属的显微组织及显微硬度与焊接线能量有关,与焊条的合金成分及含量有关,与其硬质相的类型、性能及分布等有关;合金元素钼、钒对堆焊金属品粒的细化作用效果明显.     

等离子熔覆Ni-Cr合金强化粮油食品机械螺杆的研究

采用等离子熔覆技术在粮油食品机械螺杆基材40cr合金钢表面等离子熔覆Ni-Cr合金涂层,研究了熔覆层的组织特征和显微硬度.实验结果表明:等离子熔覆层与基体的结合面是由等轴晶构成的,熔覆层与基体呈现良好的冶金结合状态;熔覆层中部分布着沿逆热流方向生长的排列较规则的枝晶组织;熔覆层表层是细小的枝晶组织.当扫描速度一定时,较高的熔覆功率下的熔覆层内的枝晶和等轴晶得到细化.熔覆层的显微硬度呈梯度过渡到基体,熔覆层外层硬度值最高,在结合面附近硬度出现显著的变化,但熔覆功率对熔覆层硬度的影响并不显著.     

用新式地层取样测试器进行纯油气层产能测试

全储层取样测试器和生产井分层取样测试器是用于油气裸眼勘探井和生产井的自动化、数字化的大型新式地层测试仪器.使用双封隔器选择性封隔地层是这两种仪器的特色.油气井经仪器直接测量后,就可以创立该井全储层原始流体性质全参数数据库及地层动态特性全参数数据库.进行产能测试时,流量从小到大取得一系列稳定的流动压力值,有大于和小于饱和压力的测点.而每次的样品经过实验室分析,可以得到需要的参数.由此,可得各小层段的油、气、水流入动态曲线及方程.将全井各油气小层段的油气水产量叠加,即可求出全井所有油气层的油气水总地层产量.使用PvT实验得出的相关参数,就可求出地面油气水总产量.     

八台阶二元光学器件套刻误差的逐层分析法研究

用逐层分析法就八台阶二元器件套刻误差对器件衍射效率的影响进行了详细的分析和讨论,给出简便,关用的计算和分析方法。     

Penetration depth for yaw-inducing bursting layer impacted by projectile

In order to accurately estimate the anti-penetration capacity of yaw-inducing bursting layer with irregular barriers on surface impacted by projectile, the theoretical model of attack angle and angular velocity for projectile impacting on irregular barrier was achieved according to the macroscopic relation of contact force versus contact time, in which the main factors such as the relative geometrical characteristics of projectile and irregular barrier, material property and impact velocity of projectile influencing on yaw-inducing effectiveness were considered. On the basis of considering synthetically the influences of attack angle, impact velocity, impact angle of projectile and uncontrolled free surface of target, the theoretical formulation of penetration depth for bursting layer with irregular barriers on surface impacted by projectile was presented by expressing the stress of an optional point on the nose of projectile according to the relation of stress versus velocity. The theoretical results indicate that in the case of oblique impact embodying effect of attack angle, the penetration depth is reduced with the increase of impact angle, attack angle or angular velocity, and penetration trajectory is also deflected obviously. The effectiveness of angular velocity influencing on penetration depth is increased with impact velocity increasing. The theoretical results are in good agreement with test data for low impact velocity.     

Shock wave-boundary layer interactions control by plasma aerodynamic actuation

This study demonstrates the potential for shock wave-boundary layer interaction control in air by plasma aerodynamic actuation. Experimental investigations on shock wave-boundary layer interactions control by plasma aerodynamic actuation are conducted in a Mach 3 in-draft air tunnel. Schlieren imaging shows that the discharges cause the oblique shock to move forward. Schlieren imaging and static pressure probes also show that separation phenomenon shifts backward and the size of separation is enlarged when plasma aerodynamic actuation is applied. The intensity of shock wave is weakened through wall pressure probe. Furthermore, numerical investigations on shock wave-boundary layer interactions control are conducted with plasma aerodynamic actuation. The discharge is modeled as a steady volumetric heat source which is integrated into the energy equation. The input energy level is about 7 kW through discharge process. Results show that the separation phenomenon shifts backward and the intensity of shock is reduced with plasma actuation. These numerical results are consistent with the experimental results.     

Concentration boundary layer model of mortar corrosion by sulfuric acid

A long time immersion experiment of mortar specimens is carried out to investigate their degradation mechanism by sulfuric acid.Water-cement ratios of mortar are ranging from 0.5 to 0.7 and the pH value of sulfuric acid is 3.5 and 4.0 respectively.The pH meter is used to monitor the soak solution and the titration sulfuric acid with given concentration is added to maintain original pH value,through which the acid consumption of mortar is recorded.A theoretical reaction rate model is also proposed based on concentration boundary layer model.The results show that theoretical model fits the experimental results well and the corrosion mechanism can be modeled by a diffusion process accompanied with an irreversible chemical reaction when pH value of soak solution is no less than 3.5.     

Ultraviolet-emitting ZnO thick layer grown by thermal oxidation with gallium

The Zn O layer with thickness of 1.6 μm in Zn O/Zn Ga2O4 composite structure was grown by the thermal oxidation of Zn S substrate with gallium. The optical property of the Zn O thick layer was investigated by time-resolved photoluminescence. A single UV emission around 375 nm with short lifetime was observed at room temperature while the visible emission was absolutely quenched. The UV emission band was composed of the neutral donor bound exciton(D0X) and donor-acceptor pair(DAP) emission peaks with large full-width at half-maximums(FWHMs) at 3.367 and 3.318 e V, respectively, at 10 K. However, the intensity of the D0 X emission was stronger than that of the DAP emission at measuring temperatures of 10–300 K.     

Switchable hydrophobic-hydrophilic layer obtained onto porous alumina by plasma-enhanced fluorination

Conventional lithographic printing processes using porous alumina for offset applications generally use "wet" routes. Recently "dry" processes have been developed which are based on a heat-induced hydrophilic/oleophilic conversion of one or more layers of the coating so that a stronger affinity to-wards ink or water fountain is created at the exposed areas with respect to the surface of the unex-posed coating. Treatments involving rf plasma-enhanced fluorination (PEF) constitute exceptional tools for modifying the surface properties of materials. Many advantages of these techniques can be indeed outlined, when compared to more conventional methods: room-temperature reactions, chemical modi-fications limited to surface only without changing the bulk properties, possible non-equilibrium reac-tions. The influence of PEF treatments on porous alumina layer used in printing plates has been tested with various fluorinated gases (CF4, C3F8 and C4F8) and characterized by XPS. The hydrophobic prop-erties of the fluorinated layer have been deduced from contact angle measurements. Using C4F8 rf-PEF treatment, the outmost surface of the hydrophilic alumina substrate used for lithographic printing is hydrophobized, or in other words, the hydrophilic substrate is converted into a support with hydro-phobic properties. Once being hydrophobized, the surface layer may be rendered hydrophilic using a heat pulse, thus giving rise to switchable hydrophobic-hydrophilic properties of the material.     

薄层层析分离鲟鱼胆汁

为了综合利用鲟鱼加工下脚料,提高鲟鱼附加值和中药产业临床应用价值,提出了采用不同的溶剂系统作展开剂分离鲟鱼胆汁的有效成分的方法.实验过程中,分别以单元溶剂、二元溶剂以及三元溶剂体系作展开剂,考察了不同体系的展开剂对鲟鱼胆汁分离效果的影响.结果表明:单元溶剂中甲苯和氯仿分离效果好,二元溶剂体系中氯仿/乙醇、氯仿/甲醇、石油醚/丙酮以及三元溶剂体系中石油醚/丙酮/甲苯(3∶1∶1,体积比)、氯仿/甲醇/甲苯(5∶1∶1,体积比)分离效果较佳.筛选出二元溶剂氯仿/甲醇(10∶1,体积比)最适宜后续的柱层析分离鲟鱼胆汁.     

Improving corrosion resistance of Q235 steel by Ni-Cr alloyed layer

Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate. The composition and microstructure of alloyed layer was analyzed by SEM and XRD. Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer. The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer, and the dense and smooth alloyed layer was prepared at 50 Pa working pressure. Compared with substrate, Ni-Cr alloyed layer exhibited higher corrosion potential, lower corrosion current density and larger charge transfer resistance, which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.     

松散堆积土中的隔水层对边坡稳定性的影响

通过大量滑坡案例的地质调查,发现隔水层在滑坡过程中产生重要的影响.为了揭示相对隔水层对边坡稳定性的影响机制,构建包含隔水层的边坡模型,模拟降雨和斜坡后缘地下水入渗的物理力学作用.模型试验结果表明,降雨入渗主要影响隔水层上部土体,使含水量快速升高、土体变形和坡体的下滑推力迅速增大,隔水层下部土体的含水量等参数基本不变.在模型试验中当使后缘地下水入渗到隔水层下部坡体时,虽然只影响隔水层下部坡体的含水量和孔隙水压力,但力学作用影响整个边坡,不仅引起隔水层下部土体的变形,使下滑推力增大,而且在更大程度上影响隔水层上部土体的变形,使隔水层上部土层的下滑推力大幅提高.