激光冲击加工表面涂层厚度的优选

研究了激光冲击技术中的涂层厚度问题，激光与涂层相互作用机理和涂层本身性能之间的关系，推导出涂层的气化速度及最佳理论厚度，并对涂层厚度的影响因素进行了分析和修正，为在激光冲击中正确应用涂层厚度计算公式提供了依据。     

基于XRD的薄膜界面结合强度试验研究

利用X射线衍射技术（XRD）分析了薄膜结合界面应力及其变化规律，通过对薄膜界面结合状态的检测，建立了X衍射法测量薄膜界面结合强度的原理、方法与过程。其检测界面结合强度方法可对薄膜试样进行非接触检测，适用于晶体或多晶体薄膜的界面结合强度测量，是一种研究无损检测薄膜结合强度的试验新方法。     

激光热处理对1Cr5Mo钢焊接接头组织结构的影响

利用CO_2激光对1Cr5Mo耐热钢焊接接头进行表面热处理,通过4XC型光学显微镜对激光热处理前后焊接接头各区显微组织和晶粒度等级进行分析,并采用X射线应力仪测定激光热处理前后焊接接头残余应力和残余奥氏体的分布规律。结果表明:经激光热处理后1Cr5Mo耐热钢焊接接头表面晶粒发生细化,焊缝区、熔合区、过热区和正火区晶粒等级由9级、9.8级、8级和10.7级提升至10级、10.2级、8.5级和11级,组织结构薄弱区域由过热区、焊缝区和熔合区减少为过热区,均匀性得到了明显改善;激光热处理消除了焊接接头表面残余拉应力,形成了深度约为0.28mm的残余压应力层,残余奥氏体含量有所提高,分布更均匀,有利于改善其力学性能。     

Microstructure and Mechanical Property of Magnetron Sputtering Deposited DLC Film

A diamond-like carbon (DLC) film was deposited on YT14 substrate using magnetron sputtering (MS). The surface morphologies, roughness and bonding spectra of obtained film were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS), respectively, and its mechanical property and bonding strength were measured using a nanoindentation and scratch tester, respectively. The results show that the C-enriched DLC film exhibits a denser microstructure and smoother surface with lower surface roughness of 21.8 nm. The ratio of C sp2 at 284.4 eV that corresponds to the diamond (111) and the C sp3 at 285.3 eV that corresponds to the diamond (220) plane for the as-received film is 0.36: 0.64, showing that the C sp3 has the high content. The hardness and Young’s modulus of DLC film by nanoindentation are 8.534 41 and 142.158 1 GPa, respectively, and the corresponding bonding strength is 74.55N by scratch test.     

激光热喷涂Co30Cr8W1.6C3Ni1.4Si涂层在PAO+2.5%MoDTC油中摩擦学特性

为了提高TC4合金的耐磨性能,采用激光热喷涂技术在其表面制备了Co₃₀Cr₈W_1.6C₃Ni_1.4Si涂层。通过扫描电子显微镜（SEM）和X射线衍射（XRD）分析了涂层的形貌和物相,并通过摩擦磨损实验研究了涂层在PAO+2.5% MoDTC（质量分数）油中的磨损行为。结果表明,激光热喷涂的Co₃₀Cr₈W_1.6C₃Ni_1.4Si涂层主要由Ti、WC_1-x、CoO、Co₂Ti₄O和CoAl相组成,在涂层界面形成冶金结合。在激光功率为1000、1200和1400 W时所制备的涂层平均摩擦因数分别为0.151、0.120和0.171,其对应的磨损率分别为1.17×10^-6、1.33×10^-6和2.80×10^-6 mm³?N^-1?m^-1,磨损机理为磨粒磨损,其枝晶尺寸对降磨起主要作用。     

激光热处理对1Cr5Mo耐热钢焊接接头拉伸性能的影响

为了改善1Cr5Mo耐热钢焊接接头拉伸力学性能,利用CO2激光对其进行了表面改性处理,通过拉伸试验考察了激光热处理对拉伸性能的影响.利用扫描电镜观察了焊接接头的断裂形式和断口形貌,并用能谱仪分析了激光热处理前后试样表面化学元素的组成,讨论了残余应力和残余奥氏体对拉伸性能的影响.结果表明,激光热处理前后试样的拉伸断口均为韧性断裂,激光热处理后断裂性能有所提高;激光热处理试样表面产生晶粒细化和残余压应力的强化层,其屈服强度和抗拉强度分别提高了3.4%和13.7%,拉伸性能得到进一步提高;激光热处理试样的残余奥氏体含量有所降低,导致焊接接头的断面收缩率下降了18.61%,而延伸率基本不变,其均匀变形能力有所增强.     

7475铝合金微弧氧化后表面-界面能谱扫描分析

利用微弧氧化法在7475铝合金表面制备一层氧化膜,通过SEM、EDS、XRD等手段对其表面-界面形貌、化学元素组成和物相进行了分析,采用能谱仪对表面和结合界面进行了面扫描和线扫描分析,并用划痕法表征了氧化膜界面结合强度。结果表明,微弧氧化后7475铝合金表面形成一层粗糙多孔的氧化膜,其组成元素与氧化膜表面的物相相应分布;O原子以扩散形式与Al原子原位生长形成Al_2O_3,主要由α-Al_2O_3、γ-Al_2O_3组成,Si原子在表面氧化形成富集的Si-Al-O相;氧化膜厚度约为50μm,由间隙层、致密层和膜-基过渡层组成,与基体的界面结合强度为71.05 N。     

石油天然气管道的焊接工艺概述及其发展分析

为了进一步探讨石油天然气管道的焊接工艺,文中首先探讨了石油天然气管道焊接工艺概述,重点分析了焊接前的准备工作和焊接的施工阶段,在焊接工艺的质量控制发展分析中探析了建立质量保证体系、严格控制焊接技术人员和检验人员的专业素质。     

高斯激光辐照下膜基系统的温度场和应力场的瞬态分析

本文根据加载激光的工艺参数以及薄膜、基体的材料特性,建立了薄膜与基体的有限元模型,对高斯激光在加载在薄膜表面后的温度场进行有限元模拟,获得膜基系统中温度随时间的变化关系以及薄膜界面结合处的温升规律。并在此基础上根据薄膜和基体的热膨胀性能,进行薄膜和基体的应力场模拟,获得了膜基系统的应力场随时间的变化关系。模拟结果表明：在激光加载过程中,薄膜和基体中的温度场随着时间增加,由于热传导系数的差异在薄膜和基体之间产生温差。在膜基系统中产生的应力场主要集中在薄膜内部,膜基界面结合处产生的应力较大会导致薄膜的脱粘。模拟结果定性地反映了薄膜和基体中温度和热应力的变化规律,为分析激光划痕法的作用过程提供了一定的理论依据,对研究膜基系统失效进程具有重要意义。     

Effect of Extrusion Temperatures on Friction-wear Behavior of Chain-wheel Fabricated by 40Cr Steel under Oil-lubrication Condition

A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope(OM), micro-hardness tester, and X-ray diffraction(XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 ℃ were analyzed using a scanning electron microscopy(SEM), energy disperse spectroscopy(EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 ℃ with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction(COF) of extruded sample at the temperature of 550 ℃ is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 ℃, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF(coefficient of friction) of extruded sample at the temperatures of 650 and 750 ℃ are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 ℃ is better than that at the temperature of 550 ℃.