铝合金漆层与氧化层激光清洗应用研究

通过对激光的单脉冲能量、光斑搭接率、离焦量等参数的对比研究发现,过高的激光能量不仅能清洗掉漆层与氧化层,还会对铝合金表面造成明显的热损伤;过高的光斑搭接率会降低清洗效率;适当的离焦量有助于非均匀漆层的清洗去除。研究结论是,对于铝合金漆层与氧化层的激光清洗,最佳的组合参数为单脉冲能量0.45 mJ、光斑搭接率33%和离焦量1 mm。     

CO2激光清洗2024铝合金表面复合涂层

使用波长为10.6μm的CO2激光器对2024铝合金表面复合漆层进行激光清洗,探讨了激光功率(60、80或100 W)和搭接率(50％、55％、60％或65％)对脱漆效果的影响,通过对比原始铝合金阳极氧化膜表面和脱漆表面的微观形貌、元素成分、粗糙度等来检验清洗质量.结果表明:随着激光功率和搭接率的增大,激光清洗质量在提高一定程度后开始下降.当激光功率为80 W,搭接率为60％时,漆层已被完全去除,同时阳极氧化层未发生损伤,重新涂漆的结合力为0级,符合飞机蒙皮重新涂漆的要求.     

橡胶模具激光清洗的工艺研究

激光清洗模具的原理是利用模具基体物质与表面附着的污垢对某一频率的激光能量吸收系数的差别,使激光能量充分被表面附着的污垢所吸收,从而受热膨胀直至气化,所形成的气体被吸收利用而不损伤模具甚至强化模具基体,以达到绿色清洗的目的。本文从橡胶模具表面颗粒受力、激光清洗的机理与主要性能参数及其光路控制,对激光加工技术的应用进行了探讨。     

激光熔覆工艺参数对高熵合金涂层性能的影响及其优化

采用同步送粉激光熔覆技术在Q235钢表面制备了CoCrFeNiMo高熵合金涂层。采用单因素试验研究了工艺参数对涂层形貌及性能的影响,并分析了其作用机理。通过正交试验得到最优工艺参数为:激光功率1000 W,进给速率4.5 mm/s,搭接率35%。此时涂层的平整度标差为0.036 mm,显微硬度为308.98 HV,平均腐蚀速率为0.0178 g/(m²·h)。结果表明,在试验范围内,涂层的平整度随着激光功率、进给速率和搭接率的提升得到改善,显微硬度和耐蚀性的变化趋势相同,它们与工艺参数对显微组织的影响相关。     

Nd∶YLiF4晶体的声光调Q脉冲激光特性研究

在激光二极管端面泵浦的情况下,采用耦合透过率为10％的输出镜,研究了Nd∶YLiF4晶体的声光调Q脉冲激光特性.当重复频率为1O kHz,泵浦功率为5.94 W时,获得了540 mW的最大平均输出功率,光光转换效率和斜效率分别为9.09％和10.7％.当重复频率为1 kHz时,获得了最佳的脉冲实验结果:最高峰值功率为49.2 kW,最大单脉冲能量为295μJ,最小脉宽为6 ns.     

激光清洗轮胎模具新工艺

激光清洗轮胎模具的原理是利用模具基体物质与表面附着的污垢对某一频率的激光能量吸收系数的差别，使激光能量充分被表面附着的污垢所吸收，从而受热膨胀直至气化，所形成的气体被吸收利用而不损伤甚至强化模具基体，以达到绿色清洗的目的。本文从激光的特性、激光器简介、激光清洗原理以及激光清洗应用分析等方面对激光加工技术新应用进行了探讨。     

CFRP表面的激光处理及其结构与性能研究

采用光纤激光器对碳纤维复合材料(CFRP)表面进行处理,通过研究激光的光斑直径(D_g)和Z轴距离(L_Z)的关系,研究了L_Z对CFRP表面形貌、结构,以及对CFRP与铝合金单搭接接头胶接拉伸剪切强度(τ)的影响。结果表明:L_Z为5～25 mm时,随着L_Z的增加,D_g增大;L_Z为20 mm时,激光处理后的CFRP表面的环氧树脂基本去除,碳纤维几乎没有被破坏,排列仍然规整,环氧树脂去除的效果较好,且其表面烧蚀率最大为7.6 g/s,CFRP与铝合金单搭接接头的τ最大为15.46 MPa。     

激光活化参数对塑料表面通过化学镀铜制备电子线路的影响

先将10 g/L CuSO_4·5H_2O+30 g/L NaH_2PO_2·H_2O活化液均匀涂覆于ABS基体表面,再采用激光活化工艺在基体表面得到具有催化活性的电子线路图形,最后通过化学镀铜得到电子线路。研究了激光功率、光斑直径和扫描速率对电子线路上铜层覆盖率的影响。表征了化学镀铜层的表面形貌、相结构、可焊性和结合力。当激光功率为2.0 W,光斑直径为0.2 mm,扫描速率为12 mm/s时,线路的活化效果最佳,化学镀铜后线路边缘整齐,铜层覆盖率为100%,电阻率为3.6μ?·cm,可焊性和结合力良好。     

透明PP塑料激光焊接工艺研究

透明聚丙烯(PP)塑料对激光透过率较高,无法对激光能量进行吸收,采用在下层PP塑料上涂敷吸收剂的方法,实现激光焊接.对激光塑料焊接工艺参数进行正交实验,当吸收剂厚度为54μm,激光功率50 W,焊接速度为100mm/s,光斑直径为1mm时,此时焊缝剪切强度达到最大的35 MPa,为最佳工艺参数.进一步对焊缝截面进行切片...     

浸没式中空纤维膜反应器的在线超声清洗

将超声波用于浸没式中空纤维膜反应器的在线清洗,考察了超声波参数和操作条件对清洗效果的影响。结果表明,超声功率352 W、频率40 kHz时,最佳超声时间为10 min,最佳清洗距离为5 cm。膜表面SEM照片显示,超声距离过近和超超声时间过长会对膜自身结构造成破坏。在以上条件下,试验采取曝气强度0.6 m3/(m2.h)的超声-曝气组合清洗方式取得了最理想的清洗效果,膜通量恢复率可达74.24%。而曝气强度不宜过大,否则清洗效果明显下降。     

激光清洗技术在轮胎模具清洗中的应用研究

介绍了激光清洗技术在轮胎模具清洗中的优势.简述了国内外激光清洗技术在轮胎模具清洗中的现状,研究了模具损伤的激光能量密度阈值,对全自动激光清洗设备的参数进行了详细的分析,确定最佳参数范围,结果表明,工艺参数适当,能快捷有效的清洁轮胎模具,而不损伤模具.     

脉冲电沉积镍-铜合金

采用脉冲电沉积技术在304不锈钢表面制备Ni-Cu合金镀层,镀液组成和工艺条件为:NiSO4ꞏ6H2O 200g/L,CuSO4ꞏ5H2O 10 g/L,十二烷基硫酸钠0.2 g/L,柠檬酸钠80 g/L,糖精0.2 g/L,pH 4.0,温度25°C,搅拌速率30 r/min,平均电流密度40~120 mA/cm2,脉冲频率0~100 Hz,占空比20%~90%,时间30 min。研究了平均电流密度、脉冲频率和占空比对Ni-Cu合金镀层的元素组成、表面形貌和显微硬度的影响,得到较优的工艺参数为:平均电流密度40 mA/cm2,脉冲频率50 Hz,占空比60%。该条件下所得Ni-Cu合金镀层由质量分数分别为56.53%和43.47%的Ni和Cu组成,呈“菜花”状形貌,结晶细致、均匀,显微硬度为614.4 HV。     

工艺参数对超声辅助脉冲电沉积镍-氮化钛复合镀层的影响

在45钢表面以超声波辅助脉冲电沉积制备Ni-TiN复合镀层。研究了平均阴极电流密度、脉冲占空比、超声功率和TiN粒子(平均直径20~30 nm)添加量对复合镀层的TiN粒子含量和显微硬度的影响。得到较优的工艺参数为:NiSO4ꞏ6H2O 300 g/L,NiCl2ꞏ6H2O 30 g/L,H3BO330 g/L,十二烷基硫酸钠0.3 g/L,TiN 25 g/L,pH 4.1~4.3,温度40°C,平均阴极电流密度4 A/dm2,脉冲占空比40%,脉冲频率1000 Hz,超声功率300 W,机械搅拌速率200 r/min,时间60 min。该条件下所得Ni-TiN复合镀层的TiN质量分数为8.35%,显微硬度为819 HV,表面平整、致密,晶粒尺寸均匀。     

Effects of different surface cleaning procedures on the superficial morphology and the adhesive strength of epoxy coating on aluminium alloy 1050

This study reports the effects of different cleaning procedures on the surface characteristics of the aluminium alloy 1050 substrates and on the adhesive strength of the epoxy coating to this alloy's surface. The cleaning procedures used in this study were (1) degreasing by acetone, (2) alkaline etching by 5 w/w% NaOH solution and (3) alkaline etching by 5 w/w% NaOH solution followed by acid cleaning by 50 v/v% HNO₃ solution. The surface morphology, chemical composition and topography of the cleaned substrates were investigated by field-emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM), respectively. The effectiveness of the cleaning procedures was also studied by polarization test and open circuit potential (OCP) measurements. The surface free energy and work of adhesion were obtained on the cleaned samples using contact angle measuring device. Pull-off test was conducted to evaluate the adhesion strength of the epoxy coating on the aluminium substrates. Results revealed that the surface cleaning of aluminium alloy by alkaline etching followed by acid cleaning method was the most efficient procedure for removing the oxide layer from the surface of aluminium compared to other cleaning procedures. The surface roughness, surface free energy, electrochemical activity and adhesion strength of the epoxy coating to the aluminium surface were significantly increased using this surface cleaning procedure.     

钛合金新型镀镍工艺的研究

通过在瓦特镀镍液中添加金属配位剂和金属阳极活化剂,对钛电极先采用阳极脉冲电流活化,再对活化后的钛电极进行脉冲电沉积,在TC11钛合金表面获得了结合力优良的镍镀层.研究了电解液组分、工艺参数对镀层结合力的影响.结果表明,在硫酸镍电解液中添加40 g/L阳极活化剂,采用1.4 A/dm2阳极脉冲电流对TC11钛合金进行电化学处理,可使TC11钛合金产生活性溶解,将脉冲电流切换为阴极电沉积后,便可在TC11钛合金表面沉积一层结合力优良的镍镀层.文章讨论了脉冲阴、阳极平均电流密度、占空比、频率、电解液组分等工艺参数对镍镀层质量的影响.     

Laser deposition of compositionally graded titanium oxide on Ti6Al4V alloy

In this study, a laser cladding process was developed to deposit dense and well-adhered titanium single tracks on the surface of Ti6Al4V alloy with a compositional and microstructural gradient. CuO doped, freeze-dried anatase powder was specially formulated for this process. The addition of CuO resulted in stable melt pool with low viscosity, low surface tension and enhanced wettability with the substrate. Continuous titanium oxide single tracks were formed with a cross-sectional profile that was advantageous for coating deposition by means of multiple overlapping scan tracks. Rapid heating and cooling associated with laser cladding produced unique solidified microstructures with a compositional gradient. No structurally critical fractures were observed in the graded oxide layers, or at the coating/substrate interfaces. Furthermore, a transition zone of oxide/metal mixture was observed at the interface, increasing the effective bonding area between the coating and the substrate.     

污染聚偏氟乙烯中空纤维超滤膜的超声清洗

中空纤维超滤膜污染和清洗影响膜处理废水工艺的经济性及可运行性.研究了平板浸没式超声处理器（40 kHz）与2000 mg·L^-1柠檬酸清洗剂对中石化某水处理厂污染聚偏氟乙烯超滤膜的清洗效果.利用自定义的除垢率和扫描电镜对清洗结果进行表征并用过滤通量来验证.证明超声对超滤膜的清洗效果显著.单根膜清洗除垢率比不加超声时提高了25%,达到80%左右,且没有破坏膜的表面和结构.得到本批污染膜及自制污染膜组件的优化清洗工艺及超声参数为：频率40 kHz、声强2200 W·m^-2、超声处理时间30 min.未使用反向冲清洗,仅切向气流结合超声清洗膜面,清洗后的通量从原来污染组件的0.0368 cm³·cm^-2·min^-1增加到0.1254 cm³·cm^-2·min^-1,恢复到相当于新膜初始通量的72.5%,通量增加率达到241%.进一步证明了超声清洗膜的可行性和有效性.     

Copper plating on titanium alloy 6-2-4-2 using an in situ high voltage pulse followed by plate-up

We have used an in situ technique that removes the oxide from the surface of the alloy titanium 6-2-4-2, followed by copper electroplating of the surface. The oxide removal is accomplished by means of a short voltage pulse from a discharging capacitor between the cathode (titanium) and anode while submerged in the plating solution. Within seconds thereafter, the electrodes are switched to a separate power supply for electroplating copper onto the titanium. From the experimental data, we believe that the oxide is removed by means of dielectric breakdown mechanisms giving rise to a statistical probability that all of the surface oxide is removed. When this occurs, we obtain adherent depositions based on standard tape testing of the deposit. We determine a set of voltage and energy density conditions which are most likely to result in good adhesion. Scanning electron micrographs of adherent copper deposits are presented.     

Experimental study of pleated fabric cartridges in a pulse-jet cleaned dust collector

Six pleated filter cartridges with different base media and geometrical dimensions were tested in a full-size dust collector periodically cleaned by a short burst of pulse-jet. The evaluation was performed under two different cleaning modes called clean-on-demand (to clean the filter once the pressure drop reaches a preset value) and clean-on-time (to clean the filter at a fixed time interval). The filter performance was evaluated by the effective residual pressure drop and downstream particle concentration. The results showed that the pleat ratio, defined as the ratio of pleat height to pleat pitch, had a great influence on the preferred operating mode for cleaning the filter. Clean-on-time mode demonstrated better performance for filters with a high pleat ratio (> 4.0), while clean-on-demand mode performed better for filters with a low pleat ratio (< 4.0). The test results also showed the tank pressure was critical for cleaning the pleated filter cartridges, whereas the pulse duration only had a small effect on the cleaning efficiency. With the same base media, cartridges with surface treatment such as fine fiber were superior to those without surface treatment. Pulse-jet cleaning could also promote particle penetration through filter media. The downstream particle concentration during cleaning was at least twice of that during filtration process for all pleated filter cartridges tested. Further, the downstream particle concentration was independent of the applied cleaning mode and the cleaning intensity in this study.