2024铝合金表面扫描式微弧氧化工艺研究

本研究利用小功率微弧氧化电源, 通过内充液式管状阴极的逐行扫描, 在2024铝合金样件表面生成微弧氧化陶瓷膜层, 对样件的局部受损部位进行了成功的修复, 从而突破了传统微弧氧化技术不能用于铝合金构件现场局部防护与修复的限制; 利用XRD、SEM、EDS等分析方法对陶瓷膜层的相组成与微观组织形貌进行了研究。利用纳米压痕仪测试了陶瓷膜层的纳米压痕硬度和弹性模量, 用动电位极化曲线测试陶瓷膜层的耐腐蚀性能。结果表明: 在恒电流模式下, 扫描式微弧氧化电压快速升高, 直接进入微弧放电阶段。其一次扫描成膜层厚度17 μm, 相对于传统微弧氧化具有很高的成膜效率。铝合金扫描式微弧氧化陶瓷膜层主要由α-Al₂O₃和γ-Al₂O₃组成, 膜层分为致密层和疏松层, 表面多微孔, 且有微裂纹; 纳米压痕测试结果表明, 陶瓷膜层纳米压痕硬度和弹性模量沿界面向外呈现先增加后减小的变化趋势。动电位极化曲线表明, 扫描式和传统微弧氧化陶瓷膜层都能够对基体起到有效的腐蚀防护作用, 传统微弧氧化陶瓷膜层的腐蚀防护作用高于扫描式。     

Study on corrosion resistance of aluminium coating deposited on magnesium-zinc-yttrium-calcium alloy by cold spray

Pure aluminium coatings were prepared on magnesium-zinc-yttrium-calcium alloy substrate via cold spraying technology with different scanning speeds and working gas temperature. The correlation between the corrosion resistance of the coatings and the different spraying process was studied. While the working gas temperature is 600 °C and the scanning speed is 1 mm/s, aluminium coating has less porosity and the coating was well combined with the substrate. Higher temperature of working gas increases the plastic deformation of particles, which lead to a dense aluminium coating. The relationship of corrosion resistance on working gas temperature and scanning speed of aluminium coatings has also been investigated by immersion corrosion test and electrochemical impedance spectroscopic techniques. The results show that the cold sprayed aluminium coatings revealed a lower porosity and higher corrosion resistance with the decreasing scanning speed and the increasing temperature of working gas. The porosity and corrosion current densities were 0.938 vol.% and 2.427 ⋅ 10⁻⁶ A/cm². The experimental results show that the aluminium coating prepared by cold spraying has a good protective effect on magnesium alloy.     

锌粉特性对机械镀锌层性能的影响

通过OLYMPUS-GX51型光学显微镜进行机械镀层金相组织检测和厚度测量、划线和划格试验及按GB/T 3091-2001 要求的硫酸铜溶液腐蚀试验,研究了锌粉粒度及形状对机械镀锌层性能的影响.试验表明:在相同机械镀锌工艺规范下,320目颗粒状锌粉镀层颗粒粗大且不均匀,厚度范围33～55 mm,500目颗粒状锌粉镀层不及500目片状锌粉镀层致密,厚度范围45～58 mm,500目片状锌粉镀层最致密颗粒分布也最均匀,厚度范围33～41 mm; 320目颗粒状锌粉、500目颗粒状锌粉、500目片状锌粉机械镀锌层与钢铁基体之间附着强度均达到有关国家标准;均匀性均达到GB/T 3091-2001要求;锌粉粒度越小对应其镀层耐蚀性及均匀性也越好;在相同粒度尺寸下(500目锌粉),片状锌粉比粒状锌粉的镀层具有更好的耐腐性.     

M38合金表面防护涂层的热腐蚀行为

通过粉末包埋渗的方法在M38高温合金表面制备了4种改性铝化物涂层：NiCr-CrAI、Al-Si、Al-Ti和Co-Al涂层,对比研究了4种涂层在900℃下的涂盐（25％NaCl＋75％Na2SO4质量分数）热腐蚀行为。结果表明,4种改性的铝化物涂层中Al-Ti涂层抗热腐蚀性最好,腐蚀产物连续、致密;Al-Si涂层与Al-Ti涂层抗热腐蚀性相当,但腐蚀表面有局部剥落现象、氧化较严重;Co-Al涂层和NiCr—CrAl涂层抗热腐蚀性能依次降低,其中Co-Al涂层裂纹较严重,NiCr-CrAl涂层氧化较严重。     

Corrosion behaviour of hot dip zinc and zinc-aluminium coatings on steel in seawater

A comparative investigation of hot dip Zn-25Al alloy, Zn-55Al-Si and Zn coatings on steel was performed with attention to their corrosion performance in seawater. The results of 2-year exposure testing of these at Zhoushan test site are reported here. In tidal and immersion environments, Zn-25Al alloy coating is several times more durable than zinc coating of double thickness. At long exposure times, corrosion rate for the Zn-25Al alloy coating remains indistinguishable from that for the Zn-55Al-Si coating of similar thickness in tidal zone, and is two to three times lower than the latter in immersion zone. The decrease in tensile strength suggested that galvanized and Zn-55Al-Si coated steel suffer intense pitting corrosion in immersion zone. The electrochemical tests showed that all these coatings provide cathodic protection to the substrate metal; the galvanic potentials are equal to −1,050, −1,025 and −880 mV (SCE) for zinc, Zn-25Al alloy and Zn-55Al-Si coating, respectively, which are adequate to keep the steel inside the immunity region. It is believed that the superior performance of the Zn-25Al alloy coating is due to its optimal combination of the uniform corrosion resistance and pitting corrosion resistance. The inferior corrosion performance by comparison of the Zn coating mainly results from its larger dissolution rate, while the failure of the Zn-55Al-Si coating is probably related to its higher susceptibility to pitting corrosion in seawater.     

Zur Bewertung von Schutzschichten gegen Heißgaskorrosion an Gasturbinenschaufeln

On the Assessment of Protective Coatings to combat Hot Gas Corrosion on Gas Turbine Blades . Turbine blades of aero-engines are normally protected from hot gas corrosion by means of aluminium diffusion coatings. The inherent negative results of these coatings – the resistance to corrosion gains with the growing thickness of the coating, but the strength generally suffers – calls for an optimum balance between resistance to hot gas corrosion and resistance to mechanical stresses for a maximally long life of the blades. Conventional criteria – chiefly that of the progress of corrosion – not being adequate for a reliable assessment of the potential gain, it is recommended that creep and fatigue tests using simultaneously superimposed corrosion be employed for evaluating protective coatings. Tests conducted at faithfully simulated service conditions on samples and blades in cast nickel material IN 100 show how increasing thickness will cause the fatigue strength and the ductility of the coating to be reduced at a more or less rapid rate. The tests suggest the conclusion that conventional coating parameters still need improving if the optimum balance between resistance to hot gas corrosion and resistance to mechanical stresses shall be gained. The still small number of tests conducted cannot provide conclusive evidence. This paper is nevertheless published in the hope that it will invite in-depth studies of the problem of high temperature protective coatings under the additional aspect of true-to-life mechanical stresses.     

Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

Cu–Al₂O₃ nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.     

Cr-Fe-ZrO2复合镀工艺效果探讨

目前,国内外尚未见有关Cr-Fe-ZrO2复合镀层制备的报道。介绍了Cr-Fe-ZrO2复合镀的工艺技术,研究了阴极电流密度、镀液温度、镀液pH值及电沉积时间对复合镀层厚度和外观的影响。利用扫描电镜观察了镀层的表面形貌,用能谱分析了复合镀层的成分,测试了复合镀层与基体的结合力和耐蚀性能。结果表明:当阴极电流密度为14 A/dm2、镀液温度为25℃、pH值为2.0、电沉积30 m in时,可以获得光亮、准镜面、厚度约7.5μm的复合镀层;镀层与基体结合良好,耐腐蚀性好;镀液稳定性较好,静置360 d后电镀的重现性能较好。     

铝合金表面等离子体电解氧化陶瓷涂层在NaCl溶液中的电化学阻抗谱研究

通过调整电解液中硅酸钠的浓度, 利用等离子体电解氧化(PEO)技术在铝合金LY12表面制备了各种陶瓷涂层, 利用光学显微镜、XRD、电化学阻抗谱(EIS)对涂层的形貌、成分和涂层在NaCl溶液中耐腐蚀性能进行了研究. 结果表明: 提高电解液中硅酸钠的浓度可以使得涂层的总厚度增加, 但过高或过低的浓度都会导致致密层厚度的减薄. 当浓度为20g/L时, 所制备的涂层的成分以氧化铝为主; 当浓度为40g/L时, 涂层的成分主要是莫来石和氧化铝; 当浓度超过60g/L 时, 涂层的成分主要为非晶相. EIS的研究表明, 涂层耐腐蚀性取决于涂层中的致密层, 增加致密层的厚度可以提高PEO涂层的耐腐蚀性, 在中性、酸性、碱性腐蚀介质中, PEO涂层都显示出对基体良好的保护作用.     

工艺方法对热浸镀铝层质量的影响

通过目视检查、硝酸腐蚀失重法、中性盐雾腐蚀试验和镀层显微分析等手段,研究了一浴法、二浴法及钝化法工艺对钢材热浸镀铝镀层质量的影响,从镀层厚度、连续性、耐蚀性和显微组织形貌几个方面进行了分析比较.结果表明:二浴法的镀层质量最好,耐腐蚀性最佳.钝化法的镀层耐腐蚀性最差.     

High Corrosion-Resistance Double-Layer Ni-P Coating on Steels

Double-layer Ni-P alloy coating with a thickness about 20 μm and different Ni-P layers was prepared by electroless deposition and its corrosion resistance was studied. The microstructure and corrosion-resistance of the coatings were analyzed by SEM, XRD, electrochemical polarization measurements and salt spray tests. The salt spray tests showed that the double-layer coating exhibits better corrosion resistance. The time of the emergence of the first red rust spot on the coating surface can reach 384 hours, and the gray rusts were firstly emergered during the salt spray tests. The electrochemical analysis revealed that the difference in the corrosion potential between the double layers plays a very important role in protecting the substrate from rusting.     

氧气流量对LY12铝合金微弧氧化膜致密性的影响

通过调整工艺参数与氧气流量在LY12铝合金表面获得均匀、致密的微弧氧化膜层。利用SEM、XRD及电化学工作站等研究膜层的厚度、微观形貌、相组成以及耐腐蚀性能,讨论通氧微弧氧化作用机制,并分析氧气流量对膜层致密性的影响。结果表明:膜层厚度随电压、氧化时间和电解液组分浓度的增加呈规律性变化;氧气的助烧结作用能促进致密层的生长,随着氧气流量的增加,致密层厚度呈现先增加后减小的规律;KF 105g/L,KOH 85g/L,NaAlO_2 12g/L,电压110V,氧化时间15min,氧气流量为0.010L/s时得到厚度30μm的致密膜层,自腐蚀电位提高至-0.11V,腐蚀电流密度下降至2.1×10^-6A/cm^2,比铝合金基体降低2个数量级以上,表现出良好的耐腐蚀性。     

热输入量对HVOF铁基非晶涂层制备及性能的影响

目的以FeCoCrMoCBYS非晶粉末为喷涂材料,采用几组不同的热输入量,使用超音速火焰喷涂(HVOF)制备成铁基非晶涂层,通过对涂层性能进行分析,研究热输入量对涂层的影响。方法通过调整煤油流量和氧气流量两个参数来控制喷涂时的热输入量。分别利用扫描电镜(SEM)、X射线衍射分析仪(XRD)、差示扫描量热仪(DSC)、维氏显微硬度计等设备,研究热输入量对涂层显微组织和显微硬度的影响,并通过电化学工作站测试涂层在1 mol/L FeCl_2溶液中的极化曲线进而分析其耐蚀性能。结果不同热输入量下制备的涂层均具有较高的非晶含量。保持其他参数不变,随着热输入量的增加,涂层变得更加致密,孔隙率最小达到1.56%。涂层显微硬度先增大后减小,涂层横截面中部位置硬度大于表面和接近基体位置。结论当热输入量达到6.4×10~5 J时,非晶含量高达96.7%,自腐蚀电流密度低,耐腐蚀性最好。     

冷喷涂Al基复合涂层的制备及耐蚀性能研究

铝合金以其轻量化特性及优异的耐腐蚀性能得到广泛应用.冷喷涂技术具有低温高速沉积的特点,是制备铝防腐涂层的有效方法.采用机械混合的方式制备了铝基-陶瓷相混合粉末,并通过冷喷涂在Al1060表面制备了Al5056,Al5056-Al2O3,Al5056-SiC,Al5056-WC 4种涂层.通过 Image-Pro Plu...     

新型Mg-Zn-Y-Nd-Zr镁合金表面复合涂层的耐腐蚀性能

为了控制镁材及镁合金在人体中的生物降解速率,采用微弧氧化法、电化学沉积法及微弧氧化+电化学沉积法在新型Mg-Zn-Y-Nd-Zr镁合金表面制备了3种涂层。利用JSM-5610V扫描电子显微镜、TESCANTS5130 SB能谱分析仪、Bruker D8 ADVANCE X射线衍射仪、VS-2005涂层附着力自动划痕仪、RST200F电化学工作站对3种涂层的形貌、成分、结构、厚度、结合力以及电化学性能进行了检测。结果表明:3种涂层均能提高新型Mg-Zn-Y-Nd-Zr镁合金的电化学性能,改善其耐蚀性;微弧氧化+电化学沉积层较单一微弧氧化层及电化学沉积层在致密性、结晶度、厚度、结合力、耐腐蚀性能方面都具有更强的指标。     

Entwicklung hochverschleißbeständiger wolframschmelzkarbidbasierter Schichten auf Aluminiumbauteilen durch Plasma‐Pulver‐Auftragschweißen

Development of high wear‐resistant FTC‐based coatings on aluminium components using plasma transferred arc welding Nowadays, functional surfaces of components can be effectively protected from extreme wear with the help of fused tungsten carbide (FTC) coatings. The wear protection of steel components using FTC has been well known for many years. This paper presents the feasible study of improving the wear resistance of aluminium components with FTC particles using plasma powder arc welding. The FTC coatings are developed with two methods: one is the dispersion of carbide particles in aluminium and the other one is the combination of dispersing and alloying of FTC‐based composite powders. In this research, coatings within a thickness range of a few millimeters are developed with varying process parameters and compositions of the filler materials. The developed coating systems are tested with regard to their specific properties and their wear resistance. Finally, their application potential is presented.     

物理气相沉积技术制备的硬质涂层耐腐蚀的研究进展

根据物理气相沉积技术制备的硬质涂层的腐蚀机制，指出提高硬质涂层的抗腐蚀性能的关键在于提高涂层的致密性和涂层/基材界面的性能，对提高硬质涂层耐蚀性的各种措施分别予以评述，提出了今后的研究方向。     

Characterization and comparison between APS coatings prepared from ball milled and plasma processed nickel–aluminium powders

Plasma spraying has wide range of applications which include corrosion, thermal and abrasion resistance coatings. In the present work, nickel and aluminium powders were ball milled and the same were thermal plasma processed to produce spherical nickel alumindes particles. Both ball milled and plasma processed powders were spray deposited on stainless steel (SS 304) substrate using atmospheric plasma spray technique (APS). The experiments were carried out for different plasma input power levels, torch to base distances and coating thicknesses. Microstructure, micro hardness, adhesive strength, and porosity of the coatings are reported and discussed. Effect of plasma processing parameters and plasma spheroidization of powders on coating properties has been evaluated and reported. High plasma power, low torch to base distance lead to high temperature supplied to in-flight particles which correspond to high hardness, low porosity and high adhesion. Spherical morphology and formation of nickel aluminide intermetallic were achieved by plasma spheroidization. Coatings prepared from plasma processed powders enhance the coating properties positively.     

Al-Zn coatings for the corrosion protection of steel

Aluminum coatings have been reported to be the most suitable for replacing toxic cadmium for the protection of steel and titanium alloys against corrosion. The relatively poor galvanic corrosion protection of aluminium coatings, however, has led to a search for a more effective coating. To this end, pure aluminium and controlled-composition Al-Zn alloy coatings were ion plated onto steel substrates. Over a range of coating conditions the aluminium and the Al-Zn alloy coatings have very similar columnar structures. They were equally successful in protecting the underlying steel. However, a simulation of the coating damage by masking the steel substrate during plating showed the galvanic corrosion protection of Al-2.5%Zn alloy coatings to be superior to that of aluminium. It is probable that this very effective sacrificial corrosion protection means that the structure of the coating is relatively unimportant and that excellent galvanic corrosion protection can be provided by low density columnar structure coatings of Al-Zn alloys.     

Effects of aluminum content and mechanical nano-alloying time on the preparation of titanium-aluminum composite coatings on magnesium-lithium alloy

A titanium-aluminum composite coating was successfully fabricated on magnesium-lithium alloy substrate by mechanical nano-alloying treatment (SMNAT). The effects of aluminum content and mechanical nano-alloying time on the microstructure and properties of titanium-aluminum composite coatings were investigated. The experimental results showed that the ratio of titanium-aluminum powder has a significant effect on the preparation of the coating. Low aluminum content and high aluminum content in the mixture powder resulted in the formation of the coatings with inhomogeneous thickness. The titanium-aluminum ratio of 3 : 1 was considered to be optimal for fabricating the coating with homogeneous thickness under the selected milling parameters. The hardness of top surface layer on titanium- aluminum coatings decreased from 292.0 HV 0.01 to 121.4 HV 0.01 with the increase of aluminum content. Additionally, the prolongation of treatment time facilitated to increase the thickness and density of the coatings, resulting to enhance their hardness and corrosion resistance.