电弧喷涂Al-Zn-Si-RE合金涂层在3.5%NaCl溶液中的电化学腐蚀行为(英文)

采用电弧喷涂方法在低碳钢表面获得高铝含量的Al-Zn-Si-RE涂层。通过测量Al-Zn-Si-RE涂层在3.5%NaCl溶液中的动电位极化曲线,腐蚀电位-时间曲线和电化学阻抗谱,系统地研究涂层的电化学腐蚀行为。通过将测量电化学阻抗谱拟合成等效电路图,研究涂层在3.5%NaCl溶液中浸泡不同时间的阻抗行为。结果表明:Al-Zn-Si-RE涂层与Zn-15Al涂层具有相似的极化行为,阳极极化曲线均无钝化特征,仅呈现出活性溶解,但其腐蚀性能优于Zn-15Al涂层。Al-Zn-Si-RE涂层可以给钢基体提供有效的牺牲阳极保护作用,且牺牲阳极保护作用在涂层腐蚀过程中占主导地位。此外,腐蚀电位-时间曲线和电化学阻抗谱结果表明:在浸泡过程中存在点蚀-溶解-再沉积、活化溶解、阴极保护、腐蚀产物引起的物理屏蔽和涂层失效五个腐蚀阶段。     

氯化物熔盐对Ti_3Al基合金表面Cr_(0.82)Al_(0.18)N涂层热腐蚀行为影响(英文)

为了研究氯化物熔盐对Cr-Al-N涂层热腐蚀性能的影响,采用反应磁控溅射的方法在Ti3Al合金表面制备了Cr0.82Al0.18N涂层,研究了涂层在Na2SO4+25%K2SO4和Na2SO4+25%Na Cl(质量分数)2种熔盐中的热腐蚀行为,采用XRD和SEM分析了涂层热腐蚀产物的相组成和形貌。结果表明:涂层在含有氯化物盐的熔盐中腐蚀时表现为失重而在硫酸盐中腐蚀时表现为增重;Cr0.82Al0.18N涂层在2种熔盐中的腐蚀都主要由Cr2O3和θ-Al2O3组成。氯化物熔盐和腐蚀产物的挥发导致了在含有氯化物熔盐中腐蚀时的失重现象。当含有氯化物盐时会增加熔盐中氧离子的活度,从而加速Cr2O3在熔盐中的溶解。此外,热腐蚀过程中产生的氯气也会参与腐蚀反应,从而加速涂层的消耗。     

Al含量对Zn-Al合金涂层电化学腐蚀行为的影响

采用粉芯丝材和高速电弧喷涂技术制备出15.9％Al、21.1％Al和30.1％Al(质量分数)3种不同Al含量的Zn-Al涂层,使用扫描电镜、能谱仪、X-射线衍射仪等先进手段观察了涂层的组织特征,并研究了Al含量对Zn-Al涂层在5％NaCl溶液中的电化学腐蚀行为的影响.结果表明,3种Zn- Al涂层的组织结构无明显差异,都呈现出典型的层状特征,组织致密,孔隙率均低于3％;3种涂层与基体的平均拉伸结合强度都大于11 MPa,而且随着Al含量的增加涂层结合强度略有增加;随着腐蚀时间的延长,Zn- 15.9Al和Zn-21.1Al涂层的自腐蚀电位和腐蚀电流存在波动,而Zn-30.1Al的白腐蚀电位始终正移、腐蚀电流不断降低,耐腐蚀性能更为优异.     

氧化物陶瓷封孔对热喷涂Inconel 625涂层热腐蚀行为的影响

目的 为了提高热喷涂涂层在苛刻环境下的耐蚀性,采用封孔剂对热喷涂涂层进行封孔,研究封孔对涂层抗热腐蚀性能的影响。方法 采用超音速火焰喷涂在20#钢表面制备Inconel 625涂层。采用正硅酸乙酯作为封孔剂基料,Cr2O3、Al2O3、ZrO2、CeO2等氧化物为填料,制备了封孔剂,采用封孔剂对制备的涂层进行封孔。研究了封孔剂对涂层耐蚀性能的影响,将封孔和未封孔的涂层涂覆75%Na2SO4+25%NaCl混合盐膜后,在650 ℃下进行腐蚀,间隔一定时间取出样品称量,获得腐蚀动力学曲线。采用XRD、SEM、EDS对高温腐蚀产物成分、结构、形貌进行分析。结果 未封孔的Inconel 625涂层腐蚀160 h后增重约4.4 mg/cm2。表面腐蚀产物有双层结构,外层富Ni较疏松、多孔,内层富Cr较为致密。同时涂层/腐蚀层界面一侧有S元素富集。封孔层在高温熔盐中轻微熔解,封孔样品腐蚀160 h后,失重仅约0.45 mg/cm2。在腐蚀过程中Ni通过封孔层向外扩散并被氧化,生成的氧化物可填补封孔层缺陷。涂层/封孔层界面形成富Cr2O3的氧化层,进一步提高了封孔涂层的抗热腐蚀性能。结论 封孔层提高了涂层致密性,能有效抑制腐蚀介质在热喷涂涂层中的扩散,封孔能明显提高Inconel625涂层的抗热腐蚀性能。     

电镀Cr涂层锆合金的腐蚀行为

在360℃、18.5 MPa的超纯水溶液中和高温(1000和1200℃)水蒸气环境中对采用电镀技术制备的Cr涂层锆合金和没有涂层的锆合金进行了腐蚀行为对比研究。结果表明：在上述腐蚀条件下,Cr涂层显著提升了锆合金的耐腐蚀性能,氧化增重显著降低。与没有涂层的锆合金相比,在高温水蒸气环境中腐蚀54 min后,Cr涂层锆合金的氧化增重下降了一个数量级,在高温高压水环境中腐蚀48 h后,其氧化增重下降了75%。腐蚀后,在Cr涂层锆合金表面形成了细长絮状结构;氧化层越靠近样品表面,结构疏松、空洞数量多且尺寸大;而在靠近Cr涂层与氧化层的界面处,结构致密、无明显尺寸空洞。     

(NiCoCrAlYSiB+AlSiY)复合涂层热腐蚀行为的研究

采用电弧离子镀（AIP）技术在镍基单晶高温合金基体上制备了NiCoCrAlYSiB涂层（普通涂层）和（Ni-COCrAlYSiB+AlSiY）复合涂层,研究了高温合金基体与2种涂层分别在900和700℃下的涂盐（Na₂SO₄+K₂SO₄和Na₂SO₄+NaCl）热腐蚀行为.结果表明:高温（900℃）热腐蚀条件下,基体合金表面主要生成NiO;普通涂层表面上要生成Cr₂O₃,而且涂层内部出现内氧化和内硫化现象;复合涂层表面主要生成Al₂O₃,外层出现程度较轻的内氧化,涂层表层Al含量仍然较高,维持表面Al₂O₃膜的形成和修复.低温（700℃）热腐蚀条件下,基体合金表面主要生成NiO;普通涂层表面主要生成Cr₂O₃,涂层内部出现严重的内氧化;复合涂层表面也出现了内氧化,高Cr的内层未受腐蚀,有助于提高涂层的抗腐蚀性能.     

(NiCoCrAlYSiB+AlSiY)复合涂层热腐蚀行为的研究

采用电弧离子镀（AIP）技术在镍基单晶高温合金基体上制备了NiCoCrAlYSiB涂层（普通涂层）和（Ni-CoCrAlYSiB+AlSiY）复合涂层,研究了高温合金基体与2种涂层分别在900和700℃下的涂盐（Na₂SO₄+K₂SO₄和Na₂SO₄+NaCl）热腐蚀行为.结果表明:高温（900℃）热腐蚀条件下,基体合金表面主要生成NiO;普通涂层表面主要生成Cr₂O₃,而且涂层内部出现内氧化和内硫化现象;复合涂层表面主要生成Al₂O₃,外层出现程度较轻的内氧化,涂层表层Al含量仍然较高,维持表面Al₂O₃膜的形成和修复.低温（700℃）热腐蚀条件下,基体合金表面主要生成NiO;普通涂层表面主要生成Cr₂O₃,涂层内部出现严重的内氧化;复合涂层表面也出现了内氧化,高Cr的内层未受腐蚀,有助于提高涂层的抗腐蚀性能.     

Al含量对Zn–Al合金涂层电化学腐蚀行为的影响

采用粉芯丝材和高速电弧喷涂技术制备出15.9%Al、21.1%Al和30.1%Al(质量分数)3种不同Al含量的Zn-Al涂层,使用扫描电镜、能谱仪、X-射线衍射仪等先进手段观察了涂层的组织特征,并研究了Al含量对Zn-Al涂层在5%NaCl溶液中的电化学腐蚀行为的影响。结果表明,3种Zn-Al涂层的组织结构无明显差异,都呈现出典型的层状特征,组织致密,孔隙率均低于3%;3种涂层与基体的平均拉伸结合强度都大于11MPa,而且随着Al含量的增加涂层结合强度略有增加;随着腐蚀时间的延长,Zn-15.9Al和Zn-21.1Al涂层的自腐蚀电位和腐蚀电流存在波动,而Zn-30.1Al的自腐蚀电位始终正移、腐蚀电流不断降低,耐腐蚀性能更为优异。     

Al含量对Zn–Al合金涂层电化学腐蚀行为的影响

采用粉芯丝材和高速电弧喷涂技术制备出15.9%Al、21.1%Al和30.1%Al(质量分数)三种不同Al含量的ZnAl涂层,使用扫描电镜、能谱仪、X射线衍射仪等先进手段观察了涂层的组织特征,并研究了Al含量对Zn–Al涂层在5%NaCl溶液中的电化学腐蚀行为的影响。结果表明,三种ZnAl涂层的组织结构无明显差异,都呈现出典型的层状特征,组织致密,孔隙率均低于3%;三种涂层与基体的平均拉伸结合强度都大于11 MPa,而且随着Al含量的增加涂层结合强度略有增加;随着腐蚀时间的延长,Zn–15.9Al和Zn–21.1Al涂层的自腐蚀电位和腐蚀电流存在波动,而Zn–30.1Al的自腐蚀电位始终正移、腐蚀电流不断降低,耐腐蚀性能更为优异。     

纳米晶涂层对DD98M合金热腐蚀行为的影响

为了研究纳米化对DD98M合金热腐蚀行为的影响,采用磁控溅射的方法制备了与其成分相同的纳米晶涂层。运用XRD、SEM/EDS、TEM分别分析了涂层的结构和热腐蚀性能。结果表明:沉积态的纳米晶涂层呈柱状晶结构,有大量沿沉积方向的柱状晶界,晶粒宽度为30~100 nm。涂层为单一的γ相且具有明显的(111)择优取向。在900℃Na_2SO_4+25%K_2SO_4以及Na_2SO_4+25%Na Cl盐中,DD98M合金在5 h内就发生了严重腐蚀。纳米晶涂层在熔融Na_2SO_4+25%K2SO4中表现出了良好的热腐蚀性能,但在Na_2SO_4+25%Na Cl盐中,纳米晶及其预氧化涂层对DD98M合金的抗热腐蚀性能的提高并不明显。纳米晶促进了涂层表面Al_2O_3膜在空气中和熔融Na_2SO_4+25%K2SO4盐中的快速形成,显著提高了DD98M合金在硫酸盐中的抗热腐蚀性能,预氧化处理则使涂层的抗热腐蚀能力进一步提高。     

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al–14.5%Zn–0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silicon sealing material shows the best anti-cavitation characteristics.     

Effects of thickness of Al thermal spray coating for STS 304

Thermal spray coating presents a sacrificial-anode cathodic protection method since differences between the potentials of materials are employed. If a base metal is exposed to seawater, due to defect in the thermal spray coating, the metal is protected by the sacrificial anodic characteristics of the coating layer because micro-cells formed by the base metal and the thermal spray coating act as cathodes and anodes, respectively. The coating thickness has little effect on the surface morphology of the coating. However, the electrochemical properties with the increasing of coating thickness present good results.     

Microstructure characteristics of coating with amorphous phases prepared from Fe-based alloy powders by plasma spray

In this paper, alloy powders mixed with a molar ratio of Fe ： P ： C of 80 ： 13 ： 7 were sprayed on Q235 steel by plasma spray method to prepare coating with amorphous phases. The phase composition of the mixed alloy powders and prepared coating were characterized by X-ray diffraction （ XRD ）. The morphology and the composition cf the coating were analyzed by scanning eleetron microscopy （SEM） nnd energy dispersive apectroscopy （ EDS ）. In addition, the thermal stability ef the coating with amorphous phases was characterized by differential thermal analyzer （ DTA ）. Tile results showed that, usirtg mixed alloy powders with a molar ratio of Fe： P： C of 80：13：7, the coating containing certain amount of amorphous alloys was suceessathlly prepared through atmospheric plasma spray technique. In the coating, the main phases were determined to be Fe, FeP aad Fe2P. The crystallization of the coating started from about 461°. Tile coating was mechanically adhered to the substrate.     

热喷涂技术替代电镀硬铬的研究进展

从热喷涂技术的发展,高速火焰喷涂(HVOF)涂层的性能,包括耐磨性、耐蚀性、对基体耐疲劳性的影响,热喷涂涂层替代电镀硬铬镀层的成本以及应用4个方面综述了近年来热喷涂技术替代电镀硬铬的研究进展.指出热喷涂技术已经在航空、冶金、包装印刷和造纸等工业领域部分替代了电镀硬铬工艺;由于热喷涂技术对于大工件、厚涂层在性能和价格上的优势,热喷涂技术在其他工业领域的应用也将得到迅速发展.     

触变注射成形Mg-9%Al-1%Zn合金组织特性和凝固行为

为了研究触变注射成形AZ91D合金中固相颗粒的形貌演变和液相的凝固行为,对该合金的组织和凝固行为进行了试验观察和理论分析。典型触变注射成形AZ91D合金由α-Mg和β-Mg17Al12两相构成,α-Mg相又可分为未熔固相和初生固相。未熔固相主要有形貌较为接近球状的固相、形貌不规则的固相、内部含有小液池的固相以及包裹液相的固相4种形貌。形貌不规则的固相被认为是球状固相和包裹液相的固相的中间发展形貌,内部含有小液池的固相可能是包裹液相的固相的初级形貌,包裹液相的固相则可能发生破裂形成不规则固相,最终发展成球状固相。球状固相被认为是最理想的也是最终的固相形貌。初生固相在液相合金中形核并长大,直至有不稳定长大行为发生为止,较为细小、圆整,主要受冷却速率的影响。Mg-Al合金二元相图的分析结果与试验观察到的组织相吻合。     

Salt spray corrosion test of micro-plasma oxidation ceramic coatings on Ti alloy

Ceramic coatings were prepared on Ti-6Al-4V alloy in NaAlO2 solution by micro-plasma oxidation (MPO). The salt spray teste of tne coated samples and the substrates were carried out in a salt spray test machine. The phase composition and surface morphology of the coatings were investigated by XRD and SEM. Severe corrosion occurred on the substrate surface, while there were no obvious corrosion phenomena on the coated samples. The coatings were composed of Al2TiO5 and a little α-Al2O3 and rutile TiO2, and the salt spray test did not change the composition of the coatings. The weight loss rate of the coatings decreased with increasing MPO time because of the increase in density and thickness of the coatings. The surface morphology of the coatings was influenced by salt spray corrosion test Among the coated samples, the coating prepared for 2 h has the best corrosion resistance under salt spray test.     

热喷涂制备非晶合金涂层的研究状况

非晶合金是一种极具发展潜力的新兴金属材料.用热喷涂方法制备非晶合金涂层是将非晶推向工程应用的有效方法.从分析非晶合金及其制备特性入手,阐述了非晶合金热喷涂涂层的特性及目前制备非晶合金涂层的两类热喷涂技术路线,展望了热喷涂制备非晶合金涂层未来的发展趋势.     

Surface characteristics of chemical conversion coating for Mg-Al alloy

The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component. The film formed at 298 K was thick, which was thought to be the combination of Si and O. In salt spray test, the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated specimen. The film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.     

元素扩散对镍基合金涂层热疲劳性能的影响

利用热喷涂技术在铜合金表面制作了镍基合金涂层.通过金相显微镜、扫描电镜分析研究了涂层界面显微结构和元素扩散情况及对涂层的抗热疲劳性能的影响.结果表明,合金元素在涂层/基体界面附近连续分布,并在涂层/基体界面呈陡然变化.热处理时涂层/基体界面区出现互扩散层,温度和时间的增加可以改善Cu元素向涂层扩散的能力,整个热处理过程中温度是主要因素,时间是次要因素,元素扩散提高了镍基合金涂层的抗热疲劳能力,使得涂层在550 ℃试验条件下,经85次热循环后未出现裂纹扩展及剥落现象.