共查询到20条相似文献,搜索用时 15 毫秒
1.
利用磁控溅射的方法在Ti_3Al合金上溅射Ti-48Al-8Cr-2Ag (原子分数/%)涂层,研究涂层对Ti_3Al合金熔盐热腐蚀和电化学腐蚀行为的影响.同时通过TEM,SEM,EDX,电化学工作站对合金的腐蚀进行研究,并对腐蚀机理进行探讨.结果表明:在熔盐热腐蚀中,涂层对基体具有很好的防护作用,这主要是因为Ti_3Al合金表面发生了大面积的脱落,而涂层试样表面腐蚀膜结合牢固.经过电化学腐蚀研究,涂层试样表面发生明显的分级钝化现象,表明涂层在Na2SO4+K2SO4溶液中具有很好的钝化性能,显示了很好的抗电化学腐蚀性能. 相似文献
2.
DongbaiXIE FhhuiWANG 《材料科学技术学报》2003,19(6):567-570
The oxidation and hot corrosion behavior of Co-Ni-Cr-Al-Ta-Y coating produced by magnetron sputtering with and without enamel coating has been investigated in air at 900℃ and in molten 75 wt pct NaCl 25 wt pct Na2SO4 at 850℃. The results show that the enamel coating possesses good hot corrosion resistance in the molten salts, in comparison with the sputtered Co-Ni-Cr-Al-Ta-Y coating. In the hot corrosion test, breakaway corrosion did not occur on the samples with enamel coating and the composition of enamel coating did not significantly change either. The oxidation resistance of the sputtered coating, which offers good adhesion, can be improved by the enamel coating. 相似文献
3.
Magnetron-sputter deposition was used to produce a Ti-48Al-8Cr-2Ag (at.%) coating on a cast alloy substrate with the same
composition. The oxidation behaviour of the cast Ti-48Al-8Cr-2Ag alloy and its sputtered coating was investigated in air at
1000°C. The resulting scale structures were analyzed in great detail by scanning electron microscopy (SEM) and transmission
electron microscopy (TEM). The nanocrystalline coating showed higher oxidation rate than the cast alloy, because an outer
TiO2 layer formed over a finegrain Al2O3 scale on the coating. The oxidation mechanism was discussed. 相似文献
4.
The effect of sputtered Ti-50Al-10Cr and Ti-50Al-20Cr coatings on both isothermal and cyclic oxidation resistance at 800 similar to 900 degreesC and hot corrosion resistance at 850 degreesC of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800 similar to 900 degreesC and poor hot corrosion resistance due to the spallation of scales formed in Na2SO4+K2SO4 melts at 850 degreesC. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy. 相似文献
5.
探究Ti-48Al-2Cr-2Nb合金钝化膜的耐腐蚀性和形成机理对提高电解加工过程中的抗杂散腐蚀具有重要意义。通过极化曲线确定了Ti-48Al-2Cr-2Nb合金的钝化电位,采用X射线光电子能谱确定了钝化膜的成分与结构,并运用电化学阻抗谱和Mott-Schottky理论分析了钝化膜的电化学性能。结果表明,Ti-48Al-2Cr-2Nb合金在NaNO3电解液中钝化电位区间为0.079~1.896V,钝化膜主要成分为Al2O3、TiO2及少量的Nb2O5,呈双层多孔结构,具有良好的耐腐蚀性。钝化膜具有n型半导体特性,载流子密度随钝化电位的增加而降低。最后,构建了钝化膜形成示意图,揭示了Ti-48Al-2Cr-2Nb合金钝化膜的形成机理与成相膜理论相符,以半球体模型延展并形成独立的相。 相似文献
6.
Microstructures and room-temperature tensile properties of isothermally-forged γ-base (γ + α2)alloys in Ti-Al-Nb-Cr-V system with different heat treatments were investigated. The results show that the microstructures of Ti-47Al-2Nb-1Cr-1V and Ti-47Al-2V-1Cr (at. pct) alloys are mainly determined by heat treating temperature in the (cr + 7) tWo-phase field, and the joint additions of Nb, Cr and V in the Ti-47Al alloy afFect Ta significantIy. The microstructure of Ti-47Al alloy with additions of Nb, Cr and V (1~2 at. pct) can be dupIex or nearly-lamellar by a suitable heat treatment after isothermal forging at 1000℃ for over 50% plastic strains.Therefore its tensile properties can be improved at room temperature. 相似文献
7.
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。 相似文献
8.
The growth mechanisms of the oxide scales of Ti-50Al and Ti-45Al-8Nb (at%) alloys at 900°C in air were investigated. The results revealed that the oxidation of γ-TiAl alloys during experiments was divided into four stages. The Ti-50Al alloy showed severe spallation after 3 h of oxidation. Nb addition to γ-TiAl alloys could improve the oxidation resistance effectively. The oxide scale growth was much slower and every oxide layer was more chemically uniform and homogeneous with Nb addition. The Ti-45Al-8Nb alloy showed no spallation even after 100 h of oxidation. 相似文献
9.
1. IntroductionNi-base superalloys are the important materialsused at high temperature and greatly rely on the presence of Cr and/or Al to form a protective scale ofCrook or Allot. Therefore, the investigation of oxidation of the simple Ni-Cr-Al ternary alloys is beneficial to the understanding of oxidation patterns of complex Ni-base superalloys. Some works have been conducted on the Ni-Cr-Al alloys with normal grain sizeand the results indicated that different oxides couldbe formed accor… 相似文献
10.
Rosalbino F Delsante S Borzone G Scavino G 《Journal of materials science. Materials in medicine》2012,23(5):1129-1137
Titanium alloys exhibit excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film,
and some of these alloys (particularly Ti-6Al-7Nb) have been chosen for surgical and odontological implants for their resistance
and biocompatibility. Treatment with fluorides (F−) is known to be the main method for preventing plaque formation and dental caries. Toothpastes, mouthwashes, and prophylactic
gels can contain from 200 to 20,000 ppm F− and can affect the corrosion behaviour of titanium alloy devices present in the oral cavity. In this work, the electrochemical
corrosion behaviour of Ti-1M alloys (M = Ag, Au, Pd, Pt) was assessed in artificial saliva of pH = 3.0 containing 910 ppm
F− (0.05 M NaF) through open circuit potential, EOC, and electrochemical impedance spectroscopy (EIS) measurements. The corrosion behaviour of the Ti-6Al-7Nb commercial alloy
was also evaluated for comparison. E
OC measurements show an active behaviour for all the titanium alloys in fluoridated acidified saliva due to the presence of
significant concentrations of HF and HF2
− species that dissolve the spontaneous air-formed oxide film giving rise to surface activation. However, an increase in stability
of the passive oxide layer and consequently a decrease in surface activation is observed for the Ti-1M alloys. This behaviour
is confirmed by EIS measurements. In fact, the Ti-6Al-7Nb alloy exhibits lower impedance values as compared with Ti-1M alloys,
the highest values being measured for the Ti-1Au alloy. The experimental results show that the corrosion resistance of the
studied Ti-1M alloys is similar to or better than that of Ti-6Al-7Nb alloy currently used as biomaterial, suggesting their
potential for dental applications. 相似文献
11.
H. L. Du P. K. Datta J. S. Burnell-Gray D. B. Lewis 《Journal of Materials Science》1995,30(10):2640-2647
The environmental response of Nb-coated Ti and Ti-6Al-4V alloy was studied at 750 °C in an atmosphere of pS2 ∼ 10−1 Pa and pO2 ∼ 10 −18 Pa. By acting as a diffusion barrier and through the formation of a Nb1−xS scale the Nb coating deposited enhanced the corrosion resistance of both Ti and Ti-6Al-4V alloy. The corrosion products
generated on uncoated titanium in the same environment and temperature were characterized by a double layered oxide scale
of TiO2 beneath which a TiS2 layer was formed. For the Ti-6Al-4V alloy, α-Al2O3 was precipitated in the external portion of the outer-layer of TiO2 whilst a layer containing Al2S3, TiS2 and vanadium sulphide (possibly V2S3) was idenitified underlying the inner TiO2 layer. After prolonged exposure (168 h), the Nb coating deposited on Ti and Ti-6Al-4V alloy was consumed. A scale following
the sequence of TiO2/TiO2+NbO2+Nb2O5/Nb1−xS/TiO2/ TiS2/(substrate) was observed on the surface of the Nb-coated Ti, whilst a scale with sequence of TiO2/V2S3/TiO2+NbO2+Nb2O5/Nb1−xS/TiO2/Al2S3+TiS2/(substrate) characterized the corrosion products formed on the Nb-coated Ti-6Al-4V alloy. 相似文献
12.
采用线性扫描(LSV)、计时电流法(CA)、电化学阻抗谱(EIS)和表面观察等方法,研究Ti-48Al-2Cr-2Nb合金在NaNO_3(质量分数为20%)溶液中高电位(7 ~16 V)电化学腐蚀行为以及外加电位对腐蚀行为的影响。阻抗谱数据采用Maxwell传输线模型进行拟合。结果表明:电流密度随着电位的增加波动变大,样品均经历了非均匀腐蚀到均匀腐蚀的过程;腐蚀后吸附反应的个数从腐蚀前的7个减少为5个;样品腐蚀后的总腐蚀抗力与总时间常数的下降均随着电位增加经历先增加后减少的过程,腐蚀粗糙程度的增加是先迅速下降然后趋于平稳。 相似文献
13.
M. M. Lachowicz K. Haimann M. B. Lachowicz R. Jasionowski S. Pawlak 《Materials Science-Poland》2012,30(3):217-225
This paper presents the results of investigation of four cast alloys based on the Fe3Al intermetallic phase. Microstructure tests using light microscopy, electron scanning microscopy and X-ray diffraction methods, have been performed. On this basis, a presence of particles rich in zirconium and molybdenum, and in case of the alloy with 28 at.% aluminium and 5 at.% chromium ?? the presence of sigma phase (FeCr), has been found. Also, the results of the study of the microstructure influence on the electrochemical corrosion resistance in the 5 % NaCl solution have been presented. The Fe-26Al-2Cr-1Mo-0.1Zr-0.005B at.% and Fe-26Al-5Cr-1Mo-0.1Zr-0.005B at.% alloys exhibited increased corrosion resistance in comparison to the Fe-23Al-1Mo-0.1Zr-0.005B at.% alloy without chromium addition. The appearance of the sigma phase in the alloy of Fe-28Al-5Cr-1Mo-0.1Zr-0.005B at.% chemical composition resulted in lowering the corrosion resistance of this alloy and a change in corrosion character from the pitting to the intercrystalline one. 相似文献
14.
化学热处理表面改性对TiAl基合金抗高温氧化性能的影响EI 总被引:1,自引:1,他引:0
研究了渗碳处理对Ti-48Al-2Cr-2Nb(at.%)合金高温循环氧化性的影响。试验发现,表面渗碳处理能够显著地改善TiAl基合金抗高温氧化能力。使用SEM、波谱分析、能谱分析和X射线衍射分析,研究了渗碳处理提高TiAl基合金抗高温氧化性能的机理。 相似文献
15.
选用适量的Ni,Cr,Mo和Nb的配比,在20钢表面超音速火焰喷涂了Ni-Cr-Mo-Nb合金层,以期提高其耐蚀性。采用XRD,SEM/EDS技术对Ni-Cr-Mo-Nb合金层及其高温腐蚀产物成分、形貌进行了分析;对Ni-Cr-Mo-Nb合金层涂覆75%Na_2SO_4+25%NaCl(质量分数)混合熔盐后于600,650℃烟气中的热腐蚀行为进行了研究。结果表明:Ni-Cr-Mo-Nb合金层结构致密,孔隙率低;Ni-Cr-Mo-Nb合金层在涂覆75%Na2SO4+25%Na Cl盐膜后的烟气中600,650℃时先增重后失重,其腐蚀产物分为2层,外层富含Ni,内层富含Cr且S含量较高,具有良好的耐蚀性能。 相似文献
16.
17.
Magnetron-sputter deposition was used to produce a Ti–48Al–8Cr–2Ag (at. %) coating on a Ti–24Al– 17Nb–0.5Mo (at. %) alloy
substrate. Oxidation behavior was studied in air at 900–1000°C. The results indicated that the oxidation rate of sputtered
Ti–48Al–8Cr–2Ag nanocrystalline coating was lower than that of the Ti3Al alloy at 900°C. The former formed a scale of merely Al2O3, and the latter formed a scale of TiO2. However, the Ti–48Al–8Cr–2Ag nanocrystalline coating showed a little bit higher oxidation rate than Ti3Al alloy at 1000°C because the outer TiO2 scale formed and columnar boundaries of the coating gave a larger actual oxidation area than the original alloy. The electrochemical
corrosion behavior was investigated in a 3.5% NaCl solution at room temperature. The coating showed excellent electrochemical
corrosion resistance in 3.5% NaCl solution because it exhibited stable passive polarization behavior without any overpassivation
phenomena. 相似文献
18.
搪瓷涂层对Ti-24Al-14Nb-3V抗氧化及热腐蚀性能的影响 总被引:7,自引:0,他引:7
研究了搪瓷涂层对Ti-24Al-14Nb-3V抗高温氧化及热腐蚀性能的影响.结果表明,在900℃下,由于搪瓷涂层具有较高的化学稳定性,且和Ti-24Al-14Nb-3V有比较接近的热膨胀系数,大大改善了Ti-24Al-14Nb-3V抗恒温氧化及循环氧化性能.在850℃(Na,K)2SO4中,虽然熔盐中的Na+与搪瓷涂层中的Ca2+进行离子交换引起搪瓷涂层少量减重,但它仍具有优异的抗熔融硫酸盐腐蚀能力.在850℃NaCl+Na2SO4中,搪瓷涂层对Ti-24Al-14Nb-3V具有一定的保护作用,但是由于熔盐中的Na+与搪瓷涂层中的Ca2+进行离子交换,和熔盐中的Cl-对搪瓷涂层的腐蚀作用及对基材的点蚀作用,使其保护作用下降. 相似文献
19.