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1.
Two surface treatments, molybdenizing and depositing NiCrAIY coating, were applied to improve the microhardness and the oxidation re-sistance of titanium and Ti-6Al-4V. Coupons were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Vickers hardness and isothermal oxidation tests were carded out to evaluate the effects of these two surface treatments on the microhardness and oxidation resistance of the substrates. The post vacuum heat treatment of the NiCrAlY coating and the molybdenizing parameters were also discussed. It is found that molybdenizing can obviously in-crease the surface hardness of titanium due to the formation of β,α", and α' phases in the diffusion layer. As γ' phase is formed after vacuum heat treatment, the NiCrAIY coating is effective in improving the surface hardness of Ti-6Al-4V. The NiCrAlY coating can obviously de-crease the oxidation rate of Ti-6Al-4V at 700-900℃, which can be attributed to the formation of Al2O3 and Cr2O3 mixed scale during the oxidation. 相似文献
2.
采用多弧离子镀技术在Ti-6Al-4V合金基底表面依次沉积Al层和NiCrAlY涂层,对比研究Ti-6Al-4V合金和NiCrAlY/Al复合涂层在高温腐蚀 (500 ℃, 30 h) 过程中微观组织结构变化及其抗高温腐蚀性能。经测定,NiCrAlY/Al复合涂层中Al层的厚度约为270 nm,NiCrAlY涂层的厚度约为3.8 μm。高温腐蚀测试结果显示,Ti-6Al-4V合金表面出现点蚀,腐蚀区域出现大量裂纹,表明合金发生严重的高温腐蚀。表面沉积NiCrAlY/Al复合涂层的Ti-6Al-4V合金经高温腐蚀后表面依然完整,未产生明显裂纹和涂层脱落。经分析,NiCrAlY/Al复合涂层在高温腐蚀过程中表面可自形成厚度约为43 nm的Al2O3和Cr2O3,连续且致密的薄氧化膜可在高温下阻隔氧气向钛合金内部的侵蚀,从而显著提高基底合金的抗高温腐蚀性能。 相似文献
3.
采用电弧离子镀(AIP)技术在Ti6Al4V基体表面沉积制备了NiCrAlY涂层. 通过金相观察(OM)、扫描电镜(SEM)与能谱(EDS)分析、 X射线衍射(XRD)分析以及显微硬度测试, 研究了真空热处理对NiCrAlY涂层组织性能的影响, 讨论了Ti6Al4V基体/NiCrAlY涂层界面元素扩散规律. 结果表明: 700.℃真空热处理后, NiCrAlY涂层中开始析出γ′-Ni3Al相, 这提高了涂层的表面硬度; 在700.℃温度下, Ti6Al4V基体/NiCrAlY涂层界面由外至内出现Ni3(Al,Ti)、 TiNi和Ti2Ni中间化合物层, 并随着温度提高, 界面处中间化合物层增厚; 700.℃时, 主要发生了镍、钛元素的扩散, 铬元素在870.℃开始发生扩散. 当温度提高到950.℃后, 由于镍元素大量向Ti6Al4V基体扩散引起涂层的退化失效. 相似文献
4.
制备了一种用于防止Ti-6Al-4V钛合金加热时表面氧化的无铅玻璃-陶瓷涂层材料,并对其相组成及有涂层钛合金氧化层进行了研究。结果表明,加热前涂层主要为玻璃相,加热后有结晶相生成,有利于从钛合金表面除去涂层;有涂层钛合金表面氧化层厚度小。可见,无铅环保型涂层能在500~1000 ℃温度范围内给Ti-6Al-4V合金提供良好的抗氧化保护。 相似文献
5.
In the present study Ni−18Cr−6Al, Ni−22Cr−10Al−1Y and TiAlO composite powders were coated on Ti−6Al−4V substrates by atmospheric
plasma spraying, and the coated specimens were evaluated by isothermal and cyclic oxidation resistance tests at 800°C. The
oxidation kinetics of the plasma sprayed NiCrAl, NiCrAlY, and TiAlO composite coated specimens obey a parabolic rate law.
The oxidation resistance of the plasma sprayed NiCrAl and NiCrAlY coatings is superior to that of plasma sprayed TiAlO composite
coating. The best oxidation resistance was observed in the plasma sprayed NiCrAlY coatings. This is mainly attributed to the
formation of Y−Al−O complex oxides and Ni3Al with higher thermal stability on the coatings. 相似文献
6.
Pure titanium and Ti-6Al-4V were exposed at 750°C in an H2/H2O/H2S PO
210–18 Pa and PS
210–1 Pa), H2/H2O (PO
210–18 Pa) and air environments for up to 240 hr. The corrosion kinetics, obtained by the discontinuous gravimetric method, showed that the sulfidation/oxidation kinetics were linear for Ti and linear-parabolic for Ti-6Al-4V in the H2/H2O/H2S environment. Both materials obeyed parabolic rate laws in the H2/H2O atmosphere after a transient period, and linear-parabolic rate laws in air. After exposure to the H2/H2O/H2S atmosphere, the titanium specimen displayed a double scale of TiO2 with an intervening TiS2 film between the double-layered scale of TiO2 and the substrate. Ti-6Al-4V also contained a double layer of TiO2 together with a stratum consisting of Al2S3, TiS2 and vanadium sulfide at the junction of the inner TiO2 layer and substrate. Some Al2O3 precipitated in the external portion of the outer TiO2 layer. Following oxidation in the low-PO
2 atmosphere a double-layered oxide of TiO2 scale formed on both Ti and Ti-6Al-4V. The scale on Ti-6Al-4V also contained an -Al2O3 film situated between the outer and inner (TiO2) layers. For both materials, multilayered-scale formation characterized air oxidation. In detail a multilayered oxide scale of TiO2 formed on the air-oxidized Ti, while a multilayered oxide scale with alternating layers of Al2O3/TiO2 developed on Ti-6Al-4V oxidized in air. 相似文献
7.
Laser treatment and PVD TiN coating of Ti-6Al-4V alloy 总被引:1,自引:0,他引:1
Improved adhesion between a coating and the base substrate is necessary for successful engineering applications. This may be achieved through generating intermediate zone between the coating and the substrate. In the present study, laser gas alloying of Ti-6Al-4V alloy was carried out. Nitrogen was introduced co-axially with the laser beam while the workpiece is scanned at a constant speed in the x-direction during the laser heating process. The laser-treated workpieces were then slightly ground and TiN PVD coated. Thickness of the coating layer was limited to 2 μm. The wear tests were conducted on the laser-treated TiN-coated workpieces. To examine the metallurgical changes, microphotographs of workpiece cross-sections were taken. To monitor the nitride compounds in the surface region, XRD was carried out. It was found that three wear stages occur. The steady wear stage is relatively longer for laser-treated TiN-coated workpiece compared to the TiN-coated workpiece. 相似文献
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9.
通过对有无NiCrAlY涂层镍基单晶合金进行不同温度的恒温氧化动力学曲线测定及组织结构观察,研究了纳米晶NiCrAlY涂层对高Cr单晶镍基合金高温氧化行为的影响。结果表明:在高温氧化期间,无涂层试样发生明显的氧化、内氧化和内氮化,在表层为Al2O3、Cr2O3的混合氧化物,在次表层氧化物中富含元素Ta,而元素Al贫化,并在近基体区域存在内氧化物;随氧化温度升高,元素Al的贫化区尺寸增大,其中,富Ta相可抑制基体中元素Al向外扩散,延缓合金的氧化速率。合金在氧化初期增重迅速,而恒温氧化增重动力学曲线呈现起伏波动的原因,归结于表面氧化膜的形成与剥落。高Cr单晶合金经溅射NiCrAlY纳米晶涂层,可有效改善合金的抗氧化性能;有涂层试样在不同温度的恒温氧化动力学曲线仅在氧化初期有轻微增重而后趋于平稳,其形成的Al2O3氧化膜不发生明显的剥落,仅在基体近涂层/基体界面区域存在少量AlN内氮化物。 相似文献
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11.
《稀有金属材料与工程》2019,36(1):19-24
通过电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)分析了Ti-6Al-4V合金表面微弧氧化膜层的微观形貌、相组成和化学成分,采用拉伸试验机及红外光谱仪(FTIR)测试了膜层的结合强度以及5~20μm波段内的红外发射率。结果表明,随着(NaPO3)6电解液中FeSO_4浓度的升高,膜层的厚度、粗糙度及结合强度增加,红外发射率呈先增加后减小的趋势,其中,FeSO4浓度为6 g/L时膜层的红外发射率达到最大值0.86。结合XRD与XPS测试结果,推断元素Fe与P分别以非晶态的Fe2O3、H2PO4-、P2O7(4-)存在。Fe掺杂与非晶态的无序结构特征有利于局域能级的生成和增强原子间的极性振动,进而提高膜层的红外发射率。 相似文献
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13.
通过热氧化/真空扩散处理在Ti-6Al-4V合金表面制备氧化涂层,采用高温磨损试验机对涂层在400 ℃空气中进行干滑动摩擦磨损试验,研究了涂层的高温磨损行为和机制。结果表明:Ti-6Al-4V合金经氧化/扩散后表面形成氧化物涂层,厚度达250 μm。相比于未处理的材料,氧化物涂层的磨损失重非常小,高温耐磨性显著提高。磨损表面均形成摩擦氧化物层,涂层的高耐磨性可归功于硬化的陶瓷涂层与具保护作用的摩擦层的共同作用。主要磨损机制为剥层磨损。 相似文献
14.
Ti-6Al-4V钛合金固体渗硼法表面改性 总被引:2,自引:0,他引:2
对TC4钛合金(Ti-6Al-4V)进行表面渗硼使其表面硬度显著提高.渗硼温度为1000℃到1050℃,渗硼时间为5 h到20h.文内测量和比较了渗硼后钛合金表面的微结构、形貌、相组成等性质,研究了渗硼过程中Ti,Al,V,B等元素的扩散行为.在低温短时间渗硼时,渗硼层厚度仅0.8μm,而在高温长时间渗硼时,渗硼层厚度可达15 μm.实验证明,渗硼层由TiB和TiB2两相组成,并且它们的含量随渗硼温度提高而增加.渗硼层表面主要含TiB2,其显微硬度可达2200 HV0.01,渗硼层内表层主要含TiB,其显微硬度为1100 HV0.01.渗硼层的硬度远高于TC4钛合金的硬度. 相似文献
15.
采用微弧氧化技术和氟硅烷修饰在医用Ti-6Al-4V合金表面构建超疏水涂层。考察微弧氧化电压对涂层表面形貌及粗糙度的影响,分析微弧氧化和超疏水涂层的相组成及元素化学状态以探讨超疏水表面的形成机制。初步研究超疏水试样的细胞毒性和抗菌性能。结果表明,随着微弧氧化电压的增加,涂层的表面粗糙度增大,而显微结构均匀性在440V最佳。经疏水处理后,试样的表面粗糙度较微弧氧化试样有所下降,而接触角随着电压的增加而先增大后减小,在440 V时获得最大值154.9°。微弧氧化涂层主要由锐钛矿及少量金红石TiO2相组成,并含有大量的–OH和一些磷的化合物,而超疏水试样表面存在大量的CF3、CF2和Si-O基团。全氟辛基三氯硅烷通过水解和脱水反应将氟硅烷嫁接于微弧氧化涂层上而形成超疏水表面。超疏水试样属于1级无毒材料,其细胞增殖率与Ti-6Al-4V合金无显著差异。此外,超疏水试样还具有一定的抗菌性,相对微弧氧化试样,其抗菌率可达93.03%。 相似文献
16.
唐达培 《稀有金属材料与工程》2017,46(6):1508-1511
基于热弹塑性理论建立了等离子喷涂羟基磷灰石涂层的热-力耦合模型。一方面,通过引入变形对温度的影响项对经典的Fourier瞬态热传导方程进行了修正,另一方面,在考虑了温度软化效应、应变硬化效应、和应变率强化效应后,采用适用于高温、高应变率条件下的Johnson-Cook模型作为本构方程。基于上述耦合模型,采用有限元方法对涂层内的残余应力场进行了模拟,同时还模拟了基体预热温度以及涂层厚度对残余应力的影响。为了验证数值模拟的可靠性,还采用“材料去除”的实验技术测试了涂层在界面处的残余应力。结果表明:在界面边缘有明显的应力集中;适当提高基体的预热温度有利于减小残余应力;涂层的残余应力随厚度的增加而增大。 相似文献
17.
利用激光熔覆在Ti-6Al-4V合金表面制备了TiAlSi+xB4C涂层,分析比较不同B4C含量对于涂层显微组织、显微硬度和耐磨性能的影响。结果表明:B4C含量不同,涂层中的物相种类差别不大;涂层的微观形貌由颗粒状晶、层状晶、胞状晶和短棒状晶组成;不同B4C含量涂层的显微硬度分布趋势大致相同,与基材相比均有明显的提高,随着B4C含量的增高,整体上涂层显微硬度逐渐增大,当B4C的含量为8%时,涂层的显微硬度最高,达到1216 HV0.1,约为基体的4.2倍;而当B4C含量过高时,涂层硬度降低,且涂层中出现微裂纹。通过磨损试验表明,不同B4C含量的涂层耐磨损性能均明显的优于Ti-6Al-4V合金基体,含8%B4C的涂层磨损量最小。熔覆不同含量B4C的涂层明显改善了基体Ti-6Al-4V合金的表面性能。 相似文献
18.
Mihai V. PopaJose Maria Calderon Moreno Monica PopaEcaterina Vasilescu Paula DrobCora Vasilescu Silviu I. Drob 《Surface & coatings technology》2011,205(20):4776-4783
Passivating coatings of brushite (CaHPO4·2H2O) were obtained on Ti and Ti-6Al-4V ELI alloy substrates by cathodic polarization. After soaking in Ringer's solution for 48 h brushite was transformed to hydroxyapatite (Ca10(PO4)6(OH)2) as confirmed by XRD, FT-IR and Raman spectroscopy. Electrochemical cyclic polarization curves of the coated biomaterials obtained in Ringer's solution at pH values of 7.1 and 8.91 as well as in Hank's Balanced Salt Solution (HBSS) at pH value of 7.4 show a nobler behavior than of the uncoated biomaterials. The coated biomaterials had lower corrosion rates than the uncoated biomaterials suggesting a protective character of the hydroxyapatite coating. Electrochemical impedance spectra (EIS) revealed capacitive behavior, owing to the protective, very resistant layer, the thickness of which increased with soaking time. The coated biomaterials presented higher electropositive open circuit potentials compared to the uncoated biomaterials as result of the protective effect of the coating. The morphology of the coatings changed with soaking time as the coatings became denser, smoother and better adhering. Hence such coatings may provide favorable structure for cell adhesion and proliferation. 相似文献
19.
Yuming Xiong Chunhong Guan Shenglong Zhu Fuhui Wang 《Journal of Materials Engineering and Performance》2006,15(5):564-569
The effect of enamel coating on the isothermal and cyclic oxidation at 900 °C in air and on the hot corrosion resistance of
Ti-24Al-14Nb-3V in both 85% Na2SO4+15%K2SO4 and 15%NaCl+85% Na2SO4 molten mixed salts at 850 °C was investigated. The results indicated that Ti-24Al-14Nb-3V alloy exhibited poor oxidation
resistance due to the formation of nonprotective Al2O3+TiO2+AlNbO4 scales and poor hot corrosion resistance due to the spallation of scales formed in molten Na2SO4+K2SO4 and NaCl+Na2SO4. Enamel coating suppressed the migration of oxygen and corrosive ions into the substrate to improve the oxidation and hot
corrosion resistance of Ti-24Al-14Nb-3V alloy. However, the dissolution of oxides components of the coating into the molten
salts degraded enamel coating and the degradation of the coating involved a process by which Cl− anion penetrated into the substrate through voids in the coating to accelerate corrosion of Ti-24Al-14Nb-3V alloy. 相似文献
20.
分析了Ti-6Al-4V合金在900 oC,930 oC,960 oC温度下的氧化行为及表层显微组织变化。在0.5-24 h时间内,氧化层不断增厚,越靠近表面氧化层越疏松。氧含量在氧化层/富氧层界面的5 μm内发生急剧下降,进入富氧层后缓慢下降直到稳定。氧化层中以TiO2为主,同时也出现了Al2O3。富氧层中的a相含量远远高于基体内部,其晶粒尺寸也发生长大。富氧层深度与热暴露时间的关系可用对数函数描述,通过线性回归分析计算出了O在富氧层中的扩散激活能为206 kJ/mol。 相似文献