Effects of Chlorate on the Hot Corrosion Behaviors of Cr0.82Al0.18N Coating Deposited on a Ti3Al Based Alloy

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。     

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/Cr复合涂层对Ti2AlNb合金抗热腐蚀性能的影响

目的改善Ti2AlNb合金在高温腐蚀盐环境中的耐热腐蚀性能。方法在Ti2AlNb合金表面通过双层辉光等离子渗铬及磁控溅射镀铝技术制备Al/Cr复合涂层,分析涂层热腐蚀前后的微观形貌和物相组成,并探究涂覆Na2SO4盐膜的试样在不同温度下(750、850、950℃)的热腐蚀行为。结果Al/Cr复合涂层组织均匀致密,且与基体结合良好,厚度约73μm,由表及里依次由Al沉积层、Al/Cr合金层、Cr沉积层、Cr扩散层四部分组成。经不同温度Na2SO4盐热腐蚀后,Al/Cr复合涂层腐蚀程度均显著小于合金基体。涂层试样经750~850℃Na2SO4盐热腐蚀后质量变化较小,850℃腐蚀增重仅0.525 mg/cm^2,而经历950℃、40 h熔盐热腐蚀后失重达到73.571 mg/cm^2,且试样截面出现剥离、脱落现象,Al/Cr复合涂层抵抗热腐蚀能力减弱。结论具有涂层保护的试样抗热腐蚀性能明显优于合金基体。Al/Cr复合涂层在750~850℃Na2SO4盐环境中具有良好的热腐蚀抗力,而更高温度段(850~950℃)的热腐蚀抗力下降。Al/Cr复合涂层在Na2SO4盐环境中良好的抗热腐蚀性得益于涂层中Al、Cr元素氧化形成以Al2O3、Cr2O3为主的混合氧化膜,有效阻碍外界氧气及腐蚀性介质侵入基体。     

高铬镍基合金熔融硫酸盐热腐蚀过程中内氧化和内硫化行为的研究

通过对镍基合金进行不同温度的恒温熔融硫酸盐热腐蚀试验,对腐蚀产物横断面进行形貌观察及微区成分分析,研究了一种高铬镍基合金在恒温热腐蚀期间腐蚀产物分布特征及内氧化、内硫化行为。结果表明,该高铬镍基合金在900和950℃腐蚀100 h期间,合金氧化和硫化同时发生,且腐蚀产物中出现分层结构,由表及里各层中的主要氧化物分别为:Al2O3和Cr2O3,Al2O3,CrS。该合金在各温度的恒温热腐蚀期间,均发生Al元素的内氧化和Cr元素的内硫化;与外氧化膜相邻的区域为Al元素的内氧化区,远离外氧化膜的基体内部形成Cr元素的内硫化区;随腐蚀温度升高,内氧化区和内硫化区深度增加,内氧化物和内硫化物的尺寸增大。     

一种定向凝固Co基合金的热腐蚀行为

利用箱式电阻炉、SEM等手段,研究了一种定向凝固Co基合金在不同介质中的热腐蚀行为及机理。研究结果表明:合金在Na2SO4中的热腐蚀最为严重,在75%Na2SO4+25%NaCl中的热腐蚀程度最轻。合金在Na2SO4中的热腐蚀过程中主要发生了酸性熔融反应,形成了Al2(SO4)3,Cr2Ni3,Cr4Ni15W和Al4CrNi15等腐蚀产物,而在NaCl中的热腐蚀主要发生了活性氧化反应,合金在75%Na2SO4+25%NaCl中热腐蚀时,部分酸性熔融反应和活性氧化反应受到抑制,主要形成了一系列的Ni-S化合物。     

含钛镍基合金在850℃和950℃的热腐蚀行为

研制了一种含钛镍基合金,并采用X射线衍射(XRD)、扫描电镜(SEM)及能谱(EDS)等手段研究了其在850℃和950℃熔融硫酸盐中的热腐蚀行为。结果表明,热腐蚀期间,合金发生了氧化、硫化现象,合金表面腐蚀产物层可分为3层,外氧化层以Al2O3、Cr2O3和Cr2O4相为主,中间层为Al2O3相,内层为CrS和Ti2S硫化物层;随腐蚀温度提高合金表面腐蚀层的厚度增加,合金内氧化物区域和内硫化物区域加深。     

溅射AlY涂层对Ni基合金氧化行为的影响

为了研究溅射AlY涂层对合金高温氧化行为的影响,在某镍基合金表面上采用磁控溅射方法制备了AlY涂层,并研究了无涂层镍基合金、溅射AlY涂层的镍基合金以及经过预氧化的溅射AlY涂层镍基合金在1100℃空气中的氧化行为。结果表明,无涂层镍基合金形成了疏松、不完整的Al2O3、Cr2O3以及NiO的混合氧化膜,且发生了内氧化;溅射AlY涂层镍基合金形成了均一的α-Al2O3膜,比表面裸露的镍基合金具有更好的抗氧化性能。溅射AlY涂层试样经预氧化后在试样表面优先形成了保护性γ-Al2O3膜,高温氧化时转变为致密的α-Al2O3膜,因此可进一步提高其抗氧化性能。稀土元素Y改善了Al2O3膜与基体的粘附性,提高合金的抗氧化性能。讨论了氧化膜的形成机理。     

一种镍基合金在850℃和950℃熔融NaCl中的热腐蚀行为

采用X射线(XRD)、扫描电镜(SEM/EDAX)等手段,研究了一种镍基合金在850℃和950℃熔融Na Cl的热腐蚀行为。结果表明:腐蚀期间,合金发生了高温氧化和热腐蚀行为;合金表面腐蚀产物分为3层,外层氧化物由Al2O3、Al Ta O4和Ni Cr2O4组成,中间层氧化物为Cr Ta O4、Ni WO4和WO3,而内层形成Al2O3内氧化物;且随腐蚀温度提高,合金表面的腐蚀层厚度及Al2O3内氧化层深度增加。     

电弧离子镀Ni—Co—Cr—A1—Y—Si—B涂层的热腐蚀性能

采用电弧离子镀技术在DZl25和DSM11两种镍基高温合金基材上沉积Ni—Co—Cr—Al—Y—Si—B涂层，研究了高温合金基材及其Ni—Co—Cr—Al—Y— Si—B涂层在900℃的75％Na2SO4 25％K2SO4熔盐中的热腐蚀行为．结果表明，Ni—Co—Cr—Al—Y—Si—B涂层在热腐蚀过程中生成了连续致密的α—Al2O3氧化膜，有效地保护了合金基材免受腐蚀破坏，合金基材的热腐蚀性能对体系后期的热腐蚀行为影响很大．     

耐热钢表面激光熔覆Co基合金涂层的高温性能

采用高功率CO2激光器在1Cr18Ni9Ti不锈钢表面激光熔覆Co基合金,研究了改性层的组织及在75%Na2SO4+25%NaCl混合盐中的热腐蚀性能.结果表明,Co基合金激光改性层组织细密,其中的Co、Cr元素在涂盐热腐蚀条件下促进了保护性氧化膜CoO、CoO•Cr2O3的形成,显著改善了1Cr18Ni9Ti不锈钢的高温热腐蚀性能.     

Effects of SO2 and SO3 on the Na2SO4 induced corrosion of nickel

The effects of SO₂ and SO₃ in the environment on the hot corrosion behavior of Ni in the temperature range 750–950°C has been studied. Below the melting point of Na₂SO₄ (884°C), rapid corrosion takes place by formation of a Na₂SO₄-NiSO₄ melt, which can penetrate the porous oxide scale and give rise to sulfide information by coming in contact with the metal. The distribution of the sulfides depends on the SO₂ level in the ambient gas. Continued corrosion occurs by a sulfidation-oxidation mechanism. At temperatures above the melting point of Na₂SO₄, accelerated degradation occurs via dissolution of the surface scale, followed by reprecipitation of the oxide in a nonprotective form.Deceased     

Initial atmospheric corrosion of zinc in presence of Na2SO4 and （NH4）2S04

Initial atmospheric corrosion of zinc in the presence of Na₂SO₄ and (NH₄)₂SO₄ was investigated via quartz crystal microbalance(QCM) in laboratory at relative humidity(RH) of 80% and 25 °C. The results show that both Na₂SO₄ and (NH₄)₂SO₄ can accelerate the initial atmospheric corrosion of zinc. The combined effect of Na₂SO₄ and (NH₄)₂SO₄ on the corrosion of zinc is greater than that caused by (NH₄)₂SO₄ and less than that caused by Na₂SO₄. Fourier transform infrared spectroscopy(FTIR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM) were used to characterize the corrosion products of zinc. (NH₄)₂Zn(SO₄)₂, Zn₄SO₄(OH)₆·5H₂O and ZnO present on zinc surface in the presence of (NH₄)₂SO₄ while Zn₄SO₄(OH)₆·5H₂O and ZnO are the dominant corrosion products on Na₂SO₄-treated zinc surface. Probable mechanisms are presented to explain the experimental results.     

Initial atmospheric corrosion of zinc in presence of Na_2SO_4 and (NH_4)_2SO_4

1 Introduction In view of the widespread use of zinc, as metallic sheet or zinc coatings, it was desirable to study its corrosion behaviour in the wide variety of atmospheres. The atmospheric corrosion of zinc has been studied in field exposures as well …     

Thermodynamics of the Na2SO4-K2SO4-CoSO4 system and their relevance to low-temperature hot corrosion

Thermodynamic calculations and experiments were performed to determine the SO₃ partial pressures and temperatures at which K₂SO₄-CoSO₄ binary mixed liquid phases form on CoO and Co₃O₄ in the presence of K₂SO₄. The calculations and experiments are in excellent agreement. Similar calculations were also made of the compositions at the liquidus surface and the associated SO₃ partial pressures for the K₂SO₄-Na₂SO₄-CoSO₄ ternary system. These calculations show that the presence of K₂SO₄ substantially reduces the SO₃ partial pressures required to stabilize a liquid salt phase on the surface of oxidized cobalt alloys at 600–800°C. Consequently, at these temperatures the hot corrosion in coal-fired systems, where K levels are high, is expected to be worse than in oil-fired systems, where K levels are low. This prediction was confirmed by experiments in a pressurized fluidized bed coal combustor and in an atmospheric pressure burner rig.     

The first-class reciprocal quaternary system H3PO4-K2SO4-K3PO4-H2SO4-H2O application to fertilizer fabrication problems

The first-class reciprocal quaternary system H₃PO₄-K₂SO₄-K_3PO₄-H₂SO₄-H₂O has been carefully investigated at 25 and 75°C. Representations have been given using the Jänecke coordinates. Using the established diagrams as a base, a procedure is proposed for preparing specific fertilizers containing potassium and phosphate ions by reacting phosphate rock with aqueous solutions of KHSO₄, addition of calculated amounts of water to the reaction mixture, elimination of an insoluble products, and programmed water evaporation.     

The effect of K2SO4 additive in Na2SO4 deposits on low temperature hot corrosion of iron-aluminum alloys

To understand the effect of K₂SO₄ additive in an Na₂SO₄ deposit on low temperature hot corrosion, the corrosion behavior of Fe-Al alloys induced by Na₂SO₄+K₂SO₄ was compared to that by Na₂SO₄ alone, and sulfation of Fe₂O₃ in the presence of either Na₂SO₄ or Na₂SO₄+K₂SO₄ was studied. It was found that K₂SO₄ additive promoted the low temperature hot corrosion, but did not change the corrosion-mechanism. Experimental results refuted the prior suggestions that the accelerated hot corrosion resulted either from the formation of K₃Fe(SO₄)₃ or from the stimulation of sulfation of Fe₃O₃. The earlier formation of the eutectic melt caused the accelerated hot corrosion, or in other words, the K₂SO₄ additive shortened the induction stage of hot corrosion.     

Acidic and basic fluxing of Ni-base superalloys in a 90Na2SO4-10K2SO4 melt at 1173 K

The influence of the electrode potential on the corrosion behavior of a series of Ni-base superalloys has been investigated in a (mole %) 90Na₂SO₄-10K₂SO₄ melt at 1173 K. Acidic fluxing occurs at positive potentials and basic fluxing at negative potentials. A protective scale is formed in an intermediate (neutral) potential range on high chromium-containing alloys such as IN-738LC, IN-939, IN-597, and IN-657. The breakthrough potentials for acidic and basic fluxing depend on the composition of the alloy. Alloys with low chromium contents such as IN-100 and IN-713LC do not form stable protective scales at any potential. Numerous sulfide phases have been identified in the scale and subscale, depending on potential, severity of attack, and material composition. NaCrS₂ only forms under basic fluxing conditions. Its presence can therefore be considered as an indication that basic fluxing conditions have existed.     

聚丙烯材料在硫酸钾装置中的应用

本文介绍了聚丙烯材料的性能、特点，利用其特点将聚丙烯材料用于管道或衬里管道，以输送腐蚀和磨蚀介质，结合使用条件分析了在使用温度下的腐蚀、磨蚀、强度使用寿命等问题。     

超音速喷涂45CT涂层在KCl+K2SO4+Na2SO4熔融盐中的热腐蚀行为

目的研究超音速喷涂45CT涂层抗KCl+K_2SO_4+Na_2SO_4熔融盐腐蚀性能,了解45CT涂层在熔融盐中的防护及失效机制。方法将试样置于KCl+K_2SO_4+Na_2SO_4混合熔盐中,获得样品在熔盐中不同温度下的腐蚀动力学规律。采用XRD、SEM、EDS对高温腐蚀产物成分、结构、形貌进行分析。结果 45CT涂层在熔融盐中的主要腐蚀产物为Cr_2O_3、NaCrO_2。在600℃和650℃下,涂层能较好地保护基体,涂层上腐蚀产物层较薄;而在700℃下,涂层退化严重,涂层内有大量金属硫化物,基体中的Fe向涂层扩散。结论在高温条件下,涂层易发生硫化,导致涂层与氧化膜的弱结合。随着测试温度升高,涂层在KCl+K_2SO_4+Na_2SO_4熔融盐中的热腐蚀越严重,涂层失效加快。