热腐蚀和盐雾腐蚀影响氮化物涂层冲蚀行为的机制

金属氮化物涂层是目前重点关注的航空发动机压气机抗冲蚀涂层体系。为了兼顾热物理化学环境和应力环境的影响,进行涂层的腐蚀-冲蚀耦合行为研究十分重要。本研究对比了TiN/Ti涂层与TiN/ZrN涂层的原始状态、热腐蚀后和盐雾腐蚀后的冲蚀行为。结果表明,对于TiN/Ti涂层,在涂层的缺陷处盐雾腐蚀时形成点蚀坑,这是发生冲蚀的薄弱环节,盐雾腐蚀后TiN/Ti涂层的抗冲蚀能力及结合力低于原始涂层和热腐蚀后的涂层。对于TiN/ZrN涂层,热腐蚀过程中液滴表面形成疏松的腐蚀产物和氧化物,使其在冲蚀时更容易脱落,热腐蚀过程中产生的层间热应力削弱了涂层的结合力。热腐蚀涂层冲蚀后呈现严重的螺旋状剥落,热腐蚀后TiN/ZrN涂层的抗冲蚀能力及结合力低于原始涂层和盐雾腐蚀后涂层。     

锆合金表面涂层耐高温高压动水腐蚀性能的研究

目的 提高锆合金在高温高压环境中耐动水腐蚀性能。方法 利用多弧离子镀技术（MAIP）在Zr-4合金表面分别制备了Al2O3涂层和Cr/TiAlN复合涂层,利用磁控溅射技术（MS）在Zr-4合金表面制备了TiN涂层。通过堆外高压釜实验,对比研究了三种不同涂层的耐高温高压动水腐蚀性能,利用自动划痕仪检测膜基结合力,利用XRD分析涂层的物相成分,利用SEM观察涂层腐蚀前后的微观形貌,利用EDS对涂层元素种类与含量进行分析。结果 多弧离子镀技术制备的Al2O3涂层和Cr/TiAlN涂层致密度较高,但表面存在少量大颗粒与微孔洞;磁控溅射技术制备的TiN涂层均匀平整,表面大颗粒较少。Al2O3涂层、TiN涂层和Cr/TiAlN涂层可承受的临界载荷分别为26、16、26.5 N。在实验条件下,Cr/TiAlN涂层和TiN涂层表面均发生了剥落或腐蚀现象,且这两种试样表面均检测出大量的ZrO2,而Al2O3涂层几乎未被破坏,基体得到了充分防护。结论 利用多弧离子镀技术在Zr-4合金表面制备的Al2O3涂层和Cr/TiAlN涂层的膜基结合力较高,利用磁控溅射技术制备的TiN涂层的膜基结合性能较差,其中Al2O3涂层具备良好的耐腐蚀性能,在高温高压动水腐蚀环境中能够有效地保护锆合金基体。     

The corrosion and wear behavior of TiN and TiAlN coated AISI 316 L stainless steel

In this study, TiN and TiAlN coatings were deposited on AISI 316 L stainless steel substrates by PVD techniques. The composition and crystalline structure of the as-deposited coatings were analyzed by energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) methods, respectively. The corrosion resistance studies of TiN-coated and TiAlN-coated samples were carried out in 0.9 wt % NaCl and SBF solutions using the electrochemical potentiodynamic polarization method and the wear behavior was evaluated with the ball-on-disk wear method at a sliding speed rate of 0.3 m/s under 2.5 N load in a dry medium. It was found that both TiN and TiAlN coatings exhibited relatively good corrosion resistance, however, TiAlN coatings showed a better corrosion resistance than TiN coatings. The TiAlN coating contributes positively against corrosion and wear behavior by increasing the surface hardness and by decreasing the friction coefficient of AISI 316 L stainless steel, respectively.     

Structure and wear resistance of TiN and TiAlN coatings on AZ91 alloy deposited by multi-arc ion plating

In order to investigate the microstructure of TiN and TiAlN coatings and their effect on the wear resistance of Mg alloy, TiN and TiAlN coatings were deposited on AZ91 magnesium alloy by multi-arc ion plating technology. TiN and Ti70Al30N coatings were prepared on the substrate, respectively, which exhibited dark golden color and compact microstructure. The microstructures of TiN and Ti70Al30N coatings were investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The micro-hardness and wear resistance of TiN and Ti70Al30N coatings were investigated in comparison with the uncoated AZ91 alloy. The XRD peaks assigned to TiN and TiAlN phases are found. The hardness of TiN coatings is two times as high as that of AZ91 alloy, and Ti70Al30N coating exhibits the highest hardness. The wear resistance of the hard coatings increases obviously as result of their high hardness.     

Electrochemical characteristics of steel coated with TiN and TiAlN coatings

The corrosion protection characteristics of titanium nitride (TiN) and titanium–aluminum nitride (TiAlN) coatings produced on cemented carbon steel targets were investigated in aqueous sodium chloride solution. All coatings were produced by cathodic arc plasma deposition. The results indicated that it was possible to follow the corrosion behavior of the coated systems over a period of 300–900 h of immersion. It was found that the TiN and TiAlN coatings had a lower corrosion rate (current density), about three orders of magnitude lower than the untreated steel substrates. The metal substrate was actually passive in these experimental conditions, and exhibited an electrochemical impedance response that could be described by means of the same equivalent circuit than for the coating. Nevertheless, the analysis of the impedance parameters allowed for direct information concerning the enhancement of the corrosion resistance of the coated system as compared to the passive uncoated metal substrate to be extracted. The major corrosion mechanism for the coated samples arises from electrolyte penetration in the pores of the deposits, which may eventually lead to the development of localized forms of corrosion.     

Wet corrosion of nitride PVD films in supercritical solutions

Nitride TiN, TiAlN and CrN films exhibit a high performance with respect to steel corrosion protection in supercritical water. However, for practical applications their corrosion resistance in water solutions is more important. Wet corrosion of nitride PVD films in neutral, acid and alkaline supercritical solutions was studied. The highest stability of the films was revealed in neutral sodium chloride and alkaline CH₃NH₂ solutions. In the latter case regular cubic spinel crystals were formed on the surface of TiAlN films. Acidic solutions destroy nitride films due to growth of corrosion products beneath the coating layer.     

Enhanced corrosion resistance of Ni–W alloy with inclusion of TiN nanoparticles by electrodeposition method

Abstract

Electrodeposition of Ni–W–TiN nanocomposite on mild steel substrate from an ammoniacal citrate bath containing dispersed titanium nitride has been demonstrated. The structure, surface morphology, composition and corrosion resistance properties of the nanocomposite deposits have been characterised by using various techniques. X-ray diffraction analysis (XRD) of the electrodeposited Ni–W–TiN nanocomposite shows that it is fcc crystalline. Scanning electron micrography (SEM) reveals smaller grains and uniform distribution of the titanium nitride in the alloy matrix. The microhardness of the nanocomposite coatings is higher than that of the alloy. The corrosion resistance of the electrodeposited nanocomposite evaluated by electrochemical impedance and Tafel polarization studies showed that the Ni–W–TiN nanocomposite is more corrosion resistant than the Ni–W alloy deposit. The finer grain and uniform distribution of the titanium nitride in alloy matrix favour the enhanced microhardness and corrosion resistance of the nanocomposite.     

Corrosion resistance of Ti–6Al–4V alloy with nitride coatings in Ringer’s solution

The corrosion behaviour of Ti–6Al–4V alloy with nitride coatings was investigated in Ringer’s solution at 36 and 40 °С. Nitride coatings of different composition, thickness and surface quality were formed because of changing nitrogen partial pressure from 1 to 10⁵ Ра and nitriding temperature from 850 to 900 °С. Results shown that nitride coatings improve anticorrosion properties of alloy at both solution temperatures. Corrosion resistance of alloy increases with the content increase of TiN phase in nitride coating. With increase of temperature from 36 to 40 °С the corrosion resistance of alloy is determined significantly by quality of nitride coating.     

盐雾腐蚀条件下Ti合金表面功能薄膜的摩擦磨损性能

目的研究Ti6Al4V合金、铬掺杂类金刚石(Cr-DLC)薄膜、钨掺杂类金刚石(W-DLC)薄膜和氮化钛(TiN)薄膜,在干摩擦和盐雾腐蚀气氛摩擦条件下的摩擦磨损性能。方法在商用Ti6Al4V合金表面通过非平衡磁控溅射制备Cr-DLC薄膜和W-DLC薄膜,通过多弧离子镀技术制备TiN薄膜。利用扫描电镜、显微硬度计、摩擦磨损试验机、白光干涉扫描轮廓仪,对薄膜的形貌、硬度、干摩擦和腐蚀摩擦性能、磨痕形貌进行测试分析。结果干摩擦条件下,Ti6Al4V合金表面沉积Cr-DLC、W-DLC和TiN三种薄膜的摩擦系数均比Ti6Al4V合金低;Ti6Al4V合金及其表面制备的三种薄膜在盐雾腐蚀气氛条件下的摩擦系数都比干摩擦条件下有所增加。与Ti6Al4V合金相比,Cr-DLC、W-DLC和TiN三种薄膜在干摩擦和盐雾腐蚀气氛摩擦条件下均减小了磨损体积。干摩擦条件下,W-DLC薄膜的磨损体积为0.0017 mm~3,耐磨性最好;盐雾腐蚀气氛摩擦条件下,TiN薄膜的磨损体积为0.0028 mm~3,表现出最佳的耐腐蚀磨损性能。通过磨痕形貌可以得出,盐雾腐蚀气氛摩擦条件下,Ti6Al4V合金表面制备的金属掺杂类金刚石薄膜的磨损受到磨粒磨损和腐蚀磨损双重机制的影响。结论三种表面功能薄膜在盐雾腐蚀气氛摩擦条件下都较好地保护了Ti合金,极大地减少了磨损损失。     

Friction and wear properties of TiN,TiAlN, AlTiN and CrAlN PVD nitride coatings

Four nitride coatings, TiN, TiAlN, AlTiN and CrAlN were deposited on YG6 (WC + 6 wt.% Co) cemented carbide by cathodic arc-evaporation technique. The friction and wear properties were investigated and compared using ball-on-disc method at high speed with SiC ball as a counter material. The tests were evaluated by scanning electron microscopy, X-ray diffractometer, energy dispersive X-ray, micro hardness tester and an optical profilometer. The results showed that TiN and TiAlN coatings presented lower friction coefficient and lower wear rate, and that high Al content AlTiN and CrAlN coatings didn't present better anti-wear properties in this test. Oxidation and abrasive wear were the main wear mechanism of TiN coating. In spite of the observation of micro-grooves and partial fractures, TiAlN possessed perfect tribological properties compared with the other coatings. High Al content increased the chemical reactivity and aroused severe adhesive wear of AlTiN coating. CrAlN coating presented better properties of anti-spalling and anti-adhesion, but abundant accumulated debris accelerated wear of the coating under this enclosed wear environment.     

热镀锌层在模拟湿热酸性大气环境中的耐蚀性研究

目的研究Q420钢表面热镀锌工艺中,Zn和Zn-Al-Ni-RE合金镀层在酸性铜离子加速盐雾试验条件下的耐蚀性能。方法 Q420钢表面预处理后进行热镀锌,根据GB 6460—1986进行铜加速醋酸盐雾腐蚀试验,对比纯Zn镀层与Zn-Al-Ni-RE合金镀层的耐蚀性。结果 Ni,RE等元素的加入使镀层表面光亮,组织更加细密。在酸性铜离子加速实验进行到192 h时,纯锌镀层的腐蚀质量损失是合金镀层的2.7倍;72 h后纯锌镀层出现红锈,120 h后合金镀层出现红锈,说明Zn-Al-Ni-RE合金镀层比纯Zn镀层更耐腐蚀。结论通过适量添加Al,Ni与稀土元素,能使Q420钢合金镀层的耐蚀性能大幅度提高。     

PVD涂层刀具高速铣削CoCrMo合金的性能研究

目的为了提高涂层硬质合金刀具的切削性能,研究了物理气相沉积PVD法制备的涂层硬质合金铣刀在高速干式环境下的铣削性能。方法采用阴极电弧技术制备了TiN、TiAlN以及TiAlSiN涂层硬质合金铣刀刀头,通过一同沉积涂层的硬质合金圆片,间接测量得出涂层的显微硬度、厚度和平均摩擦系数,并以CoCrMo合金为切削对象,进行了PVD涂层与无涂层刀具高速铣削下的对比试验。结果TiAlSiN显微硬度最高达3800HV,摩擦系数达0.3,TiAlN涂层平均膜厚为2μm,间接测得TiN、TiAlN以及TiAlSiN涂层的结合力依次为60、58、42N。在三者的切削性能中,TiAlSiN涂层的切削性能比TiAlN和TiN涂层的好,同等切削参数时,TiN刀具的高速铣削时间最短,TiAlSiN涂层的平均磨损值为0.1895,TiN的平均磨损值为0.3047。结论涂层中添加Al、Si,极大地提高了刀具的使用性能,改善了刀具切削过程中的耐磨性、红硬性,极大地延长了刀具的使用寿命。TiAlSiN涂层的硬度高,耐磨损性好,切削性能好,适合高速铣削加工。     

Hot Corrosion Studies of Detonation-Gun-Sprayed NiCrAlY?+?0.4?wt.% CeO2 Coated Superalloys in Molten Salt Environment

Rare earth oxide (CeO₂) has been incorporated in NiCrAlY alloy and hot corrosion resistance of detonation-gun-sprayed NiCrAlY + 0.4 wt.% CeO₂ coatings on superalloys, namely, superni 75, superni 718, and superfer 800H in molten 40% Na₂SO₄-60% V₂O₅ salt environment were investigated at 900 °C for 100 cycles. The coatings exhibited characteristic splat globular dendritic structure with diameter similar to the original powder particles. The weight change technique was used to establish corrosion kinetics. X-ray diffraction (XRD), field emission scanning electron microscopy/energy-dispersive analysis (FE-SEM/EDAX), and x-ray mapping techniques were used to analyze the corrosion products. Coated superfer 800H alloy showed the highest corrosion resistance among the examined superalloys. CeO₂ was found to be distributed in the coating along the splat boundaries, whereas Al streaks distributed non-uniformly. The main phases observed for the coated superalloys are oxides of Ni, Cr, Al, and spinels, which are suggested to be responsible for developing corrosion resistance.     

氮化硅掺杂环氧树脂复合涂层的制备及耐腐蚀性能研究

目的将氮化硅作为填料加入环氧树脂,提高碳钢Q235有机涂层的耐腐蚀性能。方法利用球磨法将氮化硅填料均匀分散在环氧树脂中,探究了不同氮化硅含量涂层对Q235碳钢基体的保护,利用电化学阻抗谱(EIS)、吸水率实验、附着力实验及盐雾实验表征不同氮化硅含量涂层在3.5%NaCl溶液中的耐腐蚀性能。结果添加氮化硅后,涂层的低频阻抗模值及干湿态附着力均有不同程度提高。同时,氮化硅的加入降低了涂层的吸水率,增加了涂层的耐盐雾时间。浸泡初期(0.5 h),环氧树脂涂层(不含氮化硅)的低频阻抗模值为7.7×10~8?·cm~2,添加氮化硅的涂层的低频阻抗模值均增加了两个数量级,氮化硅含量为5%涂层的低频阻抗模值最大,为8.6×10~(10)?·cm~2。随着浸泡时间的增加,不同氮化硅含量的涂层低频阻抗模值均有不同程度的降低。其中,氮化硅含量(占环氧树脂质量的百分比,后文同)为5%的涂层的低频阻抗模值降低程度最小。浸泡2400 h之后,氮化硅含量为5%的涂层的低频阻抗模值最高,仍然能够达到3.3×10~8?·cm~2。结论氮化硅填料的加入提高了涂层的耐腐蚀性能,一定程度上可以保护金属基体免受腐蚀破坏。并且,当氮化硅含量为5%时,涂层的耐腐蚀性能最好。     

Corrosion Resistance of PAPVD TiN Coating on AISI 304 Stainless Steel

In this work the corrosion resistance of PAPVD TiN hard coatings on AISI 304 stainless steel with a titanium interlayer has been addressed. Cyclic voltammetry corrosion tests in NaCl 3.5% solutions were performed for samples prepared by depositing TiN/Ti onto steel using different deposition parameters. The surface morphology of the samples was examined by using a scanning electron microscope (SEM) and phase analysis was performed by X-ray diffraction (XRD). The cyclic voltammetry curves showed two distinct behaviours. Firstly, a reduction in corrosion resistance was observed when current density was increased for the whole potential range studied. The second observation, no less important, was the increase in corrosion resistance compared to the uncoated steel. The TiN films deposited showing (III) preferred orientation showed better corrosion resistance than films presenting other orientations.     

Hot Corrosion Behavior of a High Velocity Arc-Sprayed Fe-Cr-B-C Coating

A Fe-Cr-B-C coating was prepared by electric arc spraying process to prevent the boiler tubes from hot corrosion at elevated temperatures.A hot corrosion resistance test was conducted in a mixed molten salt of Na2SO4 and K2SO4(7:3)at 700 ℃for a total period of 156 h.The microstructure and phases of the coatings before and after exposed to the hot corrosion were investigated by scanning election microscopy(SEM),optical microscopy(OM)and X-ray diffraction(XRD).The hardness and porosity were analyzed.The hot corrosion behavior of the coatings was examined by the measurement of corrosion mass gain and the observation of corrosion morphology.The results show that some splats of particles are formed on flat substrate surfaces and the coatings have a dense typical layer structure of electric arc thermally spraying deposits.Some amorphous phase exist in the coating.The coatings have an excellent resistance to hot corrosion.The formation of oxides of chromium on the exposed surface may be contributing better resistance to hot corrosion.The corrosion of the coatings follows the oxidation and sulfidation mechanism.     

Zn-Al系列高速电弧喷涂层电化学防腐性能研究

采用粉芯丝材和高速电弧喷涂技术制备高Al含量的Zn-26％Al涂层。通过电化学的方法测试涂层在5％NaCl溶液下的腐蚀行为，并与由实芯丝材纯Zn、纯Al及Zn-15％A1所制备的涂层作比较。结果表明：Zn-26％A1涂层在电解质溶液中表现出更优越的防腐性能。动电位极化测试结果说明zn-Al涂层随着Al含量的增加，其耐蚀性也提高。纯Al涂层的电化学腐蚀行为与其它涂层有明显差异，其腐蚀机理类似于点蚀。     

空心阴极离子镀TiAlN复合薄膜结构及抗氧化性能的研究

利用IPB30/30T型空心阴极离子镀膜机并改变蒸发源料中Ti、Al的比例,在不锈钢表面沉积了不同Al含量的TiAlN薄膜;电子探针分析结果表明涂层为内层富铝,外层富TiN的梯度涂层;X-ray衍射分析表明,薄膜相结构主要为δ-TiN的B1NaCl结构,薄膜的择优取向随着镀料中Al含量的增加由(111)向(220)转变.与TiN相似,TiAlN薄膜为柱状晶结构,但Al的引入使薄膜中使针孔数量和直径减小,致密性改善.600℃～800℃下静态空气中恒温氧化实验表明,TiN和TiAlN薄膜氧化时都在表面形成金红石结构的TiO2,但添加Al的薄膜具有比TiN薄膜更好的抗氧化性.扫描电镜观察表明,添加Al的薄膜表面的氧化膜平整致密,无孔洞;而TiN薄膜在氧化过程中形成数量众多的孔洞.600℃时在NaCl和水蒸气的综合作用下,不锈钢基体材料腐蚀严重,TiN涂层对不锈钢基体有一定的保护作用,但其表面腐蚀产物部分脱落,出现大量的腐蚀空洞,而TiAlN涂层表面腐蚀产物均匀致密,无明显空洞.加入Al引起薄膜结构的改善可能是薄膜抗氧化性和抗腐蚀性提高的原因.     

Korrosionseigenschaften dünner Schichten im System Ti?B?N

Corrosion properties of thin coatings in the Ti? B? N system Thin titanium nitride TiN, boride TiB₂ and boronitride Ti(B, N) hard coatings were deposited on titanium substrates by the PVD-process Magnetron-Sputter-Ion-Plating (MSIP). They were characterized by X-ray diffractometry, SEM and WDX-analysis. With increasing B-content the Vickers hardness of the coatings increases. Photoelectron spectroscopic measurements show that all coatings are covered in atmosphere by thin oxid layer. Titanium nitride is electrochemically in 1 N sulphuric acid stable up to 1.3 V (SHE), above 1.3 V it becomes oxidized to titanium oxide TiO₂ and nitrogen N₂. The oxidation products were detected with XPS. Corrosion tests in nitric acid HNO₃ show that the corrosion resistance of titanium nitride is lower than the resistance of titanium. The corrosion of titanium boride and titanium boronitride in sulphuric acid is more intensive compared to titanium nitride. The borides cannot be passivated, but dissolve completely by anodic polarization.     

Corrosion characteristics of plasma-sprayed TiN and TiC coatings on steels in salt water

The salt water corrosion characteristics of titanium nitride and titanium carbide coatings on steels, prepared by argon plasma-spraying dry Ti and TiC powders in open air, are described. Both the TiN and TiC coatings are attacked by salt water, the latter being corroded nearly twice as much as the former. The bond-coated and top-sealed (BT) coatings corrode less than the analogous coatings without these (NBNT) in the immersion tests. The BT coatings corrode more than the NBNT coatings in the salt water spray test. CaCO₃ deposits form on the TiC coatings from salt solutions containing Ca ions, but no such calcareous deposit was formed on the TiN coatings.