Al含量对Cr1–xAlxN涂层力学、热稳定性、抗氧化性及耐蚀性的影响

目的探讨Al含量对Cr_1–xAl_xN涂层结构和性能的影响。方法在阴极弧蒸发设备中,分别采用Cr、Cr_0.70Al_0.30、Cr_0.50Al_0.50、Cr_0.40Al_0.60和Cr_0.30Al_0.70靶材制备5种不同Al含量的Cr_1–xAl_xN涂层。借助能量色散X射线光谱仪(EDX)、X射线衍射仪(XRD)、纳米压痕仪、扫描电子显微镜(SEM)和电化学工作站对Cr_1–xAl_xN涂层的成分、结构、力学性能、热稳定性、抗氧化性和耐蚀性进行研究。结果5种Cr_1–xAl_xN涂层均呈单相面心立方结构,其硬度随Al含量的增加而提升,由CrN的(16.9±0.8)GPa升至Cr_0.75Al_0.25N的(25.1±0.7)GPa、Cr_0.56Al_0.44N的(27.0±1.1)GPa、Cr_0.46Al_0.54N的(28.5±1.5)GPa和Cr_0.36Al_0.64N的(30.4±0.8)GPa。所有涂层在1000℃退火后,开始出现六方h-Cr2N的衍射峰,其衍射峰强度随Al含量的上升而降低。Cr_0.75Al_0.25N、Cr_0.56Al_0.44N和Cr_0.46Al_0.54N涂层在1100℃退火后,可检测到六方纤锌矿结构w-AlN相,而高Al含量Cr_0.36Al_0.64N涂层在1000℃退火后,便可检测到w-AlN相。在1000℃氧化15 h后,CrN涂层已经完全氧化,Cr_0.75Al_0.25N、Cr_0.56Al_0.44N、Cr_0.46Al_0.54N和Cr_0.36Al_0.64N涂层的氧化层厚度分别约为0.4、0.3、0.3、0.2μm;在1100℃氧化15 h后,CrN、Cr_0.75Al_0.25N和Cr_0.56Al_0.44N涂层已完全氧化,而Cr_0.46Al_0.54N和Cr_0.36Al_0.64N涂层的氧化层厚度分别约为2.5、1.4μm。CrN、Cr_0.75Al_0.25N、Cr_0.56Al_0.44N、Cr_0.46Al_0.54N和Cr_0.36Al_0.64N涂层在3.5%的NaCl溶液中测得的极化电阻分别为567.69、5.34、71.80、160.10、92.56 k?·cm²。结论涂层的硬度和抗氧化性随Al含量的增加而提升。Al的加入在抑制Cr—N分解的同时,促进了涂层中w-AlN的生成。CrN涂层具有最优的耐蚀性,而在含Al涂层中,涂层的耐蚀性随Al含量的增加呈现出先上升、后下降的趋势。     

Study on high-temperature oxidation behaviors of Cr–Si–N films

The high-temperature oxidation behavior of CrN and Cr–Si–N films was investigated. These films were deposited on STS 304 substrates by a hybrid deposition system with arc ion plating (AIP) and DC magnetron sputtering method using separate Cr (99.99%) and Si (99.99%) targets in a gaseous mixture of Ar and N₂. Good oxidation resistance of the CrN film was further improved by the incorporation of Si into the CrN film. The oxidation products of the Cr–Si–N film were Cr₂O₃ and amorphous SiO₂, which were gradually formed by the outward diffusion of Cr, Si, and N as well as the inward diffusion of oxygen. The oxidation kinetics of the specimen showed parabolic behavior, indicating that the diffusion process prevailed during oxidation. The oxidation activation energies for CrN, CrSi_0.10N, and CrSi_0.15N coatings are 303.8, 316.4, and 333.9 kJ/mol, respectively.     

A study on corrosion resistance characteristics of PVD Cr-N coated steels by electrochemical method

The corrosion behavior of Cr-N coated steels with different phases (-Cr, CrN and Cr₂N) deposited by cathodic arc deposition on AISI H13 steel was investigated in a 3.5% NaCl solution at ambient temperature. Potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were the techniques applied to characterize the corrosion behavior. It was found that the CrN coating had a lower current density from potentiodynamic polarization tests than others. The porosity, corresponding to the ratio of the polarization resistance of the uncoated and the coated substrate, was higher in the Cr₂N coating than in the other Cr-N coated steels. EIS measurements showed, for most of the Cr-N coated steels, that the Bode plot presented two time constants. Also, the Cr₂N coating represented the characteristic of Warburg behavior after 72 h of immersion. The coating morphologies were examined in planar view and cross-section by SEM analysis and the results were compared with those of the electrochemical measurement. The CrN coating had a dense, columnar grain-sized microstructure with minor intergranular porosity. From the above results, it is concluded that the CrN coating provided a better corrosion protection than the other Cr-N coated steels.     

Corrosion resistance of chromium nitride and oxynitride layers produced under glow discharge conditions

The paper presents the results of investigations of the structure and corrosion resistance of chromium nitride, oxynitride and oxide layers produced on steels by electrochemical chromium deposition combined with glow discharge assisted nitriding, oxynitriding and oxydizing processes. The layers obtained were of the types: CrN+Cr₂N+Cr+(Cr,Fe); Cr₂N+Cr+(Cr,Fe); CrN+Cr₂N+Cr+(Cr,Fe)₇C₃; Cr₂N+Cr+(Cr,Fe)₇C₃; Cr(N,O)+Cr+(Cr,Fe)₇C₃ and Cr₂O₃. The corrosion resistance of the layers is high and can be modified by changing the process parameters, such as the temperature and chemical composition of the gas atmosphere.     

3Cr13钢450℃不同气氛等离子体渗氮层表征

对3Cr13钢在450 ℃氨气和氨氮混合气氛中分别渗氮4、8和12 h后的渗氮层进行了对比。利用光学显微镜、显微硬度计、X射线衍射仪、电化学工作站对渗氮层截面显微组织、显微硬度、相组成以及耐蚀性进行了表征。氨气渗氮层由化合物层和白亮层组成,而氨气和氮气混合气氛渗氮层中没有出现白亮层。氨气渗氮12 h后,渗氮层的表面硬度为1050.0 HV0.05;表面化合物层主要相为ε-Fe_2-3N,次要相为γ′-Fe₄N,出现了少量的CrN,白亮层相组成为γ′-Fe₄N;渗氮后极化曲线钝化区变宽,自腐蚀电流密度减小,耐蚀性提高。氨氮混合气氛渗氮12 h后,渗层的表面硬度为998.0 HV0.05;气氛中N浓度升高,渗氮8 h后CrN含量增加,次要相由氨气渗氮8 h的γ′-Fe₄N变为CrN;随着渗氮时间延长至12 h,渗层的自腐蚀电流密度降低,钝化区略有变宽,耐蚀性略有提高。     

固体渗氮C422钢的显微结构及其缺口敏感性

目的 针对固体渗氮C422(22Cr12NiMoWV)钢,开展渗氮层显微组织结构及其缺口敏感性的研究,为C422汽轮机阀杆服役可靠性评价提供技术支持.方法 采用固体渗氮剂对C422钢表面进行渗氮,通过渗氮层的成分与物相检测、显微组织结构观察、力学性能测试及断口形貌分析,揭示不同温度及时间条件下C422钢渗氮层的显微组织...     

Effect of Al additions in WC-(Cr1−xAlx)N coatings on the corrosion resistance of coated AISI D2 steel in a deaerated 3.5 wt.% NaCl solution

Multilayered WC-(Cr_1−xAl_x)N coatings were deposited on AISI D2 steel using cathodic arc ion plating (CAIP) process. Five kinds of WC-(Cr_1−xAl_x)N coatings were prepared: WC-Cr_0.6Al_0.4N, WC-Cr_0.57Al_0.43N, WC-Cr_0.53Al_0.47N, WC-Cr_0.48Al_0.52N and WC-Cr_0.45Al_0.55N. The Al concentration could be controlled by using evaporation source for Al targets and fixing the evaporation rate of the other metals (WC alloy and Cr). In this study, the corrosion behavior in deaerated 3.5 wt.% NaCl solution was investigated by electrochemical corrosion tests (potentiodynamic polarization test, galvanic corrosion test, electrochemical impedance spectroscopy (EIS)) and surface analyses (glow discharge optical emission spectroscopy, X-ray diffractometry, scratch adhesion test, scanning electron microscopy, electron probe micro-analyzer).

The results of potentiodynamic polarization test showed that the WC-Cr_0.48Al_0.52N coating with lower porosity exhibited the lower corrosion current density. The galvanic corrosion current between the coating and the substrate showed low values. In EIS measurements, the charge transfer resistance (R_ct) value of WC-Cr_0.48Al_0.52N coating only increased with the immersion time, when compared to the other coatings. It can be due to the corrosion products plugging the pores and increasing the pathway resistance.     

离子渗氮温度对Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢渗层组织和性能的影响

采用离子渗氮工艺对一种Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢进行表面改性处理。利用光学显微镜(OM)、X射线衍射(XRD)、电子探针显微分析仪(EPMA)和维氏硬度计对不同离子渗氮温度下渗层的组织和性能进行了研究。结果表明,Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢经430~520 ℃离子渗氮处理10 h后,试样表面均形成一层厚度均匀的渗氮层,表面硬度显著增大。随着离子渗氮温度的升高,渗层厚度增大,520 ℃渗氮时渗层厚度达到78 μm。当渗氮温度为430 ℃时,渗层表面主要由γ_N+CrN+γ′-Fe₄N相组成;当渗氮温度升高至520 ℃时,渗层表面主要由γ′-Fe₄N+CrN+ε-Fe_2-3N相组成。在3种渗氮温度下,渗层中均有CrN析出,导致渗层耐蚀性低于基体组织。     

Growth and characterization of Cr2N/CrN multilayer coatings

A series of monolithic and multilayer coatings of chromium nitride with various compositions and architectures were deposited at low temperatures (<200°C) on silicon substrates using ion-assisted reactive magnetron sputtering. All coatings had a total thickness in the 1.5±0.3 μm range. The multilayer coatings were designed such that their period and CrN fraction varied in the range 30–150 nm and 0.50–0.93, respectively. Real-time in situ ellipsometry was used to monitor and control the deposition process. The deposited coatings were characterized post-deposition using X-ray diffraction (XRD), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). The primary chromium nitride phases (Cr₂N and CrN) in the films were identified using XRD. The chemical composition of selected samples was determined from RBS and XPS measurements. The phase composition of the deposited layers was deduced from the analysis of the SE data. The mechanical properties of the coatings were evaluated using a nanoindenter. The measured hardness values were in excess of 20 GPa. The results of the different characterization and testing techniques were correlated and follow-up work on this project suggested.     

Characterisation and tribological evaluation of nitrogen-containing molybdenum–copper PVD metallic nanocomposite films

This paper reports on the structural, mechanical and tribological properties of molybdenum–copper nanocomposite films ‘doped’ with small amounts of nitrogen, which contain either no nitride phase (i.e. the nitrogen is held in interstitial solid solution, mainly in molybdenum) or small amounts of lower nitrides (i.e. Mo₂N). All films were deposited on Si wafers, AISI M2 high speed steel and AISI 316 stainless steel by reactive sputtering using a hot-filament-enhanced dc unbalanced magnetron system. A systematic approach was adopted to investigate the evolution of metal/metal and ceramic/metal phase combinations with increasing nitrogen content (up to 40 at.% N) in the film. Coating composition and microstructure were determined by cross-sectional TEM, SEM and XPS. XRD was used to identify (where possible) metallic and metal-nitride phases. Mechanical properties such as hardness and elastic modulus were determined by low load Knoop and instrumented Vickers indentation measurements. Reciprocating sliding, micro-abrasion and impact tests were performed to assess tribological performance.

It was found that increasing the nitrogen gas flow rate from 0 to 15 sccm (and therefore nitrogen content in the film from 0 to 24 at.% N), refined significantly the coating microstructure from columnar to a dense and more equiaxed morphology, increasing the hardness whilst maintaining (almost constant) elastic modulus values, close to that of molybdenum metal. Further increases in the nitrogen gas flow rate resulted in films that appeared to contain significant fractions of the Mo₂N ceramic phase. SEM and cross-sectional TEM analyses of the film deposited at a nitrogen flow rate of 20 sccm (containing 36 at.% N) demonstrated a microstructure consisting of 50–100 nm wide columns, which contain small regions of contrast in dark-field images, of the order of 3–5 nm wide. A maximum hardness of 32 GPa and the highest hardness/modulus ratio was however found in the (predominantly metallic) film deposited at a nitrogen gas flow rate of 15 sccm. This film also performed best in both micro-abrasion and impact wear tests; in contrast, the ‘ceramic’ film (deposited at 20 sccm nitrogen flow rate) performed better in reciprocating sliding wear.     

Properties and microstructure of VC/Cr3C2-doped WC/Co cemented carbides

This paper deals with the effects of codoped VC/Cr3C2 and sintering temperature on the magnetic and mechanical properties of ultra-fine grained WC-12%Co alloys. Results show that the synergistic action of doped VC/Cr3C2 in optimal proportion enhances both the hardness and transverse rupture strength (TRS) of the alloys, with more homogeneous microstructure. When the alloy is sintered at 1430℃ and with 0.5% Cr3C2/0.2% VC, the TRS reaches 3786 MPa, the hardness is 91.7 HRA and the grain size srnaller than 0.6 μm. The numerical analyses on grain growth during the sintering process show that both VC precipitating on the WC grain boundary and Cr3C2 dissolving in the Co phase decrease the solid/liquid interfacial energy γ, the process of dissolution and reprecipitation is greatly retarded and the coarsening of WC grains is inhibited.     

N含量对13Cr超级马氏体不锈钢耐蚀性的影响

对13Cr超级马氏体不锈钢进行氮合金化,采用淬火-配分热处理工艺,研究了不同N含量对13Cr钢的微观组织及电化学腐蚀行为的影响。结果表明:随N含量增加,板条马氏体组织表现出明显的细化行为,奥氏体含量增加,且有VN生成,从而防止N与Cr结合生成Cr₂N,促使Cr在材料表面形成以Cr₂O₃为主的致密腐蚀产物膜,提高材料耐蚀性;试验钢表面以局部腐蚀为主,试样表面有点蚀发生。随着N含量的增加,形成腐蚀产物膜的孔隙度减小;表面钝化膜为双电层结构,增加了钝化膜的稳定性,点蚀坑数量明显减少且变小;提高N含量有利于试样耐点蚀性能的改善,0.35%N试验钢表面腐蚀产物附着牢固,平整且致密,晶粒大小均匀,可起到良好的保护作用。     

马氏体不锈钢不同渗氮方法对比试验

采用离子渗氮、液体渗氮及气体渗氮对耐蚀耐热马氏体型热稳定不锈钢1Cr12Ni2WMoVNb进行表面改性,研究了不同渗氮方法下不锈钢的硬度、组织形貌、物相变化及脆性,并对3种渗氮方法下不锈钢的耐蚀性及耐高温磨损性能进行了比较。结果表明:3种渗氮方法均可大幅度提高不锈钢的表面硬度,且不同渗氮处理后不锈钢的渗层组织结构大致相同,但表面物相有所差异,离子渗氮后的表面物相主要为Fe₄N及少量CrN相,液体渗氮后为Fe₃O₄及ε相,气体渗氮后为Fe₃O₄、Fe₄N及少量ε相;3种渗氮方法均可提高不锈钢的耐磨损性能,特别是在500~600 ℃下的高温耐磨性得到了大幅提升,但不锈钢渗氮后的耐蚀性均有所降低。     

Microstructure and Properties of WB2/Cr Multilayer Films with Different Bilayer Numbers Deposited by Magnetron Sputtering

The influence of the bilayer number on the microstructure, mechanical properties, adhesion strength and tribological behaviors of the WB₂/Cr multilayer films was systematically investigated in the present study. Five groups of WB₂/Cr films with the same modulation ratio were synthesized by magnetron sputtering technique. The crystalline structure of the films was determined by X-ray diffraction. The morphologies and the microstructure of the films were observed by scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Furthermore, Nano indenter, scratch tester and ball-on-disc tribometer were used to evaluate the mechanical and tribological properties. As bilayer numbers varied from 5 to 40, the hardness increased first and then decreased with the maximum hardness of 33.9 GPa when the bilayer number is 30. The H/E^* and H³/E^*2 values calculated to evaluate the fracture toughness showed the similar changing trend with hardness. The adhesion strength reached the maximum of 67 N when the bilayer number is 30. The surface roughness and friction coefficient decreased with increasing bilayer number. The wear mechanism was also investigated, and the results suggested that the multilayer film with bilayer number of 30 exhibited the best wear resistance (1.78 × 10^-7 mm³/Nm), benefiting from the contribution of high hardness, fracture toughness and adhesion strength.     

A study of martensitic stainless steel AISI 420 modified using plasma nitriding

We studied martensitic stainless steel AISI 420, modified using glow discharge plasma nitriding. Microhardness measurements, X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to investigate the surface microhardness, crystal structure, microstructure and chemical bonding in the modified surfaces. High surface microhardness (1300 HV) over a case depth of about 60 microns is obtained. Glancing incidence X-ray diffraction (GIXRD) indicates the presence of a predominantly Fe₃N phase with dispersed CrN within 2–5 microns on the surface. In addition, using Bragg–Brentano geometry, we measured the presence of a minor phase of Fe₄N in the case depth. SEM confirms that the microstructure within 2–5 microns of the surface is different from that of the bulk. XPS shows nitride phase formation on the surface. AES measured over the cross-section of the case depth shows a direct relation of the increased surface microhardness to the high nitrogen content.     

HiPIMS技术低温沉积CrN薄膜结构及性能研究

目的 实现性能优异的CrN薄膜在低温沉积条件下的可控制备。方法 利用高功率脉冲磁控溅射技术(HiPIMS),通过调控脉冲放电波形(可调控脉冲放电模式-MPP、双极脉冲放电模式-BPH)制备了系列低温沉积工艺下的CrN薄膜。选用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、原子力显微镜(AFM)、纳米硬度测试仪及球盘摩擦试验仪表征了CrN薄膜的组织结构、微观形貌、摩擦学性能。结果 相对于传统的直流磁控溅射技术(DCMS),HiPIMS具备高溅射材料离化率,偏压作用下产生的荷能离子对成膜表面的持续轰击作用,有效提升了低温沉积条件下成膜粒子的表面迁移能,显著抑制了贯穿柱状晶的连续生长,达到了细化晶粒,改善薄膜致密性的目的。BPH模式下沉积的薄膜表面光滑致密,表面粗糙度可达4.6 nm。细晶强化作用及薄膜致密性提升使得BPH模式下制备的CrN薄膜硬度最高,可达(15.6±0.8) GPa。此外,BPH模式下沉积的CrN薄膜具备最为优异的摩擦学性能,摩擦系数低(~0.3)且运行平稳,并且在高速及重载作用下,仍能表现出优异的摩擦磨损性能。结论 HiPIMS技术中的双极脉冲放电模式可显著提升沉积粒子表面迁移能,提升CrN薄膜沉积反应动力学过程,实现低温条件下性能优异的CrN薄膜的可控制备。     

镍基合金激光熔覆-离子渗硫复合改性层组织性能

利用激光熔覆和离子渗硫技术在45钢表面制备复合改性层,采用SEM,EPMA,XRD等手段对比研究激光熔覆层和渗硫层的组织形貌、成分分布及相组成;并测试渗硫前后涂层的耐磨性和耐蚀性.结果表明,镍基合金涂层主要由γ-（Fe,Ni）,Fe_0.64Ni_0.36,M₂₃C₆,WC,M₇C₃和Fe₂B等物相组成,显微硬度达到740 HV0.2.渗硫后在激光熔覆层表面形成了以FeS为主的渗硫层,表面疏松多孔,由微纳米级的尖岛状颗粒堆砌而成.与熔覆层相比,复合改性层的摩擦系数和磨损量都显著降低,减摩和耐磨效果明显.渗硫后镍基合金激光熔覆层自腐蚀电位下降,腐蚀电流密度增大,耐蚀性略微降低.     

GNiCr40Al3Ti合金表面Cr-DLC、CrAlN和CrN薄膜在去离子水环境中的摩擦磨损性能

目的 在去离子水环境中,研究GNiCr40Al3Ti合金表面制备的铬掺杂类金刚石(Cr-DLC)、氮化铬铝(CrAlN)和氮化铬(CrN)等薄膜的摩擦磨损性能。方法 在GNiCr40Al3Ti合金表面采用离子源辅助非平衡磁控溅射制备Cr-DLC薄膜,采用多弧离子镀技术制备CrAlN薄膜和CrN薄膜。利用冷场发射扫描电镜、拉曼光谱仪和X射线衍射仪,对薄膜的微观结构和形貌进行分析。利用显微硬度计、摩擦磨损试验机、白光干涉扫描轮廓仪等,对薄膜的硬度、摩擦磨损性能、磨痕二维轮廓等进行研究。结果 在10 h连续的去离子水环境摩擦过程中,CrN薄膜的平均摩擦系数最低,仅为0.17,比GNiCr40Al3Ti合金的摩擦系数降低了54%。与GNiCr40Al3Ti合金相比,其表面制备的Cr-DLC、CrAlN和CrN薄膜在去离子水环境摩擦条件下都减小了磨损体积,其中,CrN薄膜表现出最好的耐磨性,磨损体积为0.017 mm³,仅为GNiCr40Al3Ti合金磨损体积的0.18%。Cr-DLC薄膜与CrAlN薄膜的耐磨性不及CrN薄膜,主要是由薄膜的微观结构造成的,Cr-DLC薄膜的柱状疏松结构造成薄膜过早的被磨穿,CrAlN薄膜中存在的Cr相引起薄膜硬度降低,从而降低了抗剪切的能力。结论 在去离子水环境中,CrN薄膜具有最低的摩擦系数和最佳的耐磨性。     

调制周期对磁控溅射WB2/CrN多层薄膜力学性能的影响

目的研究调制周期对磁控溅射WB_2/CrN多层膜结构及性能的影响。方法通过双靶直流磁控溅射法,在硅片、石英玻璃片及不锈钢上,制备Al B_2型WB_2薄膜与CrN薄膜及其多层复合薄膜,采用X射线衍射及扫描电子显微镜对其相结构及形貌进行观察和分析,使用维氏显微硬度仪及划痕仪对多层膜的硬度及膜基结合力进行研究。结果磁控溅射WB_2/CrN多层薄膜呈现出柱状生长趋势,且层状结构明显,仅当调制周期大于317 nm时,多层膜中才出现WB_2晶体的衍射峰。结论多层膜中的WB_2薄膜在本实验条件下的临界结晶厚度大于150 nm。随着调制周期的减小,CrN层生长取向发生由(200)晶面向多晶面的转变,WB_2层生长取向由(101)晶面向(001)晶面转变。多层膜硬度随调制周期的减小大体呈下降趋势,在调制周期为317 nm时达到最大值。结合力变化趋势与硬度相反,CrN层及多层界面有助于复合薄膜膜基结合强度的提高。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。